抄録
The seed of milk vetch which is green-manure and forage legume of the most importance in Japan, contains the hard seed of about 20 % in their seed lots. Although it is known that the hard seed content is influenced by the environmental factors such as drying condition during the seed storage, weather, soil condition and nutrient element, but it is not clear why some are of hardness and others are not in the seeds produced on the same plant. The authers have investigated on the hard seed content of milk vetch hand harvested in relation to its blooming time and maturing period, growing the plant in pots in green house and out-doors. The number of days for the maturing of milk vetch seeds produced in early blooming pods is larger than that in late blooming pods in the same plant (Table 1 & Fig. 1). It was found that the hard seed content of milk vetch is higher in green house plot than that of out-doors plot, though its differences among individuals are existing (Table 2 & Fig. 4). In the seeds produced in early blooming and maturing pods, the germination speed is rapid and the hard seed content, a portion of seeds remained hard at the end of the test period from 11 th October, 1957 to 10 th February, 1958 at room temperature, is higher than that of late blooming and maturing pods. This tendency is remarkable in the seeds of green house plot than that of out-doors plot, that is, in out-doors plot the hard seed content of the earliest blooming and maturing seeds is about 28 % and that of the latest blooming and maturing seeds is about 8 %, while in green house plot the hard seed content is about 50 % and about 6 % in the seeds of the earliest and the latest blooming and maturing ones respectively (Table 2 & Figs. 2, 3 & 4). The number of pods and seeds per head in green house plot is large in the early blooming and maturing head, and decreases accordingly to the lateness of the blooming and maturing time, but in out-doors plot the number of pods and seeds per head is large at the maturing time III and IV than II, and then decreases accordingly to the lateness (Figs. 5 & 6). No difference is found in the weight of 1000 seeds in both green house and out-doors plot in earlier blooming and maturing seeds, but the weight decreases gradually in later blooming and maturing seeds (Fig. 7). From the experimental result mentioned above, although the hard seed of milk vetch is influenced by the environmental factors such as temperature and drying condition during and after the maturing of seeds, it is found that the hard seed content of milk vetch is influenced by the time of blooming and maturing as well as the number of pods and seeds and the weight of 1000 seeds.
