Abstract
Improvement of elite safflower genotypes for drought-tolerance is hampered by a deficiency of effective selection criteria. The present study evaluated 100 genotypes of safflower in terms of their drought tolerance over a period of three years (2016–2018) under both non-stress and drought-stress conditions. The eight drought-tolerance indices of tolerance index (TOL), mean productivity (MP), geometric mean productivity (GMP), stress susceptibility index (SSI), stress tolerance index (STI), yield stability index (YSI), drought resistance index (DI), and harmonic mean (HARM) were calculated based on seed yield under drought (Ys) and non-drought (Yp) conditions. A high genetic variation was found in drought tolerance among the genotypes studied. The MP, GMP, and STI indices were able to discriminate between tolerant and drought-sensitive genotypes. Plots of the first and second principal components identified drought-tolerant genotypes averaged over the three study years. Cluster analysis divided the genotypes into three distinct groups using the drought tolerance indices. Ultimately, eight genotypes (namely, G3, G11, G13, G24, G33, G47, G58, and G61) from different origins were detected as more tolerant to drought stress suitable for use in safflower breeding programs in drought-affected areas. The most tolerant and susceptible genotypes could be exploited to produce mapping populations for drought tolerance breeding programs in safflower.
Highlights
Droughts due to alterations in rainfall patterns and climate change form a most devastating factor in food production on a global scale (Blum, 2018; Anjum et al, 2017)
A highly significant (p < 0.01) variation in seed yield was observed among the studied genotypes under both conditions and for all the tolerance indices examined (Table 2)
Based on the correlation analysis conducted in this study, geometric mean productivity (GMP), stress tolerance index (STI), and mean productivity (MP) were found to favor genotypes with a high-yield potential under stress conditions (Table 2), which agrees with the findings reported Sio-Se Mardeh et al (2006), Hao et al (2011), and Ebrahimiyan et al (2012)
Summary
Droughts due to alterations in rainfall patterns and climate change form a most devastating factor in food production on a global scale (Blum, 2018; Anjum et al, 2017). This warrants a Blue Revolution in agriculture concentrated on increasing productivity per unit of water to produce more crops per drop of water. Since the genotypes with a high yield under optimum conditions may not be drought tolerant (Blum, 2018), many studies preferred selection under both stress and non-stress conditions (Fernandez, 1992)
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