Evaluation of the relative water content and the reduction of 2,3,5-triphenyl-tetrazoliumchloride as indicators of drought tolerance in spring wheat cultivars

The aim of this study was to evaluate the relative water content and the reduction of 2,3,5,-triphenyltetrazolium-chloride, as indicators of drought stress and drought tolerance in spring wheat cultivars (Triticum aestivum L.) grown in the Western Cape. Drought stress was induced in two cultivars with known drought tolerance, namely, Gamtoos (drought tolerant) and SST 66 (slightly drought sensitive), as well as in two cultivars with unknown drought tolerance, namely, Nantes and SST 44. To assess the effect of growth stage on the reaction of the cultivars to drought stress, stress was induced during pre-anthesis and also during anthesis. Relative water content patterns for the different cultivars showed clear genotypical differences during pre-anthesis and, to a lesser extent, during anthesis. A positive correlation between the ability to maintain relative water content levels and drought tolerance was found for Gamtoos and SST 66. The results obtained with the reduction of 2,3,5-triphenyl-tetrazoliumchloride during drought stress showed only minor genotypical differences, and no correlation could be shown between the degree of reduction and drought tolerance.