Enhancing Drought Tolerance of Rice (Oryza sativa) by Giving Water Stress on Germinated Seeds

Abstract

Drought is one of the major environmental factors affecting crop growth and productivity in the tropics. At critical stages of plant growth, crop yields are greatly reduced by even short term, drought stress. The technique of seed hardening is employed to modify the physio-biochemical nature of seed, so as to become favorable for drought-resistant. The present study examined the effect of water stress on germinated rice seeds to drought tolerance at subsequent stages. Pot experiment with three rice cultivars (AT 353, AT 354, and AT 362) was conducted. Re-germination and seedling vigor were evaluated after different period of water stress to select the best water stress period. It was observed that 91% germination of seeds of 3 varieties even after 20 days water stress period. However, highest seedling vigor (24.9) was observed after eight day water stress period. Therefore, re-germinated seeds after eight day water stress were used for further experiments and drought stresses were imposed in vegetative (30 DAP), reproductive (45 DAP) and milk (80 DAP) stages. At the temporary wilting point, plants were re-watered and allowed ten days to recover. Data were collected to measure their recuperative ability after re-watering and yield performances. In all rice cultivars, hardened seeds resulted in significant increment in root length, root dry weight and number of fresh leaves/plant, after recovery in plants stressed in all growth stages. At harvesting also, plants originated from hardened seeds and water stress during different growth stages, showed comparatively higher number of panicles/per bush and higher number of grains per panicle. These results suggest that the water stress on germinated seeds can improve drought tolerance of rice at subsequent stages.