Abstract
This study was carried out on grain yield in wheat genotypes with the aim of assessing genetic potential of drought tolerance. The experiment was performed as split plot in the form of randomized complete block design with three replications under normal and drought stress conditions with 32 genotypes. Based on grain yield, and under the condition of non-stress and drought stress, 5 drought tolerance indices are estimated including Tolerance Index (TOL), Stress Tolerance (STI), Mean Productivity (MP), Geometric Mean (GMP) and, Harmonic Mean (HM) for all kinds of genotypes. The analysis of yield correlation and drought tolerance indices in two environments indicated that STI, MP, GMP, HM indices were the most suitable parameters for screening wheat genotypes. Principal components analysis exhibited that the 83 % of first principal component and the 15 % of second one justified the variation of the initial data. Drawing bi-plot diagram declared that Sabalan, Shabrang, Aria, Azar, Azadi, and T2 genotypes were highly functional and resistant to drought stress.
Highlights
Wheat (Triticum aestivum L.) is the most important crop in the world (Sleper and Poehlman, 2006) and is cultivated in more than 250 million hectares of agricultural lands of all over the world (Royo and Di Fonzo, 2005)
Based on tolerance index (TOL) as difference in the yield of two genotypes under both normal and stress conditions, the higher TOL indicates more sensitivity of plants to stress and the selection was mainly based on the low amounts of TOL, but high mean productivity (MP), the mean yield of each genotype in two conditions, shows more tolerance to stress (Rosielle and Hamblin, 1981)
When there is a significant relative difference between the yield under stress and non-stress conditions, MP index is oriented toward the yield under normal conditions so to obviate this problem, geometric mean productivity (GMP) index that is based on the geometric mean of genotypes yield under normal and stress conditions was proposed by Fernandez (1992)
Summary
Wheat (Triticum aestivum L.) is the most important crop in the world (Sleper and Poehlman, 2006) and is cultivated in more than 250 million hectares of agricultural lands of all over the world (Royo and Di Fonzo, 2005). When there is a significant relative difference between the yield under stress and non-stress conditions, MP index is oriented toward the yield under normal conditions so to obviate this problem, geometric mean productivity (GMP) index that is based on the geometric mean of genotypes yield under normal and stress conditions was proposed by Fernandez (1992). Since this index is less sensitive to different values in normal conditions and drought stress, Fernandez introduced another index called stress tolerance index (STI), in order
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