FIELD EVALUATION OF KASIB WHEAT GERMPLASM FOR DROUGHT TOLERANCE IN KAZAKHSTAN

Abstract

Wheat (Triticum aestivum L.) is a strategically important crop for global food security, particularly under increasing climate variability and drought frequency. Identifying genotypes that combine high productivity, disease resistance, and environmental adaptability remains a key objective of modern breeding. The aim of this study was to comprehensively evaluate spring wheat varieties and lines from the international KASIB nursery to identify promising genotypes with high yield potential and drought tolerance. The research was conducted in the Kostanay region at the Karabalyk Agricultural Experiment Station. Phenological observations, morphometric analysis, NDVI assessment, phytopathological screening for leaf rust resistance, and determination of the drought tolerance index (DSI) were applied. Statistical methods were used to assess trait variability and identify adaptation patterns. The results revealed significant phenotypic variability among the studied accessions. Thirty-six genotypes exhibited high NDVI values (0.55–0.67), indicating intensive biomass accumulation. The 1,000-kernel weight ranged from 24 to 57 g, with 27 accessions exceeding 40 g, reflecting high productivity potential. Phytopathological screening identified 59 genotypes with an immune response to leaf rust. Morphometric analysis showed that the length of the last internode (15–47 cm) is a key adaptive trait associated with both productivity and drought tolerance. Grain yield varied from 17.7 to 53.9 c/ha. The drought tolerance index (DSI) ranged from 0.26 to 1.17, with 23 genotypes classified as drought-tolerant (DSI ≤ 0.50). These findings confirm the high genetic and phenotypic diversity of the KASIB collection and demonstrate the effectiveness of integrating morphological, physiological, and phytopathological traits for identifying adaptive and high-yielding genotypes for breeding programs.