STUDIES ON THE POD SHATTERING IN SOYBEAN

Pod shattering reduces grain yield and is hence very important in the breeding of soybean. This study is aimed to establish an effective method for measuring the percentage of pod shattering for the purpose of mass selection. Two hundred and sixteen soybean varieties were planted in September of 1984 and pods after 20 days of harvest were treated by oven-drying at 60-degrees-C for measurement of shattering percentages. Two groups of shattering type were classified from the tested varieties, one with shattering percentage over 90% after oven-drying for 4 hours and the other with shattering percentage lower than 20% after drying for 10 hours. Representative varieties of the two types of soybean were then planted in March and July of 1985 for further experiments. The results were summarized as follows. Shattering percentage increased as pod maturity progressed and the moisture content of pod decreased. When soybean plants were left in the field for 28 days after normal maturity, most varieties of the low-shattering gorup exhbited no pod shattering, while the percentages of all varieties of the high-shattering group were over 43%. These results were closely correlated with the results of oven-drying at 60-degrees-C is an effective method for measuring pod shattering in soybean.