Early Identification of Salt Tolerant Genotypes of Rice (Oryza sativa L.) using Controlled Deterioration

The response of germination and early seedling growth to levels of salinity (0: 50, 1003 150; 200 and 250 mM NaCl) were examined in single seed lots of tell modern rice genotypes. Unaged and deteriorated rice seeds were germinated in rolled paper towels and in Petri dishes. Initial seed quality. final germination, germination rate and early seedling growth were assessed. The samples of the rice genotypes differed in their initial seed quality (measured in terms of K-i). The effect of deterioration varied depending upon the initial seed quality and the severity of the treatment imposed. Ageing (using the technique of controlled deterioration, CD) For up to 24 h had no effect oil final germination levels. Although CD for 30 h only reduced final germination slightly, ageing for 36 or 48 h reduced it greatly Controlled deterioration for 36 h or longer reduced the final length and the rate of extension of both the plumule and radicle. Combining information about germination in salt solution with that about seed quality enabled a distinction to be made between varieties which performed poorly because they were genetically salt-susceptible from those which germinated poorly due to poor seed quality It is argued that the seed vigour of seed lots used in genotype evaluation Should be assessed in order to avoid discarding potentiaity useful genotypes because of poor physiological seed quality.