Deep Rooted Rice Varieties Detected through the Observation of Root Characteristics Using the Trench Method

Abstract

Screening through the observation of root character-istics was performed in foreign rice varieties to widen the genetic diversity for drought tolerance of upland rice in Japan. A total of 255 varieties were cultivated in upland fields and their root distribution and characteristics were observed. Trench method was applied for direct observation of roots by digging a ditch at a depth of about 60cm after harvest. The root volume and thickness of each accession were evaluated at a depth of every ten or 15cm from the soil surface. The root volume or thickness at a 40 or 45cm depth showed a significant correlation with the recovery from drought exposure of seedlings. Therefore, deep-rooted varieties were expected to be more tolerant to drought. Some varieties originating from Africa, China, India and IRRI had deeper or thicker roots. IR3646, IRAT1O, IRAT109, IRAT110, JC81, SE319C and Nam Sugai 19 were selected as candidates for cross-parent in breeding for drought tolerance.