Physiological and agronomical evaluation of elite rice varieties for adaptation to heat stress

Abstract

Background: The increasing temperatures due to climate change around the world poses a serious threat to sustainable crop production. The growing adverse efects of heat stress are putting global food security at great risk. Crop improvement for adaptation to increased temperatures is therefore of paramount importance. This study aims at assessing the efects of heat stress in relation to agro-morphological and physiological traits of six rice varieties. The study was carried out in the Township of Glazoué, a rice-growing area in Benin. The experiments were laid in randomized complete block design with three replications. Two types of stress were imposed: high-temperature stress in the dry season and optimal temperatures in the rainy season. The calculated mean values of morphological, physiological, and agronomic traits were used to estimate heritability, genetic advance, PCA, and correlation. Results: The results showed that heat stress had a signifcant (p≤0.01) infuence on plant height, leaf length, number of tillers, number of internodes, days to fowering, and days to maturity, 1000-seed weight, and yield per plant. The heat stress had signifcantly delayed the fowering of all the varieties when compared to the controls. The highest values of 1000-seed weight (34. 67 g) were recorded for BRIZ-8B while the lowest (25.33 g) were recorded for NERICAL20. The highest values for the genotypic coefcient of variation (43.05%) and phenotypic coefcient of variation (99.13%) were recorded for yield per plant under heat stress. The topmost broad-sense heritability was recorded for grain width (92.72%), followed by days to maturity (69.33%), days to fowering (68.50%), number of grains per panicle (57.35%), and yield (54.55%). Conclusions: These results showed that BRIZ-8B and BRIZ-10B were the most tolerant to high temperature amongst the six varieties assessed and potentially could be recommended to farmers for production under high temperature and be used in breeding programs to improve heat tolerance in rice.