M. Yousofi Azar, A.m. Rezai,
Volume 11, Issue 42 (winter 2008)
Abstract
This study was conducted at Research Farm of Isfahan University of Technology to evaluate drought tolerance potential of 23 F2:4 wheat lines derived from the cross of Virmarin (susceptible line) and Sardari (tolerant line). A randomized complete block design with three replications was used in each irrigation treatment (i.e. irrigation after 70±3 and 120±3 mm evaporation from class A pan for non-stress and stress conditions, respectively). Drought tolerance and susceptibility indices were calculated for yield, and principal components analysis was performed on the basis of indices. Rosielle and Hambline tolerance index and Fisher and Maurer stress susceptibility index had positive and significant correlation, but their correlations with drought yield and the first two principal components were negative. High value of these components indicates low sensitivity to drought. The first component had high and positive correlations with geometric mean productivity, stress tolerance index and harmonic mean. Lines number 4, 17, 11 and 14 with high yields in drought condition, showed high values for these indices. Line number 2 with high yield in non-stress condition and in spite of high sensitivity to stress, was a superior genotype based on these indices.
A. M. Rezai, M. Yousofi Azar,
Volume 12, Issue 45 (fall 2008)
Abstract
To improve a complex character such as yield with low heritability, the use of indirect selection through other characters and a selection index based on different effective traits is recommended. This study was conducted to evaluate different selection methods by using 23 F2:4 wheat lines derived from the cross of Virmarin (susceptible cultivar) and Sardari (tolerant cultivar) at Research Farm of Isfahan University of Technology. A randomized complete block design with three replications was used in two irrigation treatments (i.e. irrigation after 70±3 and 120±3 mm evaporation from class A pan). For each irrigation treatment, different selection indices were constructed based on the number of spike per m2, days to heading, number of grain per spike and 1000 – kernel weight. Also direct and correlated responses were calculated for these traits. The results of the response to selection and correlated response indicated that in the same conditions of this study, early heading cultivars with high number of spikes and low number of grain per spike with high 1000-kernel weight will have more yield potential. Number of spike per m2 and 1000-kernel weight exhibited positive response in most of the indices and both irrigation treatments, while days to heading and number of grain per spike revealed negative responses. Thus selection based on these indices would result in early heading cultivars with high spike per m2, low number of grain per spike and high 1000–kernel weight. It was also found that Smith-Hazel and Brim-Williams indices had the highest efficiencies.
