Previous Issue

Table of Contents

Agronomy, Volume 9, Issue 5 (May 2019)

  • Issues are regarded as officially published after their release is announced to the table of contents alert mailing list.
  • You may sign up for e-mail alerts to receive table of contents of newly released issues.
  • PDF is the official format for papers published in both, html and pdf forms. To view the papers in pdf format, click on the "PDF Full-text" link, and use the free Adobe Readerexternal link to open them.
View options order results:
result details:
Displaying articles 1-50
Export citation of selected articles as:
Open AccessArticle
Wx Gene in Hordeum chilense: Chromosomal Location and Characterisation of the Allelic Variation in the Two Main Ecotypes of the Species
Agronomy 2019, 9(5), 261; https://doi.org/10.3390/agronomy9050261 (registering DOI)
Received: 17 April 2019 / Revised: 15 May 2019 / Accepted: 17 May 2019 / Published: 22 May 2019
PDF Full-text (1880 KB) | XML Full-text | Supplementary Files
Abstract
Starch, as the main grain component, has great importance in wheat quality, with the ratio between the two formed polymers, amylose and amylopectin, determining the starch properties. Granule-bound starch synthase I (GBSSI), or waxy protein, encoded by the Wx gene is the sole [...] Read more.
Starch, as the main grain component, has great importance in wheat quality, with the ratio between the two formed polymers, amylose and amylopectin, determining the starch properties. Granule-bound starch synthase I (GBSSI), or waxy protein, encoded by the Wx gene is the sole enzyme responsible for amylose synthesis. The current study evaluated the variability in Wx genes in two representative lines of Hordeum chilense Roem. et Schult., a wild barley species that was used in the development of tritordeum (×Tritordeum Ascherson et Graebner). Two novel alleles, Wx-Hch1a and Wx-Hch1b, were detected in this material. Molecular characterizations of these alleles revealed that the gene is more similar to the Wx gene of barley than that of wheat, which was confirmed by phylogenetic studies. However, the enzymatic function should be similar in all species, and, consequently, the variation present in H. chilense could be utilized in wheat breeding by using tritordeum as a bridge species. Full article
(This article belongs to the Special Issue Chromosome Manipulation for Plant Breeding Purposes)
Open AccessArticle
The Influence of Biochar and Solid Digestate on Rose-Scented Geranium (Pelargonium graveolens L’Hér.) Productivity and Essential Oil Quality
Agronomy 2019, 9(5), 260; https://doi.org/10.3390/agronomy9050260 (registering DOI)
Received: 17 April 2019 / Revised: 17 May 2019 / Accepted: 20 May 2019 / Published: 22 May 2019
PDF Full-text (562 KB) | XML Full-text
Abstract
In recent years, biochar has generated global interest in the areas of sustainable agriculture and climate adaptation. The main positive effects of biochar were observed to be the most remarkable when nutrient-rich feedstock was used as the initial pyrolysis material (i.e., anaerobic digestate). [...] Read more.
In recent years, biochar has generated global interest in the areas of sustainable agriculture and climate adaptation. The main positive effects of biochar were observed to be the most remarkable when nutrient-rich feedstock was used as the initial pyrolysis material (i.e., anaerobic digestate). In this study, the influence of solid anaerobic digestate and biochar that was produced by the slow pyrolysis of solid digestate was evaluated by comparing the differences in the crop growth performances of Pelargonium graveolens. The experiment was conducted in a greenhouse while using three different growth media (i.e., solid digestate, biochar, and vermiculite). The results indicated that: (i) the pyrolysis of solid digestate caused a reduction in the bulk density (−52%) and an increase in the pH (+16%) and electrical conductivity (+9.5%) in the derived biochar; (ii) the best crop performances (number of leaves, number of total branches, and plant dry weight) were found using biochar, particularly for plant dry weight (+11.4%) and essential oil content (+9.4%); (iii) the essential oil quality was slightly affected by the growth media; however, the main chemical components were found within the acceptable range that was set by international standard trade; and, iv) biochar induced the presence of leaf chlorosis in Pelargonium graveolens. Full article
Open AccessArticle
Integrated Rice-Duck Farming Decreases Soil Seed Bank and Weed Density in a Paddy Field
Agronomy 2019, 9(5), 259; https://doi.org/10.3390/agronomy9050259 (registering DOI)
Received: 30 April 2019 / Revised: 16 May 2019 / Accepted: 20 May 2019 / Published: 22 May 2019
PDF Full-text (3655 KB) | XML Full-text
Abstract
Coupled cropping-breeding modes have been highly recommended due to their ecological and sustainable nature. Integrated rice-duck farming is a typical ecological planting system in rice paddy fields and has been widely popularized in Asia where a considerable area of cropland has been planting [...] Read more.
Coupled cropping-breeding modes have been highly recommended due to their ecological and sustainable nature. Integrated rice-duck farming is a typical ecological planting system in rice paddy fields and has been widely popularized in Asia where a considerable area of cropland has been planting rice. In this study, two experimental treatments of turbid water or rice-duck treatment were established to compare with the control and a conventional treatment in absence of ducks. The turbid water treatment imitated the muddying effect by duck activities with the trampling and foraging effects excluded, while the rice-duck treatment included all of the mentioned effects by raising ducks in rice paddy field. Results showed that the rice-duck treatment significantly reduced soil seed bank density by more than 40% and the figures under the turbid water treatment were 18.2% and 30.5%, accordingly, in the early and late rice growing seasons. Moreover, the rice-duck treatment significantly altered the vertical distribution of soil seed bank by substantially declining the seed density in the topsoil (0–5 cm). Changes in soil seed bank density considerably contributed to the declines in above-ground weed density because a significant correlation was detected between the soil seed bank density in the early season and the weed density in the late season. Our results of declined soil seed bank and weed density in integrated rice-duck farming imply that this system is highly efficient as a biological pathway for controlling weeds. Full article
(This article belongs to the Special Issue Ecologically Sustainable Weed Management in Cropping Systems)
Open AccessReview
High-Throughput Field-Phenotyping Tools for Plant Breeding and Precision Agriculture
Agronomy 2019, 9(5), 258; https://doi.org/10.3390/agronomy9050258 (registering DOI)
Received: 14 April 2019 / Revised: 7 May 2019 / Accepted: 16 May 2019 / Published: 22 May 2019
PDF Full-text (849 KB) | XML Full-text
Abstract
High-throughput field phenotyping has garnered major attention in recent years leading to the development of several new protocols for recording various plant traits of interest. Phenotyping of plants for breeding and for precision agriculture have different requirements due to different sizes of the [...] Read more.
High-throughput field phenotyping has garnered major attention in recent years leading to the development of several new protocols for recording various plant traits of interest. Phenotyping of plants for breeding and for precision agriculture have different requirements due to different sizes of the plots and fields, differing purposes and the urgency of the action required after phenotyping. While in plant breeding phenotyping is done on several thousand small plots mainly to evaluate them for various traits, in plant cultivation, phenotyping is done in large fields to detect the occurrence of plant stresses and weeds at an early stage. The aim of this review is to highlight how various high-throughput phenotyping methods are used for plant breeding and farming and the key differences in the applications of such methods. Thus, various techniques for plant phenotyping are presented together with applications of these techniques for breeding and cultivation. Several examples from the literature using these techniques are summarized and the key technical aspects are highlighted. Full article
(This article belongs to the Section Crop Breeding and Genetics)
Open AccessArticle
The Effect of Shallow Tillage on Soil Erosion in a Semi-Arid Vineyard
Agronomy 2019, 9(5), 257; https://doi.org/10.3390/agronomy9050257 (registering DOI)
Received: 17 April 2019 / Revised: 7 May 2019 / Accepted: 17 May 2019 / Published: 22 May 2019
PDF Full-text (1735 KB) | HTML Full-text | XML Full-text
Abstract
Soil erosion has been considered a threat for semi-arid lands due to the removal of solid materials by water and wind. Although water erosion is currently considered the most important process of soil degradation, a growing interest has been drawn to the impact [...] Read more.
Soil erosion has been considered a threat for semi-arid lands due to the removal of solid materials by water and wind. Although water erosion is currently considered the most important process of soil degradation, a growing interest has been drawn to the impact of soil tillage. Although numerous studies on tillage erosion have been carried out on arable land using a moldboard plow, a chisel, and a tandem disc for different crops, there are no studies on the effect of shallow tillage on soil redistribution in vineyards. The aim of this work was to evaluate the soil tillage erosion rate in a vineyard using a 13C natural abundance tracer. A strip of soil (C3-C soil) was removed, mixed with C4-C tracer, and replaced. After the installation of the strip, tillage (upslope in one inter-row and downslope in the other inter-row) was performed with a cultivator and soil was collected along the slope with an interval of 0.2 m from the C4-C strip. Soil organic carbon and δ13C were measured and the total mass of translocated soil (T) soil was calculated. The net effect of tillage after two consecutive operations (downslope and upslope tillage) was a T of 49.3 ± 4.2 kg m−1. The estimated annual erosion rate due to tillage in the studied vineyard was 9.5 ± 1.2 Mg ha−1year−1. The contribution of the soil tillage erosion rate was compared with that of water erosion in the same vineyard, and we conclude that tillage is a threat to soil degradation. Full article
(This article belongs to the Special Issue Surface Runoff and Soil Erosion under Various Climate Conditions)
Figures

Figure 1

Open AccessFeature PaperReview
Low Lignin Mutants and Reduction of Lignin Content in Grasses for Increased Utilisation of Lignocellulose
Agronomy 2019, 9(5), 256; https://doi.org/10.3390/agronomy9050256
Received: 20 March 2019 / Revised: 9 May 2019 / Accepted: 17 May 2019 / Published: 21 May 2019
Viewed by 95 | PDF Full-text (1509 KB) | HTML Full-text | XML Full-text
Abstract
Biomass rich in lignocellulose from grasses is a major source for biofuel production and animal feed. However, the presence of lignin in cell walls limits its efficient utilisation such as in its bioconversion to biofuel. Reduction of the lignin content or alteration of [...] Read more.
Biomass rich in lignocellulose from grasses is a major source for biofuel production and animal feed. However, the presence of lignin in cell walls limits its efficient utilisation such as in its bioconversion to biofuel. Reduction of the lignin content or alteration of its structure in crop plants have been pursued, either by regulating genes encoding enzymes in the lignin biosynthetic pathway using biotechnological techniques or by breeding naturally-occurring low lignin mutant lines. The aim of this review is to provide a summary of these studies, focusing on lignin (monolignol) biosynthesis and composition in grasses and, where possible, the impact on recalcitrance to bioconversion. An overview of transgenic crops of the grass family with regulated gene expression in lignin biosynthesis is presented, including the effect on lignin content and changes in the ratio of p-hydroxyphenyl (H), guaiacyl (G) and syringyl (S) units. Furthermore, a survey is provided of low-lignin mutants in grasses, including cereals in particular, summarising their origin and phenotypic traits together with genetics and the molecular function of the various genes identified. Full article
Figures

Figure 1

Open AccessArticle
Assimilation of Sentinel-2 Leaf Area Index Data into a Physically-Based Crop Growth Model for Yield Estimation
Agronomy 2019, 9(5), 255; https://doi.org/10.3390/agronomy9050255
Received: 18 April 2019 / Revised: 13 May 2019 / Accepted: 16 May 2019 / Published: 21 May 2019
Viewed by 103 | PDF Full-text (2609 KB) | HTML Full-text | XML Full-text
Abstract
Remote sensing data, crop growth models, and optimization routines constitute a toolset that can be used together to map crop yield over large areas when access to field data is limited. In this study, Leaf Area Index (LAI) data from the Copernicus Sentinel-2 [...] Read more.
Remote sensing data, crop growth models, and optimization routines constitute a toolset that can be used together to map crop yield over large areas when access to field data is limited. In this study, Leaf Area Index (LAI) data from the Copernicus Sentinel-2 satellite were combined with the Environmental Policy Integrated Climate (EPIC) model to estimate crop yield using a re-calibration data assimilation approach. The experiment was implemented for a winter wheat crop during two growing seasons (2016 and 2017) under four different fertilization management strategies. A number of field measurements were conducted spanning from LAI to biomass and crop yields. LAI showed a good correlation between the Sentinel-2 estimates and the ground measurements using non-destructive method. A correlating fit between satellite LAI curves and EPIC modelled LAI curves was also observed. The assimilation of LAI in EPIC provided an improvement in yield estimation in both years even though in 2017 strong underestimations were observed. The diverging results obtained in the two years indicated that the assimilation framework has to be tested under different environmental conditions before being applied on a larger scale with limited field data. Full article
(This article belongs to the Special Issue Remote Sensing Applications for Agriculture and Crop Modelling)
Figures

Figure 1

Open AccessCase Report
Comparative Assessment of Biochar Stability Using Multiple Indicators
Agronomy 2019, 9(5), 254; https://doi.org/10.3390/agronomy9050254
Received: 18 April 2019 / Revised: 17 May 2019 / Accepted: 18 May 2019 / Published: 21 May 2019
Viewed by 87 | PDF Full-text (1344 KB) | HTML Full-text | XML Full-text
Abstract
Biochar application is one strategy proposed to improve carbon sequestration in soil. Maintaining high carbon content in soil for a long period requires stable biochar. In this work, we assessed biochar stability by two methodologies, i.e., laboratory incubation and chemical oxidation. Biochar was [...] Read more.
Biochar application is one strategy proposed to improve carbon sequestration in soil. Maintaining high carbon content in soil for a long period requires stable biochar. In this work, we assessed biochar stability by two methodologies, i.e., laboratory incubation and chemical oxidation. Biochar was produced at four different temperatures (400 °C, 500 °C, 600 °C, and 800 °C) from rice (Oryza sativa L.) straw and husk, applewood branch (Malus pumila), and oak (Quercus serrata Murray) residues. Results showed that the high-temperature biochars were more stable in both abiotic and biotic incubations, whereas the low-temperature biochars had reduced longevity. In addition, we showed biochars originated from woody material have higher stable carbon than those produced from rice residues. Finally, the oxidative assessment method provided a more reliable estimation of stability than the biotic incubation method and showed a strong correlation with other stability indicators. Full article
(This article belongs to the Special Issue Interaction of Biochar on Organic Waste Composting)
Figures

Figure 1

Open AccessArticle
Forced Postures in Courgette Greenhouse Workers
Agronomy 2019, 9(5), 253; https://doi.org/10.3390/agronomy9050253
Received: 13 April 2019 / Revised: 14 May 2019 / Accepted: 17 May 2019 / Published: 21 May 2019
Viewed by 77 | PDF Full-text (2462 KB) | HTML Full-text | XML Full-text
Abstract
Occupational health and safety allows the prevention of occupational diseases and accidents. Agriculture is one of the sectors in which it is important to prevent the musculoskeletal disorders that workers usually develop. The objective of this study is the evaluation of postures adopted [...] Read more.
Occupational health and safety allows the prevention of occupational diseases and accidents. Agriculture is one of the sectors in which it is important to prevent the musculoskeletal disorders that workers usually develop. The objective of this study is the evaluation of postures adopted by courgette farmers in greenhouses of the Almeria-type. OWAS (Ovako Working Posture Assessment System), an ergonomic evaluation method, is used and applied after making observations to the postures adopted by the workers who were previously video recorded. The results concluded that the four risk levels established by OWAS appeared, with 37.14% being the highest rate and belonging to risk level 2, 33.33% to risk level 1, 28.57% to risk level 3, and 0.95% to risk level 4. Therefore, depending on the severity of the postures adopted in each task, the need for changes in a short, medium, or long period of time was concluded. Full article
Figures

Figure 1

Open AccessArticle
Nematode Management in the Strawberry Fields of Southern Spain
Agronomy 2019, 9(5), 252; https://doi.org/10.3390/agronomy9050252
Received: 15 April 2019 / Revised: 8 May 2019 / Accepted: 17 May 2019 / Published: 21 May 2019
Viewed by 90 | PDF Full-text (1346 KB) | HTML Full-text | XML Full-text
Abstract
(1) Background: Spain is the sixth strawberry producer in the world, with about 6500 ha producing more than 350,000 tons, and an annual commercial value about 390 million €. Stunted and dead strawberry plants are frequently associated with plant-parasitic nematodes, but nematode diseases [...] Read more.
(1) Background: Spain is the sixth strawberry producer in the world, with about 6500 ha producing more than 350,000 tons, and an annual commercial value about 390 million €. Stunted and dead strawberry plants are frequently associated with plant-parasitic nematodes, but nematode diseases have not been characterized to date in the country. (2) Methods: A poll on the perception of the impact of nematodes on strawberry production was carried out by face-to-face interviews with farm advisors. In addition, nematological field surveys were carried out at the end of the growing season in 2017 and 2018 to determine prevalence and abundance of plant-parasitic nematodes in strawberry crops. The host suitability to Meloidogyne hapla of seventeen strawberry cultivars and the tolerance limit to M. hapla at progressively higher initial population densities (Pi) were assessed in pot experiments in a growth chamber. Comparison of the relative efficacies of several soil disinfestation methods in controlling nematode populations (M. hapla and Pratylenchus penetrans) was carried out in experimental field trials for twelve consecutive years. (3) Results: Meloidogyne spp., Pratylenchus penetrans, and Hemicycliophora spp. were the main plant-parasitic nematodes in the strawberry fields in South Spain. Root-knot nematodes were found in 90% of the fields, being M. hapla the most prevalent species (71% of the fields). A tolerance limit of 0.2 M. hapla juveniles per g of soil was estimated for strawberry, and currently cropped strawberry cultivars did not show resistance to M. hapla. Nematode population densities were reduced by more than 70% by soil fumigation with 1,3-dichloropropene, dazomet, dimethyl-disulfide, and methyl iodide. The efficacy of metam-sodium in reducing nematode populations was about 50% and that of chloropicrin, furfural, and sodium-azide, less than 40%. Combination of solarization with organic manures (biosolarization) reduced soil nematode populations by 68–73%. (4) Conclusions: Plant-parasitic nematodes (Meloidogyne, Pratylenchus, and Hemicycliophora) are widely distributed in the strawberry fields of Southern Spain. Strawberry is a poor host for M. hapla with a tolerance limit of 0.2 J2 per g of soil, and low population increases in cropping cycles of 7–8 months. Strawberry cultivars show a range of susceptibility and tolerance to M. hapla, but no resistance is found. Nematodes are effectively controlled by chemical fumigation of soils, but soil biosolarization is equally effective, and therefore, can be proposed as a sustainable alternative for pathogen control in strawberry cultivation. Full article
(This article belongs to the Special Issue Etiology and Control of Crop Diseases)
Figures

Figure 1

Open AccessArticle
Mapping the Depth-to-Soil pH Constraint, and the Relationship with Cotton and Grain Yield at the Within-Field Scale
Agronomy 2019, 9(5), 251; https://doi.org/10.3390/agronomy9050251
Received: 20 March 2019 / Revised: 13 May 2019 / Accepted: 15 May 2019 / Published: 21 May 2019
Viewed by 97 | PDF Full-text (3909 KB) | HTML Full-text | XML Full-text
Abstract
Subsoil alkalinity is a common issue in the alluvial cotton-growing valleys of northern New South Wales (NSW), Australia. Soil alkalinity can cause nutrient deficiencies and toxic effects, and inhibit rooting depth, which can have a detrimental impact on crop production. The depth at [...] Read more.
Subsoil alkalinity is a common issue in the alluvial cotton-growing valleys of northern New South Wales (NSW), Australia. Soil alkalinity can cause nutrient deficiencies and toxic effects, and inhibit rooting depth, which can have a detrimental impact on crop production. The depth at which a soil constraint is reached is important information for land managers, but it is difficult to measure or predict spatially. This study predicted the depth in which a pH (H2O) constraint (>9) was reached to a 1-cm vertical resolution to a 100-cm depth, on a 1070-hectare dryland cropping farm. Equal-area quadratic smoothing splines were used to resample vertical soil profile data, and a random forest (RF) model was used to produce the depth-to-soil pH constraint map. The RF model was accurate, with a Lin’s Concordance Correlation Coefficient (LCCC) of 0.63–0.66, and a Root Mean Square Error (RMSE) of 0.47–0.51 when testing with leave-one-site-out cross-validation. Approximately 77% of the farm was found to be constrained by a strongly alkaline pH greater than 9 (H2O) somewhere within the top 100 cm of the soil profile. The relationship between the predicted depth-to-soil pH constraint map and cotton and grain (wheat, canola, and chickpea) yield monitor data was analyzed for individual fields. Results showed that yield increased when a soil pH constraint was deeper in the profile, with a good relationship for wheat, canola, and chickpea, and a weaker relationship for cotton. The overall results from this study suggest that the modelling approach is valuable in identifying the depth-to-soil pH constraint, and could be adopted for other important subsoil constraints, such as sodicity. The outputs are also a promising opportunity to understand crop yield variability, which could lead to improvements in management practices. Full article
(This article belongs to the Special Issue Precision Agriculture)
Figures

Figure 1

Open AccessArticle
Winter Wheat Grain Quality, Zinc and Iron Concentration Affected by a Combined Foliar Spray of Zinc and Iron Fertilizers
Agronomy 2019, 9(5), 250; https://doi.org/10.3390/agronomy9050250
Received: 19 April 2019 / Revised: 11 May 2019 / Accepted: 15 May 2019 / Published: 20 May 2019
Viewed by 136 | PDF Full-text (1222 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Wheat (Triticum aestivum L.) is one of the main foods globally. Nutrition problems associated with Zinc and Iron deficiency affect more than two billion individuals. Biofortification is a strategy believed to be sustainable, economical and easily implemented. This study evaluated the effect [...] Read more.
Wheat (Triticum aestivum L.) is one of the main foods globally. Nutrition problems associated with Zinc and Iron deficiency affect more than two billion individuals. Biofortification is a strategy believed to be sustainable, economical and easily implemented. This study evaluated the effect of combined Zn and Fe applied as foliar fertilizer to winter wheat on grain yield, quality, Zn and Fe concentration in the grains. Results showed that treatments containing high Fe increased the yield. Grain crude fat content remained unaffected. Crude fiber was enhanced up to three-fold by 60% Zn + 40% Fe5.5 (5.5 kg ha−1 of 60% Zn + 40% Fe). Moreover, 80% Zn + 20% Fe5.5 (5.5 kg ha−1 of 80% Zn + 20% Fe) was the best combination for increasing crude protein. Zinc applied alone enhanced Zn concentration in grain. In addition, Fe was slightly improved by an application of Zn and Fe in the first year, but a greater increase was observed in the second year, where 100% Fe13 (13 kg ha−1 of 100% Fe) was the best in improving Fe in grain. Foliar application of Zn and Fe is a practical approach to increase Zn and Fe concentration, and to improve the quality of wheat grains. Full article
(This article belongs to the Special Issue Biofortification of Crops)
Figures

Figure 1

Open AccessArticle
Biostimulant Application with a Tropical Plant Extract Enhances Corchorus olitorius Adaptation to Sub-Optimal Nutrient Regimens by Improving Physiological Parameters
Agronomy 2019, 9(5), 249; https://doi.org/10.3390/agronomy9050249
Received: 8 April 2019 / Revised: 12 May 2019 / Accepted: 17 May 2019 / Published: 19 May 2019
Viewed by 185 | PDF Full-text (2459 KB) | HTML Full-text | XML Full-text
Abstract
The emerging role of plant biostimulants in enhancing nutrient efficiency is important for maintaining soil fertility under sub-optimal nutrient regimens. We aimed to elucidate the morpho-physiological and biochemical effects as well as mineral composition changes of greenhouse jute (Corchorus olitorius L.) treated [...] Read more.
The emerging role of plant biostimulants in enhancing nutrient efficiency is important for maintaining soil fertility under sub-optimal nutrient regimens. We aimed to elucidate the morpho-physiological and biochemical effects as well as mineral composition changes of greenhouse jute (Corchorus olitorius L.) treated with a commercial vegetal-derived biostimulant from a tropical plant extract (PE; Auxym®, Italpollina, Rivoli Veronese, Italy). Plants were sprayed in weekly intervals with a solution containing 2 mL·L−1 PE. Jute plants were supplied with three nutrient solution concentrations: full-, half-, and quarter-strength. Decreasing macronutrient concentrations in the nutrient solution (NS), especially at quarter-strength, triggered a decrease in several morphological (plant height, leaf number, and dry biomass) and physiological (net CO2 assimilation rate (ACO2) and SPAD (Soil Plant Analysis Development) index) parameters. PE application triggered specific ameliorative effects in terms of fresh yield at both half- and quarter-strength nutrient solution (15.5% and 29.5%, respectively). This was associated with an enhancement in ACO2, SPAD index, and especially the nutritional status (high nitrate, K, and Mg contents, and low Na content). The foliar application of PE, strongly increased chlorophyll b content, enhancing jute plant adaptation to fluctuating light and therefore the efficiency of photosynthesis, positively affecting starch, soluble proteins, and total amino acids content but only when jute plants were irrigated with full-strength NS, compared to the respective control treatment. At lower nutrient strength, PE reprogrammed the nitrogen distribution, allowing its remobilization from glutamate, which was quantitatively the major amino acid under lower nutrient strength, but not from chlorophylls, thus maintaining efficient photosynthesis. We confirmed that PE Auxym® acts in a balanced manner on the main metabolic pathways of the plant, regulating the uptake and transport of mineral nutrients and protein synthesis, increasing the accumulation of essential amino acids under full nutritive solutions, and re-distributing nitrogen from amino acids to allow leaf growth and expansion even under sub-optimal nutrient conditions. Overall, the use of natural plant biostimulants may be a potential solution in low-input conditions, where environmental constraints and restricted use of fertilizers may affect potential crop productivity. Full article
(This article belongs to the Special Issue Nutrition Management of Hydroponic Vegetable Crops)
Figures

Figure 1

Open AccessFeature PaperArticle
The Efficiency of a Low Dose of Biochar in Enhancing the Aromaticity of Humic-Like Substance Extracted from Poultry Manure Compost
Agronomy 2019, 9(5), 248; https://doi.org/10.3390/agronomy9050248
Received: 19 April 2019 / Revised: 15 May 2019 / Accepted: 16 May 2019 / Published: 18 May 2019
Viewed by 230 | PDF Full-text (709 KB) | HTML Full-text | XML Full-text
Abstract
Using biochar as a bulking agent in composting is gradually becoming popular for the minimization of nitrogen losses during the process and the improvement in compost quality. While a wide range of different biochar doses is applied, not much clear information was available [...] Read more.
Using biochar as a bulking agent in composting is gradually becoming popular for the minimization of nitrogen losses during the process and the improvement in compost quality. While a wide range of different biochar doses is applied, not much clear information was available about the optimum ratio. This study presents the impact of adding a low dose (2% v/v) of slow-pyrolysis oak biochar (Quercus serrate Murray), into poultry manure on the recalcitrant characteristic of humified organic matter. The influence in the chemical composition of humic-like substance was evaluated in poultry manure compost prepared with (PM+B) and without biochar (PM). The shift to slightly more stable chemical composition was shown in humic acid-like (HA) and fulvic acid-like (FA) extracted from PM+B compost, by increasing the proportion of aromatic carbon groups and thermal stability measured by thermogravimetry. We conclude that the addition of 2% biochar moderately enhances the recalcitrance of humified organic carbon and this could be feasible for the implementation of the biochar use in composting since only a small amount is required. Full article
(This article belongs to the Special Issue Interaction of Biochar on Organic Waste Composting)
Figures

Figure 1

Open AccessArticle
Effect of Row Cleaner Operational Settings on Crop Residue Translocation in Strip-Tillage
Agronomy 2019, 9(5), 247; https://doi.org/10.3390/agronomy9050247
Received: 4 April 2019 / Revised: 30 April 2019 / Accepted: 3 May 2019 / Published: 18 May 2019
Viewed by 119 | PDF Full-text (3843 KB) | HTML Full-text | XML Full-text
Abstract
Through field experiments and empirical analysis methods, this study determined the dependence of plant residue removal on the row cleaner’s settings in strip-tillage. The main research object of this study is row cleaners. By changing the slip angles (10, 15, and 22.5°), the [...] Read more.
Through field experiments and empirical analysis methods, this study determined the dependence of plant residue removal on the row cleaner’s settings in strip-tillage. The main research object of this study is row cleaners. By changing the slip angles (10, 15, and 22.5°), the gap between row cleaner discs in parallel (165, 180, and 195 mm), and the driving speed (1.3, 1.9, 2.5, and 3.1 m s−1), we determined what percentage of wheat residue was removed from the strip on the surface of the soil and what distance it was moved. The percentage of removed plant residue was determined by evaluating the differences between the masses of the plant residue taken from non-removed and removed strips. Empirical analysis of the results of the field experiments showed that both the amount of the removed plant residue and the distance it is moved to were the best when the slip angle was 15°, the gap between the discs of row cleaner was 180 mm, and the driving speed was 2.5 m s−1. With these parameters, up to three-quarters of the plant residue was removed from the soil surface of the strip, which was relocated 308 mm from the middle of the strip. If the slip angle and the driving speed are increased further, even more plant residue can be removed; however, if the plant residue is relocated too far away, it may fall into the zone of the adjacent strip. Full article
(This article belongs to the Section Agro-biosystem Engineering)
Figures

Figure 1

Open AccessArticle
Application of Nano-Silicon Dioxide Improves Salt Stress Tolerance in Strawberry Plants
Agronomy 2019, 9(5), 246; https://doi.org/10.3390/agronomy9050246
Received: 18 April 2019 / Revised: 4 May 2019 / Accepted: 8 May 2019 / Published: 17 May 2019
Viewed by 179 | PDF Full-text (3308 KB)
Abstract
Silicon application can improve productivity outcomes for salt stressed plants. Here, we describe how strawberry plants respond to treatments including various combinations of salt stress and nano-silicon dioxide, and assess whether nano-silicon dioxide improves strawberry plant tolerance to salt stress. Strawberry plants were [...] Read more.
Silicon application can improve productivity outcomes for salt stressed plants. Here, we describe how strawberry plants respond to treatments including various combinations of salt stress and nano-silicon dioxide, and assess whether nano-silicon dioxide improves strawberry plant tolerance to salt stress. Strawberry plants were treated with salt (0, 25 or 50 mM NaCl), and the nano-silicon dioxide treatments were applied to the strawberry plants before (0, 50 and 100 mg L−1) or after (0 and 50 mg L−1) flowering. The salt stress treatments reduced plant biomass, chlorophyll content, and leaf relative water content (RWC) as expected. Relative to control (no NaCl) plants the salt treated plants had 10% lower membrane stability index (MSI), 81% greater proline content, and 54% greater cuticular transpiration; as well as increased canopy temperature and changes in the structure of the epicuticular wax layer. The plants treated with nano-silicon dioxide were better able to maintain epicuticular wax structure, chlorophyll content, and carotenoid content and accumulated less proline relative to plants treated only with salt and no nano-silicon dioxide. Analysis of scanning electron microscopic (SEM) images revealed that the salt treatments resulted in changes in epicuticular wax type and thickness, and that the application of nano-silicon dioxide suppressed the adverse effects of salinity on the epicuticular wax layer. Nano-silicon dioxide treated salt stressed plants had increased irregular (smoother) crystal wax deposits in their epicuticular layer. Together these observations indicate that application of nano-silicon dioxide can limit the adverse anatomical and biochemical changes related to salt stress impacts on strawberry plants and that this is, in part, associated with epicuticular wax deposition. Full article
(This article belongs to the Special Issue Berry Crop Production and Protection)
Open AccessArticle
Consistency of Yield Ranking and Adaptability Patterns of Winter Wheat Cultivars between Multi-Environmental Trials and Farmer Surveys
Agronomy 2019, 9(5), 245; https://doi.org/10.3390/agronomy9050245
Received: 28 February 2019 / Revised: 28 April 2019 / Accepted: 13 May 2019 / Published: 15 May 2019
Viewed by 173 | PDF Full-text (1008 KB) | HTML Full-text | XML Full-text
Abstract
Cultivar recommendation based on mean performance determined by multi-environment trials (METs) conducted on research stations could be unreliable and ineffective for assessing performance in farmers’ fields. It is important to improve the efficiency of cultivar recommendation based on METs. For this purpose, it [...] Read more.
Cultivar recommendation based on mean performance determined by multi-environment trials (METs) conducted on research stations could be unreliable and ineffective for assessing performance in farmers’ fields. It is important to improve the efficiency of cultivar recommendation based on METs. For this purpose, it would be useful to validate recommendations based on yield data obtained directly from farmers, i.e., through surveys. The aim of this study was to discuss the possibility and statistical methodology of assessing cultivar performance patterns based on yield data obtained through farmer surveys. We suggest that this might be accomplished by assessing the conformity of yield ranking and yield performance patterns between MET and survey datasets in the same growing regions. As an example, we compare winter wheat (Triticum aestivum L.) yield data obtained from Polish farmers via surveys with data obtained via METs. In the METs, cultivars were evaluated at two levels of crop-management, a moderate-input management (MIM) system and a high-input management (HIM) system. Based on the yield evaluations in the current study, half of the agro-ecological regions had relatively high levels of consistency in yield rankings between the MET MIM system and survey yield dataset. This indicated a relatively high efficiency of cultivar recommendations based on METs in these regions, especially for the MIM system. For the HIM system, however, with the exception of one region, we observed a poor degree of consistency in cultivar ranking. Full article
(This article belongs to the Section Crop Breeding and Genetics)
Figures

Figure 1

Open AccessArticle
Anti-Transpirant Effects on Vine Physiology, Berry and Wine Composition of cv. Aglianico (Vitis vinifera L.) Grown in South Italy
Agronomy 2019, 9(5), 244; https://doi.org/10.3390/agronomy9050244
Received: 20 February 2019 / Revised: 2 May 2019 / Accepted: 13 May 2019 / Published: 14 May 2019
Viewed by 225 | PDF Full-text (1130 KB)
Abstract
In viticulture, global warming requires reconsideration of current production models. At the base of this need there are some emerging phenomena: modification of phenological phases; acceleration of the maturation process of grapes, with significant increases in the concentration of sugar musts; decoupling between [...] Read more.
In viticulture, global warming requires reconsideration of current production models. At the base of this need there are some emerging phenomena: modification of phenological phases; acceleration of the maturation process of grapes, with significant increases in the concentration of sugar musts; decoupling between technological grape maturity and phenolic maturity. The aim of our study was to evaluate the effect of a natural anti-transpirant on grapevine physiology, berry, and wine composition of Aglianico cultivar. For two years, Aglianico vines were treated at veraison with the anti-transpirant Vapor Gard and compared with a control sprayed with only water. A bunch thinning was also applied to both treatments. The effectiveness of Vapor Gard were assessed through measurements of net photosynthesis and transpiration and analyzing the vegetative, productive and qualitative parameters. The results demonstrate that the application of anti-transpirant reduced assimilation and transpiration rate, stomatal conductance, berry sugar accumulation, and wine alcohol content. No significant differences between treatments were observed for other berry and wine compositional parameters. This method may be a useful tool to reduce berry sugar content and to produce wines with a lower alcohol content. Full article
(This article belongs to the Special Issue Viticulture and Winemaking under Climate Change)
Open AccessArticle
Effects of Elevated CO2 on Wheat Yield: Non-Linear Response and Relation to Site Productivity
Agronomy 2019, 9(5), 243; https://doi.org/10.3390/agronomy9050243
Received: 17 April 2019 / Revised: 9 May 2019 / Accepted: 11 May 2019 / Published: 14 May 2019
Viewed by 209 | PDF Full-text (1713 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Elevated carbon dioxide (eCO2) is well known to stimulate plant photosynthesis and growth. Elevated carbon dioxide’s effects on crop yields are of particular interest due to concerns for future food security. We compiled experimental data where field-grown wheat (Triticum aestivum [...] Read more.
Elevated carbon dioxide (eCO2) is well known to stimulate plant photosynthesis and growth. Elevated carbon dioxide’s effects on crop yields are of particular interest due to concerns for future food security. We compiled experimental data where field-grown wheat (Triticum aestivum Linnaeus) was exposed to different CO2 concentrations. Yield and yield components were analyzed by meta-analysis to estimate average effects, and response functions derived to assess effect size in relation to CO2 concentration. Grain yield increased by 26% under eCO2 (average ambient concentration of 372 ppm and elevated 605 ppm), mainly due to the increase in grain number. The response function for grain yield with CO2 concentration strongly suggests a non-linear response, where yield stimulation levels off at ~600 ppm. This was supported by the meta-analysis, which did not indicate any significant difference in yield stimulation in wheat grown at 456–600 ppm compared to 601–750 ppm. Yield response to eCO2 was independent of fumigation technique and rooting environment, but clearly related to site productivity, where relative CO2 yield stimulation was stronger in low productive systems. The non-linear yield response, saturating at a relatively modest elevation of CO2, was of large importance for crop modelling and assessments of future food production under rising CO2. Full article
(This article belongs to the Special Issue Effects of CO2 on Crop Growth and Quality)
Figures

Figure 1

Open AccessArticle
Sensitivity Analysis of Plant- and Cultivar-Specific Parameters of APSIM-Sugar Model: Variation between Climates and Management Conditions
Agronomy 2019, 9(5), 242; https://doi.org/10.3390/agronomy9050242
Received: 18 April 2019 / Revised: 7 May 2019 / Accepted: 11 May 2019 / Published: 14 May 2019
Viewed by 157 | PDF Full-text (4687 KB) | HTML Full-text | XML Full-text
Abstract
With increasing demand for food and energy, there is a great need for improving sugarcane productivity. New cultivars and management strategies can be assessed using process-based crop models. Information on cultivars needs to be updated frequently, but it is still limited in most [...] Read more.
With increasing demand for food and energy, there is a great need for improving sugarcane productivity. New cultivars and management strategies can be assessed using process-based crop models. Information on cultivars needs to be updated frequently, but it is still limited in most crop models. Therefore, it is important to identify possible candidates for varietal parameterization and calibration. Because sensitivity analysis is computationally expensive, we used a less expensive emulator-based approach to conduct a global sensitivity analysis using the apsimr package and GEM-SA software. We studied the sensitivity of four yield outputs of the APSIM-Sugar model to 13 parameters in rainfed and irrigated conditions in Japan and Sri Lanka. Unlike previous studies, our aim was to give comprehensive insights into the variation in sensitivity due to variation in climate. The results confirmed distinct variation of parameter influence between climates and between management conditions. We identify possible candidates for parameterization and calibration of new cultivars for APSIM-Sugar under different environments, and show the effect of variation in climate on variation in parameter influence under different management conditions. It was confirmed that both radiation use efficiency and transpiration efficiency were sensitive and have to be examined to use new cultivars, though these are not listed as cultivar parameters. Full article
Figures

Figure 1

Open AccessArticle
Uncertainty of CERES-Maize Calibration under Different Irrigation Strategies Using PEST Optimization Algorithm
Agronomy 2019, 9(5), 241; https://doi.org/10.3390/agronomy9050241
Received: 29 March 2019 / Revised: 4 May 2019 / Accepted: 7 May 2019 / Published: 10 May 2019
Viewed by 291 | PDF Full-text (2748 KB) | HTML Full-text | XML Full-text
Abstract
An important but rarely studied aspect of crop modeling is the uncertainty associated with model calibration and its effect on model prediction. Biomass and grain yield data from a four-year maize experiment (2008–2011) with six irrigation treatments were divided into subsets by either [...] Read more.
An important but rarely studied aspect of crop modeling is the uncertainty associated with model calibration and its effect on model prediction. Biomass and grain yield data from a four-year maize experiment (2008–2011) with six irrigation treatments were divided into subsets by either treatments (Calibration-by-Treatment) or years (Calibration-by-Year). These subsets were then used to calibrate crop cultivar parameters in CERES (Crop Environment Resource Synthesis)-Maize implemented within RZWQM2 (Root Zone Water Quality Model 2) using the automatic Parameter ESTimation (PEST) algorithm to explore model calibration uncertainties. After calibration for each subset, PEST also generated 300 cultivar parameter sets by assuming a normal distribution of each parameter within their reported values in the literature, using the Latin hypercube sampling (LHS) method. The parameter sets that produced similar goodness of fit (11–164 depending on subset used for calibration) were then used to predict all the treatments and years of the entire dataset. Our results showed that the selection of calibration datasets greatly affected the calibrated crop parameters and their uncertainty, as well as prediction uncertainty of grain yield and biomass. The high variability in model prediction of grain yield and biomass among the six (Calibration-by-Treatment) or the four (Calibration-by-Year) scenarios indicated that parameter uncertainty should be considered in calibrating CERES-Maize with grain yield and biomass data from different irrigation treatments, and model predictions should be provided with confidence intervals. Full article
(This article belongs to the Special Issue Model Application for Sustainable Agricultural Water)
Figures

Figure 1

Open AccessArticle
Evaluation of Yield-Based Low Nitrogen Tolerance Indices for Screening Maize (Zea mays L.) Inbred Lines
Agronomy 2019, 9(5), 240; https://doi.org/10.3390/agronomy9050240
Received: 5 March 2019 / Revised: 26 April 2019 / Accepted: 7 May 2019 / Published: 10 May 2019
Viewed by 237 | PDF Full-text (1615 KB) | HTML Full-text | XML Full-text
Abstract
To screen the desired criterion to identify desirable genotypes and select genotypes best suited to limited nitrogen availability in order to facilitate the practice of low-nitrogen-tolerant breeding in maize, the response of 31 maize inbred lines, containing four control inbred lines (PH6WC, PH4CV, [...] Read more.
To screen the desired criterion to identify desirable genotypes and select genotypes best suited to limited nitrogen availability in order to facilitate the practice of low-nitrogen-tolerant breeding in maize, the response of 31 maize inbred lines, containing four control inbred lines (PH6WC, PH4CV, Zheng58, and Chang7-2) and others selected from the Shaan A and Shaan B heterotic groups cultivated at Northwest A&F University (Yangling, Shaanxi, China), were evaluated. The experiment was conducted following a split plot design with two replications during three growing seasons (2015, 2016, and 2017) under both high nitrogen (HN) and low nitrogen (LN) conditions at the Yulin and Yangling in Shaanxi Province, China. Seven screening indices, based on grain yield under two contrasting nitrogen (N) conditions, the stress susceptibility index (SSI), yield stability index (YSI), mean productivity (MP), geometric mean productivity (GMP), stress tolerance index (STI), harmonic mean (HM), and low nitrogen tolerance index (LNTI), were computed to assess the overall index that accurately screened the desirable genotypes. The results of the correlation analyses and principal component analysis showed that MP, GMP, HM and STI were correlated with grain yield significantly and positively under contrasting N conditions, and were able to accurately discriminate the desirable genotypes. Compared with the control inbred lines, many inbred lines selected from the Shaan A and Shaan B groups showed a higher LN tolerance. This shows that we can effectively improve the LN tolerance of maize inbred lines through LN screening. Based on the screening indices, the three-dimensional diagram and genotype and genotype × environment (GGE) biplots are agreed with this results, and we identified KA105, KB081, KA225, 91227, and 2013KB-47 as the desired genotypes that have the potential to be used to breed a high yield and stable hybrid. Full article
(This article belongs to the Section Crop Breeding and Genetics)
Figures

Figure 1

Open AccessReview
Drivers, Process, and Consequences of Native Grassland Degradation: Insights from a Literature Review and a Survey in Río de la Plata Grasslands
Agronomy 2019, 9(5), 239; https://doi.org/10.3390/agronomy9050239
Received: 23 March 2019 / Revised: 3 May 2019 / Accepted: 5 May 2019 / Published: 10 May 2019
Viewed by 252 | PDF Full-text (1385 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Natural grasslands are being progressively degraded around the world due to human-induced action (e.g., overgrazing), but there is neither a widely accepted conceptual framework to approach degradation studies nor a clear definition of what “grassland degradation” is. Most of the drivers, processes, and [...] Read more.
Natural grasslands are being progressively degraded around the world due to human-induced action (e.g., overgrazing), but there is neither a widely accepted conceptual framework to approach degradation studies nor a clear definition of what “grassland degradation” is. Most of the drivers, processes, and consequences related to grassland degradation are widespread and are usually separately quoted in the literature. In this paper, we propose a comprehensive framework with different conceptual categories, for monitoring grassland degradation, and a new definition based on current ones. We provide a conceptual update of grassland degradation based on a literature review and an expert survey, focused on the Río de la Plata grasslands (RPG). We identified “drivers” as external forces or changes that cause degradation; “processes” as measurable changes in grasslands conditions that can be evaluated using indicators; and “consequences” as the impacts or results of the process of grassland degradation. We expect that this conceptual framework will contribute to monitoring programs, to support management decisions, to design conservation measures, and to communicate the importance of grasslands conservation and the different concepts involved. Particularly for RPG, we expect that this paper will contribute to promote sustainable management practices in this important and often neglected ecosystem. Full article
(This article belongs to the Special Issue Grassland Management for Sustainable Agroecosystems)
Figures

Figure 1

Open AccessArticle
Evaluating the Impacts of Continuous and Rotational Grazing on Tallgrass Prairie Landscape Using High-Spatial-Resolution Imagery
Agronomy 2019, 9(5), 238; https://doi.org/10.3390/agronomy9050238
Received: 1 April 2019 / Revised: 4 May 2019 / Accepted: 7 May 2019 / Published: 9 May 2019
Viewed by 250 | PDF Full-text (3254 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
This study evaluated the impacts of different grazing treatments (continuous (C) and rotational (R) grazing) on tallgrass prairie landscape, using high-spatial-resolution aerial imagery (1-m at RGB and near-infrared bands) of experimental C and R pastures within two replicates (Rep A and Rep B) [...] Read more.
This study evaluated the impacts of different grazing treatments (continuous (C) and rotational (R) grazing) on tallgrass prairie landscape, using high-spatial-resolution aerial imagery (1-m at RGB and near-infrared bands) of experimental C and R pastures within two replicates (Rep A and Rep B) in the southern Great Plains (SGP) of the United States. The imagery was acquired by the National Agriculture Imagery Program (NAIP) during the agricultural growing season of selected years (2010, 2013, 2015, and 2017) in the continental United States. Land cover maps were generated by combining visual interpolation, a support vector machine, and a decision tree classifier. Landscape metrics (class area, patch number, percentage of landscape, and fragmentation indices) were calculated from the FRAGSTATS (a computer software program designed to compute a wide variety of landscape metrics for categorical map patterns) based on land cover results. Both the metrics and land cover results were used to analyze landscape dynamics in the experiment pastures. Results showed that both grass and shrubs of different pastures differed largely in the same year and had significant annual dynamics controlled by climate. High stocking intensity delayed grass growth. A large proportion of bare soil occurred in sub-paddocks of rotational grazing that were just grazed or under grazing. Rep A experienced rapid shrub encroachment, with a large proportion of shrub at the beginning of the experiment. Shrub may occupy 41% of C and 15% of R in Rep A by 2030, as revealed by the linear regression analysis of shrub encroachment. In contrast, shrub encroachment was not significant in Rep B, which only had a small number of shrub patches at the beginning of the experiment. This result indicates that the shrub encroachment is mainly controlled by the initial status of the pastures instead of grazing management. However, the low temporal resolution of the NAIP imagery (one snapshot in two or three years) limits our comparison of the continuous and rotational grazing at the annual scale. Future studies need to combine NAIP imagery with other higher temporal resolution imagery (e.g., WorldView), in order to better evaluate the interannual variabilities of grass productivity and shrub encroachment. Full article
(This article belongs to the Special Issue Grassland Management for Sustainable Agroecosystems)
Figures

Figure 1

Open AccessArticle
How to Generate Yield in the First Year—A Three-Year Experiment on Miscanthus (Miscanthus × giganteus (Greef et Deuter)) Establishment under Maize (Zea mays L.)
Agronomy 2019, 9(5), 237; https://doi.org/10.3390/agronomy9050237
Received: 18 April 2019 / Revised: 1 May 2019 / Accepted: 7 May 2019 / Published: 9 May 2019
Viewed by 274 | PDF Full-text (4061 KB) | HTML Full-text | XML Full-text
Abstract
Miscanthus is one of the most promising perennial herbaceous industrial crops worldwide mainly due to its high resource-use efficiency and biomass yield. However, the extent of miscanthus cultivation across Europe is still lagging far behind its real potential. Major limiting factors are high [...] Read more.
Miscanthus is one of the most promising perennial herbaceous industrial crops worldwide mainly due to its high resource-use efficiency and biomass yield. However, the extent of miscanthus cultivation across Europe is still lagging far behind its real potential. Major limiting factors are high initial costs and low biomass yields in the crop establishment period, especially the first year. This study explores the possibility of establishing miscanthus under maize to generate yields from the first year of cultivation onwards. A field trial with mono-cropped maize and two miscanthus establishment procedures, ‘under maize’ (MUM) and ‘standard’ (REF), was established in southwest Germany in 2016. Annual aboveground biomass was harvested in autumn (2016–2018). In 2016 and 2017, the miscanthus dry matter yield (DMY) was significantly lower in MUM than REF. However, the accumulated DMY of miscanthus and maize was as high in MUM as in maize cultivation alone. In 2018, there was no significant difference between the miscanthus DMY of REF (7.86 ± 0.77 Mg ha−1) and MUM (6.21 ± 0.77 Mg ha−1). The accumulated DMY over the three years was 31.7 Mg ha−1 for MUM, of which 10.1 Mg ha−1 were miscanthus-based, compared to 17.7 Mg ha−1 for REF. These results indicate that miscanthus establishment under maize could compensate for its lack of yield in the first year. Full article
(This article belongs to the Special Issue Bioenergy Crops: Current Status and Future Prospects)
Figures

Figure 1

Open AccessArticle
Use of Carbonized Fallen Leaves of Jatropha Curcas L. as a Soil Conditioner for Acidic and Undernourished Soil
Agronomy 2019, 9(5), 236; https://doi.org/10.3390/agronomy9050236
Received: 24 April 2019 / Revised: 5 May 2019 / Accepted: 6 May 2019 / Published: 9 May 2019
Viewed by 234 | PDF Full-text (2402 KB) | HTML Full-text | XML Full-text
Abstract
Jatropha (Jatropha curcas L.) represents a renewable bioenergy source in arid regions, where it is used to produce not only biodiesel from the seed oil, but also various non-oil biomass products, such as fertilizer, from the seed cake following oil extraction from [...] Read more.
Jatropha (Jatropha curcas L.) represents a renewable bioenergy source in arid regions, where it is used to produce not only biodiesel from the seed oil, but also various non-oil biomass products, such as fertilizer, from the seed cake following oil extraction from the seeds. Jatropha plants also generate large amounts of fallen leaves during the cold or drought season, but few studies have examined the utilization of this litter biomass. Therefore, in this study, we produced biochar from the fallen leaves of jatropha using a simple and economical carbonizer that was constructed from a standard 200 L oil drum, which would be suitable for use in rural communities, and evaluated the use of the generated biochar as a soil conditioner for the cultivation of Swiss chard (Beta vulgaris subsp. cicla “Fordhook Giant”) as a model vegetable in an acidic and undernourished soil in Botswana. Biochar application improved several growth parameters of Swiss chard, such as the total leaf area. In addition, the dry weights of the harvested shoots were 1.57, 1.88, and 2.32 fold higher in plants grown in soils containing 3%, 5%, and 10% biochar, respectively, compared with non-applied soil, suggesting that the amount of biochar applied to the soil was positively correlated with yield. Together, these observations suggest that jatropha fallen leaf biochar could function as a soil conditioner to enhance crop productivity. Full article
Figures

Figure 1

Open AccessArticle
Assessment of the Standardized Precipitation and Evaporation Index (SPEI) as a Potential Management Tool for Grasslands
Agronomy 2019, 9(5), 235; https://doi.org/10.3390/agronomy9050235
Received: 15 March 2019 / Revised: 3 May 2019 / Accepted: 5 May 2019 / Published: 9 May 2019
Viewed by 208 | PDF Full-text (959 KB) | HTML Full-text | XML Full-text
Abstract
Early warning of detrimental weather and climate (particularly drought) on forage production would allow for tactical decision-making for the management of pastures, supplemental feed/forage resources, and livestock. The standardized precipitation and evaporation index (SPEI) has been shown to be correlated with production of [...] Read more.
Early warning of detrimental weather and climate (particularly drought) on forage production would allow for tactical decision-making for the management of pastures, supplemental feed/forage resources, and livestock. The standardized precipitation and evaporation index (SPEI) has been shown to be correlated with production of various cereal and vegetable crops, and with above-ground tree mass. Its correlation with above-ground grassland or forage mass (AGFM) is less clear. To investigate the utility of SPEI for assessing future biomass status, we used biomass data from a site on the Konza Prairie (KP; for years 1984–1991) and from a site at the United States Department of Agriculture-Agricultural Research Service’s (USDA-ARS) Grazinglands Research Laboratory (GRL; for years 2009–2015), and a publicly-available SPEI product. Using discriminant analysis and artificial neural networks (ANN), we analyzed the monthly timescale SPEI to categorize AGFM into above average, average, and below average conditions for selected months in the grazing season. Assessment of the confusion matrices from the analyses suggested that the ANN better predicted class membership from the SPEI than did the discriminant analysis. Within-site cross validation of the ANNs revealed classification errors ranging from 0 to 50%, depending upon month of class prediction and study site. Across-site ANN validation indicated that the GRL ANN algorithm better predicted KP AGFM class membership than did the KP ANN prediction of GRL AGFM class membership; however, misclassification rates were ≥25% in all months. The ANN developed from the combined datasets exhibited cross-validation misclassification rates of ≤20% for three of the five months being predicted, with the remaining two months having misclassification rates of 33%. Redefinition of the AGFM classes to identify truly adequate AGFM (i.e., average to above average forage availability) improved prediction accuracy. In this regard, results suggest that the SPEI has potential for use as a predictive tool for classifying AGFM, and, thus, for grassland and livestock management. However, a more comprehensive investigation that includes a larger dataset, or combinations of datasets representing other areas, and inclusion of a bi-weekly SPEI may provide additional insights into the usefulness of the SPEI as an indicator for biomass production. Full article
(This article belongs to the Special Issue Grassland Management for Sustainable Agroecosystems)
Figures

Figure 1

Open AccessArticle
Unraveling the Regional Specificities of Malbec Wines from Mendoza, Argentina, and from Northern California
Agronomy 2019, 9(5), 234; https://doi.org/10.3390/agronomy9050234
Received: 12 April 2019 / Revised: 2 May 2019 / Accepted: 6 May 2019 / Published: 9 May 2019
Viewed by 200 | PDF Full-text (1633 KB) | HTML Full-text | XML Full-text
Abstract
This study explores the relationships between chemical and sensory characteristics of wines in connection with their regions of production. The objective is to identify whether such characteristics are significant enough to serve as signatures of a terroir for wines, thereby supporting the concept [...] Read more.
This study explores the relationships between chemical and sensory characteristics of wines in connection with their regions of production. The objective is to identify whether such characteristics are significant enough to serve as signatures of a terroir for wines, thereby supporting the concept of regionality. We argue that the relationships between characteristics and regions of production for the set of wines under study are rendered complicated by possible non-linear relationships between the characteristics themselves. Consequently, we propose a new approach for performing the analysis of the wine data that relies on these relationships instead of trying to circumvent them. This new approach follows two steps: We first cluster the measurements for each characteristic (chemical, or sensory) independently. We then assign a distance between two features to be the mutual entropy of the clustering results they generate. The set of characteristics is then clustered using this distance measure. The result of this clustering is a set of sub-groups of characteristics, such that two characteristics in the same group carry similar, i.e., synergetic information with respect to the wines under study. Those wines are then analyzed separately on the different sub groups of features. We have used this method to analyze the similarities and differences between Malbec wines from Argentina and California, as well as the similarities and differences between sub-regions of those two main wine producing countries. We report detection of groups of features that characterize the origins of the different wines included in the study. We note stronger evidence of regionality for Argentinian Malbec wines than for Californian wines, at least for the sub regions of production included in this study. Full article
Figures

Figure 1

Open AccessArticle
Exploring Optimal Tillage Improved Soil Characteristics and Productivity of Wheat Irrigated with Different Water Qualities
Agronomy 2019, 9(5), 233; https://doi.org/10.3390/agronomy9050233
Received: 15 April 2019 / Revised: 2 May 2019 / Accepted: 2 May 2019 / Published: 8 May 2019
Viewed by 188 | PDF Full-text (1269 KB) | HTML Full-text | XML Full-text
Abstract
Irrigation with low water quality can adversely affect soil characteristics, optimal moisture for tillage, and crop productivity, particularly in arid and semi-arid regions. We determined the optimal moisture for tillage processing and the effects of optimal and wet tillage on physical and chemical [...] Read more.
Irrigation with low water quality can adversely affect soil characteristics, optimal moisture for tillage, and crop productivity, particularly in arid and semi-arid regions. We determined the optimal moisture for tillage processing and the effects of optimal and wet tillage on physical and chemical soil characteristics and wheat productivity after irrigation with different water qualities (waste, saline, and highly saline water). We used the Atterberg limit to determine the suitable moisture content for tillage. Tillage at optimal moisture content improved soil characteristics by reducing soil salinity, sodicity, bulk density, shear strength, compaction, and increasing hydraulic conductivity compared to that of wet tillage. It also enhanced growth and productivity of wheat grown with low quality of water (i.e., fresh and waste water), resulting in higher grain yield and root weight at different growth stages than that of saline and highly saline water. In conclusion, tillage at optimal moisture content alleviates the impact of salinity through improving soil physical and chemical characteristics. Optimum tillage can be applied at 20 and 24 days from the previous irrigation in saline and highly saline soils, respectively. Irrigation with waste water resulted in a higher wheat grain yield than saline and highly saline water. Full article
Figures

Figure 1

Open AccessArticle
Arbuscular Mycorrhizal Fungi Modulate the Crop Performance and Metabolic Profile of Saffron in Soilless Cultivation
Agronomy 2019, 9(5), 232; https://doi.org/10.3390/agronomy9050232
Received: 7 March 2019 / Revised: 2 May 2019 / Accepted: 7 May 2019 / Published: 8 May 2019
Viewed by 576 | PDF Full-text (1928 KB) | HTML Full-text | XML Full-text
Abstract
Saffron (Crocus sativus L.) is cultivated worldwide. Its stigmas represent the highest-priced spice and contain bioactive compounds beneficial for human health. Saffron cultivation commonly occurs in open field, and spice yield can vary greatly, from 0.15 to 1.5 g m−2, [...] Read more.
Saffron (Crocus sativus L.) is cultivated worldwide. Its stigmas represent the highest-priced spice and contain bioactive compounds beneficial for human health. Saffron cultivation commonly occurs in open field, and spice yield can vary greatly, from 0.15 to 1.5 g m−2, based on several agronomic and climatic factors. In this study, we evaluated saffron cultivation in soilless systems, where plants can benefit from a wealth of nutrients without competition with pathogens or stresses related to nutrient-soil interaction. In addition, as plant nutrient and water uptake can be enhanced by the symbiosis with arbuscular mycorrhizal fungi (AMF), we also tested two inocula: a single species (Rhizophagus intraradices) or a mixture of R. intraradices and Funneliformis mosseae. After one cultivation cycle, we evaluated the spice yield, quality (ISO category), antioxidant activity, and bioactive compound contents of saffron produced in soilless systems and the effect of the applied AMF inocula. Spice yield in soilless systems (0.55 g m−2) was on average with that produced in open field, while presented a superior content of several health-promoting compounds, such as polyphenols, anthocyanins, vitamin C, and elevated antioxidant activity. The AMF symbiosis with saffron roots was verified by light and transmission electron microscopy. Inoculated corms showed larger replacement corms (+50% ca.). Corms inoculated with R. intraradices performed better than those inoculated with the mix in terms of spice quality (+90% ca.) and antioxidant activity (+88% ca.). Conversely, the mixture of R. intraradices and F. mosseae increased the polyphenol content (+343% ca.). Thus, soilless systems appeared as an effective alternative cultivation strategy for the production of high quality saffron. Further benefits can be obtained by the application of targeted AMF-based biostimulants. Full article
Figures

Figure 1

Agronomy EISSN 2073-4395 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top