Analysis of heat stress tolerance in winter wheat

Abstract

As a consequence of climate change, the incidence of extreme weather events has increased in Hungary, as elsewhere. Extremely high temperatures are the factor causing the greatest problems for agriculture and crop production. The aim was to determine the heat tolerance of two wheat varieties (Plainsman V. and Mv Magma) by measuring physiological and yield parameters under high temperature conditions (35/20°C day/night) in the phytotron. Heat stress had a substantial influence on the chlorophyll content, antioxidant enzyme activity and yield parameters of the two winter wheat varieties. Heat stress during grain filling led to a significant reduction in the yield, biomass, grain number, harvest index and thousand-kernel weight. Significant differences could be detected between the two varieties, confirming the greater heat sensitivity of Plainsman V. and the better heat tolerance of Mv Magma. The importance of the antioxidant enzyme system was demonstrated in defence against heat stress. The activity of the enzymes glutathione-Stransferase (GSH-S-Tr), ascorbate peroxidase (APx) and catalase (CAT) was enhanced in Plainsman V., and that of GSH-S-Tr and CAT in Mv Magma. The tolerance of the wheat varieties appeared to be correlated with the antioxidant level, though changes in activity were observed for different antioxidant enzymes in the two genotypes tested.