Comparison between diploid purelines of rice obtained from a haploid plant and lines from foundation seed of the same variety. : Karyological studies in haploid ricem III

Abstract

1. A haploid plant of rice varity, Norin no. 8 produced panicles with fertile seeds which showed the diploid numbcr of chromosomes in somatic cells. Plants from thc seeds and from foundation seed of the same variety were propagated in pedigrees. In order to makc comparisons between them, 30 lines taken from each of the three populations belonging to the third and fourth generations of the diploidfrom-haploid and foundation seed, respectively, were tested in a randomized block experiment with six replications. Plant height. panicle length, panicle number, grain yield per plant and other characters were measured on a single plant basis. 2. The diploid-from-haploid plants and those from foundation seed showed no difference in the characters measured. The difference between line means in each of the three populations was also found to be insignificant, except that in plant height the lines from foundation seed were found to be significant. It seems, therefore, that diploid-fromhaploid plants are genetically as pure as or purer than foundation seed. The occurrence of genetic variability due to spontaneous mutations of genes could not be detected within the four generations investigated. 3. In the standard deviation for individual variations, no significant difference was found between the diploid-fromhaploid and foundation seed lines. It may then be said that genetical purification does not bring about a tendency toward inbreeding depression in rice. 4. Triploid plants were found in the second and third generations of diploid-from-haploid plants with 1/40 and 1/80 frecluencies, respectively.