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Agronomy, Volume 9, Issue 3 (March 2019)

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Cover Story (view full-size image) The post-harvest losses are a major problem in supply chains. The development of new cultivars with [...] Read more.
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Open AccessArticle Water Stress Permanently Alters Shoot Architecture in Common Bean Plants
Agronomy 2019, 9(3), 160; https://doi.org/10.3390/agronomy9030160
Received: 24 February 2019 / Revised: 17 March 2019 / Accepted: 19 March 2019 / Published: 26 March 2019
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Abstract
The effects of water stress on crop yield through modifications of plant architecture are vital to crop performance such as common bean plants. To assess the extent of this effect, an outdoor experiment was conducted in which common bean plants received five treatments: [...] Read more.
The effects of water stress on crop yield through modifications of plant architecture are vital to crop performance such as common bean plants. To assess the extent of this effect, an outdoor experiment was conducted in which common bean plants received five treatments: fully irrigated, and irrigation deficits of 30% and 50% applied in flowering or pod formation stages onwards. Evapotranspiration, number and length of pods, shoot biomass, grain yield and harvest index were assessed, and architectural traits (length and thickness of internodes, length of petioles and petiolules, length and width of leaflet blades and angles) were recorded and analyzed using regression models. The highest irrigation deficit in the flowering stage had the most pronounced effect on plant architecture. Stressed plants were shorter, leaves were smaller and pointing downward, indicating that plants permanently altered their exposure to sunlight. The combined effect of irrigation deficit and less exposure to light lead to shorter pods, less shoot biomass and lower grain yield. Fitted empirical models between water deficit and plant architecture can be included in architectural simulation models to quantify plant light interception under water stress, which, in turn, can supply crop models adding a second order of water stress effects on crop yield simulation. Full article
(This article belongs to the Special Issue Model Application for Sustainable Agricultural Water)
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Open AccessFeature PaperCommunication Resistance of Multiple Diploid and Tetraploid Perennial Ryegrass (Lolium perenne L.) Varieties to Three Projected Drought Scenarios for the UK in 2080
Agronomy 2019, 9(3), 159; https://doi.org/10.3390/agronomy9030159
Received: 22 January 2019 / Revised: 15 March 2019 / Accepted: 22 March 2019 / Published: 26 March 2019
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Abstract
Forage plants underpin the livestock industry. Selective breeding, including polyploidization, where genome size is increased by whole genome duplication, changes the productivity and stress tolerance of new varieties. We conducted a growth chamber experiment to investigate the likely responses of Lolium perenne L. [...] Read more.
Forage plants underpin the livestock industry. Selective breeding, including polyploidization, where genome size is increased by whole genome duplication, changes the productivity and stress tolerance of new varieties. We conducted a growth chamber experiment to investigate the likely responses of Lolium perenne L. to drought, testing four diploid and four tetraploid varieties. We simulated projected spring and summer temperatures for the South-West of England in 2080, applying three projected rainfall scenarios, which varied in drought severity. Drought caused a reduction in productivity, but there was substantial variation between varieties (up to 82%), with the optimal variety changing depending on drought severity. Across three harvests, productivity declined by 43% and 27% (dry biomass) for the severe and likely drought scenarios, respectively. In the final harvest, tetraploids exhibited a greater biomass under severe drought, whereas diploids had a greater biomass under the current rainfall and likely drought scenarios. Longer stomata were observed in tetraploids; however, stomatal conductance was not significantly different between ploidy levels. Trait selection will be important for future drought adaptation. Local climate projections will need to be consulted when selecting L. perenne varieties to tolerate the spatially variable reductions in future rainfall. Full article
(This article belongs to the Special Issue Genetics and Management of Perennial Forage Crops)
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Open AccessArticle Variability in Anthocyanins, Phenolic Compounds and Antioxidant Capacity in the Tassels of Collected Waxy Corn Germplasm
Agronomy 2019, 9(3), 158; https://doi.org/10.3390/agronomy9030158
Received: 18 February 2019 / Revised: 19 March 2019 / Accepted: 22 March 2019 / Published: 25 March 2019
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Abstract
Corn tassel is a valuable co-product and an excellent source of phytochemicals with bioactive properties. The information on the genetic diversity in the tassel properties of waxy corn germplasm is important for creating new varieties that can have the potential for the commercial [...] Read more.
Corn tassel is a valuable co-product and an excellent source of phytochemicals with bioactive properties. The information on the genetic diversity in the tassel properties of waxy corn germplasm is important for creating new varieties that can have the potential for the commercial production of tassels as a co-product. Therefore, the objective of this study was to evaluate the potential of corn tassels in a set of waxy corn germplasm for the extraction of phenolic compounds with an antioxidant activity. The experiment was carried out under field conditions in the rainy season 2017 and the dry season 2017/2018. Fifty waxy corn genotypes were evaluated. Data were collected for the total anthocyanin content (TAC), total phenolic content (TPC) and the antioxidant activity was determined by the 2,2-diphenyl−1-picrylhydrazyl (DPPH) radical scavenging activity and Trolox equivalent antioxidant capacity (TEAC) assays. The season (S) had small effect on all of the parameters, accounting for 0.2–8.7% of the total variance. The genotype (G) was the largest variance component in the TAC and DPPH radical scavenging activity, accounting for 83.5–97.5% of the total variance. The G and S × G interaction contributed approximately equally to the total variance in the TPC and TEAC. Based on the TAC, TPC and antioxidant capacity variation, the genotypes were classified into seven groups. The tassels of corn genotypes belonging to three of these clusters (clusters E, F and G) had high levels of phytochemicals along with an antioxidant capacity. A significant correlation coefficient was found between the TAC and DPPH (r = 0.70 **). The TPC showed a moderate relationship with the DPPH and TEAC assays (r = 0.60 ** and 0.76 **, respectively). The information obtained from this study can be used for germplasm management and waxy corn breeding for enhancing levels of bioactive properties in waxy corn tassels. Full article
(This article belongs to the Special Issue Functional Metabolism in Crops/Agronomy)
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Open AccessArticle The Growth and Development of ‘Mini Chal’ Tomato Plug Seedlings Grown under Various Wavelengths Using Light Emitting Diodes
Agronomy 2019, 9(3), 157; https://doi.org/10.3390/agronomy9030157
Received: 11 February 2019 / Revised: 19 March 2019 / Accepted: 21 March 2019 / Published: 25 March 2019
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Abstract
This study aimed to determine the effects of various light qualities (green (G), ultraviolet-A (UV-A), and far-red (Fr)) on the growth and development of tomato plug seedlings. The ‘Mini Chal’ tomato (Solanum lycopersicum L.) seedlings were used as the plant material to [...] Read more.
This study aimed to determine the effects of various light qualities (green (G), ultraviolet-A (UV-A), and far-red (Fr)) on the growth and development of tomato plug seedlings. The ‘Mini Chal’ tomato (Solanum lycopersicum L.) seedlings were used as the plant material to which various light qualities were supplied. Fluorescent lamp (FL), combined FL and diniconazole (Dini), and R3B7 (red (R):blue (B) = 30:70) were used as the control. The different light treatments for this experiment were as follows: two G light ratios added to R3B7 (G20 and G40), three UV-A light intensities added to R3B7 (UV 0.4, UV 0.6, and UV 0.8), and three Fr light ratios added to R3B7 (Fr1, Fr2, and Fr3). Plants grown in UV 0.4 and Dini were the shortest, followed by plants grown in R3B7. R3B7 induced higher specific leaf weight than G, UV-A, and Fr did. The position of the first flower cluster was the highest for plants in FL and Fr1, and the lowest for plants in R3B7 and UV 0.6. In conclusion, different light treatments heavily affected the growth and development of ‘Mini Chal’ tomato seedlings. R3B7 was the most effective light treatment for producing high quality seedlings in a closed-type plant production system that develop well after transplanting. Full article
(This article belongs to the Section Horticultural and Floricultural Crops)
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Open AccessArticle The Sewage Sludge Biochar at Low Pyrolysis Temperature Had Better Improvement in Urban Soil and Turf Grass
Agronomy 2019, 9(3), 156; https://doi.org/10.3390/agronomy9030156
Received: 29 January 2019 / Revised: 19 March 2019 / Accepted: 21 March 2019 / Published: 25 March 2019
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Abstract
In recent years, continuous efforts have been made to understand the impact of biochar on arable soil fertility. Little is known about whether the biochar derived from municipal sewage sludge has positive impacts on urban soil. In this study, we pyrolyzed spray-dried municipal [...] Read more.
In recent years, continuous efforts have been made to understand the impact of biochar on arable soil fertility. Little is known about whether the biochar derived from municipal sewage sludge has positive impacts on urban soil. In this study, we pyrolyzed spray-dried municipal sewage sludge at 200 °C, 300 °C, 500 °C, and 700 °C for 2 h in a muffle furnace and then amended it into an urban soil to grow turf grass in pots. The outcomes demonstrated that biochar incorporation caused remarkable increases in soil organic C, black C, total N, available P, and K by 3–8, 7–25, 2–9, 10–19, and 1.4–2 times, respectively. The dry matter of turf grass increased by 43–147%, probably due to the nutritional improvement after biochar addition. The turf grass grown in biochar-added soil had 4–70% lower heavy metals than that in the control, although the soils had much higher total heavy metals, which might imply that biochar amendment reduced the bioavailability of heavy metals. Considering the cost of biochar production and its impacts on both urban soil and grass, it would be alternative to convert the spray-dried municipal sewage sludge into biochar at 200 °C for 2 h and then used as an urban soil amendment. Full article
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Open AccessArticle Prohexadione-Calcium Application during Vegetative Growth Affects Growth of Mother Plants, Runners, and Runner Plants of Maehyang Strawberry
Agronomy 2019, 9(3), 155; https://doi.org/10.3390/agronomy9030155
Received: 30 January 2019 / Revised: 16 March 2019 / Accepted: 21 March 2019 / Published: 25 March 2019
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Abstract
Strawberry (Fragaria × ananassa Duch.) is an important horticultural crop that is vegetatively propagated using runner plants. To achieve massive production of runner plants, it is important to transfer the assimilation products of the mother plant to the runner plants, and not [...] Read more.
Strawberry (Fragaria × ananassa Duch.) is an important horticultural crop that is vegetatively propagated using runner plants. To achieve massive production of runner plants, it is important to transfer the assimilation products of the mother plant to the runner plants, and not to the runner itself. Application of prohexadione–calcium (Pro–Ca), a plant growth retardant with few side effects, to strawberry is effective in inhibiting transport of assimilates to runners. This study aimed to determine the optimum application method and concentration of Pro–Ca on the growth characteristics of mother plants, runners, and runner plants for the propagation of strawberry in nurseries. Pro–Ca was applied at the rate of 0, 50, 100, 150, or 200 mg·L−1 (35 mL per plant) to plants via foliar spray or drenching under greenhouse conditions at 30 days after transplantation. Petiole lengths of mother plants were measured 15 weeks after treatment; growth was suppressed at the higher concentrations of Pro–Ca regardless of the application method. However, the crown diameter was not significantly affected by the application method or Pro–Ca concentration. The number of runners was 7.0 to 8.2, with no significant difference across treatments. Runner length was shorter at higher concentrations of Pro–Ca, especially in the 200 mg·L−1 drench treatment. However, fresh weight (FW) and dry weights (DW) of runners in the 50 mg·L−1 Pro–Ca drench treatments were higher than controls. Foliar spray and drench treatments were more effective for runner plant production than the control; a greater number of runner plants were produced with the 100 and 150 mg·L−1 Pro–Ca foliar spray treatment and the 50 and 100 mg·L−1 drench treatment. The FW and DW of the first runner plant was not significantly different in all treatments, but DW of the second runner plant, and FW and DW of the third runner plant were greatest in the 50 mg·L−1 Pro–Ca drench treatment. These results suggested that growth and production of runner plants of Maehyang strawberry were greatest under the 50 mg·L−1 Pro–Ca drench treatment. Full article
(This article belongs to the Special Issue Berry Crop Production and Protection)
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Open AccessArticle Assessing the Individual and Combined Effects of QTL for Adult Plant Stripe Rust Resistance Derived from Cappelle-Desprez
Agronomy 2019, 9(3), 154; https://doi.org/10.3390/agronomy9030154
Received: 4 February 2019 / Revised: 4 March 2019 / Accepted: 12 March 2019 / Published: 25 March 2019
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Abstract
The release of commercial wheat cultivars resistant to stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), remains one of the primary objectives in many breeding programs. Previous studies of adult plant resistance derived from the winter wheat cultivar Cappelle-Desprez [...] Read more.
The release of commercial wheat cultivars resistant to stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), remains one of the primary objectives in many breeding programs. Previous studies of adult plant resistance derived from the winter wheat cultivar Cappelle-Desprez identified the quantitative trait loci (QTL) QYr.ufs-2A, QYr.ufs-2D, QYr.ufs-5B and QYr.ufs-6D to affect stripe rust under South African conditions. Phenotypic field assessment, fluorescence microscopy and molecular analysis were used to characterise recombinant inbred lines differing in number and combinations of these QTL. Besides the confirmation of enhanced resistance through co-occurring resistance loci, varying levels of defence, conditioned by different QTL combinations were observed. Carriers of QYr.ufs-2A or QYr.ufs-2D, accompanied by at least one other QTL, exhibited higher resistance levels than lines with a single QTL. The knowledge gained in this study will help wheat breeders to develop cultivars with more diverse combinations and potentially more durable sources of stripe rust resistance. Full article
(This article belongs to the Special Issue Cereal Rust Management for Improving Global Food Security)
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Open AccessArticle Phenolic Composition and Antioxidant Activities of Soybean (Glycine max (L.) Merr.) Plant during Growth Cycle
Agronomy 2019, 9(3), 153; https://doi.org/10.3390/agronomy9030153
Received: 5 March 2019 / Revised: 18 March 2019 / Accepted: 21 March 2019 / Published: 23 March 2019
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Abstract
It is important to identify the growth stage at which the plant has the maximum antioxidant properties for the production of bioactive compounds from crops or agricultural by-products or for forage as a possible source of antioxidants in livestock. Therefore, we investigated the [...] Read more.
It is important to identify the growth stage at which the plant has the maximum antioxidant properties for the production of bioactive compounds from crops or agricultural by-products or for forage as a possible source of antioxidants in livestock. Therefore, we investigated the phenolic composition and antioxidant capacity of the aerial part of soybean at seven stages classified as vegetative stages (V5 and V6) and reproductive stages (R1, R2, R3, R4, and R5). Aqueous-methanol extracts were evaluated for their total phenolic content (TPC), ferric-reducing antioxidant power (FRAP), Trolox equivalent antioxidant capacity (TEAC), antioxidant activity as determined by photochemiluminescence assay (PCL-ACL), Fe2+ chelating ability, and antiradical activity against DPPH. The extracts with the highest TPC content were obtained at stages V6 and R5. The phenolic compounds profile, as determined by DAD-HPLC, was characterized by 19 compounds, that differed significantly by growth stage (p < 0.05). Antioxidant tests showed significant differences among stages (p < 0.05). The lowest TEAC value was found for the R2 stage and the highest values for the R3 and R1 stages. FRAP values ranged from 623 to 780 μmol Fe2+/g extract. PCL-ACL values ranged from 516 to 560 μmol Trolox eq./g extract; Fe2+ chelation ability ranged from 36.5 to 51.7%. The highest antiradical activity against DPPH was found in the extract from the V5 stage, which had the lowest EC50 value. The extracts of soybean plant can be used in pharmacy for the production of nutraceuticals by virtue of their good antioxidant activity and content of flavonols and other bioactive constituents. Full article
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Open AccessArticle Upscaling Evapotranspiration with Parsimonious Models in a North Carolina Vineyard
Agronomy 2019, 9(3), 152; https://doi.org/10.3390/agronomy9030152
Received: 11 February 2019 / Revised: 16 March 2019 / Accepted: 19 March 2019 / Published: 23 March 2019
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Abstract
Water stress can positively or negatively impact grape yield and yield quality, and there is a need for wine growers to accurately regulate water use. In a four-year study (2010–2013), energy balance fluxes were measured with an eddy-covariance (EC) system in a North [...] Read more.
Water stress can positively or negatively impact grape yield and yield quality, and there is a need for wine growers to accurately regulate water use. In a four-year study (2010–2013), energy balance fluxes were measured with an eddy-covariance (EC) system in a North Carolina vineyard (Vitis vinifera cv. Chardonnay), and evapotranspiration (ET) and the Crop Water Stress Index (CWSI) calculated. A multiple linear regression model was developed to upscale ET using air temperature (Ta), vapor pressure deficit (VPD), and Landsat-derived Land Surface Temperature (LST) and Enhanced Vegetation Index (EVI). Daily ET reached values of up to 7.7 mm day−1, and the annual ET was 752 ± 59 mm, as measured with the EC system. The grapevine CWSI was between 0.53–0.85, which indicated moderate water stress levels. Median vineyard EVI was between 0.22 and 0.72, and the EVI range (max–min) within the vineyard was 0.18. The empirical models explained 75%–84% of the variation in ET, and all parameters had a positive linear relationship to ET. The Root Mean Square Error (RMSE) was 0.52–0.62 mm. This study presents easily applicable approaches to analyzing water dynamics and ET. This may help wine growers to cost-effectively quantify water use in vineyards. Full article
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Open AccessArticle Impact of Nitrogen Fertilization on Tuber Yield, Sugar Composition and Nitrogen Uptake of Two Yacon (Smallanthus sonchifolius Poepp. & Endl.) Genotypes
Agronomy 2019, 9(3), 151; https://doi.org/10.3390/agronomy9030151
Received: 25 February 2019 / Revised: 19 March 2019 / Accepted: 19 March 2019 / Published: 22 March 2019
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Abstract
The tuberous root crop, yacon, is native to the Andean region and contains high amounts of fructooligosaccharides (FOS) with up to 70% of dry matter. Due to FOS, consumption of tubers may have health-promoting effects. However, regarding the overall cultivation system, no recommendations [...] Read more.
The tuberous root crop, yacon, is native to the Andean region and contains high amounts of fructooligosaccharides (FOS) with up to 70% of dry matter. Due to FOS, consumption of tubers may have health-promoting effects. However, regarding the overall cultivation system, no recommendations exist for farmers on nitrogen fertilization and nitrogen (N) uptake of yacon. Therefore, three different N fertilization levels (0, 40, and 80 kg N ha−1) and two genotypes (brown-shelled (BG) and red-shelled (RG)) were examined in a two-year field experiment regarding their tuber yield, sugar composition, and nitrogen uptake. Tuber yields increased with increasing fertilization level and were highest for B80 and R80 (50 and 67 t FM ha−1), while significant differences between the genotypes existed. Sugar and the amount of FOS slightly decreased with increasing N fertilization level, and ranged between 36% and 73% and 30% and 58% of dry matter, respectively. An overall decreasing amount of FOS led to a slight increase in the amount of FOS with a higher degree of polymerization. Regarding the N-use efficiency of tubers and the total plant, an N fertilization level of 40 kg N ha−1 seems to favor tuber yield. Full article
(This article belongs to the Section Innovative Cropping Systems)
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Open AccessArticle Impact of Increasing Maize Densities on Agronomic Performances and the Community Stability of Productivity of Maize/Peanut Intercropping Systems
Agronomy 2019, 9(3), 150; https://doi.org/10.3390/agronomy9030150
Received: 14 February 2018 / Revised: 18 March 2019 / Accepted: 19 March 2019 / Published: 22 March 2019
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Abstract
Rational crop community structure plays an important role in maximizing the intercropping yield advantage. Effects of increasing maize densities in maize (Zea mays L.)/peanut (Arachis hypogaea L.) intercropping on yields and other agronomic traits, and the community stability of productivity were [...] Read more.
Rational crop community structure plays an important role in maximizing the intercropping yield advantage. Effects of increasing maize densities in maize (Zea mays L.)/peanut (Arachis hypogaea L.) intercropping on yields and other agronomic traits, and the community stability of productivity were conducted across three different experimental sites. There were significant and positive correlations between maize densities and both maize grain/biomass yields and corresponding partial land equivalent ratios (LERs) across all three locations; but grain/biomass yields and partial LERs of peanut were all negatively correlated with maize densities in each or across all locations. LERs of grain yields averaged over three locations ranged from 0.89 to 0.98, while LERs of biomass yields ranged from 0.94 to 1.09 (>1.0 except for the maize inter-plant distance of 27 cm), indicating the intercropping advantage on biomass yields but not grain yields. Peanut had significantly lower kernel harvest indexes than those in monoculture. Excessive narrowing maize inter-plant distances reduced the community stability of productivity severely (especially for maize and total LERs) and are more likely to lead to abnormal maize and peanut plants. Therefore, a rational increase of maize densities in intercropping is suggested to keep the balance between maize and peanut and the comprehensive yield advantage. Full article
(This article belongs to the Section Innovative Cropping Systems)
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Open AccessArticle Post-Anthesis Photosynthetic Properties Provide Insights into Yield Potential of Tartary Buckwheat Cultivars
Agronomy 2019, 9(3), 149; https://doi.org/10.3390/agronomy9030149
Received: 21 February 2019 / Revised: 14 March 2019 / Accepted: 18 March 2019 / Published: 21 March 2019
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Abstract
Photosynthesis is the basis for plant productivity, and improvement of photosynthetic efficiency is an important way to improve crop yield. However, the relationship between photosynthetic parameters and the yield of Tartary buckwheat (Fagopyrum tataricum) under rainfed conditions is unclear. A two-year [...] Read more.
Photosynthesis is the basis for plant productivity, and improvement of photosynthetic efficiency is an important way to improve crop yield. However, the relationship between photosynthetic parameters and the yield of Tartary buckwheat (Fagopyrum tataricum) under rainfed conditions is unclear. A two-year field trial was conducted during 2016 and 2017 to assess the photosynthetic capacity of different leaves, dry matter accumulation, and yield of four Tartary buckwheat cultivars from flowering to maturity. The leaves of all cultivars aged gradually after flowering, and the leaf chlorophyll (Chl) and soluble protein (SP) contents, net photosynthetic rates (Pn), transpiration rates (Tr), and stomatal conductance (Gs) tended to decline. The Chl, SP, Pn, Tr, and Gs of cultivars (cvs.) XiQiao2 and QianKu3 were significantly higher than those of LiuKu3 and JiuJiang at each sampling time from 18 days after anthesis to maturity, but the intercellular CO2 content (Ci) showed the opposite trend. Cultivars XiQiao2 and QianKu3 produced more total dry matter (mean 17.1% higher), had higher harvest index (HI, mean 16.4% higher), and yield (mean 29.0% higher) than cvs. LiuKu3 and JiuJiang at maturity, and the difference was remarkably consistent. The yield of all the cultivars was positively correlated with leaf Chl, SP, Pn, Tr, and Gs, but negatively correlated with Ci. At late growth stages, the high-yielding cultivars maintained higher Chl, SP contents, Pn, Tr, and Gs, and showed higher dry matter accumulation and lower Ci than the low-yielding cultivars, consistent with their higher leaf photosynthetic capacity. The important factors determining the yield of Tartary buckwheat were maintaining higher leaf Chl and SP content and photosynthetic capacity and delaying aging during the grain formation stage. Enhanced rates of photosynthesis and dry matter accumulation led to higher post-anthesis accumulation of biomass with a positive impact on grain number and higher yield. Full article
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Open AccessArticle Assessment of Ultrasound Assisted Extraction as an Alternative Method for the Extraction of Anthocyanins and Total Phenolic Compounds from Maqui Berries (Aristotelia chilensis (Mol.) Stuntz)
Agronomy 2019, 9(3), 148; https://doi.org/10.3390/agronomy9030148
Received: 15 February 2019 / Revised: 15 March 2019 / Accepted: 18 March 2019 / Published: 21 March 2019
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Abstract
Research interest regarding maqui (Aristotelia chilensis) has increased over the last years due to its potential health benefits as one of the most antioxidant-rich berries. Ultrasound-assisted extraction (UAE) is an advanced green, fast, and ecological extraction technique for the production of [...] Read more.
Research interest regarding maqui (Aristotelia chilensis) has increased over the last years due to its potential health benefits as one of the most antioxidant-rich berries. Ultrasound-assisted extraction (UAE) is an advanced green, fast, and ecological extraction technique for the production of high quality extracts from natural products, so it has been proposed in this work as an ideal alternative extraction technique for obtaining extracts of high bioactivity from maqui berries. In order to determine the optimal conditions, the extraction variables (percentage of methanol, pH, temperature, ratio “sample mass/volume of solvent”, amplitude, and cycle) were analyzed by a Box-Behnken design, in conjunction with the response surface method. The statistical analysis revealed that the temperature and the percentage of methanol were the most influential variables on the extraction of the total phenolic compounds and total anthocyanins, respectively. The optimal extraction time was determined at 15 min for total phenolic compounds, while it was only 5 min for anthocyanins. The developed methods showed a high precision level with a coefficient of variation of less than 5%. Finally, the new methods were successfully applied to several real samples. Subsequently, the results were compared to those that were obtained in previous experiments by means of microwave assisted extraction (MAE). Similar extraction yields were obtained for phenolic compounds under optimized conditions. However, UAE proved to be slightly more efficient than MAE in the extraction of anthocyanins. Full article
(This article belongs to the Special Issue Berry Crop Production and Protection)
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Open AccessArticle Using Flaming as an Alternative Method to Vine Suckering
Agronomy 2019, 9(3), 147; https://doi.org/10.3390/agronomy9030147
Received: 19 February 2019 / Revised: 14 March 2019 / Accepted: 19 March 2019 / Published: 21 March 2019
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Abstract
Suckering is the process of removing the suckers that grapevine trunks put out in the spring. Suckering by hand is costly and time consuming and requires constant bending down, getting up and making repetitive motions. The mechanical removal of suckers with rotating scourges [...] Read more.
Suckering is the process of removing the suckers that grapevine trunks put out in the spring. Suckering by hand is costly and time consuming and requires constant bending down, getting up and making repetitive motions. The mechanical removal of suckers with rotating scourges can damage the vine plants. Chemical suckering is a limiting factor for wine grape growers interested in sustainable and/or organic agriculture. The aim of this research was to test flaming as an alternative method to vine suckering. A three-year experiment was conducted on a 10-year-old Sangiovese vine (775 Paulsen rootstock). The treatments consisted of flame suckering at different phenological stages, hand-suckering and a no-suckered control. Data on the number of suckers, grape yield components, and grape composition were collected and analysed. The results showed that flaming significantly reduced the initial number of suckers. This effect on the suckers was highest when the main productive shoots of the vines were at the 18-19 BBCH growth stage. Flame-suckering did not affect grape yield components and grape composition. Future studies could investigate the simultaneous use of flaming for both suckering and weed control. Full article
(This article belongs to the Special Issue Smart Management of Conservative, Organic and Integrated Agriculture)
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Open AccessArticle The Potentiality of Marine Macro-Algae as Bio-Fertilizers to Improve the Productivity and Salt Stress Tolerance of Canola (Brassica napus L.) Plants
Agronomy 2019, 9(3), 146; https://doi.org/10.3390/agronomy9030146
Received: 1 February 2019 / Revised: 9 March 2019 / Accepted: 15 March 2019 / Published: 20 March 2019
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Abstract
The present study aimed to evaluate the potentiality of three seaweeds, which belong to different algal taxa (green alga Ulva lactuca Linnaeus, brown alga Cystoseira spp., and red alga Gelidium crinale (Hare ex Turner) Gaillon) as bio-fertilizers to improve the growth and yield [...] Read more.
The present study aimed to evaluate the potentiality of three seaweeds, which belong to different algal taxa (green alga Ulva lactuca Linnaeus, brown alga Cystoseira spp., and red alga Gelidium crinale (Hare ex Turner) Gaillon) as bio-fertilizers to improve the growth and yield of canola (Brassica napus L.) plants under greenhouse conditions. Furthermore, the impact of seaweeds in alleviating the effects of salt stress (75 and 150 mM NaCl) on canola plants was also investigated. The three examined seaweeds (applied as soil amendments) successfully alleviated the harmful effects of salinity on canola plants by significantly reducing the inhibition of chlorophyll a, b, total carbohydrate accumulation, and growth promoting hormones, while increasing antioxidative compounds, such as phenols, flavonoids, anthocyanin, and osmoprotectants, including total carbohydrates and proline. Phytochemical analysis of the three examined seaweeds suggests that their stimulatory effect on growth and productivity under normal and salinity growth conditions may be linked to their constituents of a wide variety of growth promotive hormones, including indole acetic acid, indole butyric acid, gibberellic acid, cytokinins, total carbohydrates, and phenolic compounds. U. lactuca was found to be the best candidate to be used as a bio-fertilizer to improve canola growth, yield, and salt stress tolerance. Full article
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Open AccessArticle Organic Food Consumers and Purchase Intention: A Case Study in Romania
Agronomy 2019, 9(3), 145; https://doi.org/10.3390/agronomy9030145
Received: 4 February 2019 / Revised: 14 March 2019 / Accepted: 17 March 2019 / Published: 20 March 2019
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Abstract
Organic farming has become an important alternative to conventional farming, mostly because of environmental sustainability issues, and has long-term positive benefits over soil, water, air and climate change, biodiversity, prohibiting the use of genetically modified organisms, and encouraging the development of ecological services. [...] Read more.
Organic farming has become an important alternative to conventional farming, mostly because of environmental sustainability issues, and has long-term positive benefits over soil, water, air and climate change, biodiversity, prohibiting the use of genetically modified organisms, and encouraging the development of ecological services. In Romania, the organic food market follows a positive trend, although the consumption rate is still very low compared to the European Union; therefore, it is necessary to identify the main barriers in consumption but also the factors influencing the increase in demand for this category of food products. In order to accomplish these objectives, a survey based on a questionnaire was conducted in the North-West Development Region of Romania, the second most important Romanian region from an economic development perspective. Five hundred and sixty-eight questionnaires were distributed in 2016. The collected data were danalyzed using descriptive statistics and principal component analysis. The results indicated that the most important barrier in consumption was price, followed by perishability and availability. High prices, mistrust, and lack of proper promotion for organic food are the influencing factors for organic food. Full article
Open AccessArticle Isolation and Characterization of the High Silicate and Phosphate Solubilizing Novel Strain Enterobacter ludwigii GAK2 that Promotes Growth in Rice Plants
Agronomy 2019, 9(3), 144; https://doi.org/10.3390/agronomy9030144
Received: 11 February 2019 / Revised: 15 March 2019 / Accepted: 18 March 2019 / Published: 20 March 2019
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Abstract
Silicon (Si) and phosphorus (P) are beneficial nutrient elements for plant growth. These elements are widely used in chemical fertilizers despite their abundance in the earth’s crust. Excessive use of chemical fertilizers is a threat to sustainable agriculture. Here, we screened different Si [...] Read more.
Silicon (Si) and phosphorus (P) are beneficial nutrient elements for plant growth. These elements are widely used in chemical fertilizers despite their abundance in the earth’s crust. Excessive use of chemical fertilizers is a threat to sustainable agriculture. Here, we screened different Si and P solubilizing bacterial strains from the diverse rice fields of Daegu, Korea. The strain with high Si and P solubilizing ability was selected and identified as Enterobacter ludwigii GAK2 through 16S rRNA gene sequence analysis. The isolate GAK2 produced organic acids (citric acid, acetic acid, and lactic acid), indole-3-acetic acid, and gibberellic acid (GA1, GA3) in Luria-Bertani media. In addition, GAK2 inoculation promoted seed germination in a gibberellin deficient rice mutant Waito-C and rice cultivar ‘Hwayoungbyeo’. Overall, the isolate GAK2 increased root length, shoot length, fresh biomass, and chlorophyll content of rice plants. These findings reveal that E. ludwigii GAK2 is a potential silicon and phosphate bio-fertilizer. Full article
(This article belongs to the Special Issue Plant Mineral Nutrition: Principles and Perspectives)
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Open AccessArticle A Method for a Fast Evaluation of the Biostimulant Potential of Different Natural Extracts for Promoting Growth or Tolerance against Abiotic Stress
Agronomy 2019, 9(3), 143; https://doi.org/10.3390/agronomy9030143
Received: 1 March 2019 / Revised: 13 March 2019 / Accepted: 15 March 2019 / Published: 20 March 2019
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Abstract
Under adverse environmental conditions, biostimulants can help crops withstand abiotic stress while increasing productivity. We have designed a sequential system based on two different biological model organisms—the baker’s yeast Saccharomyces cerevisiae and the plant Arabidopsis thaliana—to evaluate the potential as biostimulants of [...] Read more.
Under adverse environmental conditions, biostimulants can help crops withstand abiotic stress while increasing productivity. We have designed a sequential system based on two different biological model organisms—the baker’s yeast Saccharomyces cerevisiae and the plant Arabidopsis thaliana—to evaluate the potential as biostimulants of a battery of 11 different natural extracts on a blind-test basis. Firstly, yeast assays consist in a drop test in solid medium, and a BioScreen® test with liquid cultures. The method is completed with two plant assays to assess effects on germination and growth. The designed method provided relevant data on the ability of each extract to promote biomass accumulation under normal conditions and in the presence of abiotic stresses, such as drought, salinity, or cold. Besides, this laboratory-based method allowed to assess the potential toxicity or unsuspected deleterious effect of each extract in a short period of time (six months) with low budget and space requirements. We could also test the effects of the biostimulants during germination, vegetative, and reproductive growth, under normal and stressed conditions. As each product is tested on different organisms at different developmental stages, we could get some preliminary information on the mode of action. This method enables a fast screen of many different products, in order to select potential candidates to be marketed as biostimulants, avoiding long and expensive field tests with previously uncharacterized products. Full article
(This article belongs to the Section Soil and Plant Nutrition)
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Open AccessEditorial Deep Learning Techniques for Agronomy Applications
Agronomy 2019, 9(3), 142; https://doi.org/10.3390/agronomy9030142
Received: 14 March 2019 / Accepted: 18 March 2019 / Published: 20 March 2019
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Abstract
This editorial introduces the Special Issue, entitled “Deep Learning (DL) Techniques for Agronomy Applications”, of Agronomy. Topics covered in this issue include three main parts: (I) DL-based image recognition techniques for agronomy applications, (II) DL-based time series data analysis techniques for agronomy applications, [...] Read more.
This editorial introduces the Special Issue, entitled “Deep Learning (DL) Techniques for Agronomy Applications”, of Agronomy. Topics covered in this issue include three main parts: (I) DL-based image recognition techniques for agronomy applications, (II) DL-based time series data analysis techniques for agronomy applications, and (III) behavior and strategy analysis for agronomy applications. Three papers on DL-based image recognition techniques for agronomy applications are as follows: (1) “Automatic segmentation and counting of aphid nymphs on leaves using convolutional neural networks,” by Chen et al.; (2) “Estimating body condition score in dairy cows from depth images using convolutional neural networks, transfer learning, and model ensembling techniques,” by Alvarez et al.; and (3) “Development of a mushroom growth measurement system applying deep learning for image recognition,” by Lu et al. One paper on DL-based time series data analysis techniques for agronomy applications is as follows: “LSTM neural network based forecasting model for wheat production in Pakistan,” by Haider et al. One paper on behavior and strategy analysis for agronomy applications is as follows: “Research into the E-learning model of agriculture technology companies: analysis by deep learning,” by Lin et al. Full article
(This article belongs to the Special Issue Deep Learning Techniques for Agronomy Applications)
Open AccessArticle Progression of the Total and Individual Capsaicinoids Content in the Fruits of Three Different Cultivars of Capsicum chinense Jacq.
Agronomy 2019, 9(3), 141; https://doi.org/10.3390/agronomy9030141
Received: 5 February 2019 / Revised: 14 March 2019 / Accepted: 15 March 2019 / Published: 19 March 2019
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Abstract
The evolution of individual and total capsaicinoids content in three pepper varieties of Capsicum chinense Jacq. (‘Bode’ (B), ‘Habanero’ (H), and ‘Habanero Roxo’ (Hr)) during fruit ripening was studied. The five major capsaicinoids (nordihydrocapsaicin, capsaicin, dihydrocapsaicin, homocapsaicin, and homodihydrocapsaicin) were extracted using ultrasound-assisted [...] Read more.
The evolution of individual and total capsaicinoids content in three pepper varieties of Capsicum chinense Jacq. (‘Bode’ (B), ‘Habanero’ (H), and ‘Habanero Roxo’ (Hr)) during fruit ripening was studied. The five major capsaicinoids (nordihydrocapsaicin, capsaicin, dihydrocapsaicin, homocapsaicin, and homodihydrocapsaicin) were extracted using ultrasound-assisted extraction and the extracts were analysed by ultra-performance liquid chromatography with fluorescence detection (UHPLC-Fl). The plants were grown in a glasshouse and sampled every 7 days until over-ripening. As expected, the results indicated that the total capsaicinoids content increases during the ripening of pepper fruits. The maximum contents of capsaicinoids were reached at different fruit development stages depending on the cultivar. The ‘Habanero Roxo’ pepper presented the greatest total capsaicinoids content (3.86 mg g−1 fresh weigh, F.W.), followed by the ‘Habanero’ pepper (1.33 mg g−1 F.W.) and ‘Bode’ pepper (1.00 mg g−1 F.W.). In all the samples, capsaicin represented more than 80% of the total capsaicinoids content. Due to the high variability observed in the evolution of capsaicinoids content over the ripening process, this work intends to contribute to the existing knowledge on this aspect in relation to the quality of peppers. Full article
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Open AccessArticle Effects of Nanoparticles on Plant Growth-Promoting Bacteria in Indian Agricultural Soil
Agronomy 2019, 9(3), 140; https://doi.org/10.3390/agronomy9030140
Received: 2 February 2019 / Revised: 11 March 2019 / Accepted: 13 March 2019 / Published: 18 March 2019
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Abstract
Soil bacteria are some of the key players affecting plant productivity. Soil today is exposed to emerging contaminants like metal engineered nanoparticles. The objective of this study was to evaluate the toxicological effects of silver and zinc oxide nanoparticles on bacteria classified as [...] Read more.
Soil bacteria are some of the key players affecting plant productivity. Soil today is exposed to emerging contaminants like metal engineered nanoparticles. The objective of this study was to evaluate the toxicological effects of silver and zinc oxide nanoparticles on bacteria classified as plant growth-promoting bacteria. Three types of bacteria—nitrogen fixers, phosphate solubilizers, and biofilm formers—were exposed to engineered nanoparticles. Initially, the effect of silver and zinc oxide nanoparticles was determined on pure cultures of the bacteria. These nanoparticles were then applied to soil to assess changes in composition of bacterial communities. Impacts of the nanoparticles were analyzed using Illumina MiSeq sequencing of 16S rRNA genes. In the soil used, relative abundances of the dominant and agriculturally significant phyla, namely, Proteobacteria, Actinobacteria, and Firmicutes, were altered in the presence of silver nanoparticles. Silver nanoparticles changed the abundance of the three phyla by 25 to 45%. Zinc oxide nanoparticles showed negligible effects at the phylum level. Thus, silver nanoparticles may impact bacterial communities in soil, and this in turn may influence processes carried out by soil bacteria. Full article
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Open AccessArticle Physiological and Growth Response of Pepper (Capsicum annum L.) Seedlings to Supplementary Red/Blue Light Revealed through Transcriptomic Analysis
Agronomy 2019, 9(3), 139; https://doi.org/10.3390/agronomy9030139
Received: 21 January 2019 / Revised: 2 March 2019 / Accepted: 12 March 2019 / Published: 18 March 2019
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Abstract
Red and blue light have great effects on physiological processes and growth of plants. In this experiment, we investigated the physiological and growth response of pepper (Capsicum annuum L.) to supplementary red:blue (4:1) light for 1 h (T1), 3 h (T2), and [...] Read more.
Red and blue light have great effects on physiological processes and growth of plants. In this experiment, we investigated the physiological and growth response of pepper (Capsicum annuum L.) to supplementary red:blue (4:1) light for 1 h (T1), 3 h (T2), and 5 h (T3), and the full-spectrum light-emitting diodes, LEDs, as control (CK). Thirty-day-old seedlings were grown under these treatments for 20 days in a climate-controlled room before data measurement. The results showed that the light treatments significantly (p < 0.05) affected the photosynthesis and growth indexes as well as gene expression in the pepper seedlings. Plants under T2 generally had better performance in terms of seedling growth. A total of 124, 1283, and 1091 differentially expressed genes were found in CK vs. T1, CK vs. T2, and CK vs. T3, respectively. Among the treatments, T2 in comparison with CK had 705 upregulated and 578 downregulated differentially expressed genes (DEGs). We also found that CPRF2, Paggis, HLIPS, GIGANTEA, LSH1, and FTSH genes were expressed differently under the various light treatments. Based on GeneOntology (GO) enrichment analysis, DEGs were significantly enriched on 15 GO terms of which xyloglucan:xyloglucosyl transferase activity and apoplastic, cellular polysaccharide metabolic, and cellular carbohydrate metabolic processes were closely related to light responses. A total of 96 genes that are related to plant–pathogen interaction, zeatin biosynthesis, plant hormone signal transduction, and wax/cutin/suberine biosynthesis which are involved in the pathway of light reaction in plants were significantly enriched in T2 plants compared with plants under CK. The application of red:blue light at 4:1 for 3 h improved the growth of pepper seedlings better than the other treatments and this can be tested under the Chinese Solar Greenhouse condition. Full article
(This article belongs to the Section Horticultural and Floricultural Crops)
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Open AccessArticle Exogenous Foliar Application of Glycine Betaine to Alleviate Water Deficit Tolerance in Two Indica Rice Genotypes under Greenhouse Conditions
Agronomy 2019, 9(3), 138; https://doi.org/10.3390/agronomy9030138
Received: 3 February 2019 / Revised: 25 February 2019 / Accepted: 15 March 2019 / Published: 18 March 2019
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Abstract
The aim of this investigation was to enhance overall growth, yield attributes as well as physio-biochemical adaptive strategies by exogenous foliar application of glycine betaine (GlyBet) in two rice varieties against water deficit stress under greenhouse conditions. Rice crop cvs. RD43 (low amylose [...] Read more.
The aim of this investigation was to enhance overall growth, yield attributes as well as physio-biochemical adaptive strategies by exogenous foliar application of glycine betaine (GlyBet) in two rice varieties against water deficit stress under greenhouse conditions. Rice crop cvs. RD43 (low amylose content) and SPR1 (high amylose content) grown in clay pots containing garden soil until booting stage were chosen as the test plant material, sprayed by 0 (control) or 100 mM GlyBet and subsequently subjected to: MWD (mild water deficit by 8 d water withholding; 24.80% SWC; Soil water content) or SWD (severe water deficit by 14 d water withholding; 13.63% SWC) or WW (well-watered conditions or control). Free proline content in cv. RD43 was rapidly increased in relation to the degree of water deficit and suppressed by exogenous GlyBet, while free proline in cv. SPR1 was lower than cv. RD43. Overall growth performances and yield traits in both cultivars under MWD were maintained by exogenous application of GlyBet; however, these parameters declined under SWD even after the GlyBet application. Degradation of photosynthetic pigments and chlorophyll fluorescence in pretreated GlyBet plants under SWD were prevented, resulting in elevated net photosynthetic rate (Pn). Interestingly, Pn was very sensitive parameter that sharply declined under SWD in both RD43 and SPR1 genotypes. Positive relationships between physio-morphological and biochemical changes in rice genotypes were demonstrated with high correlation co-efficiency. Based on the key results, it is concluded that foliar GlyBet application may play an important role in drought-tolerant enhancement in rice crops. Full article
(This article belongs to the Special Issue Roles of Glycine Betaine in Improving Plant Abiotic Stress Resistance)
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Open AccessArticle Growth, Secondary Metabolites and Enzyme Activity Responses of Two Edible Fern Species to Drought Stress and Rehydration in Northeast China
Agronomy 2019, 9(3), 137; https://doi.org/10.3390/agronomy9030137
Received: 13 February 2019 / Revised: 9 March 2019 / Accepted: 13 March 2019 / Published: 16 March 2019
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Abstract
The drought resistance mechanism of Matteuccia struthiopteris (L.) Todar. and Athyrium multidentatum (Doll.) Ching were measured under natural drought exposure. The results showed that the two edible fern species showed stronger resistance in the early stages of drought, mainly expressed as the decrease [...] Read more.
The drought resistance mechanism of Matteuccia struthiopteris (L.) Todar. and Athyrium multidentatum (Doll.) Ching were measured under natural drought exposure. The results showed that the two edible fern species showed stronger resistance in the early stages of drought, mainly expressed as the decrease of relative leaf water content (RLWC), increase of osmotic substances, secondary metabolites such as flavonoids (FC), total phenols (TPC), proantho cyanidins (PCC) content and enzyme activity (superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX)). The higher RLWC, FC, TPC, PCC and abscisic acid (ABA) content and lower H2O2 content indicates the stronger non-enzymatic antioxidant system and drought resistance of A. multidentatum. However, the proline (Pro) content changed slowly, and the synthesis of soluble protein (SP), total phenols, proantho cyanidins and ABA, SOD activity of two fern species were inhibited in the late stages of drought stress. This study can provide a scientific basis for the cultivation and utilization of edible fern species under forest in Northeast China. Full article
(This article belongs to the Special Issue Functional Metabolism in Crops/Agronomy)
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Open AccessArticle Impact of Row Spacing, Sowing Density and Nitrogen Fertilization on Yield and Quality Traits of chia (Salvia Hispanica L.) Cultivated in southwestern Germany
Agronomy 2019, 9(3), 136; https://doi.org/10.3390/agronomy9030136
Received: 18 February 2019 / Revised: 5 March 2019 / Accepted: 6 March 2019 / Published: 15 March 2019
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Abstract
To obtain high chia seed yields and seed qualities, a suitable crop management system needs to be developed for the given growing conditions in southwestern Germany. Field experiments were conducted at the experimental station Ihinger Hof in two consecutive years (2016, 2017). The [...] Read more.
To obtain high chia seed yields and seed qualities, a suitable crop management system needs to be developed for the given growing conditions in southwestern Germany. Field experiments were conducted at the experimental station Ihinger Hof in two consecutive years (2016, 2017). The study aimed to evaluate yield and quality traits of chia depending on different (i) row spacing (35, 50 and 75 cm), (ii) sowing densities (1, 1.5 and 2 kg ha−1) and, (iii) N-fertilization rates (0, 20 and 40 kg N ha−1). It consisted of three independent, completely randomized field experiments with three replications. Results showed that chia seed yields ranged from 618.39 to 1171.33 kg ha−1 and that a thousand seed mass of 1.14 to 1.24 g could be obtained. Crude protein-, crude oil- and mucilage contents varied from 18.11–23.91%, 32.16–33.78% and 10.00–13.74%, respectively. Results indicated that the year of cultivation and the accompanied environmental conditions, like precipitation or temperature, influenced the determined traits more than the applied agronomic practices. As average seed yields exceeded those obtained in the countries of origin (Mexico, Guatemala) while having comparable quality characteristics, chia holds great potential as an alternative crop for farmers in southwestern Germany. Full article
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Open AccessArticle Variability among Young Table Grape Cultivars in Response to Water Deficit and Water Use Efficiency
Agronomy 2019, 9(3), 135; https://doi.org/10.3390/agronomy9030135
Received: 28 January 2019 / Revised: 8 March 2019 / Accepted: 11 March 2019 / Published: 15 March 2019
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Abstract
Climate change will lead to higher frequencies and durations of water limitations during the growing season, which may affect table grape yield. The aim of this experiment was to determine the variability among 3-year old table grape cultivars under the influence of prolonged [...] Read more.
Climate change will lead to higher frequencies and durations of water limitations during the growing season, which may affect table grape yield. The aim of this experiment was to determine the variability among 3-year old table grape cultivars under the influence of prolonged water deficit during fruit development on gas exchange, growth, and water use efficiency. Six own rooted, potted table grape cultivars (cv. ‘Muscat Bleu’, ‘Fanny’, ‘Nero’, ‘Palatina’, ‘Crimson Seedless’ and ‘Thompson Seedless’) were subjected to three water deficit treatments (Control treatment with daily irrigation to 75% of available water capacity (AWC), moderate (50% AWC), and severe water deficit treatment (25% AWC)) for three consecutive years during vegetative growth/fruit development. Water deficit reduced assimilation, stomatal conductance, and transpiration, and increased water use efficiencies (WUE) with severity of water limitation. While leaf area and number of leaves were not affected by treatments in any of the tested cultivars, the response of specific leaf area to water deficit depended on the cultivar. Plant dry mass decreased with increasing water limitation. Overall, high variability of cultivars to gas exchange and water use efficiencies in response to water limitation was observed. ’Palatina’ was the cultivar having a high productivity (high net assimilation) and low water use (low stomatal conductance) and the cultivar ‘Fanny’ was characterized by the highest amount of total annual dry mass as well as the highest total dry mass production per water supplied during the experiment (WUEDM). Hence, ‘Fanny’ and ‘Palatina’ have shown to be cultivars able to cope with water limiting conditions and should be extensively tested in further studies. Full article
(This article belongs to the Special Issue Viticulture and Winemaking under Climate Change)
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Open AccessArticle May the Inclusion of a Legume Crop Change Weed Composition in Cereal Fields? Example of Sainfoin in Aragon (Spain)
Agronomy 2019, 9(3), 134; https://doi.org/10.3390/agronomy9030134
Received: 21 January 2019 / Revised: 27 February 2019 / Accepted: 9 March 2019 / Published: 14 March 2019
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Abstract
Onobrychis viciifolia (Scop.) (sainfoin) is promoted in the Spanish Aragón region through the Agro-Environmental Schemes (AES) since 2007 with the aim of enhancing biodiversity. Also, in other countries, the interest in this legume crop is growing due to its rusticity and beneficial effects [...] Read more.
Onobrychis viciifolia (Scop.) (sainfoin) is promoted in the Spanish Aragón region through the Agro-Environmental Schemes (AES) since 2007 with the aim of enhancing biodiversity. Also, in other countries, the interest in this legume crop is growing due to its rusticity and beneficial effects on the soil and livestock. However, the effect of the crop on weed flora in the subsequent cereal crops has hardly been investigated yet. With this aim, weed flora has been characterised in 2011–2014 in sainfoin fields in the second and third year of establishment (S2 and S3), in cereal monocrop (CM), in cereal after sainfoin (CS) and in organic cereal fields (OC). Additionally, the soil seedbank was determined in two years in CM and S3 fields. Weed species richness of emerged flora and of the soil seedbank was highest for sainfoin and lowest for CM, being intermediate for OC and CS regardless of the sampling year. The most feared weed species in winter cereal did not increase by growing sainfoin or in CS compared to CM. Curiously, summer annuals dominated in the soil seedbank. Sainfoin fields cause thus a shift in the weed flora, which does not seem to damage subsequent cereal crops provided fields are mouldboard ploughed after sainfoin. Full article
(This article belongs to the Special Issue Weed Management in Annual and Perennial Cropping Systems)
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Open AccessArticle Effects of Full Straw Incorporation on Soil Fertility and Crop Yield in Rice-Wheat Rotation for Silty Clay Loamy Cropland
Agronomy 2019, 9(3), 133; https://doi.org/10.3390/agronomy9030133
Received: 11 January 2019 / Revised: 27 February 2019 / Accepted: 4 March 2019 / Published: 12 March 2019
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Abstract
This 2-year field experiment investigated the effects of full straw incorporation on soil fertility and crop yield in a rice-wheat (Oryza sativa L.–Triticum aestivum L.) rotation on sandy, loamy soil. Two treatments were tested: (i) straw removal (CK) and (ii) straw [...] Read more.
This 2-year field experiment investigated the effects of full straw incorporation on soil fertility and crop yield in a rice-wheat (Oryza sativa L.–Triticum aestivum L.) rotation on sandy, loamy soil. Two treatments were tested: (i) straw removal (CK) and (ii) straw incorporation (STR). The STR significantly increased the wheat yield by an average of 58% compared with CK; however, no significant difference was found in the rice yield. Soil available nitrogen, phosphorus, and potassium in the 0–20 cm soil layer increased by more than 15% with STR compared to CK. The soil cation exchange capacity and organic carbon in the 0–20 cm soil layer increased by 8% and 22%, for STR compared to CK, respectively. Straw incorporation significantly elevated the soil saturated water content but decreased the soil bulk density compared with CK. Soil aggregates >2 mm were significantly increased after straw return. STR also notably increased the soil urease, invertase, and catalase activities in the 0–15 cm soil layer by 11.4%, 41.0%, and 12.9%, respectively, and the soil microbial carbon and nitrogen contents in the 0–20 cm soil layer by 59% and 54%. Therefore, full straw incorporation could significantly improve soil fertility and maintain crop yields for the study area. Full article
(This article belongs to the Section Soil and Plant Nutrition)
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Open AccessArticle Assessing Spatial and Temporal Variability for Some Edaphic Characteristics of Mediterranean Rainfed and Irrigated Soils
Agronomy 2019, 9(3), 132; https://doi.org/10.3390/agronomy9030132
Received: 4 February 2019 / Revised: 4 March 2019 / Accepted: 7 March 2019 / Published: 12 March 2019
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Abstract
Mediterranean soils are particularly threatened by salinization and low levels of organic matter content. In order to assess an edaphic sustainable use, we need to study its characteristics and better understand the temporal and spatial evolution. In this study, a total of 14,852 [...] Read more.
Mediterranean soils are particularly threatened by salinization and low levels of organic matter content. In order to assess an edaphic sustainable use, we need to study its characteristics and better understand the temporal and spatial evolution. In this study, a total of 14,852 ha located in a western Mediterranean basin were selected as the study site where 1417 and 1451 topsoil samples were analyzed in 2001/2002 and 2011/2012, respectively, for Soil Organic Matter (SOM) content, pH water (pHw) and electrical conductivity (EC). Classical statistics and geostatistics techniques were used and the individual soil samples were related with the cultural system (CS) practiced–rainfed/irrigation–and the Reference Soil Group (RSG)–Cambisols, Calcisols, Luvisols, and Fluvisols. Predictive maps were created by interpolation using the Ordinary Kriging algorithm. The main results of this study were that, when transitioning from a rainfed to irrigation CS, SOM content is maintained in Cambisols but decreases in the other RSGs, pHw is maintained and EC increases in Fluvisols, Luvisols, and Cambisols. Over time in the rainfed CS all RSGs maintained SOM and pHw but EC increased in Fluvisols, Luvisols, and Calcisols and in the irrigation CS SOM decreased in Luvisols, pHw increased in Fluvisols and Calcisols and EC increased in all RSGs. Full article
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Open AccessArticle Mycorrhizal Fungi Enhance Resistance to Herbivores in Tomato Plants with Reduced Jasmonic Acid Production
Agronomy 2019, 9(3), 131; https://doi.org/10.3390/agronomy9030131
Received: 23 January 2019 / Revised: 4 March 2019 / Accepted: 6 March 2019 / Published: 12 March 2019
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Abstract
Arbuscular mycorrhizal (AM) fungi favor plant growth by improving nutrient acquisition, but also by increasing their resistance against abiotic and biotic stressors, including herbivory. Mechanisms of AM fungal mediated increased resistance include a direct effect of AM fungi on plant vigor, but also [...] Read more.
Arbuscular mycorrhizal (AM) fungi favor plant growth by improving nutrient acquisition, but also by increasing their resistance against abiotic and biotic stressors, including herbivory. Mechanisms of AM fungal mediated increased resistance include a direct effect of AM fungi on plant vigor, but also a manipulation of the hormonal cascades, such as the systemic activation of jasmonic acid (JA) dependent defenses. However, how AM fungal inoculation and variation in the endogenous JA production interact to produce increased resistance against insect herbivores remains to be further elucidated. To address this question, three genotypes of Solanum lycopersicum L., a JA-biosynthesis deficient mutant, a JA over-accumulating mutant, and their wild-type were either inoculated with AM fungi or left un-inoculated. Plant growth-related traits and resistance against Spodoptera littoralis (Boisduval) caterpillars, a major crop pest, were measured. Overall, we found that deficiency in JA production reduced plant development and were the least resistant against S. littoralis. Moreover, AM fungi increased plant resistance against S. littoralis, but such beneficial effect was more pronounced in JA-deficient plant than on JA over-accumulating plants. These results highlight that AM fungi-driven increased plant resistance is negatively affected by the ability of plants to produce JA and that AM fungi complement JA-mediated endogenous plant defenses in this system. Full article
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