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Agronomy, Volume 9, Issue 10 (October 2019)

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Cover Story (view full-size image) Unmanned Aircraft System (UAS) technology has allowed for a more integrated and optimized approach [...] Read more.
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Open AccessArticle
Identification of New Hosts of Pseudocercospora fijiensis Suggests Innovative Pest Management Programs for Black Sigatoka Disease in Banana Plantations
Agronomy 2019, 9(10), 666; https://doi.org/10.3390/agronomy9100666 - 22 Oct 2019
Abstract
Black Sigatoka is the main constraint to banana production worldwide, and epidemic outbreaks are continuously causing huge losses. Successful management of diseases requires a profound knowledge of the epidemiological factors that influence disease dynamics. Information regarding alternative hosts of Pseudocercospora fijiensis, the [...] Read more.
Black Sigatoka is the main constraint to banana production worldwide, and epidemic outbreaks are continuously causing huge losses. Successful management of diseases requires a profound knowledge of the epidemiological factors that influence disease dynamics. Information regarding alternative hosts of Pseudocercospora fijiensis, the causal agent, is still very scarce. To date, only Heliconia psittacorum has been reported as an alternative plant host, and we hypothesized that other plants can house P. fijiensis. In the present report, ten plant species with suspicious leaf spots were collected inside and around commercial banana crops in Mexico. Diagnostic PCR gave positive amplification for six of these plant species, and DNA sequencing confirmed the presence of the pathogen in four. This is the first report of the presence of P. fijiensis in unrelated plants and it represents a breakthrough in the current knowledge of black Sigatoka. This finding is very important given the polycyclic nature of this disease whose successful management requires the control of initial inoculum to minimize epidemic outbreaks. The results presented herein can be used to introduce innovations in integrated black Sigatoka management programs to reduce initial inoculum, and help the international initiative to reduce the use of fungicides in banana production. Full article
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Open AccessArticle
Optimizing Genetic Parameters of CSM-CERES Wheat and CSM-CERES Maize for Durum Wheat, Common Wheat, and Maize in Italy
Agronomy 2019, 9(10), 665; https://doi.org/10.3390/agronomy9100665 - 22 Oct 2019
Abstract
The expected increase in population and the pressure posed by climate change on agricultural production require the assessment of future yield levels and the evaluation of the most suitable management options to minimize climate risk and promote sustainable agricultural production. Crop simulation models [...] Read more.
The expected increase in population and the pressure posed by climate change on agricultural production require the assessment of future yield levels and the evaluation of the most suitable management options to minimize climate risk and promote sustainable agricultural production. Crop simulation models are widely applied tools to predict crop development and production under different management practices and environmental conditions. The aim of this study was to parameterize CSM-CERES-Wheat and CSM-CERES-Maize models, implemented in the Decision Support System for Agrotechnology Transfer (DSSAT) software, to predict phenology and grain yield of durum wheat, common wheat, and maize in different Italian environments. A 10-year (2001–2010) dataset was used to optimize the genetic parameters for selected varieties of each species and to evaluate the models considering several statistical indexes. The generalized likelihood uncertainty estimation method, and trial and error approach were used to optimize the cultivar-specific parameters of these models. Results show good model performances in reproducing crop phenology and yield for the analyzed crops, especially with the parameters optimized with the trial and error procedure. Highly significant (p ≤ 0.001) correlations between observed and simulated data were found for both anthesis and yield in model calibration and evaluation (p ≤ 0.01 for grain yield of maize in model evaluation). Root mean square error (RMSE) values range from six to nine days for anthesis and from 1.1 to 1.7 t ha−1 for crop yield and index of agreement (d-index) from 0.96 to 0.98 for anthesis and from 0.8 to 0.87 for crop yield. The set of genetic parameters obtained for durum wheat, common wheat, and maize may be applied in further analyses at field, regional, and national scales to guide operational (farmers), strategic, and tactical (policy makers) decisions. Full article
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Open AccessArticle
Sustainable Intensification of Sorghum and Pearl Millet Production by Seed Priming, Seed Treatment and Fertilizer Microdosing under Different Rainfall Regimes in Mali
Agronomy 2019, 9(10), 664; https://doi.org/10.3390/agronomy9100664 - 22 Oct 2019
Abstract
Sorghum and pearl millet are the most important stable crops in the drylands of West Africa. This four-year study based on two experiments assessed different low-cost methods for intensification of sorghum and millet production under contrasting rainfall conditions in Mali. Experiment 1 assessed [...] Read more.
Sorghum and pearl millet are the most important stable crops in the drylands of West Africa. This four-year study based on two experiments assessed different low-cost methods for intensification of sorghum and millet production under contrasting rainfall conditions in Mali. Experiment 1 assessed the microdosing rates 0, 0.2, 0.4, 0.6 and 0.8 g NPK hill−1 combined with seed priming across four locations in Mali while Experiment 2 assessed the cumulative effects of the seed priming, seed treatment with pesticide, microdosing and urea top dressing. In central Mali, there was a clear effect of seed priming while there was no such effect in southern Mali with better rainfall conditions. In central Mali, the microdosing rate of fertilizer of 0.4 g NPK hill−1 (4 kg NPK ha−1) performed best, while in southern Mali the microdosing rate of 0.8 g NPK hill−1 (20 kg NPK ha−1) gave the best result. Experiment 2 showed that there was a clear effect of top dressing of 1 g urea hill−1 (25 kg urea ha−1) in southern Mali while no such effect was apparent in central Mali. In general, there was a better response to microdosing in sorghum than in pearl millet. A decision tree for crop and fertilizer management in Mali was developed, taking into consideration rainfall, crop choice, use of seed priming and microdosing rates. Full article
(This article belongs to the Section Soil and Plant Nutrition)
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Open AccessArticle
Retrieval of Evapotranspiration from Sentinel-2: Comparison of Vegetation Indices, Semi-Empirical Models and SNAP Biophysical Processor Approach
Agronomy 2019, 9(10), 663; https://doi.org/10.3390/agronomy9100663 - 22 Oct 2019
Abstract
Remote sensing evapotranspiration estimation over agricultural areas is increasingly used for irrigation management during the crop growing cycle. Different methodologies based on remote sensing have emerged for the leaf area index (LAI) and the canopy chlorophyll content (CCC) estimation, essential biophysical parameters for [...] Read more.
Remote sensing evapotranspiration estimation over agricultural areas is increasingly used for irrigation management during the crop growing cycle. Different methodologies based on remote sensing have emerged for the leaf area index (LAI) and the canopy chlorophyll content (CCC) estimation, essential biophysical parameters for crop evapotranspiration monitoring. Using Sentinel-2 (S2) spectral information, this study performed a comparative analysis of empirical (vegetation indices), semi-empirical (CLAIR model with fixed and calibrated extinction coefficient) and artificial neural network S2 products derived from the Sentinel Application Platform Software (SNAP) biophysical processor (ANN S2 products) approaches for the estimation of LAI and CCC. Four independent in situ collected datasets of LAI and CCC, obtained with standard instruments (LAI-2000, SPAD) and a smartphone application (PocketLAI), were used. The ANN S2 products present good statistics for LAI (R2 > 0.70, root mean square error (RMSE) < 0.86) and CCC (R2 > 0.75, RMSE < 0.68 g/m2) retrievals. The normalized Sentinel-2 LAI index (SeLI) is the index that presents good statistics in each dataset (R2 > 0.71, RMSE < 0.78) and for the CCC, the ratio red-edge chlorophyll index (CIred-edge) (R2 > 0.67, RMSE < 0.62 g/m2). Both indices use bands located in the red-edge zone, highlighting the importance of this region. The LAI CLAIR model with a fixed extinction coefficient value produces a R2 > 0.63 and a RMSE < 1.47 and calibrating this coefficient for each study area only improves the statistics in two areas (RMSE ≈ 0.70). Finally, this study analyzed the influence of the LAI parameter estimated with the different methodologies in the calculation of crop potential evapotranspiration (ETc) with the adapted Penman–Monteith (FAO-56 PM), using a multi-temporal dataset. The results were compared with ETc estimated as the product of the reference evapotranspiration (ETo) and on the crop coefficient (Kc) derived from FAO table values. In the absence of independent reference ET data, the estimated ETc with the LAI in situ values were considered as the proxy of the ground-truth. ETc estimated with the ANN S2 LAI product is the closest to the ETc values calculated with the LAI in situ (R2 > 0.90, RMSE < 0.41 mm/d). Our findings indicate the good validation of ANN S2 LAI and CCC products and their further suitability for the implementation in evapotranspiration retrieval of agricultural areas. Full article
(This article belongs to the Special Issue Remote Sensing of Agricultural Monitoring)
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Open AccessArticle
Lessons from Assessing Uncertainty in Agricultural Water Supply Estimation for Sustainable Rice Production
Agronomy 2019, 9(10), 662; https://doi.org/10.3390/agronomy9100662 - 21 Oct 2019
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Abstract
Agricultural water supply (AWS) estimation is one of the first and fundamental steps of developing agricultural management plans, and its accuracy must have substantial impacts on the following decision-making processes. In modeling the AWS for paddy fields, it is still common to determine [...] Read more.
Agricultural water supply (AWS) estimation is one of the first and fundamental steps of developing agricultural management plans, and its accuracy must have substantial impacts on the following decision-making processes. In modeling the AWS for paddy fields, it is still common to determine parameter values, such as infiltration rates and irrigation efficiency, solely based on literature and rough assumptions due to data limitations; however, the impact of parameter uncertainty on the estimation has not been fully discussed. In this context, a relative sensitivity index and the generalized likelihood uncertainty estimation (GLUE) method were applied to quantify the parameter sensitivity and uncertainty in an AWS simulation. A general continuity equation was employed to mathematically represent the paddy water balance, and its six parameters were investigated. The results show that the AWS estimates are sensitive to the irrigation efficiency, drainage outlet height, minimum ponding depth, and infiltration, with the irrigation efficiency appearing to be the most important parameter; thus, they should be carefully selected. Multiple combinations of parameter values were observed to provide similarly good predictions, and such equifinality produced the substantial amount of uncertainty in AWS estimates regardless of the modeling approaches, indicating that the uncertainty should be counted when developing water management plans. We also found that agricultural system simulations using only literature-based parameter values provided poor accuracy, which can lead to flawed decisions in the water resources planning processes, and then the inefficient use of public investment and resources. The results indicate that modelers’ careful parameter selection is required to improve the accuracy of modeling results and estimates from using not only information from the past studies but also modeling practices enhanced with local knowledge and experience. Full article
(This article belongs to the Special Issue Model Application for Sustainable Agricultural Water)
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Open AccessArticle
Functional Analysis of Three miRNAs in Agropyron mongolicum Keng under Drought Stress
Agronomy 2019, 9(10), 661; https://doi.org/10.3390/agronomy9100661 - 20 Oct 2019
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Abstract
Agropyron mongolicum Keng, a perennial diploid grass with high drought tolerance, belongs to the genus Agropyron, tribe Triticeae. It has made tremendous contributions toward reseeding natural pasture and seeding artificial grassland in China, especially in the arid and semi-arid area of [...] Read more.
Agropyron mongolicum Keng, a perennial diploid grass with high drought tolerance, belongs to the genus Agropyron, tribe Triticeae. It has made tremendous contributions toward reseeding natural pasture and seeding artificial grassland in China, especially in the arid and semi-arid area of northern China. As a wild relative of wheat, A. mongolicum is also a valuable resource for the genetic improvement of wheat crops. MicroRNAs are small non-coding RNA molecules ubiquitous in plants, which have been involved in responses to a wide variety of stresses including drought, salinity, chilling temperature. To date, little research has been done on drought-responsive miRNAs in A. mongolicum. In this study, two miRNA libraries of A. mongolicum under drought and normal conditions were constructed, and drought-responsive miRNAs were screened via Solexa high throughput sequencing and bioinformatic analysis. A total of 114 new miRNAs were identified in A. mongolicum including 53 conservative and 61 unconservative miRNAs, and 1393 target genes of 98 miRNAs were predicted. Seventeen miRNAs were found to be differentially expressed under drought stress, seven (amo-miR21, amo-miR62, amo-miR82, amo-miR5, amo-miR77, amo-miR44 and amo-miR17) of which were predicted to target on genes involved in drought tolerance. QRT-PCR analysis confirmed the expression changes of the seven drought related miRNAs in A. mongolicum. We then transformed the seven miRNAs into Arabidopsis thaliana plants, and three of them (amo-miR21, amo-miR5 and amo-miR62) were genetically stable. The three miRNAs demonstrated the same expression pattern in A. thaliana as that in A. mongolicum under drought stress. Findings from this study will better our understanding of the molecular mechanism of miRNAs in drought tolerance and promote molecular breeding of forage grass with improved adaption to drought. Full article
(This article belongs to the Special Issue Breeding and Genetics of Forages for Semi-Arid and Arid Rangelands)
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Open AccessArticle
Changes in the Chemical Composition of Six Lettuce Cultivars (Lactuca sativa L.) in Response to Biofortification with Iodine and Selenium Combined with Salicylic Acid Application
Agronomy 2019, 9(10), 660; https://doi.org/10.3390/agronomy9100660 - 19 Oct 2019
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Abstract
A two-year greenhouse study was conducted to assess the effects of the application of I (as KIO3), Se (as Na2SeO3), and salicylic acid (SA) in nutrient solutions on the chemical composition of six lettuce cultivars, i.e., two [...] Read more.
A two-year greenhouse study was conducted to assess the effects of the application of I (as KIO3), Se (as Na2SeO3), and salicylic acid (SA) in nutrient solutions on the chemical composition of six lettuce cultivars, i.e., two butterhead lettuces (BUTL), “Cud Voorburgu” and “Zimująca”; two iceberg lettuces (ICEL), “Maugli” and “Królowa lata”; and two Lactuca sativa L. var. crispa L. (REDL) cultivars, “Lollorossa” and “Redin”, grown in the NFT (nutrient film technique) system. The treatments were as follows: control, I+Se, I+Se+0.1 mg SA dm−3, I+Se+1.0 mg SA dm−3, and I+Se+10.0 mg SA dm−3. KIO3 was used at a dose of 5 mg I dm−3, while Na2SeO3 was used at 0.5 mg Se dm−3. The application of I+Se was a mild abiotic stress factor for the plants of the ICEL and REDL cultivars. In contrast, I+Se did not have a negative impact on the BUTLcultivars. The application of 1.0 mg SA dm−3 improved the biomass productivity in all cultivars compared with I+Se. In the majority of the cultivars, the applied combinations of I+Se and I+Se+SA resulted in a reduction in the nitrate(V) content that was beneficial to the consumer and increased levels of sugars, phenols, phenylpropanoids, flavonols, and anthocyanins. In addition, an increase in ascorbic acid content was observed, but only in the BUTL cultivars and REDL “Redin”. The application of I, Se, and SA had upward or downward effects on the concentrations of N, K, P, Ca, Mg, S, Na, B, Cu, Fe, Mn, Mo, and Zn in the leaves. Full article
(This article belongs to the Special Issue Biofortification of Crops)
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Open AccessArticle
Manure Fertilization Gives High-Quality Earthworm Coprolites with Positive Effects on Plant Growth and N Metabolism
Agronomy 2019, 9(10), 659; https://doi.org/10.3390/agronomy9100659 - 19 Oct 2019
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Abstract
Humic substances (HS) are important soil components playing pivotal roles in guaranteeing long-term soil fertility. In this study, the chemical and biological properties of HS extracted from earthworm coprolites collected in soils subjected to different fertilization inputs (no fertilization, NF; fertilization with farmyard [...] Read more.
Humic substances (HS) are important soil components playing pivotal roles in guaranteeing long-term soil fertility. In this study, the chemical and biological properties of HS extracted from earthworm coprolites collected in soils subjected to different fertilization inputs (no fertilization, NF; fertilization with farmyard manure, FM; mineral input, M; mixed inputs, FMM, half farmyard manure plus half mineral input) were investigated. Results indicated a relationship between fertilization input and composition, molecular complexity and apparent molecular weight distribution of HS produced by earthworms. Coprolites from FM and FMM soils were the most enriched in organic carbon (OC), and HS from coprolites of FM soil were the highest in humic carbon (HC). Also, soil amendment with manure increased carboxylate and aromatic groups in HS, and the fraction with a high degree of polycondensation, thus indicating a positive impact of manure on plant residues’ degradation processes. These HS were the only to display hormone-like activity, which likely accounted for their most pronounced positive effects on plant growth and metabolism, including accumulation of chlorophylls, mineral nutrition, and activity of nitrogen assimilation enzymes, in oat (Avena sativa L.) plants growing in a soil-less system. We conclude that manure input favored the turnover of OC towards the humification process that led to the production of high-quality coprolites and HS with superior biological activity, and suggests that OC in coprolites and HC in HS from earthworms might be used as reliable indicators of soil fertility. Full article
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Open AccessArticle
Effect of Different Water Salinity Levels on the Germination of Imazamox-Resistant and Sensitive Weedy Rice and Cultivated Rice
Agronomy 2019, 9(10), 658; https://doi.org/10.3390/agronomy9100658 - 19 Oct 2019
Viewed by 108
Abstract
Weeds that have become resistant to herbicides may threaten rice production. Rice cultivation is mainly carried out in coastal and river delta areas that often suffer salinity problems. The aims of this study were to evaluate the effects of salinity upon germination and [...] Read more.
Weeds that have become resistant to herbicides may threaten rice production. Rice cultivation is mainly carried out in coastal and river delta areas that often suffer salinity problems. The aims of this study were to evaluate the effects of salinity upon germination and the root and shoot seedling growth of Italian weedy rice and cultivated rice (Oryza sativa), and to find a possible correlation between salinity and herbicide resistance. Seed germination tests were conducted in Petri dishes on four imazamox-sensitive and one resistant weedy rice populations and two rice varieties: Baldo (conventional) and CL80 (imidazolinone-resistant Clearfield® variety). Different salt concentrations were tested: 0, 50, 100, 150, 200, 250, 300, 350 and 400 mM NaCl. Germination percentage, germination speed, seedling root and shoot length were affected by increasing the salt concentration in all tested populations and varieties. The germination percentage was in general more affected in resistant weedy rice and CL80. In resistant weedy rice this was partially compensated by a faster germination up to 100 mM. In terms of seedling root and shoot length, CL80 and Baldo showed the highest tolerance to salt; resistant weedy rice was not able to produce seedling roots and shoots at concentrations > 300 mM. Full article
(This article belongs to the Special Issue Herbicide Resistance in Weed Management)
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Open AccessErratum
Erratum: Nadia Antonella Valverdi, et al., Apple Scion and Rootstock Contribute to Nutrient Uptake and Partitioning Under Different Belowground Environments. Agronomy 2019, 9, 415
Agronomy 2019, 9(10), 657; https://doi.org/10.3390/agronomy9100657 - 18 Oct 2019
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Abstract
The authors wish to correct the following erratum in this paper [...] Full article
(This article belongs to the Special Issue Mineral Nutrition of Fruit Trees)
Open AccessArticle
Screening and Evaluation of Essential Oils from Mediterranean Aromatic Plants against the Mushroom Cobweb Disease, Cladobotryum mycophilum
Agronomy 2019, 9(10), 656; https://doi.org/10.3390/agronomy9100656 - 18 Oct 2019
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Abstract
The main aim of this study was to evaluate the use of essential oils (EOs) as an alternative to synthetic fungicides used in the control of cobweb disease of button mushroom (Agaricus bisporus) caused by Cladobotryum mycophilum. The EOs used [...] Read more.
The main aim of this study was to evaluate the use of essential oils (EOs) as an alternative to synthetic fungicides used in the control of cobweb disease of button mushroom (Agaricus bisporus) caused by Cladobotryum mycophilum. The EOs used were obtained by hydrodistillation from five Mediterranean aromatic species (Lavandula × intermedia, Salvia lavandulifolia, Satureja montana, Thymus mastichina, and Thymus vulgaris), analyzed by gas chromatography, and tested in vitro for their antifungal activity against C. mycophilum. In vitro bioassays showed that the EOs obtained from T. vulgaris and S. montana (ED50 = 35.5 and 42.8 mg L−1, respectively) were the most effective EOs for inhibiting the mycelial growth of C. mycophilum, and were also the most selective EOs between C. mycophilum and A. bisporus. The in vivo efficacy of T. vulgaris and S. montana EOs at two different concentrations (0.5 and 1%) were evaluated in two mushroom growing trials with C. mycophilum inoculation. The treatments involving T. vulgaris and S. montana EOs at the higher dose (1% concentration) were as effective as fungicide treatment. The effect of these EOs on mushroom productivity was tested in a mushroom cropping trial without inoculation. They had a strong fungitoxic effect at the first flush. However, a compensatory effect was observed by the end of the crop cycle and no differences were observed in biological efficiency between treatments. The main compounds found were carvacrol and p-cymene for S. montana, and p-cymene and thymol for T. vulgaris. These results suggest that T. vulgaris and S. montana EOs may be useful products to manage cobweb disease if used as part of an integrated pest management (IPM) program. Full article
(This article belongs to the Special Issue Etiology and Control of Crop Diseases)
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Open AccessArticle
Effect of Plant Growth-Promoting Rhizobacteria on Salicornia ramosissima Seed Germination under Salinity, CO2 and Temperature Stress
Agronomy 2019, 9(10), 655; https://doi.org/10.3390/agronomy9100655 - 18 Oct 2019
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Abstract
In a scenario of climate change and growing population, halophyte root microbiota interactions may be a sustainable solution to improve alternative crop production while combating abiotic stress. In this work, seeds of the cash crop halophyte Salicornia ramosissima were inoculated with five different [...] Read more.
In a scenario of climate change and growing population, halophyte root microbiota interactions may be a sustainable solution to improve alternative crop production while combating abiotic stress. In this work, seeds of the cash crop halophyte Salicornia ramosissima were inoculated with five different plant growth-promoting rhizobacteria consortia, isolated from the rhizosphere of five halophytes in southwestern Spain salt marshes. For the first time, we recorded seed germination response to three interactive abiotic stressors, CO2 (400 and 700 ppm), temperature (25 and 29 ℃) and salinity (171, 510 and 1030 mM NaCl), all of them related to climate change. Salinity played a decisive role, as no significant differences were registered between treatments at 171 mM NaCl and no germination took place at 1030 mM NaCl. At 510 mM NaCl, one rhizobacterial consortium improved seed parameters notably, increasing up to 114% germination percentage and 65% seedlings biomass. These first findings encourage us to think that cash crop halophytes like S. ramosissima and halophyte root microbiota may be valuable resources for human or animal feeding in a future climate reality. Full article
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Open AccessArticle
Manipulating the Difference between the Day and Night Temperatures Can Enhance the Quality of Astragalus membranaceus and Codonopsis lanceolata Plug Seedlings
Agronomy 2019, 9(10), 654; https://doi.org/10.3390/agronomy9100654 - 18 Oct 2019
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Abstract
Astragalus membranaceus Bunge and Codonopsis lanceolata Benth. et Hook. f. are two famous medical species in Korea, China, and Japan, mainly used for treating diseases including cancer, obesity, and inflammation. Manipulation of the difference between the day and night temperatures (DIF) is an [...] Read more.
Astragalus membranaceus Bunge and Codonopsis lanceolata Benth. et Hook. f. are two famous medical species in Korea, China, and Japan, mainly used for treating diseases including cancer, obesity, and inflammation. Manipulation of the difference between the day and night temperatures (DIF) is an efficient horticultural practice to regulate the growth and development of vegetables in a glasshouse. However, little research has focused on how the DIF influences the plug seedling quality of medicinal plants. In this study, uniform plug seedlings were cultivated in three environmentally controlled chambers under an average daily temperature of 20 °C with negative (−10 °C), zero, or positive (+10 °C) DIFs, and the same relative humidity (75%), photoperiod (12 h), and light intensity (150 μmol·m−2·s−1 photosynthetic photon flux density with white LEDs). The results showed that the DIF had a noticeable effect on the growth, development, and morphology of A. membranaceus and C. lanceolata plug seedlings. The positive DIF (+10 °C) significantly increased the biomass (shoot, root, and leaf), stem diameter, and Dickson’s quality index, indicating an enhanced plug seedling quality. Moreover, the contents of primary and secondary metabolites, including soluble sugar, starch, total phenols and flavonoids, were higher with higher DIFs, where the maximum values were found at 0 °C or +10 °C DIF. Furthermore, the increases in the chlorophyll content and stomatal conductance were obtained in a positive DIF, indicating that a positive DIF was favorable to photosynthesis. An analysis of the gene expression showed that a positive DIF (+10 °C) up-regulated the expression of photosynthetic genes, including GBSS, RBCL, and FDX. In conclusion, the results of this study recommend a positive DIF (+10 °C) for enhancing the quality of A. membranaceus and C. lanceolata plug seedlings. Full article
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Open AccessArticle
Preliminary Genetic Map of a New Recombinant Inbred Line Population for Narrow-leafed Lupin (Lupinus angustifolius L.)
Agronomy 2019, 9(10), 653; https://doi.org/10.3390/agronomy9100653 - 18 Oct 2019
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Abstract
Genetic maps are an essential tool for investigating molecular markers’ linkage with traits of agronomic importance. Breeders put a lot of emphasis on this type of markers, which are used in breeding programs implementation and speed up the process of a new variety [...] Read more.
Genetic maps are an essential tool for investigating molecular markers’ linkage with traits of agronomic importance. Breeders put a lot of emphasis on this type of markers, which are used in breeding programs implementation and speed up the process of a new variety development. In this paper, we construct a new, high-density linkage genetic map for Polish material on narrow-leafed lupin. The mapping population originated from crossing the Polish variety ‘Emir’ and the Belarusian breeding line ‘LAE-1’. A new map was constructed based on DArTseq markers—a new type of marker generated with the next-generation sequencing (NGS) technique. The map was built with 4602 markers, which are divided into 20 linkage groups, corresponding with the number of gametic chromosomes in narrow-leafed lupin. On the new map there are 1174 unique loci. The total length of all linkage group is 3042 cM. This map was compared to the reference genome of narrow-leafed lupin and the CDS sequence for model legume species: emphMedicago truncatula, emphLotus japonicus and Glycine max. Analysis revealed the presence of the DArTseq marker common for all investigated species. We were able to map 38 new, unplaced scaffolds on the new genetic map of narrow-leafed lupin. The high-density genetic map we received can be used for quantitative trait locus (QTL) mapping, genome-wide association study analysis and assembly of the reference genome for the whole genome sequencing (WGS) method Full article
(This article belongs to the Section Crop Breeding and Genetics)
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Open AccessArticle
Nondestructive and Continuous Fresh Weight Measurements of Bell Peppers Grown in Soilless Culture Systems
Agronomy 2019, 9(10), 652; https://doi.org/10.3390/agronomy9100652 - 18 Oct 2019
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Abstract
Fresh weight is a direct index of crop growth. It is difficult to continuously measure the fresh weight of bell peppers grown in soilless cultures, however, due to the difficulty in identifying the moisture condition of crops and growing media. The objective of [...] Read more.
Fresh weight is a direct index of crop growth. It is difficult to continuously measure the fresh weight of bell peppers grown in soilless cultures, however, due to the difficulty in identifying the moisture condition of crops and growing media. The objective of this study was to develop a continuous and nondestructive measuring system for the fresh weight of bell peppers grown in soilless cultures considering the moisture content of growing media. The system simultaneously measures the trellis string’s supported weight and gravitational weight using tensile load cells. The moisture weight of growing media was calibrated during the growth period using changes in moisture content before and after the first irrigation of the day. The most stable time period for the measurement, from 03:00 to 06:00, was determined by analyzing the diurnal change in relative water content. To verify the accuracy of the system, the fruits, stems, leaves, and roots’ fresh weights were measured manually. The fresh weights measured by the developed system were in good agreement with those manually measured. The results confirm that our system can reliably and accurately measure fresh weights of bell peppers grown in soilless cultures. This method can be applied to continuous growth data collection for other crops grown in soilless cultures. Full article
(This article belongs to the Special Issue Precision Agriculture)
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Open AccessArticle
Organic Manure Coupled with Inorganic Fertilizer: An Approach for the Sustainable Production of Rice by Improving Soil Properties and Nitrogen Use Efficiency
Agronomy 2019, 9(10), 651; https://doi.org/10.3390/agronomy9100651 - 18 Oct 2019
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Abstract
The current farming system is heavily reliant on chemical fertilizers, which negatively affect soil health, the environment, and crop productivity. Improving crop production on a sustainable basis is a challenging issue in the present agricultural system. To address this issue, we assumed that [...] Read more.
The current farming system is heavily reliant on chemical fertilizers, which negatively affect soil health, the environment, and crop productivity. Improving crop production on a sustainable basis is a challenging issue in the present agricultural system. To address this issue, we assumed that the combined use of organic manure and inorganic nitrogen (N) fertilizers can improve rice grain yield and soil properties without the expense of the environment. This study explores the combined effects of cattle manure (CM), poultry manure (PM), and chemical fertilizer (CF) on soil properties, rice growth, physiology, and grain yield and quality. Six treatments in the following combinations were included: T1—no N fertilizer; T2—100% CF; T3—60% CM + 40% CF; T4—30% CM + 70% CF; T5—60% PM + 40% CF; and T6—30% PM + 70% CF. Results showed that across the seasons, treatment T6 increased the net photosynthesis rate, total biomass, grain yield, and amylose content by 23%, 90%, 95%, and 10%, respectively, compared with control. This increment in net photosynthetic rate and growth was the result of 24%, 14%, 19%, and 20% higher total root length, root surface area, root volume, and root diameter, respectively. Improvements in these attributes further enhanced the grain yield and nitrogen use efficiency of rice. No significant difference between T4 and T6 was observed. The correlation analysis also confirmed that root morphological traits were positively correlated with grain yield, N uptake, and biomass accumulation. Similarly, improvement in grain yield and NUE was also associated with improved soil properties, i.e., bulk density, soil porosity, soil organic carbon, and total N under combined organic and inorganic N fertilizers treatment. Conclusively, the integration of 30% N from PM or CM with 70% N from CF (urea) is a promising option not only for higher grain yield and quality of rice but also for improved soil health. This study provides a sustainable nutrient management strategy to improve crop yield with high nutrient use efficiency. Full article
(This article belongs to the Special Issue Organic vs. Conventional Cropping Systems)
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Open AccessArticle
Dynamic of Vascular Streak Dieback Disease Incidence on Susceptible Cacao Treated with Composted Plant Residues and Trichoderma asperellum in Field
Agronomy 2019, 9(10), 650; https://doi.org/10.3390/agronomy9100650 - 18 Oct 2019
Viewed by 111
Abstract
Trichoderma asperellum, composted plant residues, and its combination can control vascular-streak dieback (VSD) disease caused by fungus Ceratobasidium theobromae in laboratory conditions. In this trial, we evaluated these treatments in two years through the application of foliar spraying and stem infusion for [...] Read more.
Trichoderma asperellum, composted plant residues, and its combination can control vascular-streak dieback (VSD) disease caused by fungus Ceratobasidium theobromae in laboratory conditions. In this trial, we evaluated these treatments in two years through the application of foliar spraying and stem infusion for T. asperellum alone, through soil amendment for compost alone, and T. asperellum plus this organic fertilizer in the field on susceptible cacao clone. The disease is characterized by full-leaf chlorosis and necrosis that can develop rapidly to the entire branch, with around 70% incidence in seven months, and we detected the pathogen in branches showing light symptoms. All treatments except for T. asperellum plus composted plant residues three and seven months post application did not have any impact on the reduction of VSD incidence in the first year. In the second year, we observed a significant reduction of the disease by both T. asperellum in combination with compost and compost alone in a time span of three to seven months, and with T. asperellum spraying and infusion in a time span of five to seven months. By comparing to the control, the efficacy of these treatments in controlling the VSD disease seven months post-first application in the last year was 44.4%, 23.5%, 23.1%, and 15.1%, respectively. Detection of trees inoculated with T. asperellum indicated that this fungus was present in root and branch tissues except for treatment through infusions, while in the uninoculated trees, Trichoderma was not present or was present at a very low level. These data showed that combination of T. asperellum and composted plant residues applied through soil amendment was able to control VSD disease effectively and could potentially be used at large scale to control this disease and other diseases infesting aerial parts of cacao, and to improve soil fertility. Full article
(This article belongs to the Special Issue Integrating Pest Management into Agricultural Production Systems)
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Open AccessArticle
Theoretical and Experimental Analysis of Nutrient Variations in Electrical Conductivity-Based Closed-Loop Soilless Culture Systems by Nutrient Replenishment Method
Agronomy 2019, 9(10), 649; https://doi.org/10.3390/agronomy9100649 - 17 Oct 2019
Viewed by 284
Abstract
In closed-loop soilless culture systems, variation in nutrients can lead to instability in the nutrient management and forced discharge of nutrients and water. Total nutrients absorbed by plants are replenished in an electrical conductivity-based closed-loop system, and fluctuation in electrical conductivity within a [...] Read more.
In closed-loop soilless culture systems, variation in nutrients can lead to instability in the nutrient management and forced discharge of nutrients and water. Total nutrients absorbed by plants are replenished in an electrical conductivity-based closed-loop system, and fluctuation in electrical conductivity within a certain range around the initial value can be expected. However, this is not always observed in systems using conventional nutrient-replenishment methods. The objectives of this study were to analyze nutrient variation in a closed-loop soilless culture system based on a theoretical model and derive an alternative nutrient-replenishment method. The performance of the derived alternative method was compared with a conventional nutrient-replenishment method through simulation analysis. A demonstration experiment using sweet peppers was then conducted to confirm whether the theoretical analysis results can be reproduced through actual cultivation. The average amounts of injected nutrients during the experimental period of four months in the conventional and alternative methods were 2257 and 1054 g, respectively. There was no significant difference in the yield of sweet peppers between the two methods. The substrate electrical conductivity in the alternative method was maintained at 2.7 dS⋅m−1 ± 0.5 within the target electrical conductivity value, while that in the conventional method gradually increased to 5.0 dS⋅m−1 ± 1.2. In a simulation study, results similar to the demonstration experiment were predicted. Total nutrient concentrations in the alternative method showed fluctuations around the target value but did not continuously deviate from the target value, while those in the conventional method showed a tendency to increase. As a whole, these characteristics of the alternative method can help in minimizing nutrients and water emissions from the cultivation system. Full article
(This article belongs to the Special Issue Soilless Culture, Growing Media and Horticultural Plants)
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Open AccessArticle
Weed Suppression in Only-Legume Cover Crop Mixtures
Agronomy 2019, 9(10), 648; https://doi.org/10.3390/agronomy9100648 - 17 Oct 2019
Viewed by 152
Abstract
Weed suppression is a potential benefit of cover crop mixtures, as species diversity may allow for combining early and late-season competition with weeds. Here, we studied if this is possible for only-legume mixtures containing species with different growth rates, by testing two legumes, [...] Read more.
Weed suppression is a potential benefit of cover crop mixtures, as species diversity may allow for combining early and late-season competition with weeds. Here, we studied if this is possible for only-legume mixtures containing species with different growth rates, by testing two legumes, alsike clover (AC; Trifolium hybridum L.) and black medic (BM; Medicago lupulina L.) in two field trials sown in 2016 and 2017. Five AC:BM ratios (100:0, 67:33, 50:50, 33:67, and 0:100) were grown at three densities (50%, 100%, and 150% of recommended seed density). Cover crop and weed aboveground biomass (CCB and WB, respectively) were harvested three times, after establishment in spring (H1), in summer (H2), and in autumn after mulching (H3). Compared to fallow plots, all monocultures and mixtures showed early-season weed suppression in terms of biomass production and more efficiency over time with an average reduction of 42%, 52%, and 96% in 2016, and 39%, 55%, and 89% in 2017 at H1, H2, and H3, respectively. Out of 54 mixture treatments, only eight mixtures showed stronger weed suppression than monocultures. Mixtures reduced WB by 28%, as an average value, in 2017 compared to the respective monocultures, but not significantly in 2016, indicating that the crop diversity effect on weeds was dependent on the growing environment. Weed suppression was significantly higher at 100% and 150% seed density than 50%, but no significant differences were determined between 100% and 150% seed density. After mulching, no density effect was observed on CCB and WB. In conclusion, AC and BM can be used as a keystone species on weed suppression for sustainable agriculture as they possess plasticity to suppress weeds when higher biomass productivity is limited by environmental conditions. However, their diversity effects are time and condition dependent. Appropriate seed density and mulching can successfully be employed in weed management, but seed density may not have an effect after mulching. Full article
(This article belongs to the Special Issue Weed Management in Annual and Perennial Cropping Systems)
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Open AccessArticle
Exploring the Genetic Diversity and Population Structure of Turkish Laurel Germplasm by the iPBS-Retrotransposon Marker System
Agronomy 2019, 9(10), 647; https://doi.org/10.3390/agronomy9100647 - 17 Oct 2019
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Abstract
Laurel is a medicinally important plant and is known to the world for its essential oil. Turkey is the main market in the laurel leaf trade by sharing about 90% of the world trade. Here we made an effort to elucidate genetic diversity [...] Read more.
Laurel is a medicinally important plant and is known to the world for its essential oil. Turkey is the main market in the laurel leaf trade by sharing about 90% of the world trade. Here we made an effort to elucidate genetic diversity and population structure of 94 Turkish laurel genotypes collected from 26 provinces and four geographical regions using inter-primer binding site (iPBS) retrotransposon markers. A total of 13 most polymorphic primers were selected which yielded 195 total bands, of which 84.10% were found polymorphic. Mean polymorphism information content (PIC) was (0.361) and diversity indices including mean effective number of alleles (1.36), mean Shannon’s information index (0.35) and overall gene diversity (0.22) revealed the existence of sufficient amount of genetic diversity in the studied plant material. Most diversity was found in genotypes collected from the Mediterranean region. Analysis of molecular variance (AMOVA) revealed that most of the variation (85%) in Turkish laurel germplasm is due to differences within populations. Model-based structure, principal coordinate analysis (PCoA) and neighbor-joining algorithms were found in agreement and clustered the studied germplasm according to their collection provinces and regions. This is a very first study exploring the genetic diversity and population structure of laurel germplasm using iPBS-retrotransposon marker system. We believe that information provided in this work will be helpful for the scientific community to take more interest in this forgotten but the medicinally important plant. Full article
(This article belongs to the Special Issue Analysis of Crop Genetic and Germplasm Diversity)
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Open AccessCommunication
Recovery of 2R.2Sk Triticale-Aegilops kotschyi Robertsonian Chromosome Translocations
Agronomy 2019, 9(10), 646; https://doi.org/10.3390/agronomy9100646 - 17 Oct 2019
Viewed by 190
Abstract
Robertsonian translocations (RobTs) in the progeny of triticale (×Triticosecale Wittmack) plants with monosomic substitution of Aegilops kotschyi chromosome 2Sk (2R) were investigated by fluorescence in-situ hybridization. Chromosome 2Sk of Ae. kotschyi is reported to possess many valuable loci, such as [...] Read more.
Robertsonian translocations (RobTs) in the progeny of triticale (×Triticosecale Wittmack) plants with monosomic substitution of Aegilops kotschyi chromosome 2Sk (2R) were investigated by fluorescence in-situ hybridization. Chromosome 2Sk of Ae. kotschyi is reported to possess many valuable loci, such as Lr54 + Yr37 leaf and stripe (yellow) rust resistance genes. We used a standard procedure to produce RobTs, which consisted of self-pollination of monosomic triticale plants, carrying 2R and 2Sk chromosomes in monosomic condition. This approach did not result in RobTs. Simultaneously, we succeeded in producing 11 plants carrying 2R.2Sk compensatory RobTs using an alternative approach that utilized ditelosomic lines of triticale carrying 2RS (short arm) and 2RL (long arm) telosomic chromosomes. Identification of molecular markers linked to Lr54 + Yr37 genes in the translocation plants confirmed that these resources can be exploited in current triticale breeding programmes. Full article
(This article belongs to the Special Issue Chromosome Manipulation for Plant Breeding Purposes)
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Open AccessArticle
Comparison of Different Multivariate Statistical Methods for Screening the Drought Tolerant Genotypes of Pearl Millet (Pennisetum americanum L.) and Sorghum (Sorghum bicolor L.)
Agronomy 2019, 9(10), 645; https://doi.org/10.3390/agronomy9100645 - 17 Oct 2019
Viewed by 124
Abstract
Drought is the main limiting factor of crops production in major regions of the world. Forage plants such as pearl millet and sorghum are drought tolerant and suitable for arid regions to grow. In this study, for selecting and introducing the best drought [...] Read more.
Drought is the main limiting factor of crops production in major regions of the world. Forage plants such as pearl millet and sorghum are drought tolerant and suitable for arid regions to grow. In this study, for selecting and introducing the best drought tolerant genotypes, seven pearl millet and five sorghum genotypes in three locations (Kerman, Jiroft, and Bardsir in Kerman Province) were studied with different climatic conditions. The experiments were conducted for three consecutive years of cultivation (2016, 2017, and 2018) under regularly irrigated conditions and the 100% (I100, full irrigation) plant water requirement and under water deficiency, (50%) plant water requirement (I50) in two randomized complete block designs in triplicate separately at each location. Eight drought tolerance/susceptibility indices were used. Multivariate factor analysis (FA) and stress tolerance score (STS) methods were employed to compare the most drought tolerant genotypes in each region. The STS method was more efficient and effective than the FA method for detecting the most drought tolerant genotype with any number of used genotypes. Based on the results of drought tolerance indices and STS, the IP13150 and IP13151 genotypes of pearl millet and speed feed genotype of sorghum in Kerman, Jiroft, and Bardsir respectively, were introduced as the most drought tolerant genotypes for three consecutive years of cultivation. Full article
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Open AccessArticle
Crop Rotation Compared with Continuous Rye Cropping for Weed Biodiversity and Rye Yield. A Case Study of a Long-Term Experiment in Poland
Agronomy 2019, 9(10), 644; https://doi.org/10.3390/agronomy9100644 - 16 Oct 2019
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Abstract
In recent years, sustainable agriculture has revitalized interest in crop rotations and their effects on crop performance and agroecosystem biodiversity, including weeds. This article used winter rye as an example and focused on the crop rotation (CR) impact on species, taxonomic and functional [...] Read more.
In recent years, sustainable agriculture has revitalized interest in crop rotations and their effects on crop performance and agroecosystem biodiversity, including weeds. This article used winter rye as an example and focused on the crop rotation (CR) impact on species, taxonomic and functional diversity of weed communities and analysed the contribution of crop rotation to protecting yield and regulating weed abundance. Long-term continuous rye cropping (CC) provided a background for comparison. Two variants of plant protection were also adopted: herbicide application (H+) and no plant protection (H−). The data from the 10th, 30th and 50th years of the experiment were included in the analysis. Diversified crop rotation with no chemical protection resulted in a satisfactory rye yield and reduced weed abundance—especially problem species—without a decrease in weed species diversity or functional diversity. When rye was grown under crop rotation, the herbicide application had no effect on yield protection, but it was harmful to weed biodiversity. The rye yield correlated negatively with weed biomass, but did not show a link with weed biodiversity. Continuation of long-term experiments as a research basis for contemporary and future scientific challenges is necessary. Full article
(This article belongs to the Special Issue Influence of Crop Rotation on Crop Yields)
Open AccessArticle
The Influence of Copper and Silver Nanocolloids on the Quality of Pressed Spring Rapeseed Oil
Agronomy 2019, 9(10), 643; https://doi.org/10.3390/agronomy9100643 - 16 Oct 2019
Viewed by 106
Abstract
The aim of this study was to evaluate the quality of virgin oil pressed from spring rape seeds cultivated with the use of colloidal nanosilver and nanocopper solutions for processing seeds and as foliar fertilizer. The results show that the use of nanometals [...] Read more.
The aim of this study was to evaluate the quality of virgin oil pressed from spring rape seeds cultivated with the use of colloidal nanosilver and nanocopper solutions for processing seeds and as foliar fertilizer. The results show that the use of nanometals for seed processing and foliar fertilization increased the content of carotenoid pigments in the oil. The pigment concentration was higher compared to oil pressed from control seeds. The application of nanocolloids onto the seeds and subsequently on the growing plants contributed to the increase of the oxidative stability of oils. Both the acid number (AN) and peroxide number (PN) values were higher in the studied oils as compared to the control, but did not exceed the required allowable levels. Increased content of silver ions and slightly increased copper content was observed in the pressed oil. An infrared spectral analysis (Fourier-Transformed Infra-Red) conducted in combination with chemometrics allowed the classification of the studied oils in terms of their chemical composition. The analysis revealed the presence of bands characteristic of Cu-O-H vibrations after soaking the seeds and spraying the plants with copper nanocolloid, and of C-O-Ag after fertilization with silver nanocolloid. Full article
(This article belongs to the Special Issue Nanotechnology Applications in Agriculture System)
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Open AccessArticle
A Study on the Potential of IAD as a Surrogate Index of Quality and Storability in cv. ‘Gala’ Apple Fruit
Agronomy 2019, 9(10), 642; https://doi.org/10.3390/agronomy9100642 - 16 Oct 2019
Viewed by 157
Abstract
The decline of relative chlorophyll contents during fruit ripening is considered to be an important indicator of fruit physiological condition. The recent availability of low-cost portable visible spectrum (VIS) spectrometers has spurred research interest towards optical sensing of chlorophyll changes in intact fruit, [...] Read more.
The decline of relative chlorophyll contents during fruit ripening is considered to be an important indicator of fruit physiological condition. The recent availability of low-cost portable visible spectrum (VIS) spectrometers has spurred research interest towards optical sensing of chlorophyll changes in intact fruit, with many scientists attempting to link the shifts in optical signals, attributed to chlorophyll changes, to different maturity and quality parameters. One of the widely available portable devices for non-destructive estimation of relative chlorophyll contents is the DA meter, which provides a maturity index that is calculated as a difference between absorption at 670 nm (near the chlorophyll-a absorption peak) and 720 nm (background of the spectrum), abbreviated as IAD. In the present study, the evolution of IAD and its relation to starch pattern index (SPI) and fruit flesh firmness (FFF) was monitored in fruit of two cv. ‘Gala’ clones during maturation and storage, aiming to identify a potential existence of a usable IAD range for the assessment and prediction of the optimal harvest window and storage potential. In both clones, canopy positions, fruit sides, and seasons IAD, SPI, and FFF generally changed in a linear fashion over time, but with partially very different slopes, i.e., they were changing at different rates. What all of these parameters had in common was the presence of a very high biological variability, which is typical of apple fruit. Significantly powerful estimations of SPI (r2 > 0.7, p < 0.005) and pre- and post-storage FFF (r2 > 0.6, p < 0.005) were achieved. However, the very large biological variability could not be neutralized, which means that the predictions always included large confidence intervals of up to 0.46–0.59 units for SPI and 0.82–1.1 kgF FFF, which ultimately makes them unusable for practical applications. Experiments done under real-life conditions in a commercial fruit storage facility on several different fruit batches confirmed that IAD measured at harvest cannot be used indiscriminately for predicting post-storage FFF of cv. ‘Gala’ originating from different orchards. Nevertheless, mean IAD values that were obtained at optimal maturity from samples of the same orchards remained stable over seasons (0.8–1.2), which strongly suggests that, provided that the calibrations and validations are not only cultivar, but also orchard-specific, IAD has a potential for estimating maturity and storability of apple fruit. In this case, IAD could replace standard maturity indices, otherwise it would be suited for use as a supplementary index for determining fruits physiological maturity status. Full article
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Open AccessArticle
Zero Tillage Improves Soil Properties, Reduces Nitrogen Loss and Increases Productivity in a Rice Farmland in Ghana
Agronomy 2019, 9(10), 641; https://doi.org/10.3390/agronomy9100641 - 15 Oct 2019
Viewed by 177
Abstract
Soil fertility in Ghana continues to decline due to the overdependency on farm machinery to till the land coupled with the continuous application of mineral fertilizer, which has a resultant effect on agricultural non-point source (AgNPS) pollution. A two-year field experiment was conducted [...] Read more.
Soil fertility in Ghana continues to decline due to the overdependency on farm machinery to till the land coupled with the continuous application of mineral fertilizer, which has a resultant effect on agricultural non-point source (AgNPS) pollution. A two-year field experiment was conducted to evaluate the effects of different tillage methods on soil properties, nitrogen loss reduction and rice productivity of a gleysol, developed over granite. Five tillage methods—namely, zero tillage direct seeding (ZTDS), zero tillage transplanting (ZTTS), reduced tillage direct seeding (RTDS), reduced tillage transplanting (RTTS), and conventional tillage (CT)—were studied in a Randomized Complete Block Design (RCBD) with three replicates. After two cropping seasons, soil bulk density was in the order of (ZTTS = ZTDS) ˃ RTDS ˃ RTTS ˃ CT. ZTDS and ZTTS were associated with significantly higher levels of nutrients in the top soil (0–20 cm) as compared with the rest of the treatments. Plant height was in the order of CT > RTTS = ZTTS > RTDS > ZTDS. The highest grain yield was recorded by both CT and ZTTS significantly different from the rest of the treatments. ZTDS recorded the highest stover yield for both years. Subsequently, CT was associated with high release of potential pollutant loads which could lead to AgNPS pollution, as is evident from the high nutrient loss. Considering the high nutrient concentration at 0–20 cm, the reduced nutrient movement and the corresponding yield improvement, ZTDS and ZTTS are recommended for farmers in Ghana to ensure sustainable rice production, reduce AgNPS pollutant movement and ultimately provide an eco-protective and friendly environment for sustainable rice production. Full article
(This article belongs to the Section Farming Sustainability)
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Open AccessArticle
Management of High-Residue Cover Crops in a Conservation Tillage Organic Vegetable On-Farm Setting
Agronomy 2019, 9(10), 640; https://doi.org/10.3390/agronomy9100640 - 15 Oct 2019
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Abstract
A three year on-farm conservation-tillage experiment was initiated in fall of 2008 at Randle Farm LLC, located in Auburn, AL. Our objective was to evaluate and demonstrate implementation of tenable conservation vegetable production practices using high amounts of cover crop residues that reduce [...] Read more.
A three year on-farm conservation-tillage experiment was initiated in fall of 2008 at Randle Farm LLC, located in Auburn, AL. Our objective was to evaluate and demonstrate implementation of tenable conservation vegetable production practices using high amounts of cover crop residues that reduce soil erosion, improve soil productivity and quality, reduce energy costs, and promote farm profitability. Cereal rye, crimson clover, and a rye and crimson clover mixture were evaluated as cover crops; these were terminated using either a prototype two-stage roller/crimper alone or followed by an application of 2.5 L a.i. ha−1 45% cinnamon (Cinnamomum verum L.) oil (cinnamaldehyde, eugenol, eugenol acetate,)/45% clove oil (eugenol, acetyl eugenol, caryophyllene) mixture in the spring prior to crop establishment. A winter fallow conventional tillage system was included for comparison. Watermelons, cantaloupes, and okra then were transplanted into each cover crop and termination treatment combination in mid-May, utilizing a modified transplanter equipped with a custom fitted subsoiling shank and row cleaners to alleviate soil compaction and facilitate transplanting. In all years, all cover crop treatments exceeded 4000 kg ha−1 and in 2009 and 2011, exceeded 6000 kg ha−1. At 21 days after termination in 2010 when the slowest termination occurred, higher termination rates were obtained for cereal rye (95% to 96%) followed by lower termination rates for the clover/rye mixture (83% to 85%); the lowest termination rates were obtained for crimson clover (66% to 68%). Commercially available cinnamon/clove oil solution provided little cover crop termination above that provided by a roller crimper alone. Volumetric soil moisture content for rolled/crimped cover crops was consistently higher compared to the conventional system, indicating that flattened and desiccated cover crop residue provided water conservation. In 2010 and 2011, yields for cantaloupe, okra, and watermelons were consistently higher for the conventional system compared with no-till system with cover crops likely due to weed cultivation limitations and insect pressure. Future studies need to focus on weed control and integrated pest management. Full article
(This article belongs to the Special Issue Smart Management of Conservative, Organic and Integrated Agriculture)
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Open AccessArticle
Sensitivity of Maize Yield in Smallholder Systems to Climate Scenarios in Semi-Arid Regions of West Africa: Accounting for Variability in Farm Management Practices
Agronomy 2019, 9(10), 639; https://doi.org/10.3390/agronomy9100639 - 15 Oct 2019
Viewed by 194
Abstract
Climate change is estimated to exacerbate existing challenges faced by smallholder farmers in Sub-Sahara Africa. However, limited studies quantify the extent of variation in climate change impact under these systems at the local scale. The Decision Support System for Agro-technological Transfer (DSSAT) was [...] Read more.
Climate change is estimated to exacerbate existing challenges faced by smallholder farmers in Sub-Sahara Africa. However, limited studies quantify the extent of variation in climate change impact under these systems at the local scale. The Decision Support System for Agro-technological Transfer (DSSAT) was used to quantify variation in climate change impacts on maize yield under current agricultural practices in semi-arid regions of Senegal (Nioro du Rip) and Ghana (Navrongo and Tamale). Multi-benchmark climate models (Mid-Century, 2040–2069 for two Representative Concentration Pathways, RCP4.5 and RCP8.5), and multiple soil and management information from agronomic surveys were used as input for DSSAT. The average impact of climate scenarios on grain yield among farms ranged between −9% and −39% across sites. Substantial variation in climate response exists across farms in the same farming zone with relative standard deviations from 8% to 117% at Nioro du Rip, 13% to 64% in Navrongo and 9% to 37% in Tamale across climate models. Variations in fertilizer application, planting dates and soil types explained the variation in the impact among farms. This study provides insight into the complexities of the impact of climate scenarios on maize yield and the need for better representation of heterogeneous farming systems for optimized outcomes in adaptation and resilience planning in smallholder systems. Full article
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Open AccessArticle
Mapping an Agricultural Field Experiment by Electromagnetic Induction and Ground Penetrating Radar to Improve Soil Water Content Estimation
Agronomy 2019, 9(10), 638; https://doi.org/10.3390/agronomy9100638 - 15 Oct 2019
Viewed by 142
Abstract
A growing interest in proximal sensing technologies for estimating soil water content (SWC) will be highlighted. On this matter the objectives of this study were: (1) to use both the combined electromagnetic induction (EMI) sensor and Ground Penetrating Radar (GPR) to characterize an [...] Read more.
A growing interest in proximal sensing technologies for estimating soil water content (SWC) will be highlighted. On this matter the objectives of this study were: (1) to use both the combined electromagnetic induction (EMI) sensor and Ground Penetrating Radar (GPR) to characterize an innovative field experiment located in southern Italy, in which different agricultural practices are tested, including a soil hydraulic arrangement; (2) to implement a geostatistical approach in order to merge different geophysical sensor data as auxiliary variables for SWC estimation. The multi-sensor recorded data were: (1) SWC data measured by gravimetric method; (2) Differential Global Positioning System height; (3) apparent electrical conductivity measured by an EMI sensor; (4) depths of soil discontinuities individuated by GPR radargrams interpretation; and (5) amplitude of GPR signal data at two different frequencies. Geostatistical techniques were used both to map all variables and improve the SWC estimation. The findings of this research indicate that: (1) the GPR radargrams identified four reflection events as a consequence of interfaces; (2) the EMI and GPR mapping provided identification of areas with high potential for water stagnation; and (3) the outputs of geophysical sensors can be effectively used as auxiliary tools to supplement the sampling of the target variable and to improve water content estimation. Full article
(This article belongs to the Special Issue Precision Agriculture for Sustainability)
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Open AccessArticle
Integrative Effects of Rice-Straw Biochar and Silicon on Oil and Seed Quality, Yield and Physiological Traits of Helianthus annuus L. Grown under Water Deficit Stress
Agronomy 2019, 9(10), 637; https://doi.org/10.3390/agronomy9100637 - 14 Oct 2019
Viewed by 185
Abstract
Water deficit stress can negatively affect oil quality, crop yields and soil infertility. Thus, we investigated the effects of rice-straw biochar, foliar silicon and their combination on quality, yield and physiological traits of sunflower grown under three water deficit stress treatments. Water stress [...] Read more.
Water deficit stress can negatively affect oil quality, crop yields and soil infertility. Thus, we investigated the effects of rice-straw biochar, foliar silicon and their combination on quality, yield and physiological traits of sunflower grown under three water deficit stress treatments. Water stress treatments were 50% (WS0; no stress), 70% (WS1; moderate stress) and 90% (WS2; severe stress) depletion of the available soil moisture. The results showed that WS1 and WS2 negatively affected oil quality, mycorrhizal spores, yield and physiological traits of the sunflower; however, biochar, silicon and their combination significantly (p ≤ 0.05) improved most of those traits. Oil and oleic acid contents of sunflower grown under WS2 were decreased by 18% and 25.8% compared to those grown under WS0, respectively. Nevertheless, the biochar and silicon combination resulted in higher oil (10.2%) and oleic acid (12.2%) in plants grown under WS2 than those grown in untreated plots. Also, a significant increase (182% and 277%) in mycorrhizal spores was obtained in soil treated combination of biochar and silicon under WS1 and WS2 in comparison to untreated soil, respectively. On the other hand, plants grown under WS1 and WS2 exhibited reduced seed yield ha−1 by 16.5% and 53.5% compared to those grown under WS0, respectively. However, seed yield ha−1 were increased by 26.8% and 27.1% in plots treated with combined treatment compared to untreated plants, respectively. In addition, the biochar and silicon combination significantly increased stomatal conductance by 21.4% and 12.1%, reduced proline by 56.6% and 51.2% and reduced catalase activity by 13.4% and 17.3% under WS1 and WS2 compared to those grown in untreated plots, respectively. Therefore, the combined treatment of biochar and silicon can minimize and alleviate the negative effects of WS1 and WS2, improve oil quality, physiological traits, microbial activity and seed yield ha−1 in sunflower plants. Full article
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