Response Of Grain Yield Research Articles

Assessing the impact of early and terminal droughts on root growth, grain yield and yield stability in old and modern wheat cultivars on the Loess Plateau

Understanding changes in root traits of high-yielding genotypes that consistently perform during different drought periods is crucial for improving wheat production and yield stability. A 2-year field trial and a pot experiment were conducted to determine the response of root growth and grain yield to early and terminal droughts in old and modern cultivars (FC3: 1960s and CH1: 2010s) under rainfed and irrigated conditions in the field. Rainfed wheat faced terminal drought in 2015–2016 and early drought in 2016–2017. Plants in the pot experiment were exposed to terminal drought, early drought, and well-watered. Both field and pot experiments showed higher grain yield in modern cultivar CH1 compared to FC3. Early and terminal droughts reduced grain yield in both cultivars, with a greater reduction in FC3. CH1 exhibited higher yield stability under drought conditions and experienced less reduction in early drought. Compared to FC3, CH1 produced more root biomass in the early growth stage. At anthesis, CH1 had significantly lower root biomass and root length density in the topsoil layer (00.2 m) and higher in the subsoil layer (0.21.0 m) than FC3, respectively. At maturity, the retention rate of subsoil root biomass in CH1 was higher, especially under early drought (80.2 % in field and 93.9 % in pot experiments). Both cultivars consumed similar seasonal water use, but CH1 reduced pre-anthesis water use and consumed more water after anthesis. This study indicates that modern cultivar had vigorous root growth at early stage. A higher proportion of root biomass preserved in deep soil after anthesis enhanced post-anthesis water use and photosynthetic rate, improved post-anthesis dry matter accumulation, and thus resulted in higher thousand kernel weight. These factors ensure higher yield and yield stability under both early and terminal drought stress.

Evaluation of source–sink manipulation through defoliation treatments in promising bread wheat lines under optimal irrigation and rainfed conditions

The source–sink (S-S) ratio during the grain-filling period is crucial for wheat crop yield. The aim of this study was to investigate the relative sensitivity of grain yield in response to treatments of S-S ratio changes to determine the extent of S-S limitation during grain filling in modern wheat genotypes. The S-S manipulation treatments included four levels: check (CH), removal of flag leaf (RFL), removal of all leaves (RAL), and removal of the upper half of the spikes (RHS). The results showed significant differences between genotypes (pb< 0.001%) in all traits. Drought stress decreased grain weight per spike (GWS) (g) and grain yield (GY) (kg/ha) by 18% and 25%, respectively. The average reduction in GWS under irrigation and rainfed conditions was 8.25% and 6.71% for RFL and 12.25% and 11.15% for RAL, respectively. By RFL and RAL, increasing the remobilization from the stem and spike straw helped to reduce the effects of source limitation. Also, by RHS, the reduction in photosynthetic materials production in both conditions was only equivalent to 38% and 29% of the expected values, respectively, which shows the presence of strong sinks in vegetative organs (stem and spike) compared to grains. Vegetative organs seem to have a larger sink for the uptake of photosynthetic materials than grains when the source–sink ratio increases. However, high-yield genotypes showed more severe source limitation, while low-yield genotypes showed more relative sink limitation. Overall, to increase the yield potential in high-yielding genotypes, photosynthetic sources and sinks in low-yielding genotypes should be improved.

Drip Fertigation Enhances the Responses of Grain Yield and Quality to Nitrogen Topdressing Rate in Irrigated Winter Wheat in North China.

Conventional water and nitrogen (N) management practice in north China, comprising flood irrigation and N fertilizer broadcast (FB), limits sustainable wheat production. Drip fertigation (DF) has been widely adopted in wheat production in recent years and has effectively improved yields. However, the responses of the yield and quality to the N topdressing rate (NTR) under DF are still unclear. This study determined the responses of the wheat yield and quality to NTR under DF, as well as assessing whether DF could synergistically increase the yield and quality. A field experiment was conducted in north China for two seasons (2021-2023) using a split-plot design with three replicates. The main plot used the management practice (FB and DF) and the sub-plot had N treatment (no N applied, and NTRs of 0, 40, 80, 120, and 160 kg ha-1 with 150 kg N ha-1 as basal fertilizer, denoted as N0, T0, T40, T80, T120, and T160, respectively). Our results showed that high and saturated wheat yields (12.08 and 11.46 t ha-1) were obtained under DF at T80, and the highest yields were produced at T160 (11.71 and 11.30 t ha-1) under FB. Compared with FB, the greatest yield increase of 10.4-12.6% was achieved at T80 under DF. A higher spike number due to the increased effective stem percentage and a greater grain weight because of enhanced post-anthesis biomass production (BPpost) explained the improved yield under DF. The enhanced post-anthesis radiation use efficiency (RUE) led to the greater BPpost under DF. The enhanced specific leaf N, antioxidant capacity, and stomatal conductance under DF explained the higher light-saturated photosynthesis rate of flag leaves, which partly led to the increased post-anthesis RUE. NTR higher than 80 kg ha-1 did not enhance the yield, but it significantly improved the gliadin and glutelin contents, thereby leading to a higher total protein content, better gluten characteristics, and superior processing quality. Therefore, drip fertigation is a practical strategy for increasing both yield and quality with reduced water input and appropriate N input in irrigated winter wheat in north China. Applying 80 kg ha-1 of NTR under drip irrigation produces a high yield, but further gain in grain quality needs a higher NTR.

Leaf photosynthetic performance is not a key factor affecting grain yield in spring wheat subjected to heat and combined heat and drought stresses

AbstractThe yield traits and physiological responses of three wheat genotypes were studied when subjected to heat and combined heat and drought stress at anthesis under either aCO2 (400 ppm) or eCO2 (800 ppm) in a greenhouse. The heat treatment was 7‐days at day/night 35/28°C, and the combined heat and drought was withholding irrigation from the heat‐stressed plants until the photosynthetic rate reached <5 μmol m−2 s−1. The LM62 genotype had higher photosynthetic rate compared with LM19, though no significant difference in grain yield was found. eCO2 increased photosynthesis at 35°C and significantly lowered the electron transport rate at high intercellular CO2 concentrations. Maximum velocity of Rubisco carboxylation (Vcmax) and the maximum velocity of RuBP regeneration in leaves (Jmax) increased in 35°C compared with 25°C, though when normalized to 25°C both Vcmax and Jmax decreased in the heat‐stressed plants, indicating that an inhibition had occurred. The maximum photochemical efficiency of photosystem II (Fv/Fm) decreased under heat, which correlated with the yield loss caused by the stress. Fv/Fm also decreased under combined heat and drought, though it did not related to the declined yield. A small leaf area prolonged the drying period of Gladius, and it was the genotype with the lowest decrease in yield because of stress. It is concluded that the effects of heat and combined heat and drought stress on the gas exchange and photosynthetic capacity on leaf area basis are not directly linked to the yield performance among wheat genotypes, while the morphological characteristics of the plants are important determinants of grain yield in response to those abiotic stresses.

Dissecting the effect of heat stress on durum wheat under field conditions.

Heat stress negatively affects wheat production in several ways, mainly by reducing growth rate, photosynthetic capacity and reducing spike fertility. Modeling stress response means analyzing simultaneous relationships among traits affecting the whole plant response and determinants of grain yield. The aim of this study was to dissect the diverse impacts of heat stress on key yield traits and to identify the most promising sources of alleles for heat tolerance. We evaluated a diverse durum wheat panel of 183 cultivars and breeding lines from worldwide, for their response to long-term heat stress under field conditions (HS) with respect to non stress conditions (NS), considering phenological traits, grain yield (GY) and its components as a function of the timing of heat stress and climatic covariates. We investigated the relationships among plant and environmental variables by means of a structural equation model (SEM) and Genetic SEM (GSEM). Over two years of experiments at CENEB, CIMMYT, the effects of HS were particularly pronounced for the normalized difference vegetation index, NDVI (-51.3%), kernel weight per spike, KWS (-40.5%), grain filling period, GFP (-38.7%), and GY (-56.6%). Average temperatures around anthesis were negatively correlated with GY, thousand kernel weight TKW and test weight TWT, but also with spike density, a trait determined before heading/anthesis. Under HS, the correlation between the three major determinants of GY, i.e., fertile spike density, spike fertility and kernel size, were of noticeable magnitude. NDVI measured at medium milk-soft dough stage under HS was correlated with both spike fertility and grain weight while under NS it was less predictive of grain weight but still highly correlated with spike fertility. GSEM modeling suggested that the causal model of performance under HS directly involves genetic effects on GY, NDVI, KWS and HD. We identified consistently suitable sources of genetic resistance to heat stress to be used in different durum wheat pre-breeding programs. Among those, Desert Durums and CIMMYT'80 germplasm showed the highest degree of adaptation and capacity to yield under high temperatures and can be considered as a valuable source of alleles for adaptation to breed new HS resilient cultivars.

Boron Fertilization Improves the Agronomic Performance of Soybean Genotypes in the Brazilian Cerrado

Currently, Brazil is the largest producer and exporter of soybeans in the world. Most of this cultivation is concentrated in the Cerrado region, which has soils with low boron levels. Boron performs functions that are directly linked to plant performance. The objective of this study was to evaluate the agronomic performance of soybean cultivars with and without boron fertilization. Two field experiments were carried out in the agricultural years 2018/2019 and 2019/2020. Each experiment was carried out in a randomized block design with four replications and 10 soybean cultivars (Desafio, Foco, Bonus, Maracaí, 7067, 7110, 7739, 8372, 7100, and Population). Boron fertilization was carried out at the V3 stage of the crop using ulexite (10% of boron) at a rate of 3194 kg ha−1 and 0.0 kg ha−1 of B. The application of boron to the soil increased plant height, pod insertion height, number of branches, main stem diameter, and number of pods per plant, in addition to increasing the cycle of these cultivars. The cultivars 7110, 7739 and Desafio did not statistically differ in terms of grain yield in response to boron fertilization. The cultivars Foco, Bonus, Maracaí, 7067, 8372, 7100, and Population responded favorably to this fertilization. Furthermore, genetic breeding programs incorporate advanced strategies, such as the use of boron fertilization, in order to improve the performance of the selected genotypes. Implementing boron fertilization as an integral part of breeding programs helps not only to achieve high-yielding cultivars but also to optimize key agronomic traits. This integrated approach not only boosts breeding research but also provides a solid basis for sustainable and efficient agricultural practices.

Response of maize grain yield and components to foliar iron nanoparticle application

During the spring season of 2021, a field experiment was conducted at the College of Agricultural Engineering Sciences - University of Baghdad (Abi Ghraib location). To investigate the impact of nano iron concentrations and their application dates on the yield and its components of maize. A factorial experiment was carried out in a split-plot arrangement. The main plots occupied the spraying dates (beginning of the male flowering stage, 50% female flowering and completion of female flowering) and symbolized in sequence. At the same time, the iron concentrations (0, 100, 200 and 300 mg. L-1) occupied sub-plots according to RCBD with three replicates. The results revealed that the dates of spraying nano iron substantially influenced most of the features tested. The early date (beginning of the male flowering stage) gave the highest average length of the ear (16.374 cm), the number of rows per ear (16.3 row ear-1), and the number of grains per ear (563.4 grain ear-1) and the total grain yield of 6.096 tons ha.-1. The results also showed that the concentrations of nano iron 300 mg L-1were superior in all the characteristics of the yield components and the grain yield, as it produced the most significant average for ear length, number of rows, number of grains per row, number of grains in the ear, weight of 500 grains, and total grain yield. It is concluded from this study that spraying at the beginning of the flowering stage is the most responsive to spraying the nano iron element, especially at the concentration of 300 mg L-1. Keywords: Nano iron; flowering stage; ear length; grain yield

Is green manure a viable substitute for inorganic fertilizer to improve grain yields and advance carbon neutrality in paddy agriculture?

Green manure is a widely applied to increase grain yield, while it also attributes to greenhouse gas (GHG) emissions in agriculture ecosystems. Combining green manure with inorganic fertilizer inputs is a common practice that can influence soil GHG emissions and grain yield, however, its impacts on grain yield and global warming potential (GWP) under different initial soil conditions before rotating experiments and agronomic management in paddy fields remain unclear. We synthesized 508 data pairs to evaluate the responses of CO2 emissions, CH4 emissions, N2O emissions, and grain yield to combined inputs of green manure plus inorganic fertilizer compared with only inorganic fertilizer application. Our findings indicate that both inorganic fertilizer plus extra green manure (GM-E) and green manure substitutes for inorganic fertilizer (GM-S) could increase CO2 emissions (22.5 %−76.8 %), CH4 emissions (100 %−103 %), N2O emissions (29.8 %−50.9 %), and yield (2.21 %−19.6 %). Except for GM-E, which showed a non-significant increase in grain yield. The initial soil properties before rotating experiments, the types and timing of green manure application were key drivers of GHG emissions and yield, and extra green manure applied in areas with low initial soil pH and high C:N can increase GWP and yield. Overall, the mixed green manure application had greater impact than leguminous or non-leguminous green manure applied alone. The responses of GHG emissions and yield to GM-S were modulated by mean annual precipitation and initial soil properties before rotating experiments, and green manure substitutes for inorganic fertilizer in areas with high initial soil pH and low C:N can increase GWP and yield. Meanwhile, excessive precipitation caused a reduction in yield and a significant increase in GWP intensity. Our results showed that extra green manure applications of less than 68.1 kg N ha−1 would not significantly increase GWP. Therefore, an effective green manure strategy can achieve a win-win situation for the dual challenge of agricultural production and climate change mitigation.

Responses of grain yield and water-nitrogen dynamic of drip-irrigated winter wheat (Triticum aestivum L.) to different nitrogen fertigation and water regimes in the North China Plain

Responses of grain yield and water-nitrogen dynamic of drip-irrigated winter wheat (Triticum aestivum L.) to different nitrogen fertigation and water regimes in the North China Plain

Yield components and yield quality of old and modern wheat cultivars as affected by cultivar release date, N fertilization and environment in Germany

Wheat (Triticum aestivum L.) is the main staple crop worldwide. Understanding the genotype × management × environment (G × M × E) interaction is critical for breeding, yield, grain quality estimation and to develop sustainable production systems that meet food and feed demand. Many studies have explored grain yield changes and yield stability over time, as well as G × M × E (i.e., the effect of breeding progress), but limited studies have looked at these effects on yield components and grain quality parameters. A field experiment was conducted to understand the G × M × E interactions for yield components of winter wheat cultivars. The study was carried out for three seasons (2015–2018) using a split plot design with four replications, with nitrogen (N) fertilizer levels (0, 120 and 240 kg N ha-1), in the main plot and cultivars in the subplot. Three old cultivars (released before 1960), Heines II, Heines Rot, Heines VII and three modern cultivars (released after 1960), Jubilar, Sperber and Tommi, were selected. Total aboveground biomass (TAGB), grain yield, harvest index (HI), thousand kernel weight (TKW), grains m-2, grain protein and hectoliter weight (HLW) were collected at harvest. The three-way interaction was significant for most variables except for grain protein, but after applying the AIC method, the three-way interaction was just relevant for HI. The 0 N level always resulted in lowest TAGB, grain yield, grains m-2, grain protein and HLW for all cultivars. All cultivars showed a positive response in grain yield when applying 120 kg ha-1 of N but no significant further yield increase was observed with higher N levels. With regards to HI, cultivar differences were more apparent during the wettest year 2016. The HI tends to decrease with increasing N levels and was the highest in modern cultivars with Tommi and Sperber, though in 2017, also Heines VII showed one of the highest HI across treatments. Grain protein content progressively increased with N level, but newer cultivars like Tommi and Sperber, showed some of the lowest protein contents. Yield component contribution to grain yield has changed over time with grain number, grain size and HI, becoming more important for yield realization. Modern cultivars, especially Tommi, performed better than the rest of the cultivars under sufficient N supply. Optimal N-rates among cultivars differ for grain yield and grain protein, posing a challenge to maintain wheat supply to the increasing wheat demand in the future but also to meeting sustainability targets to reduce and optimize resource use.

Responses of Physiological Traits and Grain Yield to Short Heat Stress during Different Grain-Filling Stages in Summer Maize

Maize kernel growth is sensitive to heat stress, which is predicted to result in yield loss. However, the response of maize to short-term heat stress during different kernel-growth stages is still not clear. A 3-year field experiment, included two heat-stress treatments (LSH, lag-stage heat stress; FSH, effective-filling-stage heat stress), was conducted in 2019–2021. The results showed that LSH and FSH significantly reduced the grain yield by 8.7–14.9% and 11.6–17.6%, respectively, compared with the control (CK). LSH mainly reduced the kernel number per ear, and FSH mainly reduced the kernel weight. Heat stress reduced the SPAD and chlorophyll content during the effective-filling stage, but not in the lag stage. Photosynthesis was obviously reduced under heat stress during both stages; however, the photosynthesis rate during the lag stage was higher than during the effective-filling stage. The decreased amplitude of dry matter under LSH was higher than under FSH during the heating period. However, there was no difference between the CK and LSH samples in terms of dry-matter accumulation from the end of heat stress to harvest, which was significantly reduced under FSH. Additionally, decreased starch-synthesis-related enzyme activity, i.e., adenosine diphos-phoglucose pyrophosphprylase, contributed to the kernel number and kernel weight loss in LSH and FSH, respectively. The kernel-growth rate (per ear) was lowered, but the growth duration was not shortened in this study. Consequently, LSH mainly reduced the photosynthesis rate (Pn), resulting in kernel abortion and yield penalty. FSH mainly reduced the Pn and chlorophyll content, which reduced the kernel weight, and increased yield loss.

Combining field data and modeling to better understand maize growth response to phosphorus (P) fertilizer application and soil P dynamics in calcareous soils

We used field experimental data to evaluate the ability of the agricultural production system model (APSIM) to simulate soil P availability, maize biomass and grain yield in response to P fertilizer applications on a fluvo-aquic soil in the North China Plain. Crop and soil data from a 2-year experiment with three P fertilizer application rates (0, 75 and 300 kg P2O5 ha−1) were used to calibrate the model. Sensitivity analysis was carried out to investigate the influence of APSIM SoilP parameters on the simulated P availability in soil and maize growth. Crop and soil P parameters were then derived by matching or relating the simulation results to observed crop biomass, yield, P uptake and Olsen-P in soil. The re-parameterized model was further validated against 2 years of independent data at the same sites. The re-parameterized model enabled good simulation of the maize leaf area index (LAI), biomass, grain yield, P uptake, and grain P content in response to different levels of P additions against both the calibration and validation datasets. Our results showed that APSIM needs to be re-parameterized for simulation of maize LAI dynamics through modification of leaf size curve and a reduction in the rate of leaf senescence for modern stay-green maize cultivars in China. The P concentration limits (maximum and minimum P concentrations in organs) at different stages also need to be adjusted. Our results further showed a curvilinear relationship between the measured Olsen-P concentration and simulated labile P content, which could facilitate the initialization of APSIM P pools in the NCP with Olsen-P measurements in future studies. It remains difficult to parameterize the APSIM SoilP module due to the conceptual nature of the pools and simplified conceptualization of key P transformation processes. A fundamental understanding still needs to be developed for modelling and predicting the fate of applied P fertilizers in soils with contrasting physical and chemical characteristics.

Response of Rice Grain Yield and Soil Fertility to Fertilization Management under Three Rice-Based Cropping Systems in Reclaimed Soil

Reasonable cropping systems and fertilizer management are vital for improving the quality of barren soil. The effectiveness of different crop rotation methods and fertilizers in soil improvement depends on various factors, including soil type, climate conditions, and crop type. In the present study, based on three rice-based cropping systems, the effects of organic fertilizers combined with slow-release fertilizers on rice yield and soil fertility in reclaimed soil were analyzed. The results showed that the rice grain yield was highest under the rice-fallow rotation system (RF) with the application of rapeseed meal fertilizer. Available nutrients such as AN, N_NH4+, TP, and AK showed a significant positive correlation with rice grain yield (p < 0.05). PCA and PERMANOVA analysis supported significant variation in CAZyme abundance among cropping systems (R2 = 0.60, p = 0.001) and significant differences between slow-release fertilizer treatments and organic fertilizer treatments (p < 0.05), but not among the three organic fertilizer treatments. Network analysis indicated positive stronger correlations among all functional enzymes in organic fertilizer treatments compared to chemical fertilizer treatments. RDA and correlation heat map results showed that C/N ratios and N_NH4+ were strongly related to CAZyme composition. PLS-PM analysis revealed that soil available nitrogen positively influenced several variables, while rice grain yield was negatively influenced by soil enzymes and TOC. These findings suggested that under appropriate cropping systems, partially substituting chemical fertilizers with organic fertilizers can effectively enhance the availability of nutrients in the soil, alter the activity of carbon-cycling microorganisms, and increase rice grain yield.

Soil factors that contribute to the abundance and structure of the diazotrophic community and soybean growth, yield, and quality under biochar amendment

BackgroundA 2-year field trial was conducted to test the effect of biochar addition (0, 15, 30, and 45 t hm−2) on soil properties, nutrients, diazotrophic community diversity, abundance, and structure, and soybean growth, yield, and quality. Furthermore, we aimed to explore the responses of diazotrophs, grain yield, and quality to nine soil environmental factors. Rhizosphere soil and plant samples were collected after harvest.ResultsBiochar application resulted in a lower soil bulk density (γd) but higher total organic carbon (TOC), effective phosphorus (AP) and total nitrogen (TN). Compared with untreated soil, the diversity index of diazotrophic bacteria in biochar-amended soil decreased, but the abundance of diazotrophic bacteria increased. The microbial community remained stable when a small amount of biochar was applied but changed as biochar amount increased. Furthermore, biochar reduced the proportion of unique nitrogen-fixing bacteria, but did not affect that of common nitrogen-fixing bacteria between biochar-amended and untreated soils, and increased the relative abundance of Bradyrhizobium (B9 vs. B0) and Sinorhizobium (B18 or B21 vs. B0) involved in symbiotic nitrogen fixation. The main components and content of fatty acids (except for stearic acid) and the content of protein and soybean oil remained stable under biochar application. The low biochar treatment (15 t hm−2) promoted soybean growth and yield. Redundancy analysis suggested that TN greatly influenced the diazotrophic community structure at the phylum and genus levels, and that pH, TOC, and NO3−-N greatly influenced grain yield and quality.ConclusionsSoil diazotroph environment can be improved by targeted farmland implementation based on changes in soil physicochemical properties, which would benefit biological N fixation in agricultural soils and further increase economic benefit.Graphical

Response of Fertilization of Nitrogen on Agronomical Attributes of Soybean

Soybean also known golden bean is a dual purpose crop grown to meet the requirement of both high protein and oil content. Fertilizers are one of the important components of farming system due to their requirement to provide essential nutrients to crop. The current research work was done to study the effect of the different rates of nitrogen fertilization on the growth and yield of soybean were studied. Field experiments were conducted at Instructional Research Farm, Krishi Nagar, Jabalpur, Madhya Pradesh, India during kharif season in the month of July to October in the year 2019‒2020. This research has been conducted in order to examine the beneficial effects of additional application of nitrogen at grain development stage on yield attributes and yield of soybean. The experimental material was early maturing variety of soybean JS 20-34. Treatments were given in 12 combinations in the split plot design. Plant samples were collected at R1 and R3 for dry matter yield and nitrogen determination. Grain yields were determined and grain samples were collected at harvest. A positive grain yield in response to nitrogen fertilizer was observed in different treatments. These imply that additional nitrogen applications are important for getting higher yields. In the current research we came to the conclusion that additional nitrogen fertilizer application to soybean crop has positive impact on several agronomical attributes of the crop.

Agronomic and Physiological Performances of High-Quality Indica Rice under Moderate and High-Nitrogen Conditions in Southern China

High-quality (i.e., higher appearance and eating quality) rice (Oryza sativa L.) is being increasingly and widely planted in China with the improvement of people’s living standards and the achievement of rice breeding efforts in recent years. However, the agronomic and physiological performances of high-quality indica rice (HQIR) under different nitrogen (N) application conditions in southern China are little known. Two-year consecutive field experiments were conducted with two HQIR and two ordinary-quality indica rice (OQIR) varieties under moderate and high-N application rates, with yield and yield components, biomass, N uptake, and their related traits, being investigated. We found that grain yields of HQIR were slightly decreased, but grain yields of OQIR were significantly increased by 7.0–9.6% under a high N rate, compared with a moderate N rate within two years. Thereby, OQIR produced a 5.7–14.7% and 18.7–25.6% higher grain yield than HQIR under moderate and high N rates, respectively. The different responses of grain yield to N application rates were mainly due to a decreased grain setting rate in HQIR and increased spikelets m−2 in OQIR under a high N rate. Furthermore, a high N rate significantly reduced pre-anthesis AE (apparent exportation of pre-anthesis stem and leaf blade dry matter) and improved the grain-leaf area ratio, while it did not increase post-anthesis dry matter, compared with a moderate N rate in HQIR, which might result in carbon-metabolic deterioration, an imbalance of the source–sink relationship and, subsequently, a lower supply of carbohydrate in panicle. Our results suggest that a moderate N rate (165 kg N ha−1) is beneficial for the HQIR varieties to balance the maximum grain yield and high quality in southern China.

Common Bean Productivity and Micronutrients in the Soil-Plant System under Residual Applications of Composted Sewage Sludge.

Composted sewage sludge (CSS) is an organic fertilizer that can be used as a source of micronutrients in agriculture. However, there are few studies with CSS to supply micronutrients for the bean crop. We aimed to evaluate micronutrient concentrations in the soil and their effects on nutrition, extraction, export, and grain yield in response to CSS residual application. The experiment was carried out in the field at Selvíria-MS, Brazil. The common bean cv. BRS Estilo was cultivated in two agricultural years (2017/18 and 2018/19). The experiment was designed in randomized blocks with four replications. Six different treatments were compared: (i) four increasing CSS rates, i.e., CSS5.0 (5.0 t ha-1 of applied CSS, wet basis), CSS7.5, CSS10.0, CSS12.5; (ii) a conventional mineral fertilizer (CF); (iii) a control (CT) without CSS and CF application. The available levels of B, Cu, Fe, Mn, and Zn were evaluated in soil samples collected in the 0-0.2 and 0.2-0.4 m soil surface horizons. The concentration, extraction, and export of micronutrients in the leaf and productivity of common beans were evaluated. The concentration of Cu, Fe, and Mn ranged from medium to high in soil. The available levels of B and Zn in the soil increased with the residual rates of CSS, which were statistically not different from the treatments with CF. The nutritional status of the common bean remained adequate. The common bean showed a higher requirement for micronutrients in the second year. The leaf concentration of B and Zn increased in the CSS7.5 and CSS10.0 treatments. There was a greater extraction of micronutrients in the second year. Productivity was not influenced by the treatments; however, it was higher than the Brazilian national average. Micronutrients exported to grains varied between growing years but were not influenced by treatments. We conclude that CSS can be used as an alternative source of micronutrients for common beans grown in winter.

Evaluation and Prediction of Silicon Bioavailability in Diverse Silicon Fertilizers

Silicon (Si) is a widely recognized beneficial element in plants. The application of Si fertilizers has become a rather common agronomic practice for sustainable agricultural production. However, due to the vast diversity of Si fertilizers, no official method is currently available for estimating the availability of Si in different Si fertilizers to direct their field application. In this study, we evaluated the bio-available Si concentration in eight Si fertilizers differing in Si form and pH by using different extraction methods including HCl, NaOH, Amberlite resin, 3-morpholinopropane-1-sulfonic acid (MOPS), ammonium acetate, and citric acid. To test the effectiveness of these methods, we investigated the relationships between bio-available Si and plant growth and Si accumulation by conducting a pot experiment with rice. The results indicate that the Si fertilizers applied increased shoot biomass and grain weight, but no single extraction method could be used to assess the bioavailability of Si in all the Si fertilizers tested. Accordingly, based on Si sources and pH, we classified the tested fertilizers into three categories, i.e. alkaline, acid and amorphous Si fertilizers, to find out their suitable extractant. The correlation analyses clearly show that 1) ammonium acetate could accurately predict Si availability and shoot biomass for alkaline Si fertilizers (Slag and Fulibang), 2) the amount of Si extracted by 0.2 M NaOH from amorphous Si fertilizers (Elkem A, Elkem B and Tangshan) correlated well with Si availability and shoot biomass and 3) the amount of Si extracted by 1.0 M NaOH and citric acid from acid fertilizers (Shanjia 1, Shanjia 2 and Shanying) could be used to assess Si availability and shoot biomass response, respectively. Furthermore, resin extraction was the best predictor of grain yield response for alkaline Si fertilizers (Slag and Fulibang) and acid fertilizers (Shanjia 1, Shanjia 2 and Shanying), whereas the amount of Si extracted by 0.5 M NaOH could satisfactorily estimate the response of grain yield for amorphous Si fertilizers.

Response of Grain Yield to Planting Density and Maize Hybrid Selection in High Latitude China—A Multisource Data Analysis

Identifying the relationships between the yield of rainfed maize and planting densities as well as the hybrids used is crucial for ensuring the sustainable development of the grain industry in high latitude China. In this study, we collected 108 grain yield date points from our multiyear (2017–2020) field experiments and combined 213 data points collected from 21 published papers to appraise the impact of planting density and hybrids on maize yield. It was found that grain yield forms a curvilinear relationship with plant density as it increased from 22,500 to 112,500 plants ha−1. The optimum plant density (OPD) was determined to be 72500 plants ha−1, with a maximum maize grain yield of 10.56 Mg ha−1. The interannual variability in grain yields among hybrids with different planting densities was mainly due to the differences in dry matter (DM), especially post-silking. Grain yields increased significantly with a rise in the proportion of post-silking DM to DM at maturity. In addition, both the collected literature and our field experiments showed that the OPD was positively correlated with solar radiation accumulated during the maize growth period and with each hybrid’s year of release. This study suggests that increasing plant density and selecting new hybrids with suitable growth periods are effective approaches for increasing grain yield in high latitude China.

Adapting to climate variability for rice cultivation paddies in the lowland coastal regions of Kien Giang Province, Vietnam

Summary Globally, coastal cultivation regions (CCRs) are facing irrigation water shortages due to the impacts of climate change (ICV). CCRs have repeatedly suffered from saline irrigation water, increases in temperature, and reduced rainfall, resulting in irrigation water shortages. The aim of this study was, therefore, to evaluate the impacts of weather variables on the rice water requirement (RWR) in CCRs in Kien Giang Province. The response of rice grain yield to weather variables was estimated by simulating the AquaCrop model under different crop cultivation schedules (CCSs). These schedules involved advancing or delaying the sowing date by 30 days compared to the current common sowing date (baseline) for winter-spring (WS) and summer-fall (SF) vegetation seasons. The AquaCrop model demonstrated accurate simulation capabilities, as indicated by the high correlation values of statistical error indexes during the validation and calibration procedures. The findings revealed that rice grain yields would enhance up to 7.8% and 5.6% compared to the baseline when CCSs involve sowing 20 days earlier for WS vegetation season and are advanced by 20 days for SF vegetation season. Overall, modifying CCSs for coastal rice paddies in the study area, while considering weather variables, would have a positive contribution by mitigating the adverse effects of ICV.