Effect of short-term heat stress on growth, physiology and antioxidative defence system in wheat seedlings

An experiment was conducted to find out the effect of short-term heat stress on morpho-physiological characters and antioxidants in 10 diverse wheat genotypes. Seed were aseptically grown in test tubes containing filter paper whose lower half was dipped in one-fourth MS media. Heat stress conditions were created by exposing the seedlings at 45 A degrees C for 2 h after 7 days of their germination. Measurements were taken after 3 days of treatment. Heat stress significantly reduced the shoot dry mass, root dry mass, shoot length and root length in all the genotypes. The chlorophyll content and membrane stability index decreased, whereas proline content increased in heat-treated plants. There was significant increase in the activity of catalase, guaiacol peroxidase and superoxide dismutase under stress conditions. The genotypic variations were also significant. On the basis of a coordinated simulation of all these parameters, wheat genotypes Raj 4037 and PBW 373 were identified as tolerant to high temperature stress. The study provides evidence that the tolerant genotypes were equipped with better management of physiological processes along with an efficient antioxidative defence system, sensitivity of which can be evaluated to a sufficient level of certainty at seedling stage.