Significant Reduction In Grain Yield Research Articles

Experimental Warming Reduces the Grain Yield and Nitrogen Utilization Efficiency of Double-Cropping indica Rice in South China

The effect of climate warming on rice production in China is profound, yet there has been limited research on how it affects the grain yield, nitrogen (N) uptake, and N utilization efficiency (NUtE) of the double-cropping indica rice in South China. To address this gap, we conducted a free air temperature increase (FATI) experiment in Guangdong province during 2020 and 2021. Our findings revealed that warming led to a significant reduction in grain yield, with early rice (ER) and late rice (LR) experiencing average decreases of 5.2% and 6.3%, respectively, compared to control treatments. This decline was primarily attributed to the reduced grain weight of ER and the fewer spikelet numbers per panicle of LR under warming conditions. Although the dry matter translocation, harvest index, and N translocation efficiency of ER remained unchanged under warming conditions, these of LR decreased by an average of 58.1%, 8.8%, and 22.3%, respectively. Additionally, while warming did not affect the N uptake in ER at maturity, it significantly increased the N uptake in LR by an average of 11.0%. Therefore, under warming conditions, the NUtE of both ER and LR was markedly decreased by 6.9% and 15.5% over the two years. These results indicate that climate warming may have significant negative impacts on the grain yield and the NUtE of indica rice within double-rice cropping systems in South China. Understanding these dynamics is vital for maintaining the stability of rice yields in anticipation of future climate warming.

Performance of basmati rice (Oryza sativa) under variable irrigation and nitrogen management

A field experiment was conducted during the rainy seasons (kharif) of 2021 and 2022 at research farm of ICAR- Indian Agricultural Research Institute, New Delhi to study the effect of irrigation regimes and integrated use of prilled urea and nano-urea as a source of N, on productivity and profitability of basmati rice (Oryza sativa L.). The experiment was conducted in a three-time replicated split-plot design (SPD) comprised of 3 irrigation regimes, viz. irrigation at 1, 3 and 6 days after disappearance of surface water (DADSW) assigned to main-plots and 4 N-management variants including; 100% RDN (recommended dose of N, 120 kg/ha); 75% RDN + 4% nano-urea (NU) 2 sprays (75% RDN + 2 NU); 50% RDN + 2 NU; and no-N (control) in sub-plots. Irrigating basmati rice 1 DADSW exhibited the highest panicle weight (2.67–3.09 g) and number of grains/panicle (115.9, 109.8), across the years, respectively that were significantly higher than 3 and 6 DADSW. The most delayed irrigation at 6 DADSW caused significant reduction in grain yield, the magnitude of reduction was 13–19% over irrigation at 3 DADSW and substantially by 23–28% over 1 DADSW. Fertilizing rice crop with 100% RDN and 75% RDN + 2 NU resulted in statistically similar yield attributes and grain yield; however, both were, significantly superior to 50% RDN + 2 NU and no-N. Net returns, benefit cost (B:C) ratio and monetary efficiency were significantly higher when crop was irrigated 1 DADSW than 3 and 6 DADSW. The N-management options followed the trend as RDN>75% RDN + 2 NU ˃50% RDN > no-N for all studied economic parameters.

Evaluating the Effects of Drought Stress on Biomass and Yield Traits in Sorghum Genotypes

The study aimed to identify drought-tolerant sorghum genotypes by evaluating twenty sorghum genotypes over two Rabi seasons (2021-22 and 2022-23) under irrigated and rainfed conditions using a split plot design. Results showed that moisture stress significantly affected sorghum performance, including leaf and stem dry matter accumulation, grain yield per plant, stover yield, and harvest index. Among the genotypes, BJV-44 and M-35-1 exhibited the least decline in grain yield per plant under rainfed conditions, with yields of 76.17 and 73.50 g/plant, respectively, compared to irrigated conditions. Conversely, genotypes M 148-138 and Tandur L experienced the most significant reductions in grain yield per plant under rainfed conditions. Basavana pada exhibited the highest harvest index. The study concluded that BJV-44 and M-35-1 are drought-tolerant sorghum genotypes with relatively higher grain yields per plant under rainfed conditions, providing valuable insights into sorghum genotype performance and resource utilization in drought-prone regions.

Productivity and profitability of rice (Oryza sativa) varieties as influenced by age of seedlings in north-eastern Himalayan region

An experiment was conducted during boro (rabi) season of 2012–13 and 2013–14, at Gerua, Kamrup, Asom, India, to study the effect of different age of seedlings on growth and yield of rice (Oryza sativa L.) varieties. Ten treatment combinations of 2 different duration rice varieties, i.e. ‘Chandrama’ (175 days) and ‘Naveen’ (155 days), and 5 ages of seedlings (40, 50, 60, 70 and 80 days) were tested. ‘Chandrama’ rice recorded significantly higher grains/panicle and 1,000-seed weight as well as grain yield (5.93 and 6.50 t/ha) over ‘Naveen’ rice. Days to 50% flowering decreased with the increment in age of seedling by 2–10 days, whereas total maturity duration increased by 6–28 days. In case of age of seedlings, 40 and 50 days old seedlings showed higher values of growth and yield attributes that reflected in grain yield. There was gradual yield decrease with increment in the age of seedling due to reduced values of tillers/m2 , filled grains/panicle. The yield penalty was non-significant in case of long-duration rice variety ‘Chandrama’, while in case of ‘Naveen’, there was significant reduction in grain yield when seedling age exceeded beyond 60 days. ‘Naveen’ rice with 40 and 50 days old seedlings recorded significantly higher grain yield over 70 and 80 days seedlings respectively. Earlier farmers using their own local rice landraces which were long duration and less affected by age of seedling but with development of new semi-dwarf, medium-duration rice varieties need to be transplanted at optimum age of seedling. Thus, the age of seedling can be extended up to 60 days for those rice varieties having long duration (>175 days) while for short duration (<155 days), it should not be extended beyond 50 days.

Impact of defoliation at the reproductive stage in different leaves of the soybean plant

Inadequate phytosanitary management can cause a significant reduction in the leaf area of soybean, which directly impacts its yield. The aim of this study was to evaluate the impact of defoliation in the lower, middle and upper leaves of the canopy, at three reproductive stages, on soybean yield, as a tool for improving phytosanitary management. The design was randomized blocks in 3x3+1 factorial scheme, with 4 replicates. The 10 treatments resulted from the combination of 3 defoliation positions on the plant (lower, middle and upper leaves) and 3 phenological stages of the crop (R1, R3 and R5), in addition to a control without defoliation. Morphological and production components and grain yield were evaluated. The data were subjected to analysis of variance and, when a significant difference was identified, the means were subjected to the Dunnett test. It was observed that plants showed a reduction in height in treatments with defoliation in the upper leaves at R1 and R3 stages. For the variables thousand-grain weight and grain yield there was difference only when defoliation was performed at the R5 stage in the upper leaves, resulting in a 16.6% loss in grain yield compared to the control. The soybean crop tolerates a defoliation level of 33.3% up to the R4 stage, in any of the leaves, without significant reduction in grain yield. Upper leaves, from the R5 stage, should be prioritized in the applications of phytosanitary products, which aim to reduce the damage caused by defoliation.

Elevated CO2 ameliorates the high temperature stress effects on physio-biochemical, growth, yield traits of maize hybrids

The rising temperatures and levels of carbon dioxide in the atmosphere are anticipated to have a significant impact on the productivity of agricultural crops. Although, the individual effects of elevated CO2 and temperature have been extensively studied in C3 and C4 crops, there remains a scarcity of research investigating their interactive effects specifically on maize hybrids. The impact of elevated temperature and its interaction with elevated CO2 on phenology, physiology, biomass, and grain yield of maize hybrids was assessed in a field experiment using Free Air Temperature Elevation (FATE) facility. The results showed that elevated temperature (eT) increased the anthesis silking interval (ASI), while the presence of elevated CO2 along with elevated temperature (eT + eCO2) mitigated this effect. The differential expression were observed between hybrids depending on their genetic potential. Furthermore, the net photosynthetic rate (Anet), stomatal conductance (gs), and transpiration rate (Tr) of hybrids decreased under elevated temperature but eT + eCO2 condition helped in reverting its impact to some extent. In term of leaf composition, the highest level of total soluble sugars (TSS) and starch was observed under eT + eCO2 conditions, possibly due to improved Anet in the presence of elevated eCO2. The negative impact of eT was also evident through increased proline and MDA content, but eT + eCO2 ameliorated the adverse effect of eT. The biomass and grain yield also responded similarly, among the hybrids 900M GOLD recorded superior performance for grain yield at eT condition exceeding 35 °C. On the other hand, DHM117 experienced a significant reduction in grain yield under eT, but performed better under eT + eCO2 due to its improved physiological response to eCO2. The study indicated that elevated levels of carbon dioxide can actually mitigate the detrimental effects of elevated temperature on maize crop. This positive impact on maize crop can be attributed to an enhanced physiological performance in the presence of eCO2 which enables the plants to maintain satisfactory yield levels despite the challenging environmental conditions.

Curling Leaf 1, Encoding a MYB-Domain Protein, Regulates Leaf Morphology and Affects Plant Yield in Rice.

The leaf is the main site of photosynthesis and is an important component in shaping the ideal rice plant architecture. Research on leaf morphology and development will lay the foundation for high-yield rice breeding. In this study, we isolated and identified a novel curling leaf mutant, designated curling leaf 1 (cl1). The cl1 mutant exhibited an inward curling phenotype because of the defective development of sclerenchymatous cells on the abaxial side. Meanwhile, the cl1 mutant showed significant reductions in grain yield and thousand-grain weight due to abnormal leaf development. Through map-based cloning, we identified the CL1 gene, which encodes a MYB transcription factor that is highly expressed in leaves. Subcellular localization studies confirmed its typical nuclear localization. Transcriptome analysis revealed a significant differential expression of the genes involved in photosynthesis, leaf morphology, yield formation, and hormone metabolism in the cl1 mutant. Yeast two-hybrid assays demonstrated that CL1 interacts with alpha-tubulin protein SRS5 and AP2/ERF protein MFS. These findings provide theoretical foundations for further elucidating the mechanisms of CL1 in regulating leaf morphology and offer genetic resources for practical applications in high-yield rice breeding.

Interactive effects of irrigation system and level on grain yield, crop water use, and greenhouse gas emissions of summer maize in North China Plain

Irrigation management is one of most critical factors influencing soil N2O and CO2 emissions in dryland agriculture. To explore the effects of irrigation systems and levels on the mitigation of N2O and CO2 emissions from maize fields and to determine the balance among greenhouse gases (GHG) emission, water-saving and grain yield, a two–year field experiment was conducted in the North China Plain (NCP) during the growing seasons of 2018 and 2019. Two irrigation systems (i.e., flood irrigation, FI, and drip irrigation, DI) were adopted with four irrigation levels in each system, including 65 mm/event (sufficient irrigation, CK), 50 mm/event (decreased by 23 %), 35 mm/event (by 46 %) and 20 mm/event (by 69 %), respectively. The results showed that both irrigation systems and levels had significant effects on soil N2O and CO2 emissions (P < 0.05). Nitrous oxide (N2O) and CO2 emissions peaked following irrigation or irrigation + fertilization events during sowing to early filling stage (R1), with the peak values increasing with irrigation levels. Meanwhile, peak values from FI were higher than those from DI at 50 mm and 65 mm irrigation levels. The average cumulative N2O and CO2 emissions of DI treatments were 14.9 % and 6.23 % lower than those of FI treatments (P < 0.05), respectively. Soil moisture was identified as one of the most crucial factors influencing N2O and CO2 fluxes. Deficit irrigation efficiently deceased cumulative N2O and CO2 emissions, but moderate to severe deficit irrigation brought significant reduction in grain yield. Drip irrigation with a slight deficit irrigation level (decreased by 23 %) obtained the best economic and environmental benefits, which achieved the dual goal of lower GHG emissions but higher WUE without sacrificing grain yield.

DROUGHT EFFECTS ON PHYSIOLOGICAL PARAMETERS OF DURUM AND BREAD WHEAT

The present research discusses the dynamics of changes in the surface of assimilation organs of different durum and bread wheat genotypes differing in the maturation period due to drought conditions. Under drought conditions, the soil water potential decreases, and in the later stages of the plants, the turgor pressure decreases, the stomata close, and a sharp decrease in photosynthetic activities. The situation creates stress in the crop plant, and various biochemical, physiological, and molecular reactions arise to overcome and protect itself from stress, allowing the plant to develop resistant mechanisms to adapt to the external environment. The existent research aimed to determine drought effects on assimilating surface areas and productivity traits of durum and bread wheat genotypes differing in their maturation periods grown under various climatic and soil conditions, with the comparison of the physiological indices. The experiments proceeded on wheat genotypes with contrasting maturation periods (early, medium, and late) during 2021–2022 at the Research Institute of Crop Husbandry, Absheron, Azerbaijan. The assimilating surface area of various organs underwent comparative studies in two durum (Garagylchyg-2 and Alinja-84) and two bread wheat (Nurlu-99 and Gobustan) cultivars under normal water supply and drought conditions. Post anthesis water stress caused a 34% and 27% reduction in grain yield and 1000-grain weight, respectively, while no significant effect on the grains per spike and spikes per m2. The averages of grain yield and 1000-grain weight of different wheat cultivars in the controlled condition showed 696±36 g/m2 and 43.1±0.8 g/m2, respectively, while under water-stress conditions, these values significantly decreased to 452±57 g/m2 and 31.6±1.4 g. The significant reduction in grain yield due to post-anthesis water stress might be due to a reduction in photo-assimilates production.

Agronomic and Physiological Indices for Reproductive Stage Heat Stress Tolerance in Green Super Rice

Optimum growing temperature is necessary for maximum yield-potential in any crop. The global atmospheric temperature is changing more rapidly and irregularly every year. High temperature at the flowering/reproductive stage in rice causes partial to complete pollen sterility, resulting in significant reduction in grain yield. Green Super Rice (GSR) is an effort to develop an elite rice type that can withstand multiple environmental stresses and maintain yield in different agro-ecological zones. The current study was performed to assess the effect of heat stress on agronomic and physiological attributes of GSR at flowering stage. Twenty-two GSR lines and four local checks were evaluated under normal and heat-stress conditions for different agro-physiological parameters, including plant height (PH), tillers per plant (TPP), grain yield per plant (GY), straw yield per plant (SY), harvest index (HI), 1000-grain weight (GW), grain length (GL), cell membrane stability (CMS), normalized difference vegetative index (NDVI), and pollen fertility percentage (PFP). Genotypes showed high significant variations for all the studied parameters except NDVI. Association and principal component analysis (PCA) explained the genetic diversity of the genotypes, and relationship between the particular parameters and grain yield. We found that GY, along with other agronomic traits, such as TPP, SY, HI, and CMS, were greatly affected by heat stress in most of the genotypes, while PH, GW, GL, PFP, and NDVI were affected only in a few genotypes. Outperforming NGSR-16 and NGSR-18 in heat stress could be utilized as a parent for the development of heat-tolerant rice. Moreover, these findings will be helpful in the prevention and management of heat stress in rice.

Identification of a novel major QTL from Chinese wheat cultivar Ji5265 for Fusarium head blight resistance in greenhouse.

A novel major QTL for FHB resistance was mapped to a 6.8Mb region on chromosome 2D in a Chinese wheat cultivar Ji5265, and diagnostic KASP markers were developed for detecting it in a worldwide wheat collection. Fusarium head blight (FHB) is a serious disease in wheat (Triticum aestivumL.) and causes significant reductions in grain yield and quality worldwide. Breeding for FHB resistance is the most effective strategy to minimize the losses caused by FHB; therefore, identification of major quantitative trait loci (QTLs) conferring FHB resistance and development of diagnostic markers for the QTLs are prerequisites for marker-assisted selection (MAS). Ji5265 is a Chinese wheat cultivar resistant to FHB in multiple environments. An F6 population of 179 recombinant inbred lines (RILs) was developed from Ji5265 × Wheaton. The population was genotyped by genotyping-by-sequencing (GBS) and phenotyped for FHB Type II resistance in greenhouses. A major QTL, designatedas QFhb-2DL, was mapped in a 6.8Mb region between the markers GBS10238 and GBS12056 on the long arm of chromosome 2D in Ji5265 and explained ~ 30% of the phenotypic variation for FHB resistance. The effect of QFhb-2DL on FHB resistance was validated using near-isogenic lines (NILs) derived from residual heterozygotes from an F6 RIL of Ji5265 × Wheaton. The two flanking markers were converted into Kompetitive allele-specific PCR (KASP) markers (KASP10238 and KASP12056) and validated to be diagnostic in a collection of 2,065 wheat accessions. These results indicate that QFhb-2DL is a novel major QTL for resistance to FHB spread within a spike (Type II) and the two KASP markers can be used for MAS to improve wheat FHB resistance in wheat breeding programs.

Influence of Sowing Time on the Quality and Micronutrient Contents of Bread Wheat (Triticum aestivum L)

Background: Wheat is a staple crop that feeds millions of people, but its productivity is significantly reduced under high temperatures. Maintaining grain quality under climate change is critical for human nutrition, end - use functional properties and commodity value. The current study aimed at assessing the quality and micronutrient contents under two environments for variability, correlation and path analysis.&#x0D; Research Methodology: The research was carried in the experimental area of Wheat and Barley Section, Department of Genetics and Plant Breeding, CCSHAU, Hisar during 2019-20. The assessement was done for 48 wheat genotypes under two temperature levels (timely and late sown environment) in RBD design with three replications.&#x0D; Results: Heat stress caused a significant reduction in grain yield, grain appearance score, hectoliter weight, sedimentation value, iron and zinc content whereas an increase in crude protein, total gluten content, wet gluten content, total soluble sugar. In the present study, total soluble sugar, wet gluten content, total gluten content showed highest values of variability, heritability, genetic advance as % of mean and thus are the most important quantitative traits to be taken into consideration for effective selection. A positive correlation was seen between grain yield and hectoliter weight in timely sown environment. Path analysis revealed highest positive direct effect for hectoliter weight and sedimentation value in timely sown condition while sedimentation value and iron content for late sown environment and thus in the process of selection much attention should be given to them as these characters are helpful for indirect selection.&#x0D; Conclusion: A negative association between high yield and good quality should be an important target for the next breeding efforts or to determine a quality parameter that performs consistently in both environments.

Cold plasma can alleviate cadmium stress by optimizing growth and yield of wheat (Triticum aestivum L.) through changes in physio-biochemical properties and fatty acid profile.

Cold plasma (CP) application has increasing interest due to its environmental-friendly, high efficient, and low cost aspects to mitigate deletion effects of heavy metals on plants. A pot experiment was carried out to evaluate the CP application on yield, physiological, and fatty acid profile of wheat (Triticum aestivum L.) in a completely randomized design (CRD) with five replicates. Cadmium (Cd) was applied at four levels (0, 50, 100, and 150 μM), and CP were used on germinated seeds at three levels (0, 60, and 120 s) in a hydroponic system. The results showed CP alleviated the Cd accumulation in roots, shoots, and grains. The significant reduction of grain yield (GY) and thousand grain yield (TGY) was observed in plants exposed to 100 and 150 μM compared with the control plants; however, CP improved GY and TGY particularly at severe Cd stress. The minimum chlorophyll (Chl) and relative water content (RWC) were observed in plants exposed in 100 μM Cd and non-CP treatments. Proline increased by Cd stress but decreased with CP in most treatments. Unlike proline, methionine showed significant reduction under Cd stress. The fatty acid profile of wheat represented that severe Cd stress decreased monounsaturated fatty acid (MUFA) but increased polyunsaturated fatty acid (PUFA). Heat map (HM) showed that GY and methionine were the most sensitive traits under treatments of Cd and CP. Totally, we suggest the use of 120 s of CP to mitigate Cd stress on wheat plants.

Monitoring Lodging Extents of Maize Crop Using Multitemporal GF-1 Images

Maize crop lodging is a recurrent phenomenon which results in significant reduction of grain yield and quality in addition to the impediment of mechanical harvesting. The large-scale monitoring of maize crop lodging is important for production policy adjustment and agricultural insurance compensation. In this article, we derived a variety of features from multitemporal GaoFen-1 (GF-1) images before and after maize crop lodging. We screened the most sensitive features of the spectrum, texture, and vegetation index to monitor maize crop lodging. The recursive feature elimination method based on cross-validation and mutual information were compared to obtain the optimal feature combination for monitoring the lodging extents of maize crop. The random forest classifier was used to classify the lodging extents. The results showed that the most sensitive features of the spectrum, texture, and vegetation indices of lodging extents included the difference of reflectance in blue, green, and red bands, the difference of normalized difference vegetation index, the difference of ratio vegetation index, the difference of enhanced vegetation index difference, the difference of mean value of blue band, the difference of mean value of green band, and the difference of mean value of red band. The total accuracy of lodging extents classification was 87.50%, and the Kappa coefficient was 0.83 for testing samples. Based on multiple features derived from GF-1 images before and after lodging, the lodging extents of maize crop can be monitored on a large scale.

Layering smart management practices to sustainably maintain rice yields and improve water use efficiency in eastern India

Rice in eastern India is widely cultivated using conventional management practices, including puddled transplanting (PTR) for crop establishment, which are water and energy intensive. To conserve water and maximise its efficient use, improved crop management practices must be identified which are feasible and attractive to farmers. These improved practices include dry direct seeding of rice (dDSR), improved medium-duration rice varieties and alternate wetting and drying (AWD) irrigation management. These have separately been shown to reduce the irrigation water requirement for rice cultivation while maintaining yields similar to those of traditional high yielding long-duration varieties. We conducted a field experiment over two rice-growing seasons to examine the effects on rice grain yield and water productivity of layering these improved management practices, compared to conventional PTR with traditional long-duration rice. We also assessed the usefulness of simple perforated tubes to implement AWD management in the field. dDSR reduced rice grain yield by 3–6% while requiring 23% less irrigation water over PTR. The medium-duration hybrid rice variety produced 2–4% higher grain yield under direct seeding while using 4–5% less irrigation water than the long-duration variety. AWD reduced irrigation water use by 26–52% but also reduced grain yield by 3–14%. Water use efficiency was improved by dDSR, AWD and by using medium-duration hybrid variety. Combining all three management practices reduced irrigation water use by an average of 18% while improving irrigation water productivity by 21%, without significant reduction in grain yield under shallow AWD of 10 cm depth in dDSR and upto 15 cm depth for PTR. This combination is a novel approach to sustainably improve farmers’ rice productivity. Additionally, simple perforated tubes are an effective and innovative tool for farmers to implement AWD management. Our research suggests that farmers in eastern India and similar rice-growing agro-ecologies could reduce the irrigation water applied and increase water use efficiency while maintaining rice crop productivity by combining dry direct seeding with a medium-duration rice variety under AWD irrigation management.

Genome sequence of the English grain aphid, Sitobion avenae and its endosymbiont Buchnera aphidicola.

The English grain aphid, Sitobion avenae, is a major agricultural pest of wheat, barley and oats, and one of the principal vectors of barley yellow dwarf virus leading to significant reductions in grain yield, annually. Emerging resistance to and increasing regulation of insecticides has resulted in limited options for their control. Using PacBio HiFi data, we have produced a high-quality draft assembly of the S. avenae genome; generating a primary assembly with a total assembly size of 475.7 Mb, and an alternate assembly with a total assembly size of 430.8 Mb. Our primary assembly was highly contiguous with only 326 contigs and a contig N50 of 15.95 Mb. Assembly completeness was estimated at 97.7% using BUSCO analysis and 31,007 and 29,037 protein-coding genes were predicted from the primary and alternate assemblies, respectively. This assembly, which is to our knowledge the first for an insecticide resistant clonal lineage of English grain aphid, will provide novel insight into the molecular and mechanistic determinants of resistance and will facilitate future research into mechanisms of viral transmission and aphid behavior.

Evaluating temperature thresholds and optimizing sowing dates of wheat in Bihar

&#x0D; Studies on wheat-weather relationship were carried out at Pusa (25.98 oN, 85.67 oE, 52 m), Bihar situated in middle Gangetic plains of India, with three popular wheat cultivars viz. RW 3711, HD 2824 and HD273, grown under five fixed dates of sowing viz. 15 November, 25 November, 5 December, 15 December and 25 December, for five consecutive rabi seasons from 2011-12 to 2015-16. Thresholds of maximum temperature (Tmax), minimum temperature (Tmin) and bright sunshine hours (BSH), associated with higher productivity, occurring at different phenophases, were determined. Results revealed that temperature played a crucial role in achieving higher grain yield of wheat. Both Tmax and Tmin during flowering to milking and flowering to maturity phases increased with delayed sowing dates beyond 25 November with consequent reductions in grain yield. During 50 % flowering to milk stage, Tmax and Tmin above 24.6 oC and 11.6 oC, respectively, reduced grain yield below 4000 kg ha-1; significant reduction in grain yield was also noted beyond maximum temperature of 26.9 oC. During flowering to milk and flowering to maturity phases, Tmax and Tmin exhibited highly significant negative correlation with grain yield, indicating higher temperatures causing lower grain yield. With delayed sowing, sensitive phases of the crop experienced higher air temperatures which led to reduction in grain yield. An increase of Tmax from 29.2 to 32.1 oC during flowering to maturity phases reduced the wheat productivity drastically in this region of Indo-Gangetic plains. Grain yield declined by 399 kg ha-1 per 1 oC rise in Tmax during 50 % flowering to maturity stage. Considering grain yield vis-à-vis temperature regimes during flowering to maturity stage, the most important recommendation for the farmers of the region would be to finish wheat sowing before 25 November in order to enable them to escape terminal heat stress in wheat and thereby realizing higher grain yield. The anthesis-time management by manipulating sowing dates could be a realistic adaptation strategy for attaining optimum grain yield under changing climate scenario.&#x0D;

The effect of different methods of seed pretreatment on agronomic characteristics of flaxseed under post flowering drought stress in Kermanshah region

Background and Objective: This research was conduct to investigate the effect of seed priming on the grain yield and its related traits of linseed under post flowering water deficit in Razi University during the 2015-2016 crop year. Materials and Methods: A factorial experiment with three replications was used. factors were include: 1) cultivars (Indian and Hungarian, 2) seed pre-treatment include: five seed bacteria inoculations (Bacillus sp., Bacillus megatrium, Bacillus amyloliqueufaciens, Bacillus pumilus, Pseudomonas geniculata), Hydro priming, KNO3 and control treatment and 3) Stop watering after flowering and control were evaluated. Results: The results showed that, in control treatment, grain yield of Indian and Hungarian cultivars (1536 and 1497 kg/ha respectively) had not significant difference, but biomass yield of Hungarian cultivar (6129 kg/ha) was significantly higher than of Indian cultivar (4575 kg/ha). Water deficit caused significant reduction in grain yield, biological yield, the number of pod per plant, the number of grain per plant, thousands grain weight, the number of empty pod per plant, plant height, the number of main branches and the number of subsidiary branches in two evaluated cultivars. Seed priming treatments not only significantly mitigated water deficit effect on grain yield and its components but also in control treatment, increased these traits significantly. Bacillus megatrium and Bacillus amyloliqueufaciens had the best positive effect on evaluated traits. Conclusion: It seems that use of appropriate and indigenous strains of plant growth promoting bacteria can be one of the suitable strategies for increasing the productivity of crops under drought stress conditions.

Heat Stress Affects Seed Set and Grain Quality of Vietnamese Rice Cultivars during Heading and Grain Filling Period

Environmental stress trigger a variety of rice plant response, ranging from alters seed set, grain yield and grain quality during flowering and grain filling stage. Efforts are required to improve our understanding of the impact of heat stress on rice production, which are essential strategies in rice cultivation. This article investigated the seed set, yield components and grain yield of Vietnamese rice cultivars (Indica germplasm) under high temperature environment during the flowering and grain filling stage. Six rice cultivars, including popular cultivars and new cultivars of Cuu Long Delta Rice Research Institute, and one popular extraneous cultivar with differences in maturing time, were grown in pots at high temperature (HT) and natural temperature condition as control (CT). All rice cultivars were subjected to the high temperature starting from the heading stage to the harvest maturity, applied by greenhouse effect. The greenhouse has about 25 cm window opening on 3 sides for air ventilation. The seed set rate of the heat-sensitive rice genotypes decreased significantly under HT, leading to a significant reduction in grain yield. The lowest seed set was recorded in “OM4900” (44.3%) and “OM18” (39.9%) under high temperature environment. The lower yield in all rice cultivars at an elevated temperature resulted in a dramatic decrease of filled grains and contributed to a loss of 1000-grain weight. ‘“OM892” is a potential rice cultivar for heat tolerant breeding program due to the seed set percentage was above 80% in both HT and CT conditions. High temperature during the grain filling stage resulted in a decreased amylose and increased chalkiness for all OM cultivars.

Identification of tolerance to metribuzin and imazethapyr herbicides in faba bean

AbstractWeeds cause serious constraint to faba bean (Vicia fabaL.) productivity. Broad weed control is hampered by the availability of postemergence herbicides to control them, as the current faba bean cultivars are highly susceptible to them. Therefore, the deployment of postemergence herbicide tolerance is desirable in faba bean. To address this, 130 accessions were screened for their response in mature plants under field conditions to the recommended dosage of two herbicides, metribuzin at 250 g a.i. ha−1and imazethapyr at 75 g a.i. ha−1at Marchouch and Terbol stations. The recorded herbicide damage score (HDS) varied from 1 (no visual damage) to 5 (full damage with death of more than 50% of plants) at both locations. Low but highly significant (p&lt; .01) and positive correlation (+0.26) was obtained between the recorded HDS at both locations. Both herbicides significantly delayed flowering and maturity time occurrence, reduced plant height and grain yield, and increased number of branches. Reduction index (RI) correlated positively with HDS score at Terbol station in different seasons and at Marchouch in 2016–2017 seasons. Eleven tolerant accessions were identified and further evaluated to 1×, 1.5×, and 2× of recommended dose of both herbicides. The results indicated that the harmful effect of herbicides on grain yield reduction intensified from 13.4 to 27.2% and from −7.6 to 1.8% as the dose of metribuzin and imazethapyr increased respectively from 250 to 500 g a.i. ha−1and from 75 to 150 g a.i. ha−1. Tolerance to metribuzin and imazethapyr in eight faba bean accessions was confirmed with no significant reduction in grain yield.