Variation among wheat (Triticum easativum L.) genotypes in response to the drought stress: I – selection approaches

ABSTRACT The agronomic and physiological traits, drought tolerance indexes, principal component analysis and Ward`s method were applied to assess the differences among 20 wheat genotypes in response to drought. Statistically significant correlation was observed for measured traits. Drought susceptibility index (DSI), stress tolerance index (STI) and stress index (SI) were most useful to identify genotypes differing in their response to drought. Utility of the indexes was confirmed by physiological markers of drought tolerance i.e. membrane injury and leaf water status. Variation of the genotypes in biomass and grain yield during drought stress was also verified by clustering methods. Finally, integration of physiological and statistical methods presented in this work, allows to both, indicate that tolerance to drought in wheat has a common genetic background, and select the most diverse genotypes. Based on the results, we recommend a tool for breeders, useful to select the genotypes resistant and sensitive to drought. Abbreviations: DM: dry matter; DSI: drought susceptibility index; FWC: field water capacity; GY: grain yield; GMP: geometric mean productivity index; H: plant height; LI: leakage index related to membrane injury; MPRO: mean productivity index; MHAR: harmonic mean index; NoT: number of tillers; NoG, W-1000: number of grains and weight of 1000 grains, respectively; NoLMT, NoLAT, NoLT: number of leaves on main tiller, adventitious tillers and total leaf number, respectively; PCA: principal component analysis; RTC: relative trait change; RWC, RT, WD: relative water content, relative turgidity and water deficit, respectively SI: stress index; SPAD: leaf greening; STI: stress tolerance index; TI: tolerance index; WCA: Ward`s cluster analysis