Yuichi Nagaya

Pod Dehiscence in Relation to Chemical Components of Pod Shell in Soybean

Abstract The relationship between chemical components of pod shell and pod dehiscence was investigated using 25 soybean cultivars; 16 with easily dehiscing pods (susceptible cultivars) and 9 with hardly dehiscing pods (resistant cultivars). After air-drying for about three weeks, the pod shells were ground and analyzed for the contents of neutral detergent fiber (NDF), acid detergent fiber (ADF), acid detergent lignin (ADL), hemi-cellulose (HCe), cellulose (Ce), uronic acid and calcium. The correlation of the contents of chemical components with the percentage of pod dehiscence (%PD) was examined by principal component analysis. The first principal ingredient score was given by the formula; score = – 0.421[ADF] – 0.038[ADL] + 0.821[HCe] – 0.382[Ce] + 20.556, where, [ADF], [ADL], [HCe] and [Ce] are percentage of each component in dried pod shell. This score gave an eigenvalue of 30.2 and contribution rate of 97.1%, and the score was higher in the susceptible cultivars than in the resistant cultivars on the average. The multiple regression analysis of the relationship between %PD and the content of chemical components also showed that %PD was best predicted by the regression equation with two chemical components, [HCe] and [Ce]. Water retention capacity and cellulose crystallinity of the pod shell were less different between the susceptible and resistant cultivars. The results in this study suggested that the chemical analysis of dry pod shell may provide useful information on breeding and selection of the resistant cultivars.

Pod Dehiscence in Relation to Pod Position and Moisture Content in Soybean

Abstract The relationship between pod dehiscence and the position and moisture content of pods was examined in two soybean cultivars, Fukuyutaka and Keito-daizu. The frequency of pod dehiscence at different parts of the stem was assessed by the strain-gauge method. Pods of the two cultivars were classifi ed into indehiscent, dehiscent (dehisced by the strain-gauge method) and naturally dehiscent pods. The moisture content of pods was measured after drying in a hot-air oven at 105±1°C for 24 hrs. In both Fukuyutaka and Keito-daizu, the pods at maturity were not dehisced at any part of the stem due to the high moisture content of pods. After maturity, the frequency of pod dehiscence at the upper part of the stem increased as the moisture content of pods decreased in both Fukuyutaka and Keito-daizu. A similar tendency was observed in both the fi eld and the pot experiments. The frequency of pod dehiscence was higher at the upper part of the stem and increased as the moisture content of pods decreased.