Selective fertilization in plants in relation to plant breeding. I. Chinese cabbage (Brassica pekinensis RUPR.). 2. Mechanisms involved in selective fertilization.

Abstract

Existence of selective fertilization in Chinese cabbage and its dependency essentially on compatibility between varieties were previously reported (Murakami, 1964 ) . With a view to seek, in detail, the mechanisms involving selective fertilization in this crop, another series of experiments were conducted. The methods used for this purpose were different artificial mix-pollinations and the subject materials being Kashin and Matsushimashin No. 2, the two of the flve varieties which were included in the previous trials. When a pollen mixture of the above two varieties was used on Kashin (seed parent), the results of studies in its progeny revealed that inter-varietal hybrids originated predominantly from the basal portion of a pod rather than its upper portion (Table 1). This suggested that the pollen growth of Matsushimashin No. 2 was perhaps faster than that of Kashin. However, in another experiment where styles were cut off at definite intervals after mixpollinations, the results of studies in their subsequent progenies revealed no significant differences among the frequencies of inter-varietal hybrids in the tested cases (Table 2) . In yet another experiment with dual pollinations, the frequncies of intervarietal hydrids in the progenies of some plants of Kashin, contrary to expectations, were found to be almost constant (Fig. 1).