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Agronomy, Volume 10, Issue 6 (June 2020) – 161 articles

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Cover Story (view full-size image) Fusarium spp. are key pathogens in maize seeds and seedlings. Seed-borne infections have an [...] Read more.
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Open AccessFeature PaperArticle
Effects of Harvest Time on the Yield and Quality of Winter Wheat Hay Produced in Northern Italy
Agronomy 2020, 10(6), 917; https://doi.org/10.3390/agronomy10060917 - 26 Jun 2020
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Abstract
The aim of this work was to study the yield and nutritional characteristics of winter wheat hay. A selection of cultivars recommended for three main purposes: grain, whole plant (biomass) and dual purpose (grain and biomass) production were cultivated and harvested from heading [...] Read more.
The aim of this work was to study the yield and nutritional characteristics of winter wheat hay. A selection of cultivars recommended for three main purposes: grain, whole plant (biomass) and dual purpose (grain and biomass) production were cultivated and harvested from heading to grain dough stages. Yield dry weight (YDW), dry matter (DM) and undigested neutral detergent fiber (uNDF) increased with advancing maturity, ranging from 9 t ha−1, 20 and 11% of DM to 16 t ha−1, 43 and 17% of DM, respectively; while crude protein (CP) and neutral detergent fiber (NDF) decreased from 11 and 59% of DM to 6 and 54% of DM, respectively. Our study showed that dual purpose winter wheat cultivars displayed similar performance of CP, NDF and net energy for lactation, when harvested at heading or grain milk stages. In addition, winter wheat recommended to be harvested as whole plant showed similar values of YDW, sugar and starch contents, when harvested at grain dough and milk stages. These characteristics are strategic in hay production, allowing a more flexible harvesting strategy. These results might be useful to improve the hay production, given useful information on harvest time and improving agricultural sustainability covering the soil in autumn and winter. Full article
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Open AccessArticle
Productivity of Selected African Leafy Vegetables under Varying Water Regimes
Agronomy 2020, 10(6), 916; https://doi.org/10.3390/agronomy10060916 - 26 Jun 2020
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Abstract
African leafy vegetables (ALVs) are nutrient dense and can contribute to crop and dietary diversity, especially in water-stressed environments. However, research on their productivity under limited water availability remains scant. The objective of the study was to evaluate growth, physiology and yield responses [...] Read more.
African leafy vegetables (ALVs) are nutrient dense and can contribute to crop and dietary diversity, especially in water-stressed environments. However, research on their productivity under limited water availability remains scant. The objective of the study was to evaluate growth, physiology and yield responses of three ALVs (Vigna unguiculata, Corchorus. Olitorius and Amaranthus cruentus) and a reference vegetable (Beta vulgaris var. cicla) to varying water regimes [30%, 60% and 100% of crop water requirement (ETc)]. Field trials using a randomised complete block design, replicated three times, were conducted over two summer seasons, 2015/16 and 2016/17. Leaf number, plant height, chlorophyll content index (CCI), chlorophyll fluorescence (CF), and yield were measured in situ. For A. cruentus and C. olitorius, water stress (30% ETc) was shown to produce a lower yield, although leaf number, plant height and chlorophyll content index were unaffected, while for B. vulgaris, leaf number and yield were reduced by water stress. For V. unguiculata, CF, CCI, plant height, leaf number, and yield were not affected by water stress, indicating its suitability for production in water scarce environments. Using 60% ETc was suitable for the production of A. cruentus, C. olitorius and B. vulgaris var. cicla, whereas 30% ETc is recommended for V. unguiculata. The yield results of V. unguiculata indicate that it performs better, while the yield of A. cruentus and C. olitorius is comparable to that of B. vulgaris under similar conditions, indicating potential for marginal production. Full article
Open AccessArticle
Response to the Cold Stress Signaling of the Tea Plant (Camellia sinensis) Elicited by Chitosan Oligosaccharide
Agronomy 2020, 10(6), 915; https://doi.org/10.3390/agronomy10060915 - 26 Jun 2020
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Abstract
Cold stress caused by a low temperature is a significant threat to tea production. The application of chitosan oligosaccharide (COS) can alleviate the effect of low temperature stress on tea plants. However, how COS affects the cold stress signaling in tea plants is [...] Read more.
Cold stress caused by a low temperature is a significant threat to tea production. The application of chitosan oligosaccharide (COS) can alleviate the effect of low temperature stress on tea plants. However, how COS affects the cold stress signaling in tea plants is still unclear. In this study, we investigated the level of physiological indicators in tea leaves treated with COS, and then the molecular response to the cold stress of tea leaves treated with COS was analyzed by transcriptomics with RNA-Sequencing (RNA-Seq). The results show that the activity of superoxide dismutase (SOD) activity, peroxidase (POD) activity, content of chlorophyll and soluble sugar in tea leaves in COS-treated tea plant were significantly increased and that photosynthesis and carbon metabolism were enriched. Besides, our results suggest that COS may impact to the cold stress signaling via enhancing the photosynthesis and carbon process. Our research provides valuable information for the mechanisms of COS application in tea plants under cold stress. Full article
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Open AccessArticle
Different Summer and Autumn Water Deficit Affect the Floral Differentiation and Flower Bud Growth in Apricot (Prunus armeniaca L.)
Agronomy 2020, 10(6), 914; https://doi.org/10.3390/agronomy10060914 - 26 Jun 2020
Viewed by 311
Abstract
In deciduous fruit species, floral bud initiation, differentiation and organogenesis take place during the summer–autumn season that precedes anthesis. Among factors able to modify the regularity of these processes, water availability represents a crucial aspect. This investigation aimed to assess the influence of [...] Read more.
In deciduous fruit species, floral bud initiation, differentiation and organogenesis take place during the summer–autumn season that precedes anthesis. Among factors able to modify the regularity of these processes, water availability represents a crucial aspect. This investigation aimed to assess the influence of different summer and autumn water deficit and re-watering treatments on floral morphogenesis, xylem vessel differentiation and quality of flower buds. Trials were carried out on two-year-old potted apricot trees (cv. ‘Portici’) which were submitted to different regimes: (i) fully irrigated plants; (ii) stressed plants in June (S1), July (S2) and October (S3) followed to re-watering. Midday stem water potential was used to determine water status, and leaf gas exchanges were measured during trials. Histological analyses on floral differentiation, xylem progression within flower buds and biological observations were carried out. Both summer water stress periods affected the floral differentiation leading to a temporary shutdown. The S1 trees were able to recover the development of meristematic apices while S2 had a strong delay. All drought treatments caused a slower xylem progression, variations in bud size, blooming entity and flower anomalies. Results particularly highlights the importance of water availability also in early autumn. Full article
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Open AccessArticle
Genotype × Light Quality Interaction on Rose Architecture
Agronomy 2020, 10(6), 913; https://doi.org/10.3390/agronomy10060913 - 25 Jun 2020
Viewed by 460
Abstract
Plant shape, and thereby plant architecture, is a major component of the visual quality of ornamental plants. Plant architecture results from growth and branching processes and is dependent on genetic and environmental factors such as light quality. The effects of genotype and light [...] Read more.
Plant shape, and thereby plant architecture, is a major component of the visual quality of ornamental plants. Plant architecture results from growth and branching processes and is dependent on genetic and environmental factors such as light quality. The effects of genotype and light quality and their interaction were evaluated on rose bush architecture. In a climatic growth chamber, three cultivars (Baipome, Knock Out® Radrazz and ‘The Fairy’) with contrasting architecture were exposed to three different light spectra, using white (W), red (R), and far-red (FR) light-emitting diodes (LEDs), i.e., W, WR, and WRFR. The R/FR ratio varied between treatments, ranging from 7.5 for WRFR to 23.2 for WR. Light intensity (224.6 μmol m−2 s−1) was the same for all treatments. Plants were grown up to the order 1 axis flowering stage, and their architecture was digitized at two observation scales—plant and axis. Highly significant genotype and light quality effects were revealed for most of the variables measured. An increase in stem length, in the number of axes and in the number of flowered axes was observed under the FR enriched light, WRFR. However, a strong genotype × light quality interaction, i.e., a genotype-specific response was highlighted. More in-depth eco-physiological and biochemical investigations are needed to better understand rose behavior in response to light quality and thus identify the determinants of the genotype × light quality interaction. Full article
(This article belongs to the Special Issue Control of LED Lighting Based on Plant Physiological Principles)
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Open AccessArticle
Biochar Mitigates Combined Effects of Drought and Salinity Stress in Quinoa
Agronomy 2020, 10(6), 912; https://doi.org/10.3390/agronomy10060912 - 25 Jun 2020
Viewed by 393
Abstract
Abiotic stresses such as drought and salinity constantly threaten food security. Biochar as a soil amendment has the potential to ameliorate soil and alleviate drought and salinity stress. Multiple studies have been conducted to evaluate the effect of biochar in alleviating independent drought [...] Read more.
Abiotic stresses such as drought and salinity constantly threaten food security. Biochar as a soil amendment has the potential to ameliorate soil and alleviate drought and salinity stress. Multiple studies have been conducted to evaluate the effect of biochar in alleviating independent drought or salinity stress. However, the potential of biochar in mitigating the combined drought and salinity stress on plants has not been studied so far. Therefore, a pot experiment was conducted in the climate-controlled chamber with the objective to investigate the effect of biochar on growth, physiology, and yield of quinoa under independent and combined drought and salinity stress. Quinoa plants were subjected to three irrigation treatments i.e., full irrigation (FI), deficit irrigation (DI), and alternate root-zone drying irrigation (ARD), two saline water treatments (0 and 400 mM) and two levels of biochar (0% and 5% by weight). In the FI treatment, plants were irrigated daily to maintain pot water-holding capacity. In limited irrigation treatments, 70% water of FI was applied either to the whole pot in DI or to one side of the pot alternating in ARD, respectively. The results showed that combined drought and salinity stress drastically affected growth and performance of quinoa compared to the independent drought or salinity stress. However, soil amendment with biochar had positive effect in mitigating both independent and combined effect of drought and salinity on quinoa plants. Furthermore, biochar amendment in ARD under salinity significantly enhanced plant height, shoot biomass, and grain by 11.7%, 18.8%, and 10.2% as compared with DI under salinity, respectively. In addition, leaf photosynthetic rate (An) and stomatal conductance (gs) decreased under limited saline irrigation. Moreover, the interactive effect of biochar and ARD efficiently adjusted the balance between chemical signal (leaf ABA) and hydraulic signal (leaf water potential). Thus, intrinsic water use efficiency (WUEi) and yield in ARD were significantly enhanced compared to DI, especially under salinity stress. Overall, biochar in combination with ARD might be a wise approach for sustaining crop productivity in salt affected and drought stressed areas of the world to ensure food security. Full article
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Open AccessArticle
Biostimulatory Action of Arbuscular Mycorrhizal Fungi Enhances Productivity, Functional and Sensory Quality in ‘Piennolo del Vesuvio’ Cherry Tomato Landraces
Agronomy 2020, 10(6), 911; https://doi.org/10.3390/agronomy10060911 - 25 Jun 2020
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Abstract
Arbuscular mycorrhizal fungi (AMF) are a promising tool to improve plant nutrient use efficiency (NUE) and tolerance against abiotic stresses. Moreover, AMF can potentially increase plant productivity and reduce the negative externalities of the agricultural sector. Our study aimed to elucidate whether AMF [...] Read more.
Arbuscular mycorrhizal fungi (AMF) are a promising tool to improve plant nutrient use efficiency (NUE) and tolerance against abiotic stresses. Moreover, AMF can potentially increase plant productivity and reduce the negative externalities of the agricultural sector. Our study aimed to elucidate whether AMF (containing Rhizoglomus irregulare and Funneliformis mosseae) could positively affect not only tomato growth and productivity but also the nutritional and nutraceutical quality of yellow-pigmented type (‘Giagiù’) and red-pigmented type (‘Lucariello’) tomatoes (Solanum lycopersicum L.). These cherry tomatoes are landraces of the Protected Designation of Origin (PDO) ‘Pomodorino del Piennolo del Vesuvio’ (PPV), one of the most typical agricultural products of the Campania region (Southern Italy). AMF rose fruit yield by increasing the number of fruits per plant (+49% and +29% in ‘Giagiù’ and ‘Lucariello’, respectively) but not of the fruit mean mass. AMF increased lycopene (+40%), total ascorbic acid (TAA; +41%), alanine (+162%), gamma-Aminobutyric acid (GABA; +101%) and branched-chain amino acids (BCAAs; +53%) in ‘Lucariello’. In ‘Giagiù’, AMF increased calcium (+63%), zinc (+45%), ASP (+70%), GABA (+53%) and the essential amino acids arginine (+58%) and lysine (+45%), also indicating a genotype-specific response. In both landraces, AMF improved nutrient uptake and biosynthesis of important molecules involved in the control the oxidative stress and cellular pH. In addition to the beneficial effects of human health, the molecules influenced by the AMF treatment are expected to extend the shelf life of tomato fruits, thus further promoting the useful agronomic application of AMF for premium tomatoes marketed fresh or in pendulums (‘piennoli’). Full article
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Open AccessArticle
Compatibility between “Arbequina” and “Souri” Olive Cultivars May Increase Souri Fruit Set
Agronomy 2020, 10(6), 910; https://doi.org/10.3390/agronomy10060910 - 25 Jun 2020
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Abstract
The “Souri” olive cultivar, which is autochthonous to the eastern Mediterranean region, has been the major olive variety cultivated traditionally under rain-fed conditions in northern Israel. The aim of this study was to determine the optimal pollen donor for the olive cultivar Souri [...] Read more.
The “Souri” olive cultivar, which is autochthonous to the eastern Mediterranean region, has been the major olive variety cultivated traditionally under rain-fed conditions in northern Israel. The aim of this study was to determine the optimal pollen donor for the olive cultivar Souri in order to maximize Souri fruit set. Artificial cross pollination of Souri flowers with several local varieties has identified the “Nabali” as the most efficient pollinizer of the Souri. However, further experiments using artificial cross pollination conducted with cultivars not common to this region have revealed the “Arbequina” as a more efficient pollinizer of the Souri cultivar than the Nabali. Based on a preliminary paternity analysis, the Nabali was identified as the dominant pollinizer of Souri trees in traditional olive orchards in the north of Israel. However, in a multi-variety orchard, molecular paternity analysis has shown Arbequina to be the most frequent pollinizer. We then tested, during two consecutive years, whether the presence of a pollen-producing Arbequina tree adjoining Souri trees in the field will increase their fruit set. We found that Souri fruit set was 8.36% when pollinized by an Arbequina tree in close proximity to them, significantly higher than the fruit set of 5.6% for Souri trees without the nearby Arbequina cultivar. On the basis of these trials, we expect that the yield of Souri orchards will improve if Arbequina trees are planted. Full article
(This article belongs to the Special Issue Mediterranean Olive Trees and Olive Oil under Climate Change)
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Open AccessArticle
Morphological and Chemical Traits as Quality Determinants of Common Thyme (Thymus vulgaris L.), on the Example of ‘Standard Winter’ Cultivar
Agronomy 2020, 10(6), 909; https://doi.org/10.3390/agronomy10060909 - 25 Jun 2020
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Abstract
Common thyme is regarded as one of the most important culinary plants. The purpose of the work was to determine the intraspecific variability of common thyme with respect to morphological and chemical characters including the content and composition of essential oil and phenolic [...] Read more.
Common thyme is regarded as one of the most important culinary plants. The purpose of the work was to determine the intraspecific variability of common thyme with respect to morphological and chemical characters including the content and composition of essential oil and phenolic compounds in the herb. The objects of the study were 12 clones, vegetatively multiplied from randomly selected individual plants of cultivar ‘Standard Winter’. The morphological observations and harvest of raw materials were carried out in the first year plants’ vegetation. The highest differences between clones were on fresh and dry weight of herb (CV = 0.38 and 0.36, respectively), width of leaves (CV = 0.21), and density of glandular trichomes on the abaxial surface of leaves (CV = 0.29). Examined clones were also differentiated as to the chemical features. Essential oil content (performed by hydrodestillation) and composition (by GC-MS and GC-FID) were determined and they ranged from 2.10 to 4.38 g × 100 g−1 DW. Here, thymol, γ-terpinen, and p-cymen were the dominant compounds. Clone no. 4 was distinctive as to the highest content of essential oil followed by the highest share of thymol (54.59%). The total content of phenolic acids and flavonoids (determined according to PPh 6th) also differed among clones (CV = 0.38 and 0.36, respectively). Using a validated HPLC-DAD method, the following compounds were identified: caffeic, rosmarinic, p-coumaric acids, luteolin 7-O-glucoside, naryngenin, and (−)-epicatechin. Here, rosmarinic acid followed by luteolin 7-O-glucoside were present in the highest amounts (611.47–2675.59 and 46.77–325.11 mg × 100 g−1 DW, respectively). The highest differences between clones were the contents of p-coumaric acid (CV = 0.59), luteolin 7-O-glucoside (CV = 0.50) and rosmarinic acid (CV = 0.40). Such a high range of variability can provide problems with raw material standardization. Nevertheless, it opens possibilities for breeders, whereas individual plants/clones may become valuable components for breeding. Full article
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Open AccessArticle
Different Ground Vegetation Cover Management Systems to Manage Cynodon dactylon in an Irrigated Vineyard
Agronomy 2020, 10(6), 908; https://doi.org/10.3390/agronomy10060908 - 25 Jun 2020
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Abstract
Ground cover management in vineyards in Spain is focused on minimizing soil erosion and compaction. Such practices have influenced the weed community structure in the inter-rows, contributing to the spread of the high noxious weed Cynodon dactylon (L.) Pers. This fact highlights the [...] Read more.
Ground cover management in vineyards in Spain is focused on minimizing soil erosion and compaction. Such practices have influenced the weed community structure in the inter-rows, contributing to the spread of the high noxious weed Cynodon dactylon (L.) Pers. This fact highlights the need for further investigation of the interaction between ground cover practices and weed control techniques. In this study, the effect of four different ground cover managements (M) in the inter-rows on C. dactylon population dynamics (changes in coverage and frequency) was assessed over three seasons (2015–2017): (M1) a no-till spontaneous vegetation ground cover managed by shredding; (M2) a no-till spontaneous vegetation ground cover managed by shredding plus herbicide application, (M3) tilled soil and spontaneous vegetation growing; and (M4) tilled soil and a barley cover crop seeded (Hordeum vulgare L.). Cynodon dactylon and the other weeds responded differently to the various weed control methods. After three seasons, the barley cover crop was the most efficient management system to control C. dactylon and other weeds. Final soil cover in barley cover crop and tilled soil with spontaneous vegetation were 0.5% and 1.1%, respectively, compared to 3.7% and 7.7% obtained by spontaneous vegetation shredded with and without herbicide application, respectively. In addition, total weed frequency varied from 9.7% for barley cover crop to 45.8% for spontaneous vegetation only shredded. Weed community composition changed due to the pressure exerted by each management and the adaptive strategy of the different species. This study highlights the importance of knowledge of how vegetation management influences weed flora to improve the sustainability of wine grape production systems. Full article
(This article belongs to the Special Issue Weed Management & Sustainable Agriculture)
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Open AccessArticle
Hemp-Based Phytoaccumulation of Heavy Metals from Municipal Sewage Sludge and Phosphogypsum Under Field Conditions
Agronomy 2020, 10(6), 907; https://doi.org/10.3390/agronomy10060907 - 25 Jun 2020
Viewed by 331
Abstract
The aim of this study was to evaluate the ability of three hemp cultivars to accumulate heavy metals under sewage sludge (SS) and phosphogypsum (PG) application. The field study was carried out from 2014 to 2016 on Luvisol (loamy sand) in Poland. The [...] Read more.
The aim of this study was to evaluate the ability of three hemp cultivars to accumulate heavy metals under sewage sludge (SS) and phosphogypsum (PG) application. The field study was carried out from 2014 to 2016 on Luvisol (loamy sand) in Poland. The experiment scheme included five treatments—T0: the control without fertilization, T1: 170 kg N (nitrogen) ha−1 from sewage sludge, T2: 170 kg N ha−1 from sewage sludge and 100 kg ha−1 of phosphogypsum, T3: 170 kg N ha−1 from sewage sludge and 500 kg ha−1 of phosphogypsum, and T4: 170 kg N ha−1 from sewage sludge and 1000 kg ha−1 of phosphogypsum. It was found that the application of municipal sewage sludge enriched the soil with the bioavailable forms of heavy metals to the greatest extent and contributed to the highest increase in their contents in vegetative and generative organs of hemp plants. These parameters showed a phosphogypsum dose-dependent decline, which could hinder the phytoextraction process. The greatest extractions of heavy metal(loid)s (HMs) from the soil treated with SS and PG were achieved by the Tygra variety, which had the highest bioconcentration factor (BCF) and biomass yield. Full article
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Open AccessArticle
Betaine Hydrochloride Treatment Affects Growth and Phenylpropanoid Accumulation in Tartary Buckwheat (Fagopyrum tataricum) Seedlings under Salt Stress
Agronomy 2020, 10(6), 906; https://doi.org/10.3390/agronomy10060906 - 25 Jun 2020
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Abstract
Betaine is one of the most competitive compounds that accumulate in different cellular compartments to adjust osmotic balance. Among the various stressors, salinity stress often leads to osmotic and ionic stress in plants, either increasing or decreasing certain secondary plant metabolites. In this [...] Read more.
Betaine is one of the most competitive compounds that accumulate in different cellular compartments to adjust osmotic balance. Among the various stressors, salinity stress often leads to osmotic and ionic stress in plants, either increasing or decreasing certain secondary plant metabolites. In this study, different concentrations of NaCl, betaine, and combined NaCl and betaine were used in time-course experiments to investigate growth pattern variation and accumulation of phenylpropanoid compounds in buckwheat sprouts. A significant increase in growth was observed with the application of 0.1–1.0 mM betaine. Although overall, the total phenylpropanoid compounds were lower compared to the control, the sole application of 50 mM NaCl and 1.0 mM betaine especially enhanced the accumulation of some of these compounds in comparison to others. Betaine application at lower concentrations was found to enhance the growth of buckwheat sprouts slightly. The results of this study show that phenylpropanoid content did not increase significantly in any of the treatments. However, it was proven that the phenylpropanoid biosynthetic pathway is stimulated under abiotic stress, resulting in a higher accumulation of various phenylpropanoid compounds. This suggests that the level of accumulation of phenylpropanoid compounds due to abiotic stress may be species-dependent. Full article
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Open AccessArticle
Proposed Techniques to Supplement the Loss in Nutrient Cycling for Replanted Coffee Plantations in Vietnam
Agronomy 2020, 10(6), 905; https://doi.org/10.3390/agronomy10060905 - 25 Jun 2020
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Abstract
Nutrient cycling of the coffee ecosystem is often characterized by nutrient losses during the harvest, tree’s growth, leaching and erosion. The “Coffee Rejuvenation Strategies in Vietnam” has risked not being complete on schedule, with the low survival rate of seedlings on replanted soil, [...] Read more.
Nutrient cycling of the coffee ecosystem is often characterized by nutrient losses during the harvest, tree’s growth, leaching and erosion. The “Coffee Rejuvenation Strategies in Vietnam” has risked not being complete on schedule, with the low survival rate of seedlings on replanted soil, due to the nutrient loss and imbalance supplements after a long-term of monoculture and intensive cultivation. In this study, measures, including biochemical and organic treatments were applied to replanted coffee farm, in order to supplement the loss of nutrient cycling. Survival rate, growth indicators, and soil properties from the controls and treatments, were monitored and compared during the experimental periods. The results suggested the optimal tillage model as follow: Remove old coffee trees with their stumps and roots; liming 1.5 tons/ha; dry tillage soil for the first 6 months; Intercrop Mexican marigold (Tagetes erecta) with new coffee plants for the next 6 months; From the second year, apply 5 kg of microbial organic fertilizer /hole/year; bury 30 kg of green manure/hole/2–3 years; apply NPK fertilizers according to the governmental recommended procedure. This would be a proposed integrating tillage method to supplement the lost nutrients and restore the fertility of replanted coffee soil in Vietnam. Full article
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Open AccessArticle
Integrating Biochar and Inorganic Fertilizer Improves Productivity and Profitability of Irrigated Rice in Ghana, West Africa
Agronomy 2020, 10(6), 904; https://doi.org/10.3390/agronomy10060904 - 25 Jun 2020
Viewed by 295
Abstract
The efficiency of mineral fertilizer use in most soils in Sub-saharan Africa is low. Prominent among the reasons for this is low soil carbon stock. In this study, we hypothesized that in the short term, combined use of biochar and inorganic fertilizer in [...] Read more.
The efficiency of mineral fertilizer use in most soils in Sub-saharan Africa is low. Prominent among the reasons for this is low soil carbon stock. In this study, we hypothesized that in the short term, combined use of biochar and inorganic fertilizer in irrigated rice (Oryza sativa var KRC Baika) cropping systems will increase soil organic carbon storage, N recovery and agronomic efficiency of N use (above world average of 55% and 20 kg grain·kg−1·N respectively) and improved economic returns compared to the sole use of inorganic fertilizer. A two-year (4‒cropping cycles) field trial was, thus, conducted on a Vertisol. The experiments were designed as split–plot with two (0 and 10 t·ha−1) biochar and four (0, 45, 90, 120 kg·ha−1·N) nitrogen application rates. Additionally, the effect of biochar on the chemical properties of the soil was investigated using standard protocols. Biochar application improved the soil organic carbon storage in the topsoil. There were significant interactions between the application of biochar and nitrogen fertilizer on yield parameters. Introducing biochar significantly increased root volume and nutrient (N, P and K) uptake, resulting in increased grain and straw yield. Grain yields under biochar amended plots were higher than sole fertilizer amended plots in 14 out of 16 instances (cropping cycles × N rates). The increase in grain yield was between 12 to 29% across N rates. Biochar amendment also enhanced agronomic N use and apparent N recovery efficiencies in 3 out of the 4 cropping cycles. Gross margin indicated that biochar application under irrigated rice cropping systems is economically feasible in all cropping cycles and N rates. However, the value cost ratio of biochar application was higher than for sole inorganic fertilizer in three out of the four cropping cycles (each cropping cycle has three N rates). The soil organic carbon storage of biochar amended soil increased by 17% under unfertilized condition and by 32% under fertilized condition. To enable the promotion and efficient use of the biochar technology in enhancing productivity and profitability in irrigated rice, extension officers and farmers will need to be trained on how to char the rice husk to reduce emissions prior to upscaling the technology to farmers. Full article
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Open AccessArticle
Response of Upland Rice (Oryza sativa L.) Inoculated with Non-Native Plant Growth-Promoting Bacteria
Agronomy 2020, 10(6), 903; https://doi.org/10.3390/agronomy10060903 - 25 Jun 2020
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Abstract
A deep-rooting upland rice variety (Kinandang Patong) was evaluated for its growth response to bio-fertilization at early stages. Five non-native plant growth-promoting bacteria previously isolated from yams (Dioscorea spp.) were inoculated to upland rice under growth chamber and greenhouse conditions. Effects of [...] Read more.
A deep-rooting upland rice variety (Kinandang Patong) was evaluated for its growth response to bio-fertilization at early stages. Five non-native plant growth-promoting bacteria previously isolated from yams (Dioscorea spp.) were inoculated to upland rice under growth chamber and greenhouse conditions. Effects of the inoculation varied depending on bacterial strains and growing conditions. Growth of 14-day rice seedlings was improved by all tested bacterial strains. Under growth chamber, the strain S-333 increased plant length, shoot dry weight and nitrogen content as compared to the control, but total dry weight, nitrogen uptake, leaf chlorophyll content and number of tillers were higher with N fertilizer application. Under greenhouse conditions, most rice growth parameters were improved by inoculation with the strain S-7. The correlations between the bacterial plant-growth-promoting traits and rice growth parameters under growth chamber conditions were all negative for phosphate solubilization indexes. Our results suggest that bacterial inoculation can replace half (S-343 and S-611) of or the full (S-7) rate of chemical N fertilizer required, depending on bacterial strains and growing environments, although δ15N value in control plants was lower than in inoculated plants under growth chamber conditions, suggesting that the bacteria improve rice growth through mechanisms other than biological nitrogen fixation. Full article
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Open AccessArticle
Energy, Production and Environmental Characteristics of a Conventional Weaned Piglet Farm in North West Spain
Agronomy 2020, 10(6), 902; https://doi.org/10.3390/agronomy10060902 - 25 Jun 2020
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Abstract
Postweaning is one of the most sensitive and energy-demanding phases of swine production. The objective of this research was to assess the energy, production and environmental characteristics of a conventional farm with temperature-based environmental control. The selected energy, environmental and production variables were [...] Read more.
Postweaning is one of the most sensitive and energy-demanding phases of swine production. The objective of this research was to assess the energy, production and environmental characteristics of a conventional farm with temperature-based environmental control. The selected energy, environmental and production variables were measured on farm, in a high livestock density area of NW Spain, for seven production cycles. The quantification of variables was aimed at obtaining the maximum performance with the lowest possible use of resources, focusing on animal welfare and production efficiency. The Brown–Forsythe, Welch and Games-Howell tests revealed significant differences in terms of temperature, relative humidity and CO2 concentrations among production cycles, and among the critical, postcritical and final periods. Improved humidity management resulted in a 17% reduction of climate control energy, which involved energy savings in the range of 33% to 47% per kg produced at the end of the postweaning cycle. Accordingly, adding humidity as a control variable could result in higher ventilation rates, thereby improving animal welfare, reducing heating energy use and increasing weight gain per unit climate control energy. In addition, the strong correlations found between heating energy and relative humidity (R2 = 0.73) and ventilation energy and CO2 (R2 = 0.99) suggest that these variables could be readily estimated without additional sensor costs. Full article
(This article belongs to the Section Agricultural Engineering)
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Open AccessArticle
Integration of Extra-Large-Seeded and Double-Podded Traits in Chickpea (Cicer arietinum L.)
Agronomy 2020, 10(6), 901; https://doi.org/10.3390/agronomy10060901 - 24 Jun 2020
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Abstract
A large seed size in the kabuli chickpea (Cicer arietinum L.) is important in the market not only due to its high price but also for its superior seedling vigor. The double-podded chickpea has a considerable yield and stability advantage over the [...] Read more.
A large seed size in the kabuli chickpea (Cicer arietinum L.) is important in the market not only due to its high price but also for its superior seedling vigor. The double-podded chickpea has a considerable yield and stability advantage over the single-podded chickpea. The study aimed at (i) integrating extra-large-seeded and double-podded traits in the kabuli chickpea, (ii) increasing variation by transgressive segregations and (iii) estimating the heritability of the 100-seed weight along with important agro-morphological traits in F2 and F3 populations. For these objectives, the large-seeded chickpea, Sierra, having a single pod and unifoliolate leaves, was crossed with the small-seeded CA 2969, having double pods and imparipinnate leaves. The inheritance pattern of the extra-large-seeded trait was polygenically controlled by partial dominant alleles. Transgressive segregations were found for all agro-morphological traits. Some progeny with 100-seed weights of ≥55 g and two pods had larger seed sizes than those of the best parents. As outputs of the epistatic effect of the double-podded gene in certain genetic backgrounds, three or more flowers or pods were found in some progeny. Progeny having imparipinnate leaves or two or more pods should be considered in breeding, since they had higher numbers of pods and seeds per plant and seed yields than their counterparts. Full article
(This article belongs to the Special Issue Genetics, Genomics, and Breeding of Legume Crops)
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Open AccessArticle
Humboldtian Diagnosis of Peach Tree (Prunus persica) Nutrition Using Machine-Learning and Compositional Methods
Agronomy 2020, 10(6), 900; https://doi.org/10.3390/agronomy10060900 - 24 Jun 2020
Viewed by 292
Abstract
Regional nutrient ranges are commonly used to diagnose plant nutrient status. In contrast, local diagnosis confronts unhealthy to healthy compositional entities in comparable surroundings. Robust local diagnosis requires well-documented data sets processed by machine learning and compositional methods. Our objective was to customize [...] Read more.
Regional nutrient ranges are commonly used to diagnose plant nutrient status. In contrast, local diagnosis confronts unhealthy to healthy compositional entities in comparable surroundings. Robust local diagnosis requires well-documented data sets processed by machine learning and compositional methods. Our objective was to customize nutrient diagnosis of peach (Prunus persica) trees at local scale. We collected 472 observations from commercial orchards and fertilizer trials across eleven cultivars of Prunus persica and six rootstocks in the state of Rio Grande do Sul (RS), Brazil. The random forest classification model returned an area under curve exceeding 0.80 and classification accuracy of 80% about yield cutoff of 16 Mg ha−1. Centered log ratios (clr) of foliar defective compositions have appropriate geometry to compute Euclidean distances from closest successful compositions in “enchanting islands”. Successful specimens closest to defective specimens as shown by Euclidean distance allowed reaching trustful fruit yields using site-specific corrective measures. Comparing tissue composition of low-yielding orchards to that of the closest successful neighbors in two major Brazilian peach-producing regions, regional diagnosis differed from local diagnosis, indicating that regional standards may fail to fit local conditions. Local diagnosis requires well-documented Humboldtian data sets that can be acquired through ethical collaboration between researchers and stakeholders. Full article
(This article belongs to the Special Issue Mineral Nutrition of Fruit Trees)
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Open AccessArticle
Plant Performance and Metabolomic Profile of Loquat in Response to Mycorrhizal Inoculation, Armillaria mellea and Their Interaction
Agronomy 2020, 10(6), 899; https://doi.org/10.3390/agronomy10060899 - 24 Jun 2020
Viewed by 324
Abstract
A greenhouse experiment was established with loquat plants to investigate the role of arbuscular mycorrhizal fungi (AMF) in the control of the white root rot fungus Armillaria mellea and to determine the changes produced in the plant metabolome. Plants inoculated with two AMF, [...] Read more.
A greenhouse experiment was established with loquat plants to investigate the role of arbuscular mycorrhizal fungi (AMF) in the control of the white root rot fungus Armillaria mellea and to determine the changes produced in the plant metabolome. Plants inoculated with two AMF, Rhizoglomus irregulare and a native AMF isolate from loquat soils, were infected with Armillaria. Although mycorrhization failed to control the Armillaria root infection, the increased growth of infected plants following inoculation with the native mycorrhizal isolate suggests an initial tolerance towards Armillaria. Overall, metabolomics allowed highlighting the molecular basis of the improved plant growth in the presence of Armillaria following AMF colonization. In this regard, a wide and diverse metabolic response was involved in the initial tolerance to the pathogen. The AMF-mediated elicitation altered the hormone balance and modulated the production of reactive oxygen species (mainly via the reduction of chlorophyll intermediates), possibly interfering with the reactive oxygen species (ROS) signaling cascade. A complex modulation of fucose, ADP-glucose and UDP-glucose, as well as the down-accumulation of lipids and fatty acids, were observed in Armillaria-infected plants following AMF colonization. Nonetheless, secondary metabolites directly involved in plant defense, such as DIMBOA and conjugated isoflavone phytoalexins, were also involved in the AMF-mediated plant response to infection. Full article
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Open AccessArticle
Effect of Bacterial Strains Isolated from Stored Shiitake (Lentinula edodes) on Mushroom Biodeterioration and Mycelial Growth
Agronomy 2020, 10(6), 898; https://doi.org/10.3390/agronomy10060898 - 24 Jun 2020
Viewed by 234
Abstract
Shiitake (Lentinula edodes) is a fungus that attracts the attention of consumers and researchers due to its flavour and bioactive compounds with biological activities. However, it swiftly loses quality because of its short shelf life. The present work evaluated the shelf [...] Read more.
Shiitake (Lentinula edodes) is a fungus that attracts the attention of consumers and researchers due to its flavour and bioactive compounds with biological activities. However, it swiftly loses quality because of its short shelf life. The present work evaluated the shelf life of cultivated shiitake carpophores with a weekly monitoring of the physico-chemical, microbiological, and sensory parameters under three different storage conditions. To establish the mycopathogenicity of fruitbody-inhabiting bacterial microbiota, 48 strains were isolated from shiitake throughout its storage time and subsequently inoculated on cap cuticles and slices. Additionally, an antibiogram of these bacterial strains against shiitake mycelium was performed. Shiitake had a total microbial load of 5 log cfu/g, composed mainly of Pseudomonas genus, followed by Enterobacteriaceae family, and moulds and yeasts. Among the 48 bacterial strains identified, 18 belonged to the Enterobacteriaceae family and 21 to the Pseudomonas genus. The biodeterioration capacity of the isolated strains increased throughout the conservation period, with slices being more damaged than cap cuticles. We observed a mycopathogenic behaviour of Burkholderia sp., Ewingella americana, Serratia sp., Microbacterium sp. and Rahnella sp. strains, although only the latter highly inhibited shiitake vegetative mycelium growth. Full article
(This article belongs to the Special Issue Research Progress on Added-Value Edible Fungi)
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Open AccessArticle
Manipulation of Fruit Dry Matter via Seasonal Pruning and Its Relationship to d’Anjou Pear Yield and Fruit Quality
Agronomy 2020, 10(6), 897; https://doi.org/10.3390/agronomy10060897 - 24 Jun 2020
Viewed by 317
Abstract
Orchard-side optimization of fruit quality is experiencing renewed research focus in the fresh fruit industry as new technologies and quality metrics have emerged to enhance consumer acceptance and satisfaction. Fruit dry matter, one such quality index gaining traction among numerous fresh fruit commodities, [...] Read more.
Orchard-side optimization of fruit quality is experiencing renewed research focus in the fresh fruit industry as new technologies and quality metrics have emerged to enhance consumer acceptance and satisfaction. Fruit dry matter, one such quality index gaining traction among numerous fresh fruit commodities, was targeted for improvement in d’Anjou pear with the application of seasonal pruning cycles (fall, fall and summer, winter, and winter and summer) across two growing seasons in 2016 and 2017 in a mid-aged, traditionally managed commercial orchard in the Columbia basin, Washington, USA. Dry matter was assessed non-destructively on pears using near-infrared spectroscopy at harvest and fruit categorized in to low (<13%), moderate (13–16%), and high (>16%) dry matter quality categories, revealing that fall pruning positively impacted average predicted fruit dry matter in comparison to winter pruning (15.1 vs. 14.2% in 2016 and 13.7 vs. 13.1% predicted dry matter in 2017 for winter vs. fall pruning, respectively), as well in the abundance of high dry matter fruits. The addition of summer pruning to either fall or winter pruning increased fruit size by up to 13% of proportion of fruits 80 mm or greater in diameter. Further, a tendency for summer pruning to decrease yield (up to nearly 30 kg/tree lower yields), average fruit dry matter (up to 0.5% lower average predicted dry matter), and abundance of high dry matter fruits (up to 11% fewer high predicted dry matter fruits) was observed. Fruit quality classes assembled on predicted dry matter verified the utility of this emerging parameter as a fruit quality metric for pears as demonstrated by more desirable post-harvest eating characteristics such as higher soluble solids content corresponding to greater at-harvest predicted dry matter categories. Targeted seasonal pruning in association with precise at-harvest dry matter fruit sorting may preserve the profitability of pear cultivation through their impact on fruit quality and associated consumer experiences. Full article
(This article belongs to the Special Issue In-Field Estimation of Fruit Quality and Quantity)
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Open AccessArticle
Co-Regulation of Long Non-Coding RNAs with Allele-Specific Genes in Wheat Responding to Powdery Mildew Infection
Agronomy 2020, 10(6), 896; https://doi.org/10.3390/agronomy10060896 - 24 Jun 2020
Viewed by 265
Abstract
Powdery mildew (caused by Blumeria graminis f. sp. tritici; Bgt) is an important fungal disease of wheat (Triticum aestivum) worldwide, and results in significant crop damage in epidemic years. Understanding resistance mechanisms could have undoubted benefits in controlling disease [...] Read more.
Powdery mildew (caused by Blumeria graminis f. sp. tritici; Bgt) is an important fungal disease of wheat (Triticum aestivum) worldwide, and results in significant crop damage in epidemic years. Understanding resistance mechanisms could have undoubted benefits in controlling disease and minimizing crop losses. The recent explosion in genomic knowledge and the discovery of noncoding RNAs have led to the idea that long ncRNAs (lncRNAs) might be key regulators of protein-coding gene expression. However, in-depth functional analyses of lncRNAs in wheat remain limited. Here, we evaluated the possible role of lncRNAs in regulating functional genes in wheat responding to Bgt pathogen, using genome-wide transcriptome data and quantitative RT-PCR. Our results demonstrated that both long intron ncRNAs (linncRNA) and long intergenic ncRNAs (lincRNAs) play roles in regulating allele-specific genes, including transcription factors, both positively and negatively. The correlation of expression between lincRNAs and flanking functional genes increased as the spacing distance decreased. Co-expression of microRNAs, their target lncRNA and target functional genes showed that lincRNA interacted competitively with functional genes via miRNA regulation. These results will be beneficial for further dissecting molecular mechanisms of lncRNAs functions at the transcriptional and post-transcriptional levels in wheat. Full article
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Open AccessArticle
Soybean Fertilized by P-Phases from Bagasse-Based Materials: P-Extraction Procedures, Diffusive Gradients in Thin Films (DGT), and X-ray Diffraction Analysis (XRD)
Agronomy 2020, 10(6), 895; https://doi.org/10.3390/agronomy10060895 - 23 Jun 2020
Viewed by 509
Abstract
The Brazilian sugarcane industry produced around 173 million tons (Mt) of bagasse in 2018. Bagasse is a by-product of juice extraction for ethanol and sugar production and is combusted in order to generate power, producing up to 10 Mt of ash per year. [...] Read more.
The Brazilian sugarcane industry produced around 173 million tons (Mt) of bagasse in 2018. Bagasse is a by-product of juice extraction for ethanol and sugar production and is combusted in order to generate power, producing up to 10 Mt of ash per year. This ash contains various concentrations of plant nutrients, which allow the ash to be used as a crop fertilizer. However, the concentration and extractability of phosphorus (P), an essential plant nutrient, are low in bagasse ash. To increase the P content, we co-gasified and co-combusted bagasse with P-rich chicken manure. The resulting ash was thermochemically post-treated with alkali additives (Na2SO4 and K2SO4) to increase the availability of P to plants. We aimed to: (i) investigate the effect of thermochemical post-treatment of co-gasification residue and co-combustion ash on P availability to soybeans, (ii) explore the potential of chemical extraction methods (citric acid, neutral ammonium citrate, formic acid, and Mehlich-I) and diffusive gradients in thin films (DGT) to predict the availability of P to soybeans, and (iii) identify the responsible P-phases using X-ray diffraction. We evaluated P availability to soybeans growing in Brazilian Oxisol soil in two independent greenhouse pot experiments. The positive effect of thermochemical treatment on P availability from gasification residue was confirmed through the observation of increased P uptake and biomass in soybean plants. These findings were confirmed by chemical extraction methods and DGT. The gasification residue contained whitlockite as its main P-bearing phase. Thermochemical post-treatment converted whitlockite into highly soluble CaNaPO4. In contrast, co-combustion ash already contained highly soluble Ca(Na,K)PO4 as its main P-bearing phase, making thermochemical post-treatment unnecessary for increasing P availability. In conclusion, increased extractability and availability of P for soybeans were closely connected to the formation of calcium alkali phosphate. Our findings indicate that this combined methodology allows for the prediction of P-fertilization effects of ash. Full article
(This article belongs to the Section Soil and Plant Nutrition)
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Open AccessArticle
Study of the Mechanics and Micro-Structure of Wheat Straw Returned to Soil in Relation to Different Tillage Methods
Agronomy 2020, 10(6), 894; https://doi.org/10.3390/agronomy10060894 - 23 Jun 2020
Viewed by 293
Abstract
A field experiment was conducted to study the effects of different tillage methods, and their interaction on the dynamic changes of straw decomposition rate, mechanical properties, and micro-structure of the stalk. A nylon mesh bag technique was used. An obvious change was observed [...] Read more.
A field experiment was conducted to study the effects of different tillage methods, and their interaction on the dynamic changes of straw decomposition rate, mechanical properties, and micro-structure of the stalk. A nylon mesh bag technique was used. An obvious change was observed in the decomposition rate of straw, and its mechanical, and micro-structural properties. The decomposition rate of straw was increased in all tillage treatments. Specifically, it increased consistently in conventional and dry rotary tillage, and sharply in wet rotary tillage. Furthermore, for all tillage, the mechanical properties like shear and bending strengths decreased sharply while compressive strength first decreased linearly and then increased, whereas the micro-structure of wheat straw showed a fluctuating trend, i.e., it changed neither regularly nor consistently over time. Moreover, the micro-structure of the stalk explained the morphological changes to the straw that returned to the field, which may impact the mechanical properties. However, these changes could not explain the degradation trend of straw directly. The findings of the study could be used as a theoretical reference for the design of tillage and harvesting machinery keeping in view soil solidification and compaction dynamics. Full article
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Open AccessArticle
Assessing the Orange Tree Crown Volumes Using Google Maps as a Low-Cost Photogrammetric Alternative
Agronomy 2020, 10(6), 893; https://doi.org/10.3390/agronomy10060893 - 23 Jun 2020
Viewed by 377
Abstract
The accurate assessment of tree crowns is important for agriculture, for example, to adjust spraying rates, to adjust irrigation rates or even to estimate biomass. Among the available methodologies, there are the traditional methods that estimate with a three-dimensional approximation figure, the HDS [...] Read more.
The accurate assessment of tree crowns is important for agriculture, for example, to adjust spraying rates, to adjust irrigation rates or even to estimate biomass. Among the available methodologies, there are the traditional methods that estimate with a three-dimensional approximation figure, the HDS (High Definition Survey), or TLS (Terrestrial Laser Scanning) based on LiDAR technology, the aerial photogrammetry that has re-emerged with unmanned aerial vehicles (UAVs), as they are considered low cost. There are situations where either the cost or location does not allow for modern methods and prices such as HDS or the use of UAVs. This study proposes, as an alternative methodology, the evaluation of images extracted from Google Maps (GM) for the calculation of tree crown volume. For this purpose, measurements were taken on orange trees in the south of Spain using the four methods mentioned above to evaluate the suitability, accuracy, and limitations of GM. Using the HDS method as a reference, the photogrammetric method with UAV images has shown an average error of 10%, GM has obtained approximately 50%, while the traditional methods, in our case considering ellipsoids, have obtained 100% error. Therefore, the results with GM are encouraging and open new perspectives for the estimation of tree crown volumes at low cost compared to HDS, and without geographical flight restrictions like those of UAVs. Full article
(This article belongs to the Special Issue Precision Agriculture for Sustainability)
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Open AccessArticle
Metabolomic Analysis for Compositional Differences of Bush Tea (Athrixia phylicoides DC.) Subjected to Seasonal Dynamics
Agronomy 2020, 10(6), 892; https://doi.org/10.3390/agronomy10060892 - 23 Jun 2020
Viewed by 234
Abstract
Bush tea (Athrixia phylicoides DC.) is a South African indigenous herbal tea rich in secondary metabolites with medicinal significance. However, studies on the effects of seasonal changes on bush tea and quantification of its metabolites using untargeted approach have not been explored. [...] Read more.
Bush tea (Athrixia phylicoides DC.) is a South African indigenous herbal tea rich in secondary metabolites with medicinal significance. However, studies on the effects of seasonal changes on bush tea and quantification of its metabolites using untargeted approach have not been explored. Therefore, this study’s objective was to investigate the effects of seasonal variation on the metabolites of bush tea using LC-MS/MS (Liquid Chromatography with Tandem Mass Spectrometry) and 1H NMR (High-Resolution Proton Nuclear Magnetic Resonance) techniques. Bush tea leaves were plucked once in each season namely, autumn (March to May), winter (June to August), spring (September to November), and summer (December to February). The primary metabolites including non-essential amino acids, organic acids, and vitamins in bush tea were predominantly elevated during summer and spring. The 1H NMR-based metabolomic analysis revealed that bush tea metabolome was strongly affected by seasonal variations, using the partial least squares-discriminant analysis (PLS-DA) which demonstrated four distinct groups of seasons. Similarly, the 1H NMR based metabolic profiling of bush tea subjected to different seasons resulted in putative annotation of six phenolic compounds which included rutin, 4-(hydroxyphenyl) propyl coumarate, caffeic acid, hymenoxin, quercetin, and kaempferol. The phenolics and primary metabolites differed remarkably per season with enhanced accumulation observed in the summer and spring harvested bush tea. The LC-MS and 1H NMR metabolomics analysis suggests that summer and spring can be recommended as preferred plucking seasons for bush tea leaves and twigs. Full article
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Open AccessCommunication
Effect of Bead Composition, PVS Type, and Recovery Medium in Cryopreservation of Bleeding Heart ‘Valentine’—Preliminary Study
Agronomy 2020, 10(6), 891; https://doi.org/10.3390/agronomy10060891 - 23 Jun 2020
Viewed by 254
Abstract
Bleeding heart (Lamprocapnos spectabilis (L.) Fukuhara) is a valuable ornamental and medicinal perennial. To date, there are few studies focused on cryopreservation of this species, although it could be useful in storage and breeding. This research is aimed at analyzing the effect [...] Read more.
Bleeding heart (Lamprocapnos spectabilis (L.) Fukuhara) is a valuable ornamental and medicinal perennial. To date, there are few studies focused on cryopreservation of this species, although it could be useful in storage and breeding. This research is aimed at analyzing the effect of bead composition, type of plant vitrification solution (PVS), and the recovery medium of cryopreservation of bleeding heart. Shoot tips of L. spectabilis ‘Valentine’ were used in the study. The explants were precultured on modified Murashige and Skoog medium (MS; 1962), supplemented with 9% sucrose, 1.0-mg·L−1 kinetin (KIN), and 2.62-mg·L−1 abscisic acid. Next, in the first experiment, the shoot tips were embedded in 3% calcium alginate, based either on an MS medium or distilled sterile water. The produced synseeds were inoculated on the recovery medium with 3.0-mg·L−1 KIN, 0.5-mg·L−1 6-benzyladenine (BA), or cytokinin–free control. Based on the results of the first study, in the second experiment, precultured shoot tips were embedded in 3% calcium alginate based on MS medium and dehydrated with PVS2 or PVS3 for various durations. The pre-treated explants were plunged in liquid nitrogen and, after rewarming, inoculated on the recovery MS medium with 0.5-mg·L−1 BA. PVS3 was more effective in securing the shoot tips than PVS2. The highest recovery level (68.3%) was reported after a 150-min pretreatment with PVS3. Explants from this experimental combination also proliferated the highest number of shoots, as well as those with the greatest length. On the other hand, a higher share of dry weight was found in PVS2-derived shoots (13.5–18.2%) compared with plants produced after PVS3 treatment (10.6–11.4%). The obtained results here can serve as a good basis for further studies related to synthetic seeds and cryopreservation of bleeding heart. Full article
(This article belongs to the Special Issue Recent Advances in Research and Production of Ornamental Plants)
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Open AccessArticle
Health Risk Assessment in Agricultural Soil Potentially Contaminated by Geogenic Thallium: Influence of Plant Species on Metal Mobility in Soil-Plant System
Agronomy 2020, 10(6), 890; https://doi.org/10.3390/agronomy10060890 - 23 Jun 2020
Viewed by 236
Abstract
In agricultural soils, thallium (Tl) of geogenic origin may represent a potential risk for human health, mainly via ingestion of food crops. In this work, a pot experiment was carried out to evaluate (1) the bioavailability of Tl and other potentially toxic elements [...] Read more.
In agricultural soils, thallium (Tl) of geogenic origin may represent a potential risk for human health, mainly via ingestion of food crops. In this work, a pot experiment was carried out to evaluate (1) the bioavailability of Tl and other potentially toxic elements (PTEs) in an agricultural soil with naturally occurring Tl; (2) the uptake and accumulation of PTEs in Lactuca sativa L. var. acephala, Diplotaxis tenuifolia L. DC and Silene latifolia Poir; (3) the health risks arising from plant and soil ingestion by different subpopulations and dermal contact of soil by farmers. In soil, only Tl and Pb pseudototal contents were above Italian screening values. Nevertheless, the promptly bioavailable contents of all PTEs were always below internationally recognized trigger values. Plants affected PTE bioavailability in soil by their rhizodepositions and accumulated PTEs in their shoots. Acceptable risks (hazard index < 1) arose from dietary intake of both L. sativa L., D. tenuifolia L. and dermal contact of soil by farmers. Significant health risks can derive from the intake of S. latifolia Poir. (accumulating high Tl concentrations), in particular by children (HI = 74). In conclusion, an adequate management and crop selection are needed to profitably exploit soils with geogenic Tl for agricultural purposes. Full article
(This article belongs to the Special Issue Agronomic Approaches for Remediation of Contaminated Soils)
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Open AccessArticle
Potential of Biochar to Alternate Soil Properties and Crop Yields 3 and 4 Years after the Application
Agronomy 2020, 10(6), 889; https://doi.org/10.3390/agronomy10060889 - 22 Jun 2020
Cited by 1 | Viewed by 320
Abstract
Several studies have reported that biochar can improve soil properties which are linked with higher crop yields and this effect is long-term. This paper aimed to study the effects of biochar (0, 10 and 20 t ha−1) and its combinations with [...] Read more.
Several studies have reported that biochar can improve soil properties which are linked with higher crop yields and this effect is long-term. This paper aimed to study the effects of biochar (0, 10 and 20 t ha−1) and its combinations with N-fertilization (zero, first and second level of N-fertilization) after 3 and 4 years of its application on improving soil characteristics of loamy Haplic Luvisol and crop yields (Dolná Malanta, Slovakia). The results indicated an increase in soil pH (+7%), improvement in sorption properties (hydrolytic acidity decreased by 11%, sum of basic cations and base saturation increased by 20% and 5%, respectively) and soil organic carbon rose by 27% with increasing biochar rate in the soil. N-fertilization applied to biochar treatments was a stabilizing moment in C sequestration even in the case of its labile forms. Overall, humus stability and quality were not significantly changed, however in biochar treatments without N-fertilization, the humus stability and quality decreased 3 and 4 years after biochar application. Yield parameters differed with relation to climate conditions during both vegetation crop seasons, however the combination of 20 t ha−1 of biochar with the first and second level of N-fertilization had the highest potential to increase the grain yield. Full article
(This article belongs to the Special Issue Impact of Biochar and Compost on Soil Quality and Crop Yield)
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Open AccessReview
Rice (Oryza sativa L.) Establishment Techniques and Their Implications for Soil Properties, Global Warming Potential Mitigation and Crop Yields
Agronomy 2020, 10(6), 888; https://doi.org/10.3390/agronomy10060888 - 22 Jun 2020
Viewed by 665
Abstract
Rice-based intensive cropping systems require high input levels making them less profitable and vulnerable to the reduced availability of labor and water in Asia. With continuous conventional puddled rice transplanting, the situation is exacerbated by damaged soil structure, declining underground water and decreasing [...] Read more.
Rice-based intensive cropping systems require high input levels making them less profitable and vulnerable to the reduced availability of labor and water in Asia. With continuous conventional puddled rice transplanting, the situation is exacerbated by damaged soil structure, declining underground water and decreasing land and water productivity. To minimize these negative effects a range of new crop establishment practices have been developed (zero tillage, dry direct seeding, wet direct seeding, water seeding, strip planting, bed planting, non-puddled transplanting of rice, mechanical transplanting of rice crop and combinations thereof) with varying effects on soil health, crop productivity, resource saving and global warming mitigation potential. Some of these allow Conservation Agriculture (CA) to be practiced in the rice-based mono-, double- and triple cropping systems. Innovations in machinery especially for smallholder farms have supported the adoption of the new establishment techniques. Non-puddling establishment of rice together with increased crop residue retention increased soil organic carbon by 79% and total N (TN) in soil by 62% relative to conventional puddling practice. Rice establishment methods (direct seeding of rice, system of rice intensification and non-puddled transplanting of rice) improve soil health by improving the physical (reduced bulk density, increased porosity, available water content), chemical (increased phosphorus, potassium and sulphur in their available forms) and biological properties (microbiome structure, microbial biomass C and N) of the soil. Even in the first year of its practice, the non-puddled transplanting method of rice establishment and CA practices for other crops increase the productivity of the rice-based cropping systems. Estimates suggest global warming potential (GWP) (the overall net effect) can be reduced by a quarter by replacing conventional puddling of rice by direct-seeded rice in the Indo-Gangetic Plains for the rice-based cropping system. Moreover, non-puddled transplanting of rice saves 35% of the net life cycle greenhouse gases (GHGs) compared with the conventional practice by a combination of decreasing greenhouse gases emissions from soil and increasing soil organic carbon (SOC). Though the system of rice intensification decreases net GHG emission, the practice releases 1.5 times greater N2O due to the increased soil aeration. There is no single rice establishment technology that is superior to others in all circumstances, rather a range of effective technologies that can be applied to different agro-climates, demography and farm typologies. Full article
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