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Open AccessEditor’s ChoiceEditorial
Viticulture and Winemaking under Climate Change
Agronomy 2019, 9(12), 783; https://doi.org/10.3390/agronomy9120783 - 21 Nov 2019
Cited by 1
Abstract
The importance of viticulture and the winemaking socio-economic sector is acknowledged worldwide. The most renowned winemaking regions show very specific environmental characteristics, where climate usually plays a central role. Considering the strong influence of weather and climatic factors on grapevine yields and berry [...] Read more.
The importance of viticulture and the winemaking socio-economic sector is acknowledged worldwide. The most renowned winemaking regions show very specific environmental characteristics, where climate usually plays a central role. Considering the strong influence of weather and climatic factors on grapevine yields and berry quality attributes, climate change may indeed significantly impact this crop. Recent-past trends already point to a pronounced increase in the growing season mean temperatures, as well as changes in the precipitation regimes, which has been influencing wine typicity across some of the most renowned winemaking regions worldwide. Moreover, several climate scenarios give evidence of enhanced stress conditions for grapevine growth until the end of the century. Although grapevines have a high resilience, the clear evidence for significant climate change in the upcoming decades urges adaptation and mitigation measures to be taken by the sector stakeholders. To provide hints on the abovementioned issues, we have edited a special issue entitled: “Viticulture and Winemaking under Climate Change”. Contributions from different fields were considered, including crop and climate modeling, and potential adaptation measures against these threats. The current special issue allows the expansion of the scientific knowledge of these particular fields of research, also providing a path for future research. Full article
Open AccessEditor’s ChoiceEditorial
Crop Evapotranspiration
Agronomy 2019, 9(10), 614; https://doi.org/10.3390/agronomy9100614 - 05 Oct 2019
Cited by 2
Abstract
Evapotranspiration (ET) is one of the largest components of the water cycle, and accurately measuring and modeling ET is critical for improving and optimizing agricultural water management. However, parameterizing ET in croplands can be challenging due to the wide variety of irrigation strategies [...] Read more.
Evapotranspiration (ET) is one of the largest components of the water cycle, and accurately measuring and modeling ET is critical for improving and optimizing agricultural water management. However, parameterizing ET in croplands can be challenging due to the wide variety of irrigation strategies and techniques, crop varieties, and management approaches that employ traditional tabular ET and make crop coefficient approaches obsolete. This special issue of Agronomy highlights nine approaches to improve the measurement and modeling of ET across a range of spatial and temporal resolutions and differing environments that address some of the challenges encountered. Full article
(This article belongs to the Special Issue Crop Evapotranspiration)
Open AccessEditor’s ChoiceEditorial
Deep Learning Techniques for Agronomy Applications
Agronomy 2019, 9(3), 142; https://doi.org/10.3390/agronomy9030142 - 20 Mar 2019
Cited by 7
Abstract
This editorial introduces the Special Issue, entitled “Deep Learning (DL) Techniques for Agronomy Applications”, of Agronomy. Topics covered in this issue include three main parts: (I) DL-based image recognition techniques for agronomy applications, (II) DL-based time series data analysis techniques for agronomy applications, [...] Read more.
This editorial introduces the Special Issue, entitled “Deep Learning (DL) Techniques for Agronomy Applications”, of Agronomy. Topics covered in this issue include three main parts: (I) DL-based image recognition techniques for agronomy applications, (II) DL-based time series data analysis techniques for agronomy applications, and (III) behavior and strategy analysis for agronomy applications. Three papers on DL-based image recognition techniques for agronomy applications are as follows: (1) “Automatic segmentation and counting of aphid nymphs on leaves using convolutional neural networks,” by Chen et al.; (2) “Estimating body condition score in dairy cows from depth images using convolutional neural networks, transfer learning, and model ensembling techniques,” by Alvarez et al.; and (3) “Development of a mushroom growth measurement system applying deep learning for image recognition,” by Lu et al. One paper on DL-based time series data analysis techniques for agronomy applications is as follows: “LSTM neural network based forecasting model for wheat production in Pakistan,” by Haider et al. One paper on behavior and strategy analysis for agronomy applications is as follows: “Research into the E-learning model of agriculture technology companies: analysis by deep learning,” by Lin et al. Full article
(This article belongs to the Special Issue Deep Learning Techniques for Agronomy Applications)
Open AccessEditor’s ChoiceEditorial
Biotic and Abiotic Stress Responses in Crop Plants
Agronomy 2018, 8(11), 267; https://doi.org/10.3390/agronomy8110267 - 19 Nov 2018
Cited by 12
Abstract
Agricultural productivity depends on increasingly extreme weather phenomena, and the use of germplasm that has to be continuously improved by plant breeders to become tolerant to various biotic and abiotic stresses. Molecular plant biologists try to understand the mechanisms associated with stress responses [...] Read more.
Agricultural productivity depends on increasingly extreme weather phenomena, and the use of germplasm that has to be continuously improved by plant breeders to become tolerant to various biotic and abiotic stresses. Molecular plant biologists try to understand the mechanisms associated with stress responses and provide knowledge that could be used in breeding programs. To provide a partial overview about our current understanding about molecular and physiological stress responses, and how this knowledge can be used in agriculture, we have edited a special issue on “Biotic and Abiotic Stress Responses in Crop Plants”. Contributions are from different fields including heat stress responses, stress responses during drought and salinity, as well as during flooding, and resistance and susceptibility to pathogenetic stresses and about the role of plant functional metabolites in biotic stress responses. Future research demand in particular areas of crop stress physiology is discussed, as well as the importance of translational research and investigations directly in elite crop plants and in the genetic resources available for breeding. Full article
Open AccessEditor’s ChoiceEditorial
Starch Biosynthesis in Crop Plants
Agronomy 2018, 8(6), 81; https://doi.org/10.3390/agronomy8060081 - 25 May 2018
Cited by 1
Abstract
Starch is a water-insoluble polyglucan synthesized inside the plastids of plant tissues to provide a store of carbohydrate. Starch harvested from plant storage organs has probably represented the major source of calories for the human diet since before the dawn of civilization. Following [...] Read more.
Starch is a water-insoluble polyglucan synthesized inside the plastids of plant tissues to provide a store of carbohydrate. Starch harvested from plant storage organs has probably represented the major source of calories for the human diet since before the dawn of civilization. Following the advent of agriculture and the building of complex societies, humans have maintained their dependence on high-yielding domesticated starch-forming crops such as cereals to meet food demands, livestock production, and many non-food applications. The top three crops in terms of acreage are cereals, grown primarily for the harvestable storage starch in the endosperm, although many starchy tuberous crops also provide an important source of calories for various communities around the world. Despite conservation in the core structure of the starch granule, starches from different botanical sources show a high degree of variability, which is exploited in many food and non-food applications. Understanding the factors underpinning starch production and its final structure are of critical importance in guiding future crop improvement endeavours. This special issue contains reviews on these topics and is intended to be a useful resource for researchers involved in improvement of starch-storing crops. Full article
(This article belongs to the Special Issue Starch Biosynthesis in Crop Plants)
Open AccessEditor’s ChoiceEditorial
Transdisciplinary Graduate Training in Predictive Plant Phenomics
Agronomy 2018, 8(5), 73; https://doi.org/10.3390/agronomy8050073 - 16 May 2018
Cited by 1
Abstract
Novel methods to increase crop productivity are required to meet anticipated demands for food, feed, fiber, and fuel. It is becoming feasible to use modern sensors and data analysis techniques for predicting plant growth and productivity based on genomic, phenotypic, and environmental data. [...] Read more.
Novel methods to increase crop productivity are required to meet anticipated demands for food, feed, fiber, and fuel. It is becoming feasible to use modern sensors and data analysis techniques for predicting plant growth and productivity based on genomic, phenotypic, and environmental data. To design and construct crops that deliver desired traits requires trained personnel with scientific and engineering expertise as well as a variety of “soft” skills. To address these needs at Iowa State University, we developed a graduate specialization called “Predictive Plant Phenomics” (P3). Although some of our experiences may be unique, many of the specialization’s principles are likely to be broadly applicable to others interested in developing graduate training programs in plant phenomics. P3 involves transdisciplinary training and activities designed to develop communication, teambuilding, and management skills. To support students in this demanding and unique intellectual environment, we established a two-week boot camp before their first semester and founded a community of practice to support students throughout their graduate careers. Assessments show that P3 students understand the transdisciplinary training concepts, have formed a beneficial and supportive community, and interact with diverse faculty outside of their home departments. To learn more about the P3 program, visit www.predictivephenomicsinplants.iastate.edu. Full article
(This article belongs to the Special Issue Precision Phenotyping in Plant Breeding)
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Research

Jump to: Editorial, Review

Open AccessEditor’s ChoiceArticle
Effects of Root Temperature on the Plant Growth and Food Quality of Chinese Broccoli (Brassica oleracea var. alboglabra Bailey)
Agronomy 2020, 10(5), 702; https://doi.org/10.3390/agronomy10050702 - 14 May 2020
Abstract
Root temperature has long been considered an essential environmental factor influencing the plant’s physiology. However, little is known about the effect of root temperature on the quality of the food produced by the plant, especially that of horticultural crops. To fill this gap, [...] Read more.
Root temperature has long been considered an essential environmental factor influencing the plant’s physiology. However, little is known about the effect of root temperature on the quality of the food produced by the plant, especially that of horticultural crops. To fill this gap, two independent root cooling experiments (15 °C vs. 20 °C and 10 °C vs. 20 °C) were conducted in autumn 2017 and spring 2018 in hydroponics with Chinese broccoli (Brassica oleracea var. alboglabra Bailey) under greenhouse conditions. The aim was to investigate the effect of root temperature on plant growth (biomass, height, yield) and food quality (soluble sugars, total chlorophyll, starch, minerals, glucosinolates). A negative impact on shoot growth parameters (yield, shoot biomass) was detected by lowering the root temperature to 10 °C. Chinese broccoli showed no response to 15 °C root temperature, except for an increase in root biomass. Low root temperature was in general associated with a higher concentration of soluble sugars and total chlorophyll, but lower mineral levels in stems and leaves. Ten individual glucosinolates were identified in the stems and leaves, including six aliphatic and four indolic glucosinolates. Increased levels of neoglucobrassicin in leaves tracked root cooling more closely in both experiments. Reduction of root temperature by cooling could be a potential method to improve certain quality characters of Chinese broccoli, including sugar and glucosinolate levels, although at the expense of shoot biomass. Full article
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Open AccessEditor’s ChoiceArticle
The Impact of Herbicide Application and Defoliation on Barley Grass (Hordeum murinum subsp. glaucum) Management in Mixed Pasture Legumes
Agronomy 2020, 10(5), 671; https://doi.org/10.3390/agronomy10050671 - 11 May 2020
Abstract
Barley grass (Hordeum murinum subsp. glaucum.) is an annual weed associated with grain revenue loss and sheep carcass damage in southern Australia. Increasing herbicide resistance led to a recent investigation into effective integrated weed management strategies for barley grass in southern [...] Read more.
Barley grass (Hordeum murinum subsp. glaucum.) is an annual weed associated with grain revenue loss and sheep carcass damage in southern Australia. Increasing herbicide resistance led to a recent investigation into effective integrated weed management strategies for barley grass in southern Australia. Field studies in Wagga Wagga, New South Wales (NSW) during 2016 and 2017 examined the effect of post-emergent herbicide applications and strategic defoliation by mowing on barley grass survival and seed production in a mixed legume pasture. Statistically significant differences between herbicide-only treatments in both years showed propaquizafop to be more than 98% effective in reducing barley grass survival and seed production. Paraquat was not effective in controlling barley grass (58% efficacy), but led to a 36% and 63.5% decrease in clover and other weed biomass, respectively, after 12 months and increased lucerne biomass by over three-fold after 24 months. A single repeated mowing treatment resulted in a 46% decline in barley grass seedling emergence after 12 months and, when integrated with herbicide applications, reduced other weed biomass after 24 months by 95%. Resistance to acetyl-CoA carboxylase (ACCase)-inhibiting herbicides observed in local barley grass populations led to additional and more focused investigation comparing the efficacy of other pre- and post-emergent herbicides for barley grass management in legume pastures. Haloxyfop-R + simazine or paraquat, applied at early tillering stage, were most efficacious in reducing barley grass survival and fecundity. Impact of defoliation timing and frequency on barley grass seedlings was also evaluated at various population densities, highlighting the efficacy of repeated post-inflorescence defoliations in reducing plant survival and seed production. Results highlight the importance of optimal environmental conditions and application timing in achieving efficacious control of barley grass and improving pasture growth and biomass accumulation. Full article
(This article belongs to the Special Issue Herbicide Resistance in Weed Management)
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Open AccessEditor’s ChoiceArticle
Effect of Row Spacing, Sowing Density, and Harvest Time on Floret Yield and Yield Components of Two Safflower Cultivars Grown in Southwestern Germany
Agronomy 2020, 10(5), 664; https://doi.org/10.3390/agronomy10050664 - 08 May 2020
Cited by 1
Abstract
The current demand for safflower florets (Carthamus tinctorius L.) in the food-coloring industry, especially in Europe, is rising. The present production, mainly located in China, is not sufficient. Unlike for the production of seeds, there are currently no recommendations for the cultivation [...] Read more.
The current demand for safflower florets (Carthamus tinctorius L.) in the food-coloring industry, especially in Europe, is rising. The present production, mainly located in China, is not sufficient. Unlike for the production of seeds, there are currently no recommendations for the cultivation of safflower for floret production in Germany. Therefore, field experiments were conducted at the experimental station Ihinger Hof, Southwestern Germany, in 2017 and 2018. The aim was to evaluate yield and yield parameters, such as number of capitula, floret yield, and carthamidin content for (i) two cultivars grown with (ii) two row spacing (12 and 33 cm) using (iii) two sowing densities (40 and 75 plants m−2), and (iv) five harvest dates. Results showed that lower sowing densities resulted in a significantly larger number of branches and capitula per plant and higher yields of florets and carthamidin. Harvesting two to three weeks after flowering resulted in the significantly highest floret and carthamidin yields. More capitula per plant, higher carthamidin contents, and higher floret and carthamidin yields were obtained with the Chinese cultivar. In general, yields of flowering florets (2.30–468.96 kg ha−1), carthamidin contents (2.53–8.29%), and carthamidin yields (0.04–37.86 kg ha−1) were comparable to or higher than in other studies. In conclusion, this study showed that safflower has great potential for the production of florets in Southwest Germany, for the food-color industry. Full article
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Open AccessEditor’s ChoiceArticle
Exploring the Genetic Architecture of Root-Related Traits in Mediterranean Bread Wheat Landraces by Genome-Wide Association Analysis
Agronomy 2020, 10(5), 613; https://doi.org/10.3390/agronomy10050613 - 25 Apr 2020
Abstract
Background: Roots are essential for drought adaptation because of their involvement in water and nutrient uptake. As the study of the root system architecture (RSA) is costly and time-consuming, it is not generally considered in breeding programs. Thus, the identification of molecular markers [...] Read more.
Background: Roots are essential for drought adaptation because of their involvement in water and nutrient uptake. As the study of the root system architecture (RSA) is costly and time-consuming, it is not generally considered in breeding programs. Thus, the identification of molecular markers linked to RSA traits is of special interest to the breeding community. The reported correlation between the RSA of seedlings and adult plants simplifies its assessment. Methods: In this study, a panel of 170 bread wheat landraces from 24 Mediterranean countries was used to identify molecular markers associated with the seminal RSA and related traits: seminal root angle, total root number, root dry weight, seed weight and shoot length, and grain yield (GY). Results: A genome-wide association study identified 135 marker-trait associations explaining 6% to 15% of the phenotypic variances for root related traits and 112 for GY. Fifteen QTL hotspots were identified as the most important for controlling root trait variation and were shown to include 31 candidate genes related to RSA traits, seed size, root development, and abiotic stress tolerance (mainly drought). Co-location for root related traits and GY was found in 17 genome regions. In addition, only four out of the fifteen QTL hotspots were reported previously. Conclusions: The variability found in the Mediterranean wheat landraces is a valuable source of root traits to introgress into adapted phenotypes through marker-assisted breeding. The study reveals new loci affecting root development in wheat. Full article
(This article belongs to the Special Issue Molecular Marker Technology for Crop Improvement)
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Open AccessEditor’s ChoiceArticle
Deep Phenotyping of Yield-Related Traits in Wheat
Agronomy 2020, 10(4), 603; https://doi.org/10.3390/agronomy10040603 - 23 Apr 2020
Abstract
The complex formation of grain yield (GY) is related to multiple dry matter (DM) traits; however, due to their time-consuming determination, they are not readily accessible. In winter wheat (Triticum aestivum L.), both agronomic treatments and genotypic variation influence GY in interaction [...] Read more.
The complex formation of grain yield (GY) is related to multiple dry matter (DM) traits; however, due to their time-consuming determination, they are not readily accessible. In winter wheat (Triticum aestivum L.), both agronomic treatments and genotypic variation influence GY in interaction with the environment. Spectral proximal sensing is promising for high-throughput non-destructive phenotyping but was rarely evaluated systematically for dissecting yield-related variation in DM traits. Aiming at a temporal, spectral and organ-level optimization, 48 vegetation indices were evaluated in a high-yielding environment in 10 growth stages for the estimation of 31 previously compared traits related to GY formation—influenced by sowing time, fungicide, N fertilization, and cultivar. A quantitative index ranking was evaluated to assess the stage-independent index suitability. GY showed close linear relationships with spectral vegetation indices across and within agronomic treatments (R2 = 0.47–0.67 ***). Water band indices, followed by red edge-based indices, best used at milk or early dough ripeness, were better suited than the widely used normalized difference vegetation index (NDVI). Index rankings for many organ-level DM traits were comparable, but the relationships were often less close. Among yield components, grain number per spike (R2 = 0.24–0.34 ***) and spike density (R2 = 0.23–0.46 ***) were moderately estimated. GY was mainly estimated by detecting total DM rather than the harvest index. Across agronomic treatments and cultivars, seasonal index rankings were the most stable for GY and total DM, whereas traits related to DM allocation and translocation demanded specific index selection. The results suggest using indices with water bands, near infrared/red edge and visible light bands to increase the accuracy of in-season spectral phenotyping for GY, contributing organ-level traits, and yield components, respectively. Full article
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Open AccessEditor’s ChoiceArticle
Optimizing Training Population Size and Content to Improve Prediction Accuracy of FHB-Related Traits in Wheat
Agronomy 2020, 10(4), 543; https://doi.org/10.3390/agronomy10040543 - 09 Apr 2020
Abstract
Genomic selection combines phenotypic and molecular marker data from a training population to predict the genotypic values of untested lines. It can improve breeding efficiency as large pools of untested lines can be evaluated for selection. Training population (TP) composition is one of [...] Read more.
Genomic selection combines phenotypic and molecular marker data from a training population to predict the genotypic values of untested lines. It can improve breeding efficiency as large pools of untested lines can be evaluated for selection. Training population (TP) composition is one of the most important factors affecting the accuracy of genomic prediction. The University of Minnesota wheat breeding program implements genomic selection at the F5 stage for Fusarium head blight (FHB) resistance. This study used field data for FHB resistance in wheat (Triticum aestivum L.) to investigate the use of small-size TPs designed with and without stratified sampling for three FHB traits in three different F5 populations (TP17, TP18, and TP19). We also compared the accuracies of these two TP design methods with the accuracy obtained from a large size TP. Lastly, we evaluated the impact on trait predictions when the parents of F5 lines were included in the TP. We found that the small size TP selected randomly, without stratification, had the lowest predictive ability across the three F5 populations and across the three traits. This trend was statistically significant (p = 0.05) for all three traits in TP17 and two traits in TP18. Designing a small-size TP by stratified sampling led to a higher accuracy than a large-size TP in most traits across TP18 and TP19; this is because stratified sampling allowed the selection of a small set of closely related lines. We also observed that the addition of parental lines to the TP and evaluating the TP in two replications led to an increase in predictive abilities in most cases. Full article
(This article belongs to the Special Issue Breeding Healthy Cereals: Genetic Improvement of Fusarium Resistance)
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Open AccessEditor’s ChoiceArticle
Harvest Season and Genotype Affect Head Quality and Shelf-Life of Ready-to-Use Broccoli
Agronomy 2020, 10(4), 527; https://doi.org/10.3390/agronomy10040527 - 07 Apr 2020
Abstract
Pre-harvest climatic conditions and genotype may have important effects on head quality and post-harvest performance of fresh-cut broccoli. The present work evaluates the effect of the growing cycle (summer–autumn (SA), winter (W), winter–spring (WS), and spring (S)) and genotype on qualitative (dry matter, [...] Read more.
Pre-harvest climatic conditions and genotype may have important effects on head quality and post-harvest performance of fresh-cut broccoli. The present work evaluates the effect of the growing cycle (summer–autumn (SA), winter (W), winter–spring (WS), and spring (S)) and genotype on qualitative (dry matter, concentration of chlorophylls, carotenoids, and color) and antioxidative (ascorbic acid, dehydroascorbic acid, total phenol concentrations, and antioxidant capacity) traits of broccoli heads and minimally processed florets. The WS raw product showed the best color indices (L* = 38.6, C* = 9.3 and h° = 123.8) as well as the highest chlorophyll (0.23 µg mg−1 fresh weight) but the lowest total phenol concentration (5.5 µg mg−1 dry weight - DW), whereas the ascorbic acid level (2.3 µg mg−1 DW) was comparable to or lower than that the other growing cycles. The WS florets confirmed their best visual quality, even showing an improved total phenol level after 14 days of cold storage. The climatic conditions experienced by broccoli plants grown in SA, W, and S periods were stressful as they resulted in a slight reduction in the visual quality of the heads, though only the SA florets showed a distinctive decay during storage. The lower post-harvest performance of SA grown broccoli was confirmed in all the tested cultivars, despite ‘Naxos’ seeming more tolerant. On the contrary, the greatest content of ascorbic acid (3.2 µg mg−1 DW) in the W heads and of phenols (11.1 µg mg−1 DW) in S heads was maintained during storage, thus preserving floret color. Full article
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Open AccessEditor’s ChoiceArticle
Impact and Control of Powdery Mildew on Irrigated Soybean Varieties Grown in Southeast Australia
Agronomy 2020, 10(4), 514; https://doi.org/10.3390/agronomy10040514 - 03 Apr 2020
Abstract
Powdery mildew—caused by the fungus Erisyphe diffusa (syn. Microsphaera diffusa)—was first observed in commercial soybean crops in southern New South Wales (NSW), Australia, in 2011. Its detection raised concerns that soybean production might be constrained if the severity of the disease reached [...] Read more.
Powdery mildew—caused by the fungus Erisyphe diffusa (syn. Microsphaera diffusa)—was first observed in commercial soybean crops in southern New South Wales (NSW), Australia, in 2011. Its detection raised concerns that soybean production might be constrained if the severity of the disease reached the levels observed in northern Australia. Field experiments were conducted over four consecutive seasons to examine the response of three soybean cultivars—Djakal, SnowyA and the breeding line N005A-80—to two fungicides and two fungicide application regimes. The cultivar Djakal was identified as having a high level of resistance to powdery mildew. The severity of infection symptoms varied between seasons. The most severe symptoms were observed during the 2014–2015 season which resulted in the largest grain yield reduction of 20% for the cultivar SnowyA. All fungicide treatments provided a significant reduction in the severity of symptoms, with the split application of tebuconazole and both the single and split applications of tebuconazole + prothioconazole providing the most effective control of the disease. Few other grain yield effects were found, even when strong disease control was achieved. This was a suspected result of the consistent late-in-the-season onset of the disease. Few differences were observed among the treatments in terms of lodging severity, date of physiological maturity, or grain oil and protein concentrations. It was concluded that both fungicides provided effective control of powdery mildew. However, when disease pressure is low, application might not be warranted in southern NSW. Full article
(This article belongs to the Section Pest and Disease Management)
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Open AccessEditor’s ChoiceArticle
The Microbiology of Hemp Retting in a Controlled Environment: Steering the Hemp Microbiome towards More Consistent Fiber Production
Agronomy 2020, 10(4), 492; https://doi.org/10.3390/agronomy10040492 - 01 Apr 2020
Abstract
Industrial hemp (Cannabis sativa L.) production is increasing dramatically in the US due to recent changes which lift restrictions on the growth and sale of hemp products; however, due to the decades-long prohibition of hemp, there is a lack of current research [...] Read more.
Industrial hemp (Cannabis sativa L.) production is increasing dramatically in the US due to recent changes which lift restrictions on the growth and sale of hemp products; however, due to the decades-long prohibition of hemp, there is a lack of current research with respect to varieties and best agricultural practices for the many uses of this versatile crop. Natural fiber production relies on retting, a microbially-mediated process necessary for the separation of fibers from the plant which can occur unevenly in the field environment and result in inconsistent fiber quality and lower processing efficiency. In this study, the microbiome of hemp stalks is investigated throughout the retting process using 16S rRNA gene amplicon sequencing using the Illumina MiSeq platform. Field retting conditions were simulated in a controlled greenhouse environment in order to determine the effects of different moisture levels and soil contact on the retting process. Samples were taken over six time points, reflecting the community of freshly cut stalks to optimally-retted material, and finally over-retted material showing degraded fibers. The results show a very consistent population throughout retting, dominated primarily by Proteobacteria, but showing an increase in the abundance of the Bacteroidetes, namely Chryseobacterium, in time points corresponding to optimally-retted and over-retted stalks in treatments receiving higher moisture levels, but not in the low-moisture treatment. Soil application did not appear to influence the microbial community throughout retting, indicating a resilient population present in and on the hemp stalks at harvest. Full article
(This article belongs to the Special Issue Drivers of Microbial Diversity and Roles in Agroecosystems)
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Open AccessEditor’s ChoiceArticle
Performance of a Set of Eggplant (Solanum melongena) Lines With Introgressions From Its Wild Relative S. incanum Under Open Field and Screenhouse Conditions and Detection of QTLs
Agronomy 2020, 10(4), 467; https://doi.org/10.3390/agronomy10040467 - 27 Mar 2020
Abstract
Introgression lines (ILs) of eggplant (Solanum melongena) represent a resource of high value for breeding and the genetic analysis of important traits. We have conducted a phenotypic evaluation in two environments (open field and screenhouse) of 16 ILs from the first [...] Read more.
Introgression lines (ILs) of eggplant (Solanum melongena) represent a resource of high value for breeding and the genetic analysis of important traits. We have conducted a phenotypic evaluation in two environments (open field and screenhouse) of 16 ILs from the first set of eggplant ILs developed so far. Each of the ILs carries a single marker-defined chromosomal segment from the wild eggplant relative S. incanum (accession MM577) in the genetic background of S. melongena (accession AN-S-26). Seventeen agronomic traits were scored to test the performance of ILs compared to the recurrent parent and of identifying QTLs for the investigated traits. Significant morphological differences were found between parents, and the hybrid was heterotic for vigour-related traits. Despite the presence of large introgressed fragments from a wild exotic parent, individual ILs did not display differences with respect to the recipient parent for most traits, although significant genotype × environment interaction (G × E ) was detected for most traits. Heritability values for the agronomic traits were generally low to moderate. A total of ten stable QTLs scattered across seven chromosomes was detected. For five QTLs, the S. incanum introgression was associated with higher mean values for plant- and flower-related traits, including vigour prickliness and stigma length. For one flower- and four fruit-related-trait QTLs, including flower peduncle and fruit pedicel lengths and fruit weight, the S. incanum introgression was associated with lower mean values for fruit-related traits. Evidence of synteny to other previously reported in eggplant populations was found for three of the fruit-related QTLs. The other seven stable QTLs are new, demonstrating that eggplant ILs are of great interest for eggplant breeding under different environments. Full article
(This article belongs to the Special Issue Genotypic and Environmental Interactions for the Improvement of Crops)
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Open AccessEditor’s ChoiceArticle
Pre- and Postharvest Factors Control the Disease Incidence of Superficial Scald in the New Fire Blight Tolerant Apple Variety “Ladina”
Agronomy 2020, 10(4), 464; https://doi.org/10.3390/agronomy10040464 - 27 Mar 2020
Abstract
Superficial scald is a physiological disorder that develops during cold storage affecting apples and causes substantial market losses. Malus × domestica cv. Ladina, a new scab resistant and fire blight tolerant variety, commercialized in 2012, shows a physiological disorder similar to superficial scald [...] Read more.
Superficial scald is a physiological disorder that develops during cold storage affecting apples and causes substantial market losses. Malus × domestica cv. Ladina, a new scab resistant and fire blight tolerant variety, commercialized in 2012, shows a physiological disorder similar to superficial scald after storage. Here, we used different pre- and postharvest approaches to characterize the occurrence of these superficial scald symptoms in Malus × domestica cv. Ladina. Over a period of seven years, fruits from multiple orchards were stored for five to seven months and the occurrence of superficial scald was assessed in fruits after cold storage and controlled atmosphere (CA) storage. Apples picked at different stages of ripeness within the same year differed in superficial scald development. Additionally, superficial scald differed significantly between years and locations, strongly suggesting that maturity at harvest, weather during the growing season, and orchard management play important roles in scald occurrence. Treatment with 1-methylcyclopropene (1-MCP) after harvest, and storage in a dynamically controlled atmosphere (DCA) significantly reduced the occurrence of superficial scald, whereas storage under ultralow oxygen concentrations (ULO) showed mild but not significant effects. Low calcium concentrations in the fruit flesh and peel were associated with stronger superficial scald occurrence. Full article
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Open AccessEditor’s ChoiceArticle
Appraisal of Biodegradable Mulching Films and Vegetal-Derived Biostimulant Application as Eco-Sustainable Practices for Enhancing Lettuce Crop Performance and Nutritive Value
Agronomy 2020, 10(3), 427; https://doi.org/10.3390/agronomy10030427 - 20 Mar 2020
Abstract
Scientists, extensions specialists, and growers are seeking sustainable agricultural practices that are able to cope with these objectives in order to ensure global food security and minimize environmental damage. The use of mulching films and plant biostimulants in agriculture seems to be a [...] Read more.
Scientists, extensions specialists, and growers are seeking sustainable agricultural practices that are able to cope with these objectives in order to ensure global food security and minimize environmental damage. The use of mulching films and plant biostimulants in agriculture seems to be a valid solution for tackling these rising concerns. A greenhouse experiment was conducted in order to elucidate the morpho-physiological and nutritive characteristics of lettuce (Lactuca sativa L.) in response to foliar application of a tropical plant extract (PE) biostimulant and the use of plastic mulches. Two biodegradable mulch treatments (Mater-Bi® 1 and Mater-Bi® 2) were compared to black polyethylene (LDPE) and bare soil. Biodegradable mulch film Mater-Bi® 1 produced a comparable marketable fresh yield to the commercial standard polyethylene (LDPE), whereas Mater-Bi® 2 exhibited the highest crop productivity. When averaged over biostimulant application, lettuce plants grown with biodegradable film Mater-Bi® 2 exhibited superior quality traits in terms of K, Ca, total ascorbic acid, and carotenoids content. The combination of film mulching (LDPE, Mater-Bi® 1 or Mater-Bi® 2) with the tropical plant extract biostimulant exhibited a positive and significant synergistic effect (+30%) on yield. The PE-biostimulant induced higher values of SPAD index and total chlorophyll content when compared to untreated greenhouse lettuce. The mineral content of leaf tissues was greater by 10% and 17% (for P and Ca, respectively) when compared to the untreated lettuce (no PE application). Nitrate content was significantly reduced by 23% in greenhouse lettuce plants receiving PE as compared to the untreated control. The positive effect of Mater-Bi® 2 film on the ascorbic acid content has also been highlighted when combined with the biostimulant application, where a major amplification of total ascorbic acid (+168%) was recorded in comparison to the untreated lettuce. Overall, our work can assist leafy vegetables growers in adopting good agricultural practices, such as biodegradable plastic mulches and vegetal-derived biostimulants, to improve the sustainability of greenhouse production. Full article
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Open AccessEditor’s ChoiceArticle
Pear Flower Cluster Quantification Using RGB Drone Imagery
Agronomy 2020, 10(3), 407; https://doi.org/10.3390/agronomy10030407 - 17 Mar 2020
Abstract
High quality fruit production requires the regulation of the crop load on fruit trees by reducing the number of flowers and fruitlets early in the growing season, if the bearing is too high. Several automated flower cluster quantification methods based on proximal and [...] Read more.
High quality fruit production requires the regulation of the crop load on fruit trees by reducing the number of flowers and fruitlets early in the growing season, if the bearing is too high. Several automated flower cluster quantification methods based on proximal and remote imagery methods have been proposed to estimate flower cluster numbers, but their overall performance is still far from satisfactory. For other methods, the performance of the method to estimate flower clusters within a tree is unknown since they were only tested on images from one perspective. One of the main reported bottlenecks is the presence of occluded flowers due to limitations of the top-view perspective of the platform-sensor combinations. In order to tackle this problem, the multi-view perspective from the Red–Green–Blue (RGB) colored dense point clouds retrieved from drone imagery are compared and evaluated against the field-based flower cluster number per tree. Experimental results obtained on a dataset of two pear tree orchards (N = 144) demonstrate that our 3D object-based method, a combination of pixel-based classification with the stochastic gradient boosting algorithm and density-based clustering (DBSCAN), significantly outperforms the state-of-the-art in flower cluster estimations from the 2D top-view (R2 = 0.53), with R2 > 0.7 and RRMSE < 15%. Full article
(This article belongs to the Special Issue Application of Remote Sensing in Orchard Management)
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Open AccessEditor’s ChoiceArticle
Screening of Nematicides against the Lotus Root Nematode, Hirschmanniella diversa Sher (Tylenchida: Pratylenchidae) and the Efficacy of a Selected Nematicide under Lotus Micro-Field Conditions
Agronomy 2020, 10(3), 373; https://doi.org/10.3390/agronomy10030373 - 08 Mar 2020
Abstract
In Japan, Hirschmanniella diversa is an important pest in lotus cultivation in paddy fields and only lime nitrogen is registered for its control. Therefore, additional nematicides are required to control the nematode. The objective of this study was to screen for an effective [...] Read more.
In Japan, Hirschmanniella diversa is an important pest in lotus cultivation in paddy fields and only lime nitrogen is registered for its control. Therefore, additional nematicides are required to control the nematode. The objective of this study was to screen for an effective nematicide. Fourth-stage juveniles and adults of H. diversa sampled from a lotus field were tested in in vitro solution experiments against 37 pesticides that are registered for the pest control of crops in Japan. Carbamate-based benfuracarb, organophosphate-based fenthion, nereistoxin-based cartap hydrochloride and cyanamide showed nematicidal effects against H. diversa. Benfuracarb at 1 μg/mL showed a nematostatic effect on H. diversa in an agar plate assay. Further, H. diversa treated with benfuracarb did not resume activity 7 days post nematicide treatment when transferred to distilled water. Benfuracarb was tested in micro-field experiments, in which H. diversa density and lotus tuber damage levels were monitored. Results showed that benfuracarb reduced H. diversa densities in the roots during the cultivation period in 2012 and consistently reduced damage levels during a five year study period. Thus, benfuracarb is recommended as an effective nematicide to be used for H. diversa control in lotus cultivation. Full article
(This article belongs to the Special Issue Effects of Nematodes on Crops)
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Open AccessEditor’s ChoiceArticle
Impact of Growth Stage and Biomass Fractions on Cannabinoid Content and Yield of Different Hemp (Cannabis sativa L.) Genotypes
Agronomy 2020, 10(3), 372; https://doi.org/10.3390/agronomy10030372 - 08 Mar 2020
Cited by 1
Abstract
The medicinal use of cannabinoids renewed the interest in industrial hemp (Cannabis sativa L.). The aim of this study was to evaluate the impact of growth stage and biomass fractions of seven industrial hemp genotypes. The study focused on biomass yield, content [...] Read more.
The medicinal use of cannabinoids renewed the interest in industrial hemp (Cannabis sativa L.). The aim of this study was to evaluate the impact of growth stage and biomass fractions of seven industrial hemp genotypes. The study focused on biomass yield, content of cannabidiolic acid/cannabidiol (CBDA/CBD), cannabigerolic acid/cannabigerol (CBGA/CBG), and tetrahydrocannabinolic acid (THCA). The experiment was conducted in 2017 and 2018. The biomass samples were taken at the vegetative (S1), bud (S2), full-flowering (S3) and seed maturity stage (S4). Plants were fractionated into inflorescence, upper and lower leaves. The average inflorescence dry yield of genotypes Futura75, Fédora17, Félina32 and Ferimon ranged between 257.28 g m−2 to 442.00 g m−2, resulting in a maximum yield of CBDA at S4, with 4568.26 mg m−2, 6011.20 mg m−2, 4975.60 mg m−2 and 1929.60 mg m−2, respectively. CBGA was exclusively found in genotype Santhica27, with a maximum CBGA yield of 5721.77 mg m−2 in inflorescence at growth stage S4 and a dry weight yield of 408.99 g m−2. Although these industrial hemp genotypes are mainly cultivated for fibre and seed production, however, cannabinoids offer an additional value. For an optimized harvest result, yield of extractable material and overall yield of cannabinoids must be considered. Full article
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Open AccessEditor’s ChoiceArticle
Ozone Induced Loss of Seed Protein Accumulation Is Larger in Soybean than in Wheat and Rice
Agronomy 2020, 10(3), 357; https://doi.org/10.3390/agronomy10030357 - 04 Mar 2020
Abstract
We investigated the effects of ozone (O3) on seed protein accumulation in soybean, rice, and wheat based on existing literature. We identified 30, 10, and 32 datasets meeting the requirements for soybean, rice, and wheat, respectively. Data for each crop were [...] Read more.
We investigated the effects of ozone (O3) on seed protein accumulation in soybean, rice, and wheat based on existing literature. We identified 30, 10, and 32 datasets meeting the requirements for soybean, rice, and wheat, respectively. Data for each crop were combined in response regressions for seed protein concentration, seed protein yield, and seed yield. Although seed yield in rice was less sensitive to O3 than in wheat, there was a significant positive effect of O3 on the seed protein concentration of the same magnitude in both crops. Soybean, an N-fixing high-protein crop, responded differently. Even though the effect on seed yield was similar to wheat, there was no indication of any effect of O3 on seed protein concentration in soybean. The negative influence of O3 on seed protein yield was statistically significant for soybean and wheat. The effect was larger for soybean (slope of response function: −0.58% per ppb O3) than for wheat (slope: −0.44% per ppb) and especially compared to rice (slope: −0.08% per ppb). The different response of protein concentration in soybean, likely to be associated with adverse O3 effects on N fixation, has large implications for global protein production because of the much higher absolute protein concentration in soybean. Full article
(This article belongs to the Special Issue Agronomy and Agroecology in a Polluted Atmosphere)
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Open AccessEditor’s ChoiceArticle
Biochar, Vermicompost, and Compost as Soil Organic Amendments: Influence on Growth Parameters, Nitrate and Chlorophyll Content of Swiss Chard (Beta vulgaris L. var. cycla)
Agronomy 2020, 10(3), 346; https://doi.org/10.3390/agronomy10030346 - 03 Mar 2020
Abstract
Soil addition with organic amendments is an issue that receives growing attention in the agricultural sector. However, the effects of such materials on plant growth and crop yield are highly variable in the literature. This study aims to evaluate the influence of soil [...] Read more.
Soil addition with organic amendments is an issue that receives growing attention in the agricultural sector. However, the effects of such materials on plant growth and crop yield are highly variable in the literature. This study aims to evaluate the influence of soil addition with biochar (from vine pruning residues), vermicompost (from cattle manure), and three different composts (from olive pomace or cattle anaerobic digestate), on the quali-quantitative response of Swiss chard (Beta vulgaris L. var. cycla) grown in pots. The organic amendments were applied to the soil in two doses to provide 140 and 280 kg N ha−1, respectively. Two growth cycles were considered, and, at each leaf cut, plants were analyzed for growth parameters (height, fresh weight, leaf number, and leaf area) and qualitative characteristics (nitrogen, nitrate, and pigment leaf content). Swiss chard responded positively to organic amendment and, particularly when the soil was treated with compost from animal wastes, higher plant growth and pigment leaf content were observed. Nitrate leaf content was always well below the NO3 thresholds established by the European Commission Regulations. Biochar application did not show a positive effect on the quali-quantitative characteristics of Swiss chard, likely due to benefits that may be achieved over time. Full article
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Open AccessEditor’s ChoiceArticle
Divergent Genomic Selection for Herbage Accumulation and Days-To-Heading in Perennial Ryegrass
Agronomy 2020, 10(3), 340; https://doi.org/10.3390/agronomy10030340 - 02 Mar 2020
Abstract
Increasing the rate of genetic gain for dry matter (DM) yield in perennial ryegrass (Lolium perenne L.), which is a key source of nutrition for ruminants in temperate environments, is an important goal for breeders. Genomic selection (GS) is a strategy used [...] Read more.
Increasing the rate of genetic gain for dry matter (DM) yield in perennial ryegrass (Lolium perenne L.), which is a key source of nutrition for ruminants in temperate environments, is an important goal for breeders. Genomic selection (GS) is a strategy used to improve genetic gain by using molecular marker information to predict breeding values in selection candidates. An empirical assessment of GS for herbage accumulation (HA; proxy for DM yield) and days-to-heading (DTH) was completed by using existing genomic prediction models to conduct one cycle of divergent GS in four selection populations (Pop I G1 and G3; Pop III G1 and G3), for each trait. G1 populations were the offspring of the training set and G3 populations were two generations further on from that. The HA of the High GEBV selection group (SG) progenies, averaged across all four populations, was 28% higher (p < 0.05) than Low GEBV SGs when assessed in the target environment, while it did not differ significantly in a second environment. Divergence was greater in Pop I (43%–65%) than Pop III (10%–16%) and the selection response was higher in G1 than in G3. Divergent GS for DTH also produced significant (p < 0.05) differences between High and Low GEBV SGs in G1 populations (+6.3 to 9.1 days; 31%–61%) and smaller, non-significant (p > 0.05) responses in G3. This study shows that genomic prediction models, trained from a small, composite reference set, can be used to improve traits with contrasting genetic architectures in perennial ryegrass. The results highlight the importance of target environment selection for training models, as well as the influence of relatedness between the training set and selection populations. Full article
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Open AccessFeature PaperEditor’s ChoiceArticle
Absence of Yield Reduction after Controlled Water Stress during Prehaverst Period in Table OliveTrees
Agronomy 2020, 10(2), 258; https://doi.org/10.3390/agronomy10020258 - 11 Feb 2020
Cited by 1
Abstract
Deficit irrigation scheduling is becoming increasingly important under commercial conditions. Water status measurement is a useful tool in these conditions. However, the information about water stress levels for olive trees is scarce. The aim of this experiment was to evaluate the effect on [...] Read more.
Deficit irrigation scheduling is becoming increasingly important under commercial conditions. Water status measurement is a useful tool in these conditions. However, the information about water stress levels for olive trees is scarce. The aim of this experiment was to evaluate the effect on yield of a moderate controlled water stress level at the end of the irrigation season. The experiment was conducted in the experimental farm of La Hampa (Coria del Río, Seville, Spain) during three years. A completely randomized block design was performed using three different irrigation treatments. Deficit irrigation was applied several (4 or 2) weeks before harvest. Irrigation was controlled using the midday stem water potential, with a threshold value of −2 MPa and compared with a full irrigated treatment. This water stress did not reduced gas exchange during the deficit period. The effect on yield was not significant in any of the three seasons. In the high-fruit load season, fruit volume was slightly affected (around 10%), but this was not significant at harvest. Results suggest an early affection of fruit growth with water stress, but with a slow rate of decrease. Moderate water stress could be useful for the management of deficit irrigation in table olive trees. Full article
(This article belongs to the Special Issue Optimizing Plant Water Use Efficiency for a Sustainable Environment)
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Open AccessEditor’s ChoiceArticle
RNA-Binding Proteins as Targets to Improve Salt Stress Tolerance in Crops
Agronomy 2020, 10(2), 250; https://doi.org/10.3390/agronomy10020250 - 08 Feb 2020
Abstract
Salt stress drastically reduce crop productivity. In order to identify genes that could improve crop salt tolerance, we randomly expressed a cDNA library of the halotolerant sugar beet in a sodium-sensitive yeast strain. We identified six sugar beet genes coding for RNA binding [...] Read more.
Salt stress drastically reduce crop productivity. In order to identify genes that could improve crop salt tolerance, we randomly expressed a cDNA library of the halotolerant sugar beet in a sodium-sensitive yeast strain. We identified six sugar beet genes coding for RNA binding proteins (RBP) able to increase the yeast Na+-tolerance. Two of these genes, named Beta vulgaris Salt Tolerant 3 (BvSATO3) and BvU2AF35b, participate in RNA splicing. The other four BvSATO genes (BvSATO1, BvSATO2, BvSATO4 and BvSATO6) are putatively involved in other processes of RNA metabolism. BvU2AF35b improved the growth of a wild type yeast strain under salt stress, and also in mutant backgrounds with impaired splicing, thus confirming that splicing is a target of salt toxicity. To validate the yeast approach, we characterized BvSATO1 in sugar beet and Arabidopsis. BvSATO1 expression was repressed by salt treatment in sugar beet, suggesting that this gene could be a target of salt toxicity. Expression of BvSATO1 in Arabidopsis increased the plant salt tolerance. Our results suggest that not only RNA splicing, but RNA metabolic processes such as such as RNA stability or nonsense-mediated mRNA decay may also be affected by salt stress and could be biotechnological targets for crop improvement. Full article
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Open AccessEditor’s ChoiceArticle
Effect of Agronomic Practices on Yield and Quality of Borage at Harvest and During Storage as Minimally-Processed Produce
Agronomy 2020, 10(2), 242; https://doi.org/10.3390/agronomy10020242 - 06 Feb 2020
Cited by 2
Abstract
Borage (Borago officinalis L.) is a hairy pubescent herb known throughout the world for its folk medicinal uses, as well as for many culinary uses. There is still little information on the cultivation needs of this species, especially for its use as [...] Read more.
Borage (Borago officinalis L.) is a hairy pubescent herb known throughout the world for its folk medicinal uses, as well as for many culinary uses. There is still little information on the cultivation needs of this species, especially for its use as vegetable crop and as fresh-cut produce. Hence, the aim of the research was to study the effects of agronomic practices on yield and quality of borage and on the storability as minimally-processed product. Two experiments were carried out in two consecutive years in order to evaluate the effect of plant density and plastic mulching on yield and quality of two borage accessions at harvest and during storage as minimally-processed produce for 14 days at 4 °C. The highest plant density (8 plants m2) determined the highest yield of plants and minimally-processed leaves with good quality retention during storage. Mulching had a positive effect on earliness, yield, and shelf life of minimally-processed leaves but also increased nitrate accumulation and reduced ascorbic acid content. Borage plants with lower spacing grown on mulched soil showed the best yield of plants and minimally-processed leaves irrespective of the borage accession tested. Borage plants can be used to produce minimally-processed entire leaves with good quality characteristics. Full article
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Open AccessEditor’s ChoiceArticle
Plant- and Seaweed-Based Extracts Increase Yield but Differentially Modulate Nutritional Quality of Greenhouse Spinach through Biostimulant Action
Agronomy 2018, 8(7), 126; https://doi.org/10.3390/agronomy8070126 - 21 Jul 2018
Cited by 32
Abstract
Plant biostimulants (PBs) such as protein hydrolysates and seaweed extracts are attracting the increasing interest of scientists and vegetable growers for their potential toenhance yield and nutritional quality. The current study assessed crop productivity, leaf colorimetry, mineral profile and bioactive compounds of greenhouse [...] Read more.
Plant biostimulants (PBs) such as protein hydrolysates and seaweed extracts are attracting the increasing interest of scientists and vegetable growers for their potential toenhance yield and nutritional quality. The current study assessed crop productivity, leaf colorimetry, mineral profile and bioactive compounds of greenhouse spinach in response to the foliar application of three PBs: legume-derived protein hydrolysate [PH], extract of seaweed Ecklonia maxima or mixture of vegetal oils, herbal and seaweed Ascophyllum nodosum extracts. Plants were PB-treated at a rate of 3 mL L−1 four times during their growth cycle at weekly intervals. Foliar PB applications enhanced fresh yield, dry biomass and leaf area of spinach in comparison with untreated plants. Improved yield performance with PB applications was associated with improved chlorophyll biosynthesis (higher SPAD index). The three PB treatments elicited an increase in bioactive compounds (total phenols and ascorbic acid), thus raised the functional quality of spinach. The application of PH enhanced K and Mg concentrations and did not result in increased nitrate accumulation as observed with the other two PB treatments. Our findings can assist vegetable farmers and the agro-food industry in adopting innovative and sustainable tools such as PB for complementing a high yield with premium quality. Full article
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Open AccessEditor’s ChoiceArticle
CO2-Induced Changes in Wheat Grain Composition: Meta-Analysis and Response Functions
Agronomy 2017, 7(2), 32; https://doi.org/10.3390/agronomy7020032 - 25 Apr 2017
Cited by 33
Abstract
Elevated carbon dioxide (eCO2) stimulates wheat grain yield, but simultaneously reduces protein/nitrogen (N) concentration. Also, other essential nutrients are subject to change. This study is a synthesis of wheat experiments with eCO2, estimating the effects on N, minerals (B, [...] Read more.
Elevated carbon dioxide (eCO2) stimulates wheat grain yield, but simultaneously reduces protein/nitrogen (N) concentration. Also, other essential nutrients are subject to change. This study is a synthesis of wheat experiments with eCO2, estimating the effects on N, minerals (B, Ca, Cd, Fe, K, Mg, Mn, Na, P, S, Zn), and starch. The analysis was performed by (i) deriving response functions to assess the gradual change in element concentration with increasing CO2 concentration, (ii) meta-analysis to test the average magnitude and significance of observed effects, and (iii) relating CO2 effects on minerals to effects on N and grain yield. Responses ranged from zero to strong negative effects of eCO2 on mineral concentration, with the largest reductions for the nutritionally important elements of N, Fe, S, Zn, and Mg. Together with the positive but small and non-significant effect on starch concentration, the large variation in effects suggests that CO2-induced responses cannot be explained only by a simple dilution model. To explain the observed pattern, uptake and transport mechanisms may have to be considered, along with the link of different elements to N uptake. Our study shows that eCO2 has a significant effect on wheat grain stoichiometry, with implications for human nutrition in a world of rising CO2. Full article
(This article belongs to the Special Issue Impact of CO2 Concentration and Enrichment on Crops)
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Review

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Open AccessEditor’s ChoiceReview
Interaction between Humic Substances and Plant Hormones for Phosphorous Acquisition
Agronomy 2020, 10(5), 640; https://doi.org/10.3390/agronomy10050640 - 01 May 2020
Abstract
Phosphorus (P) deficiency is a major constraint in highly weathered tropical soils. Although phosphorous rock reserves may last for several hundred years, there exists an urgent need to research efficient P management for sustainable agriculture. Plant hormones play an important role in regulating [...] Read more.
Phosphorus (P) deficiency is a major constraint in highly weathered tropical soils. Although phosphorous rock reserves may last for several hundred years, there exists an urgent need to research efficient P management for sustainable agriculture. Plant hormones play an important role in regulating plant growth, development, and reproduction. Humic substances (HS) are not only considered an essential component of soil organic carbon (SOC), but also well known as a biostimulant which can perform phytohormone-like activities to induce nutrient uptake. This review paper presents an overview of the scientific outputs in the relationship between HS and plant hormones. Special attention will be paid to the interaction between HS and plant hormones for nutrient uptake under P-deficient conditions. Full article
(This article belongs to the Special Issue Hormone Signaling and Regulation in Cultivated Plants)
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Open AccessFeature PaperEditor’s ChoiceReview
Chilling and Heat Requirements of Temperate Stone Fruit Trees (Prunus sp.)
Agronomy 2020, 10(3), 409; https://doi.org/10.3390/agronomy10030409 - 18 Mar 2020
Cited by 1
Abstract
Stone fruit trees of genus Prunus, like other temperate woody species, need to accumulate a cultivar-specific amount of chilling during endodormancy, and of heat during ecodormancy to flower properly in spring. Knowing the requirements of a cultivar can be critical in determining [...] Read more.
Stone fruit trees of genus Prunus, like other temperate woody species, need to accumulate a cultivar-specific amount of chilling during endodormancy, and of heat during ecodormancy to flower properly in spring. Knowing the requirements of a cultivar can be critical in determining if it can be adapted to a particular area. Growers can use this information to anticipate the future performance of their orchards and the adaptation of new cultivars to their region. In this work, the available information on chilling- and heat-requirements of almond, apricot, plum, peach, and sweet cherry cultivars is reviewed. We pay special attention to the method used for the determination of breaking dormancy, the method used to quantify chilling and heat temperatures, and the place where experiments were conducted. The results reveal different gaps in the information available, both in the lack of information of cultivars with unknown requirements and in the methodologies used. The main emerging challenges are the standardization of the conditions of each methodology and the search for biological markers for dormancy. These will help to deal with the growing number of new cultivars and the reduction of winter cold in many areas due to global warming. Full article
(This article belongs to the Special Issue Fruit and Nut Tree Phenology in a Warming World)
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Open AccessEditor’s ChoiceReview
Is Phytomelatonin a New Plant Hormone?
Agronomy 2020, 10(1), 95; https://doi.org/10.3390/agronomy10010095 - 09 Jan 2020
Cited by 7
Abstract
Melatonin (N-acetyl-5-methoxytryptamine) is of particular importance as a chronobiological hormone in mammals, acting as a signal of darkness that provides information to the brain and peripheral organs. It is an endogenous synchronizer for both endocrine (i.e., via neurotransmitter release) and other [...] Read more.
Melatonin (N-acetyl-5-methoxytryptamine) is of particular importance as a chronobiological hormone in mammals, acting as a signal of darkness that provides information to the brain and peripheral organs. It is an endogenous synchronizer for both endocrine (i.e., via neurotransmitter release) and other physiological rhythms. In this work we will try to add to the series of scientific events and discoveries made in plants that, surprisingly, confirm the great similarity of action of melatonin in animals and plants. The most relevant milestones on the 25 years of phytomelatonin studies are presented, from its discovery in 1995 to the discovery of its receptor in plants in 2018, suggesting it should be regarded as a new plant hormone. Full article
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Open AccessFeature PaperEditor’s ChoiceReview
Relationship of Melatonin and Salicylic Acid in Biotic/Abiotic Plant Stress Responses
Agronomy 2018, 8(4), 33; https://doi.org/10.3390/agronomy8040033 - 22 Mar 2018
Cited by 29
Abstract
Melatonin (N-acetyl-5-methoxytryptamine) was discovered in plants in 1995, while salicylic acid was the name given to the active ingredient of willow in 1838. From a physiological point of view, these two molecules present in plants have never been compared, even though [...] Read more.
Melatonin (N-acetyl-5-methoxytryptamine) was discovered in plants in 1995, while salicylic acid was the name given to the active ingredient of willow in 1838. From a physiological point of view, these two molecules present in plants have never been compared, even though they have a great number of similarities, as we shall see in this work. Both molecules have biosynthesis pathways that share a common precursor and both play a relevant role in the physiology of plants, especially in aspects related to biotic and abiotic stress. They have also been described as biostimulants of photosynthetic processes and productivity enhancers in agricultural crops. We review the coincident aspects of both molecules, and propose an action model, by which the relationship between these molecules and other agents and plant hormones can be studied. Full article
(This article belongs to the Special Issue Salicylic Acid in Plant Stress Responses)
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Open AccessEditor’s ChoiceReview
Climate Change Trends and Impacts on California Agriculture: A Detailed Review
Agronomy 2018, 8(3), 25; https://doi.org/10.3390/agronomy8030025 - 26 Feb 2018
Cited by 31
Abstract
California is a global leader in the agricultural sector and produces more than 400 types of commodities. The state produces over a third of the country’s vegetables and two-thirds of its fruits and nuts. Despite being highly productive, current and future climate change [...] Read more.
California is a global leader in the agricultural sector and produces more than 400 types of commodities. The state produces over a third of the country’s vegetables and two-thirds of its fruits and nuts. Despite being highly productive, current and future climate change poses many challenges to the agricultural sector. This paper provides a summary of the current state of knowledge on historical and future trends in climate and their impacts on California agriculture. We present a synthesis of climate change impacts on California agriculture in the context of: (1) historic trends and projected changes in temperature, precipitation, snowpack, heat waves, drought, and flood events; and (2) consequent impacts on crop yields, chill hours, pests and diseases, and agricultural vulnerability to climate risks. Finally, we highlight important findings and directions for future research and implementation. The detailed review presented in this paper provides sufficient evidence that the climate in California has changed significantly and is expected to continue changing in the future, and justifies the urgency and importance of enhancing the adaptive capacity of agriculture and reducing vulnerability to climate change. Since agriculture in California is very diverse and each crop responds to climate differently, climate adaptation research should be locally focused along with effective stakeholder engagement and systematic outreach efforts for effective adoption and implementation. The expected readership of this paper includes local stakeholders, researchers, state and national agencies, and international communities interested in learning about climate change and California’s agriculture. Full article
(This article belongs to the Special Issue Climate Change in Agriculture: Impacts and Adaptations)
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Open AccessEditor’s ChoiceReview
Understanding Starch Structure: Recent Progress
Agronomy 2017, 7(3), 56; https://doi.org/10.3390/agronomy7030056 - 25 Aug 2017
Cited by 102
Abstract
Starch is a major food supply for humanity. It is produced in seeds, rhizomes, roots and tubers in the form of semi-crystalline granules with unique properties for each plant. Though the size and morphology of the granules is specific for each plant species, [...] Read more.
Starch is a major food supply for humanity. It is produced in seeds, rhizomes, roots and tubers in the form of semi-crystalline granules with unique properties for each plant. Though the size and morphology of the granules is specific for each plant species, their internal structures have remarkably similar architecture, consisting of growth rings, blocklets, and crystalline and amorphous lamellae. The basic components of starch granules are two polyglucans, namely amylose and amylopectin. The molecular structure of amylose is comparatively simple as it consists of glucose residues connected through α-(1,4)-linkages to long chains with a few α-(1,6)-branches. Amylopectin, which is the major component, has the same basic structure, but it has considerably shorter chains and a lot of α-(1,6)-branches. This results in a very complex, three-dimensional structure, the nature of which remains uncertain. Several models of the amylopectin structure have been suggested through the years, and in this review two models are described, namely the “cluster model” and the “building block backbone model”. The structure of the starch granules is discussed in light of both models. Full article
(This article belongs to the Special Issue Starch Biosynthesis in Crop Plants)
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Open AccessFeature PaperEditor’s ChoiceReview
Plant Responses to Salt Stress: Adaptive Mechanisms
Agronomy 2017, 7(1), 18; https://doi.org/10.3390/agronomy7010018 - 23 Feb 2017
Cited by 215
Abstract
This review deals with the adaptive mechanisms that plants can implement to cope with the challenge of salt stress. Plants tolerant to NaCl implement a series of adaptations to acclimate to salinity, including morphological, physiological and biochemical changes. These changes include increases in [...] Read more.
This review deals with the adaptive mechanisms that plants can implement to cope with the challenge of salt stress. Plants tolerant to NaCl implement a series of adaptations to acclimate to salinity, including morphological, physiological and biochemical changes. These changes include increases in the root/canopy ratio and in the chlorophyll content in addition to changes in the leaf anatomy that ultimately lead to preventing leaf ion toxicity, thus maintaining the water status in order to limit water loss and protect the photosynthesis process. Furthermore, we deal with the effect of salt stress on photosynthesis and chlorophyll fluorescence and some of the mechanisms thought to protect the photosynthetic machinery, including the xanthophyll cycle, photorespiration pathway, and water-water cycle. Finally, we also provide an updated discussion on salt-induced oxidative stress at the subcellular level and its effect on the antioxidant machinery in both salt-tolerant and salt-sensitive plants. The aim is to extend our understanding of how salinity may affect the physiological characteristics of plants. Full article
(This article belongs to the Special Issue Further Metabolism in Plant System)
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