sadhana maurya

Rice crop is known to be sensitive to heat stress particularly at the flowering stage. Breeding approaches for improving heat tolerance in rice needs understanding of heat tolerance mechanisms and suitable heat tolerance donors. A study was planned for screening of rice genotypes and identification of novel heat tolerant donor(s) and physiologically characterize the component traits using contrasting set of genotypes in green house environment. Genotypes were categorized as tolerant and sensitive to heat stress using heat susceptibility index and cumulative stress response index for spikelet fertility, pollen viability, and grain yield. Among the set of genotypes screened, IET 22218 recorded high spikelet fertility (> 85%), pollen viability (> 95%) at high temperature (39–44 °C) with relative humidity (> 60–80%). This genotype recorded higher photosynthesis, canopy temperature depression, and accumulation of endogenous level of polyamines both under optimum and heat stress ...

Rice is one of the important cereal crops. Two contrasting rice genotypes viz. MTU-1010 (heat tolerant) and PR-113 (heat sensitive), were exposed to heat stress at flowering stage using high temperature tunnel. Heat stress caused a significant increase in H 2 O 2 and TBARS, while significantly decreased photosynthesis, relative water content (23–30%) and specific leaf weight (SLW) in sensitive genotype. Interestingly, MTU-1010 showed no significant changes in rate of photosynthesis, H 2 O 2 and TBARS content, under heat stress as compared to control. However, a significant increase was recorded in activity of antioxidant enzymes like SOD, APX and GPX, both in flag leaf and spikelet tissues of MTU-1010. Besides the antioxidant defense, significantly higher SLW and RWC were documented in MTU-1010 as compared to PR-113, across the treatments. It was found that higher spikelet fertility, rate of photosynthesis and induced antioxidant system and transpiration, RWC and SLW mainly contribu...

Abstract Heat stress is a major constrain to sustain rice production and grain quality. Rising atmospheric [CO2] is predicted to increase photosynthesis resulting in higher biomass and yield. Conversely, both elevated (e[CO2]) and heat stress (HT) are documented to deteriorate grain quality traits in rice. However, interactive effect of e[CO2] + HT on rice grain yield, quality traits and particularly mineral composition under natural field condition in tropical environments are limited. Independent field experiments were conducted to assess the potential impact of e[CO2] alone and in combination with HT on grain yield, quality traits and mineral composition of two rice cultivars Nerica-L-44 (heat tolerant) and Indian basmati rice variety Pusa 1121, using field based open top chamber (OTC) facility. Elevated [CO2] significantly influenced grain quality traits by increasing chalkiness (69–83%), amylose content (18–37%), decreasing protein content by 4% and altering grain mineral nutrient composition across the cultivars. Proportion of chalky grains was further increased in Nerica-L-44 and Pusa 1121 under e[CO2] + HT interaction. Correlation analysis revealed negative relationship of grain minerals with chalkiness and amylose content. In summary, independent exposure of rice to e[CO2] reduced grain quality and e[CO2] + HT further increased the negative effects on grain nutrient and quality.

The success of drought tolerance breeding programs can be enhanced through molecular assortment of germplasm. This study was designed to characterize molecular diversity within and between Lens species with different adaptations to drought stress conditions using SSR markers. Drought stress was applied at seedling stage to study the effects on morpho-physiological traits under controlled condition, where tolerant cultivars and wilds showed 12.8-27.6% and 9.5-23.2% reduction in seed yield per plant respectively. When juxtaposed to field conditions, the tolerant cultivars (PDL-1 and PDL-2) and wild (ILWL-314 and ILWL-436) accessions showed 10.5-26.5% and 7.5%-15.6% reduction in seed yield per plant, respectively under rain-fed conditions. The reductions in seed yield in the two tolerant cultivars and wilds under severe drought condition were 48-49% and 30.5-45.3% respectively. A set of 258 alleles were identified among 278 genotypes using 35 SSR markers. Genetic diversity and polymorp...