トマトにおける果重と種子量の相関について (第2報)

Abstract

Relationships among fruit weight, number of seeds and several characteristics, such as number of locules and weight per seed, which was related to the two characters, fruit weight and number of seeds, were statistic-genetically studied by a variety test consisting of ten varieties which were grown under five conditions of environment in order to elucidate the role of seed on the tomato fruit.Higher positive genotypic correlations were recognized among fruit weight, number of seeds and locules, and positive genotypic correlations seemed to exist between days to flowering and fruit weight, number of seeds, seed weight per fruit, respectively. On the other hand, multiple regression analysis was conducted upon some characteristics, in which fruit weight was assigned to dependent variate and number of seeds, and locules, weight per seed and days to flowering were selected as independent variates. These results revealed that the number of seeds (seed weight per fruit) had a very close genetic relation with fruit weight, and the number of locules followed secondly. It proved, however, that the close relation between the number of locules and fruit weight was combined without any influence on other characteristics such as the number of seeds and days to flowering, while the influence of the number of seeds on fruit weight was divided into the two path ways, that is, the indirect effect by number of locules, days to flowering and weight per seed, and the direct effect by the number of seeds itself.Positive genotypic correlations seemed to exist in the two combinations of weight per seed and percentage of seed germination, and fruit weight per seed and the number of locules. On the other hand, negative genotypic correlations seemed to exist between the number of locules and weight per seed, percentage of seed germination, respectively.Environmental correlations were generally smaller than genotypic correlations and also fewer in the number of combination in which correlation was found. A positive environmental correlation was found between fruit weight and number of seeds (seed weight per fruit), but not found in the following combinations: the number of locules and fruit weight, and the number of locules and number of seeds (seed weight per fruit). Also, the effect of developed and undeveloped seed on fruit weight was discussed.In this study the within-variety correlation between fruit weight and number of seeds again showed varietal difference. Furthermore, it was inferred that there were two kinds of varieties which had a comparatively stable or instable correlation under several environmental conditions.