Abstract
Using seven parent varieties of Japonica-Indica hybrid bred in Korea, 16 aman, 17 aus, 10 boro, 15 bulu and 15 tjereh rice varieties, excised seminal roots (root-tips) were cultured in modified White's medium containing 0% or 0.2% casamino acids. The excised roots were cultured at 28°C in the dark for two weeks. The results obtained were as follows. 1. In Japonica type parents, the excised seminal root growth was better in the 0.2% casamino acids lot than in the 0% lot. In Indica type parents, on the other hand, main root length was almost same between the two lots of casamino acids concentration in each of three varieties, while the length was shorter in the 0.2% casamino acids lot than in the 0% lot in two varieties. But, dry root weight was larger in the former than in the latter in every variety (Table 1). 2. In all the varieties belonging to aman and tjcreh ecotypes, main root length was shorter in the 0.2% casamino acids lot than in the 0% lot. In each ot aus, boro and bulu ecotypes, the length in the above half of varieties was shorter in the 0.2% casamino acids lot than in the 0% lot and it was opposite in the rest. Dry root weight, on the other hand, was larger in the 0.2% casamino acids lot than in the 0% lot in all the varieties in every ecotype (Table 2).
