Evaluation of Yield‐Based Drought Tolerance Indices for Screening Safflower Genotypes

Abstract

Drought tolerance is not often considered an independent trait by plant breeders because the collective result of many traits of a plant with positive or negative interactions may be fairly general and polygenic in nature. The objective of this study was to evaluate six drought tolerance indices, namely the stress susceptibility index (SSI), yield stability index (YSI), tolerance index (TOL), mean productivity (MP), geometric mean productivity (GMP), and stress tolerance index (STI), to be used in screening safflower (Carthamus tinctorius L.) genotypes. For this purpose, 64 genotypes were grown during two growing seasons (2011)(2012) under both normal and drought-stress field conditions at the Research Farm of Isfahan University of Technology located at Lavark, Najaf-Abad, Iran. The drought tolerance indices were calculated based on seed yield under drought stress and nonstress conditions. Results of combined analysis of variance showed the significant influences of drought stress on seed yield as well as significant differences among genotypes for seed yield and the indices. Results of calculated correlation coefficients and multivariate analyses showed that GMP and STI indices were able to discriminate between drought-sensitive and -tolerant safflower genotypes. Cluster analysis using the drought-tolerance indices divided the 64 genotypes into tolerant and susceptible groups. Based on multivariate analyses using the indices singly or in combinations, it was possible to identify the most yield-stable genotypes across the environments. Overall, we concluded that GMP and STI indices can be efficiently exploited not only to screen drought tolerance but also to identify superior genotypes for both stress and nonstress field conditions in safflower.

Relationship Among Agro-Morphological Traits in Bread Wheat (Triticum aestivum) Genotypes Under Irrigated and Rainfed Conditions

“…The TOL and SSI indices were positively correlated with grain yield under irrigated condition, while they were negatively correlated with grain yield under rainfed condition. The observed relations were in agreement with those reported by Bahrami et al (2014) in safflower and Nouri et al (2011) in durum wheat. Fernandez (1993) that selection based on STI, GMP and MP would identify genotypes with higher levels of yield potential and stress tolerance, whereas, SSI and TOL indices had a significant negative correlation with seed yield under stress conditions but a positive correlation with seed yield under non-stress conditions.…”

Selection efficiency of yield based drought tolerance indices to identify superior sorghum [Sorghum bicolor (L.) Moench] near isogenic lines (NILs) under two-contrasting environments

“…This cluster was also superior to grand mean of all other traits averaged over all clusters, indicating that this cluster contained desirable genotypes according to yield obtained from both environments and selection indices. This study is in line with previous reports that stated genotypes can be classified adapted to moisture-stressed and non-stressed conditions using cluster analysis in various crops (Eivazi et al, 2013;Johari-Pireivatlou, 2014;Bahrami et al, 2014;Sory et al, 2017). Generally, this study showed that selection can be improved though MRP, MP, GMP, STI, and HM.…”

Evaluating the Contribution of Ionic and Agronomic Components toward Salinity Tolerance in Safflower

“…Thus plants may modify architecture by reducing the branch numbers as observed in our experiment, thus implying an alteration in the balance between source and sinks, to overcome salinity stress. It appears that root as the sink organ plays a crucial role in conferring salinity tolerance in safflower as is the case for drought tolerance (Bahrami et al, 2014). Deeper root growth is not only a mechanism to avoid moisture deficits but also important for adaptation to salinity because roots would use water of higher potential in the subsoil where less salts accumulated.…”