Morphblogical and Physiological Studies on Occurrence of Abortive Seeds in Leguminous Forage Crops : IV. Occurrence of abortive seeds and their position in pod of common vetch

Abstract

This paper deals with the results of studies on occurrence of abortive seeds and their position in pod of common vetch, Vicia sativa L. When classified with respect to the ovule number in pod, 85.5 percent of 380 pods examined were 7-and 8-ovuled pods as shown in Fig. 1. In this experiment, therefore, 7- and 8-ovuled pods were used as materials. The results obtained are sumrnarized as follows. 1) The occurrence of abortive seeds was least frequent at the medium position in a pod and increased toward both the basal and the apical ends, with a more marked tendency to abort toward the basal one as shown in Fig.2 and 3. 2) By examination of the dry weight of each 1081 abortive seeds which were taken out from 380 pods of 10 plants at the matured stage, in comparison with the average dry weight of the normally growing ovules collected on every 5th day after flowering, it was presumed that the majority of abortive seeds would occur within 10 days after flowering as shown in Table.1 and Fig.4. 3) The state of fertilization was observed, using 7-ovuled ovaries at 2nd day after flowering. 97.7 percent of the ovules observed were normally functional. A few non-fertilized ovules were found out, but they were of rather less importance in occurrence of abortive seeds, because the frequency of them was merely less than 3 percent as shown in Table 2. Thus, it was confirmed that the majority of abortive seeds occurred as a result of collapse of fertilized ovules. 4) When observed the embryonal development of undeveloped fertilized ovules, in comparison with normally developing ones, it was confirmed that in the majority of them their normal embryonal development were arrested before 10th day after flowering as shown in Fig.5. 5) It appears that the difference in occurrence of abortive seeds found out between at both basal and apical positions and at medium one may be caused by their competition on absorbing water and nutrients.