抄録
Variation of the vascular bundle system in 83 Asian rice cultivars and its usefulness in the distinction of the 3 types, indica, tropical-japonica and temperate-japonica were investigated. The 83 cultivars were classified into 46 indica and 37japonica cultivars by the discriminant function, D1, based on the data of phenol reaction, sensitivity to KCI03 and apiculus hair length. Next, the 37japonica cultivars were subdivided into 8 tropical- and 29 temperate-japonica using the score of D2 which was computed from the ratio of length to width of the kernel, alkali digestibility and mesocotyl length. The number of vascular hundles(Vb) in the peduncle and the ratio of Vb to rachis branches(Rb)(V/R ratio) differed among the 3 types; the indica and tropical-japonica cultivars had more Vbs and showed a higher V/R ratio than the temperate-japonica cultivars. Then, the new discriminant function(D3) for identification of indica and japonica and D4 for that of tropical- and temperate-japonica were calculated based on Vb, Rb and V/R ratio. D3 and D4 improved the precision of distinguishing indica from japonica, and tropical- from temperate-japonica; the probability of misclassification decreased from 1.4%(D1) to 0.7%(D3), and from 4.8%(D2) to 0.4%(D4), respectively. In conclusion, the variation of vascular bundle system was a highly useful character for identification of Asian rice cultivars.
