Physiological Screening of Rice (Oryza sativa L.) Varieties/Line in Submergence Condition

Screening of rice genotypes for submergence tolerance in vivo and in vitro condition for tolerant and susceptible genotypes was carried out. Important factor linked to flash flooding tolerant, showed higher survival because of their shorter stature and may not elongate much and continued growth when fully or partially submerged because of the sub1 mediated suppression of elongation. However, rather than increasing submergence tolerance, seedling vigour was more beneficial when post transplant growth was not limited by nutrient are other stresses. During the stress period it was observed that the enhancement of shoot elongation during submergence in water that is too deep to permit re-emergence by small seedlings represents a futile escape strategy that takes place at the expense of existing dry matter in circumstances where underwater photosynthetic carbon fixation is negligible. Consequently, it compromises survival or recovery growth once flood water levels recede and plants are re-exposed to the aerial environment. Tolerance is greater in cultivars where acceleration of elongation caused by submergence is minimal.