Evaluation of Drought Tolerance in Durum Wheat Landraces Using Grain Yield-Based Drought Selection Indices

Durum wheat is considered as the 10th most important crop in the world. Drought stress is among the principal constraints to global wheat production. Improvement of new varieties having good adaptation to stressful conditions is an important goal of wheat breeding programs. In this regard, the exploitation of genetic diversity retained in landraces and wild relativesis is very important. The aim of this research was to evaluate durum wheat landraces collected from different contries for drought tolerance.

In this study 196 durum wheat landraces belong to 18 countries were evaluated for drought tolerance using several yield-based drought indices. The trials were conducted in the experimental field of dryland agricultural research institute (Sararood branch) based on alpha lattice design with two replications under rainfed and supplemental irrigation conditions during 2020-2021 cropping season.

Analysis of variance revealed significant environment, genotype, and genotype × environment interaction effects for grain yield. Based on genotype-by-index (GI) biplot analysis the drought selection indices were classified into four groups. The first group included drought response index (DRI), yield stability index (YSI), yield index (YI) and yield under rainfed condition. The second group composed of stress tolerance index (STI) and geometric mean productivity (GMP) which were able to select genotypes producing higher yield in both conditions. The third group included mean productivity (MP) and yield under irrigated condition. Fourth group composed of stress susceptible index (SSI), tolerance index (TOL), Schneider’s Stress Severity Index (SSSI) and yield reduction percentage (RI) which were able to separate genotypes having higher yield in non-stress and low yield in stress condition. Cluster analysis identified three distinct groups having different yield performance and drought tolerance.

Generally, based on the results of this research, selection for higher values of DRI, STI and GMP and lower values of SSI, TOL and RI at the same time can be considered as a appropriate strategy for identification of drought tolerant landraces. The members of first group which mostly composed from landraces belong to Iran, Japan, Turkey and Afghanistan could be considered as high-yielding drought tolerant.