Studies on the Mechanism of Seedcoat Cracking and its Prevention in Soybeans : I. Regional and varietal difference in cracking of seedcoat in soybeans

[摘要] The type of cracking of seedcoat and the percentage of seeds having cracked seedcoats were investigated on the seeds of 104 cultivars of soybean which were collected from 34 prefectures all over Japan, and also on the seeds of 53 cultivars which were grown in our experimental farm, in order to clarify the actual condition of cracking of seedcoat in soybeans. 1. The type of cracking of seedcoat was classified into three types, i.e. spot type, line type and irregular type (Fig. 1). Fifty three cultivars out of 104 cultivars used in this investigation were spot type, 27 cultivars were irregular type, and only 18 cultivars were line type (Table 1). 2. A marked difference was found among cultivars in the percentage of seeds having cracked seedcoat, and the mean value of the percentage in 104 cultivars was 25.0±24.8 per cent, which ranges from 0 per cent at the minimum to 100 per cent at the maximum (Fig. 3). The cultivars which has no cracked seedcoat were only six, three in Hokkaido and each one in Iwate, Niigata and Nagasaki prefectures, respectively. The cultivars which has below 10 per cent of seeds having cracked seedcoats were 38, and the cultivars which has above 50 per cent of seeds having cracked seedcoats were 15 out of 104 cultivars. 3. Regional difference was also found in the percentage of seeds having cracked seedcoats. It was the lowest in the seeds harvested in Hokkaido with 3.7 per cent, and was lower in the seeds harvested in Kanto-Tosan and Kyushu with 14.6 per cent and 19.2 per cent, respectively. On the other hand, it was the highest in the seeds harvested in Chugoku with 43.4 per cent and was higher in Tokai, Hokuriku and Shikoku with 41.6 per cent, 35.4 per cent and 33.3 per cent, respectively (Table 1). 4. In the same cultivars, the percentage of seeds having cracked seedcoats also differed in the regions where the seeds were harvested (Table 2). 5. In the seeds of cultivars harvested in the experimental farm at Kakamigahara, it was found that the percentage of seeds having cracked seedcoats increased in the seeds of cultivars collected from the regions showing lower percentage of seeds having cracked seedcoats, and the percentage of seeds having cracked seedcoats and the weight of 100 seeds decreased in the seeds of cultivars collected from the regions showing higher percentage of seeds having cracked seedcoats (Table 3). 6. No correlation was fonud between the percentage of seeds having cracked seedcoats and the percentage of seed germination, and the weight of 100 seeds. But negative correlation was found between the percentage of seeds having cracked seedcoats and the thickness of seedcoats, and the percentage of seedcoats (Table 4 and Fig. 4).

[学科分类] 农业科学（综合）