Investigation of Terminal Season Drought Stress effects on Grain Yield and Some Agronomic and Physiological Traits in Promising Barley (Hordeum Vulgare L.) Genotypes

Drought stress is known as one of the main factors limiting agricultural production. Investigation of the effect of drought stress on grain yield and other agronomic and physiological traits can be useful in identifying drought-tolerant cultivars. The aim objective of the present study was to study the effect of terminal drought stress on some of the agronomic and physiological characteristics in a set of promising barley lines.

This study was carried out at the Cereal Research Station located in Seed and Plant Improvement Institute, Karaj, Iran during 2020-2021 cropping seasons. The plant material consisted of 17 promising genotypes of barley along with a commercial cultivar (cv. Jolgeh). All genotypes were investigated in two separate experiments based on a randomized complete block design with three replications under two control and drought stress conditions.

The results of combined analysis of variance showed a significant difference between control and drought stress conditions in terms of all measured traits except spike length and the number of seeds per spike. Furthermore, a significant difference was observed among the tested genotypes in terms of all measured traits except initial chlorophyll fluorescence, maximum quantum yield of PSII, and maximum primary yield of photochemistry of PSII. However, the interaction effect between drought stress conditions and genotype was only significant for the number of days to physiological maturity, grain filling period, main spike length, and chlorophyll content.The results of principal component analysis (PCA) revealed that the first five components accounted for 84.80% of the total phenotypic variation, under drought stress condition. Considering the angle among trait-vectors indicated that some of traits such as number of days to anthesis and to physiological maturity, awn length, plant height, leaf area index, chlorophyll content, and number of seeds per spike positively correlated with grain yield in the drought stress condition. In general, our results showed that genotypes G2, G3, G6, G7, G12, and G18 were identified as the best genotypes compared with other tested genotypes.

According to results, genotype G7 due to its highest grain yield and ideal agronomic and physiological features can be candidates for further complementary investigations in multi-environmental trials with the aims of realization of a new commercial cultivar.