Subspecific Characteristics and Classification of Rice Varieties Developed Through Indica and Japonica Crossing

Six characteristics, i.e., hull color, chaff and leaf pubescences, length of 1st and 2nd rachis, grain length/width ratio and phenol reaction, of rice progenies from indica and japonica crossing were studied using the Cheng's index classification method. The results indicated that F1 generations performed more like indica, while F2 generations were approximately in a normal distribution. Both of the rice progenies were more affected by indica and female parents than by japonica and male parents. Among the six Cheng's index traits of the parents and F1 generations, and between the traits and Cheng's indexes, significant correlations (both at α=0.05 and α=0.01) were found in most cases. No significant correlations were found among the 6 Cheng's index traits of F2 generations in most cases, but significant correlations (α=0.01) existed between these traits and Cheng's indexes. The six Cheng's index traits of F2 ranged successively, and many individuals showed over-parent genetics, with the same trends in both direct cross and reciprocal cross. Among the 6 index traits,chaff and leaf pubescences almost presented in a two-peak value, while the others in a mono-peak value. The hull color,phenol reaction and length of 1 st and 2nd rachis were distributed in deviation, with the first two traits presented more in japonica individuals and the last trait more in indica. The grain length/width ratios were nearly in a normal distribution.