SOMACLONAL VARIATION IN RICE - DROUGHT TOLERANCE AND OTHER AGRONOMIC CHARACTERS

The ability to withstand drought was studied in R(2) families raised b y self-pollination from 149 R(1) plants regenerated from callus of mat ure rice seed (cvs FR13A, Kurkaruppan, Khao Dawk Mali 105, Nam Sagui 1 9, and Calrose 76). Compared to parental controls, significant improve ment in drought tolerance as assessed by dry weight production, was fo und in 6% of the cv. FR13A families, but not in any of Kurkaruppan or Khao Dawk Mali 105 families tested in a controlled-temperature glassho use. When a similar study was undertaken using an in vitro selection s tep (using polyethylene glycol), significant improvement in drought to lerance 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 latt er study when in vitro selection was not used. Variation in other agro nomically important characters was observed in the R(2) families grown under similar, but well-watered, environmental conditions.