NONDWARF RICE SEEDLING BIOASSAY FOR GIBBERELLINS

The use of nondwarf rice (Oryza sativa L.) cultivars treated with unic onazole as test plants for gibberellin (GA) bioassay instead of Tan-gi nbozu dwarf rice variant was investigated. The sensitivity of six nond warf rice cultivars to GAs was increased substantially by treatment of the seeds with uniconazole. The minimum detectable dose of a GA in th e nondwarf cultivars treated with uniconazole was 1- to 1/10-fold of t hat in the nontreated Tan-ginbozu and 3- to 10-fold of that in unicona zole-treated Tan-ginbozu. The relative activity of several GAs on trea ted nondwarf rice cultivars was not largely different from that to Tan -ginbozu. Considering that seeds of nondwarf rice are available commer cially, the nondwarf rice seedling assay would be useful as a simple a ssay for systematic analysis of GAs, and also as a routine teaching to ol in high schools and universities.