SOMACLONAL VARIATION IN RICE - DROUGHT TOLERANCE AND OTHER AGRONOMIC CHARACTERS

The ability to withstand drought was studied in R(2) families raised by self-pollination from 149 R(1) plants regenerated from callus of mature rice seed (cvs FR13A, Kurkaruppan, Khao Dawk Mali 105, Nam Sagui 19, and Calrose 76). Compared to parental controls, significant improvement in drought tolerance as assessed by dry weight production, was found in 6% of the cv. FR13A families, but not in any of Kurkaruppan or Khao Dawk Mali 105 families tested in a controlled-temperature glasshouse. When a similar study was undertaken using an in vitro selection step (using polyethylene glycol), significant improvement in drought tolerance was found in 6% of Khao Dawk Mali 105 families, but not in any of the Nam Sagui 19 families. No improvements were noted in this latter study when in vitro selection was not used. Variation in other agronomically important characters was observed in the R(2) families grown under similar, but well-watered, environmental conditions.