Association of Drought and Heat Tolerance Parameters in Wheat

The association of different plant characters with drought tolerance of genotypes was studied in wheat under rainfed condition in winter season. The leaf samples were subjected to heat injury at 45°C on 45-day-old seedlings, and stomata on upper and lower surfaces were counted in the laboratory. Among T. aestivum varieties, HD 2189 exhibited 45.2 and 31.5 stomata per microscopic field at upper and lower surfaces, while among T. durums, Bijiga Yellow recorded the highest number of stomata (56.4/mm²) and flag leaf area (30.51 dm²). The variety HI 7483 had the highest flag leaf area of 43.22 dm². Waxy coat on the leaf was 100% in UP 2029 and HS 90, while N 59, MACS 9, Bijiga Yellow and Ajantha were characterised by glossy leaf surface. Leaf folding was very low in varieties K 68, Hindi 62, n 59 and Bijiga Yellow (3–4%). The number of stomata had significant negative association with waxmess, leaf folding, temporary wilting and grain yield per ear. Similar trend was observed for number of stomata on the lower surface. Therefore, waxiness, leaf folding, wilting percent, heat injury and stomata number are suggested as the most reliable traits in screening for drought and high temperature tolerance.