Genetic Behavior of Some Rice Genotypes under Normal and High Temperature Stress

Abstract

Thirteen rice genotypes were grown in the two successive rice seasons 2017 and 2018 to assess the presence of variability for desired traits and estimate genetic parameters and correlations for traits under normal and heat stress conditions. Analysis of variance revealed significant differences due to environments, genotypes and their interaction for all studied characteristics in both seasons. The estimates of genotypic (GCV) and phenotypic (PCV) coefficient of variation were highly significant for all studied traits and generally, the PCV values were higher than GCV values, in both seasons. Leaf rolling and sterility percentage increased under heat stress, while days to heading, plant height, number of tillers and number of panicles / plant, 100-grainweight and grain yield/plant decreased under heat stress in comparison to normal condition. As mean performance Giza 179, Giza 178 and Sakha 101 surpassed other genotypes in grain yield and its important attributes, while WAB56-50/Sakha101-1, WAB56-50/Sakha101-2 and IR65907-206-7-8/Gyehwa71 gave the lowest grain yield in both seasons. Giza178 and WAB56-50/Sakha101-1 recorded the lowest values of geometric mean productivity, stress susceptibility index and yield index which refer to those genotypes highly tolerance to heat stress, while Giza 177 and Sakha 101 gave the highest values to be the most heat susceptible genotypes under study. Highly positive and significant phenotypic correlations were observed between yield index and leaf rolling, sterility percentage, geometric mean productivity and stress susceptibility index, otherwise number of tillers/plant, number of panicles/panicle and panicle weight, as yield attributes had highly significant negative correlation with the yield index. From the results we can conclude that, the genotypes can be scored as heat tolerant, based on days to heading, leaf rolling, tillering productivity and spikelets sterility percentage.

Rice Yield under High-Temperature Stress is Influenced by Morpho –Physiological Traits

“…CO51 invariably recorded a higher panicle weight of 3.21 g under control, but 24.16 percent reduction of panicle weight was recorded in comparision to N22 (10.10%) at HTS (Table . 1). These results were similar to the findings of Gaballah and Abu (2019) where panicle length and panicle weight of rice genotypes were reduced due to heat stress.…”

“…During ripening, the panicle is a highly sensitive organ to high-temperature stress (Morita et al, 2004). Panicle length and panicle weight in rice may get affected as temperature attains beyond (Gaballah and Abu, 2019). Paddy yield had a strong genetic correlation with the number of grains per panicle and 1000 grain weight (Karwa et al, 2020).…”

Evaluation of some Rice Genotypes (Oryza sativa L.) Under Normal and Heat Stress Conditions تقييم تراکيب وراثية مختلفه من الأرز تحت الظروف الطبيعية والإجهاد الحراري

“…The correlation between grain yield and flag leaf angle was positive and significant under normal condition while it was negative and highly significant under heat stress condition indicating that genotypes with erect flag leaf are more desirable for cultivating in high temperature regions. A similar result was obtained by Gaballah and Abu El-Ezz (2019) who reported that flag leaf angle was highly significant positive correlated with leaf rolling and sterility %, and highly significant negative correlated with panicles plant -1 , panicle weight and grain yield plant -1 under normal and heat stress conditions. The correlation between grain yield and flag leaf area and plant height traits was negative under normal condition but it was positive under stress condition meaning that those traits are good indicators for tolerance under stress condition.…”

Flowering Synchronization in Hybrid Rice Parental Lines at Different Sowing Dates

“…Genetic distance was correlated positively with grain length, panicle number and length: width ratio and correlated negatively with grain width, grain yield and seed setting rate [26,27]. Highly positive and significant phenotypic correlations were observed between yield index and leaf rolling, sterility percentage [28].…”