Rice is an integral component of the daily food consumptions in China. Drought stress diminishes rice productivity and deteriorates its quality. To further improve the identification and selection system of drought-tolerant rice varieties, this experiment used 130 new rice hybrid combinations as research materials and water stress was carried out during the whole life span, with normal water management as the control, so as to construct a synergistic evaluation standard of drought-tolerance of rice in terms of yield and quality by examining the characteristics of plant height, fruiting rate, yield per plant, and quality. The study showed that (1) the coefficients of variation of the drought tolerance coefficients of the 11 indexes ranged from 3.50% to 44.35%, with the largest coefficient of variation being the yield per plant at 44.35% and the smallest being the grain length at 3.50%. According to the principal component analysis, the cumulative contribution of the first four principal components was 73.022%, which were the total number of grains, the number of solid grains, the effective panicles and plant height. The correlation analysis showed that the drought tolerance composite evaluation value was extremely significantly correlated with plant height, effective panicles, total grain number, number of solid grains, fruiting rate, thousand grain weight and grain width. Based on the results of stepwise regression analysis, the number of grains, plant height and thousand grain weight can be used as drought-resistant identification indexes. (2) Based on the variation characteristics of protein, brown rice rate, refined rice rate, whole refined rice rate and straight-chain starch content, 50 high-quality combinations were selected. The results of cluster analysis showed that the 50 rice combinations were divided into three groups, Group I strong drought-resistant with materials HD009, HD024, HD171, HD207, HD432, HD447, HD0451, a total of 7 materials up to the first level of rice indicators; Group II medium drought-resistant with 21 materials up to the first level of rice indicators; Group III drought-sensitive material HD522 up to the first level of rice indicators.

皖两优1008是安徽省农业科学院水稻研究所用皖25S与优质抗旱恢复系DJ1008配组育成的两系杂交水稻新组合,具有米质优、抗旱性好、父母本生育期相同易制种的优良特性,2021年4月通过安徽省农作物品种审定委员会审定.

Rice (Oryza Sativa L.) is an essential constituent of the global food chain. Drought stress significantly diminished its productivity and threatened global food security. This review concisely discussed how drought stress negatively influenced the rice's optimal growth cycle and altered its morpho-physiological, biochemical, and molecular responses. To withstand adverse drought conditions, plants activate their inherent drought resistance mechanism (escape, avoidance, tolerance, and recovery). Drought acclimation response is characterized by many notable responses, including redox homeostasis, osmotic modifications, balanced water relations, and restored metabolic activity. Drought tolerance is a complicated phenomenon, and conventional breeding strategies have only shown limited success. The application of molecular markers is a pragmatic technique to accelerate the ongoing breeding process, known as marker-assisted breeding. This review study compiled information about quantitative trait loci (QTLs) and genes associated with agronomic yield-related traits (grain size, grain yield, harvest index, etc.) under drought stress. It emphasized the significance of modern breeding techniques and marker-assisted selection (MAS) tools for introgressing the known QTLs/genes into elite rice lines to develop drought-tolerant rice varieties. Hence, this study will provide a solid foundation for understanding the complex phenomenon of drought stress and its utilization in future crop development programs. Though modern genetic markers are expensive, future crop development programs combined with conventional and MAS tools will help the breeders produce high-yielding and drought-tolerant rice varieties.

Rice drought resistance is a complicated quantitative feature involving a range of biological and agronomic variables, but little is known about the underlying genetics and regulatory mechanisms that regulate drought tolerance. This study used 120 recombinant inbred lines (RILs), derived from a cross between drought tolerant Lvhan 1 and susceptible Aixian 1. The RILs were subjected to drought stress at the first ear stage, and phenotypic data of 16 agronomic and physiological traits under varying conditions were investigated. Genome-wide association study (GWAS) on the drought resistance index of traits was carried out. A total of 9 quantitative trait loci (QTLs) associated with drought-related traits were identified on chromosomes 2, 6, 7, 8, 9, and 10, which includes QTLs for plant height (PH) qPH10.1, effective panicles number (EPN) qEPN6.1, panicle length (PL) qPL9.1, thousand-grain weight (TGW) qTGW2.1, qTGW6.1, qTGW8.1, leaf length (LL) qLL7.1, leaf width (LW) qLW7.1, and leaf area (LA) qLA7.1. The fraction of phenotypic variation explained by individual QTL varied from 10.6% to 13.9%. Except for days to flowering (DTF), the mean values of all traits under normal water management conditions were considerably higher than those under drought conditions. Except for the DTF, the drought resistance index of all rice traits was less than 1, indicating that drought treatment reduced the EPN, FGPP, SSR, PH, and LA, which affected the growth and development of rice. The drought resistance index of DTF was 1.02, indicating that drought prolonged the heading time of rice and diminish the yield parameters. Along with identifying QTLs, the results also predicted ten candidate genes, which are directly or indirectly involved in various metabolic functioning related to drought stress. The identification of these genomic sites or QTLs that effectively respond to water scarcity will aid in the quest of understanding the drought tolerance mechanisms. This study will facilitate the marker-assisted rice breeding and handy in the breeding of drought-tolerant rice varieties.

粒长、粒宽、粒厚、百粒质量是影响玉米籽粒产量的重要性状,本研究主要统计分析了100份甜玉米种质资源的粒长、粒宽、粒厚和百粒质量等4个种子性状,并利用37297个单核苷酸多态性(SNP)标记位点关联分析了控制甜玉米种子性状的重要位点.结果表明,100份甜玉米种质资源种子性状具有丰富的遗传多样性,性状变异幅度比较大,其中粒长为4.65～10.43 mm,粒宽为5.13～9.42 mm,粒厚为2.04～7.50 mm,百粒质量为4.51～20.09 g;表型变异分析发现,百粒质量的变异系数最大,为32.60％,粒宽的变异系数最小,为10.61％,且4个籽粒性状的频率分布曲线基本符合正态分布.相关性分析结果表明,粒长、粒宽、粒厚与百粒质量呈极显著正相关,粒长与粒厚呈极显著负相关.全基因组关联分析共检测到控制4个种子性状的75个SNP标记位点,其中有17个SNP标记位点与粒长性状有关,24个SNP标记位点与粒宽性状有关,11个SNP标记位点与粒厚性状有关,23个SNP标记位点与百粒质量性状有关.

Silver nanoparticles were biosynthesized from Conyzacanadensis leaf extract with the help of a microwave oven. The UV-vis spectrum showed the maximum absorption at 441 nm, corresponding to the surface plasmon resonance of silver nanoparticles. Transmission electron microscope and scanning electron microscope images showed that the synthesized silver nanoparticles were spherical or near-spherical with an average diameter of 43.9 nm. X-ray diffraction demonstrated nanoparticles with a single-phase cubic structure. As-synthesized silver nanoparticles displayed prominent antifungal activity against Bipolaris maydis. The colony inhibition rate reached 88.6% when the concentration of nanosilver colloid was 100 μL·mL−1 (v/v). At such a concentration, no colony formation was observed on the solid plate. The diameter of the inhibition zone was 13.20 ± 1.12 mm. These results lay the foundation for the comprehensive control of plant pathogens using an environmentally friendly approach.