SOMACLONAL VARIATION IN RICE - SUBMERGENCE TOLERANCE AND OTHER AGRONOMIC CHARACTERS

The ability to withstand complete submergence was studied in R2 seedlings raised by self-pollination from 158 R1 plants regenerated from callus of mature rice seeds (cultivars FR13A and Calrose). Compared to parental controls, significant improvement in submergence tolerance as assessed by percentage survival, number of new leaves and chlorophyll content of the third leaf, was found in 5 of the 115 cv. FR13A somaclones and 3 of the 43 cv. Calrose somaclones tested using an aquarium system in a controlled-temperature glasshouse. With some exceptions these improvements were also observed in the R3 generation when tested under field conditions in Thailand. Variation in other agronomically important characters was observed in the R2 plants grown in a temperature glasshouse under 2 contrasting environments.