Rescue of Soybean Flowers Destined to Abscise
Many soybean [Glycine max (L.) Merr.] flowers abscise and do not contribute to yield. The objectives of this research were to determine the effectiveness of a proximal pod removal treatment designed to rescue soybean flowers destined to abscise and to determine if the effectiveness of this treatment changes with time after anthesis. ‘Williams 82’ soybean was grown in the field during 1985 and 1986. Racemes were tagged at anthesis of the flower at Position 1 (positions numbered along rachis from proximal to distal ends). Proximal pods (Positions 1 and 2) were removed from one half of the tagged racemes at varying times after anthesis. In 1985, this action resulted in nine treatments (4,6,7,8, 11, 12, 13, 15, and 16 d between anthesis and proximal pod removal). In 1986, five treatments of 3, 5, 7, 9, and 11 d were used. Abscission percentages for the untreated racemes, averaged over the 2 yr, were 5, 12, 30, and 59% for Positions 1, 2, 3, and 4, respectively. Average abscission percentages (all day intervals and both years) for Position 3 were 30% with proximal pods present and 7% with proximal pods removed. For Position 4, average abscission percentages were 59% with proximal pods present and 9% with proximal pods removed. Average seed weights pod−1 (all day intervals and both years) for Position 3 were 0.377 g with proximal pods present and 0.527 g with proximal pods removed. For Position 4, the average seed weights pod−1 were 0.540 g with proximal pods present and 0.610 g with proximal pods removed. In 1986, proximal pod removal increased number of seeds pod−1. Effectiveness of the proximal pod removal treatment in reducing abscission probability and increasing total seed weight pod−1 was not related to length of time between anthesis and proximal pod removal. The fate of pods destined to abscise can be reversed up to at least 11 d after anthesis.