Premature abscission of phaseolus bean pods: The role of plant growth substances

Abstract

A 2x5 factorial experiment was conducted to study the effect of concentrations of 6-benzyladenine (BA) applied at five post anthesis stages on pod development of Phaseolus vulgaris L., especially in relation to abscission. The terminal raceme of a five-node cultivar (cv 344) was used for the study. There were no significant differences between treated plants and controls with respect to numbers of flowers that opened and those that developed into pods. BA not only delayed the onset of pod abscission but also slowed it down, giving it a protracted duration. The cytokinin was effective in reducing pod abscission when application commenced between anthesis and six days after anthesis. BA affected pod retention on the distal triad of the terminal raceme where normally all pods drop off. All treated racemes had significantly (P <0.01) more seeds at the time of harvest than controls, the overall increase in seed number being due to increased seed number in pods borne on the medial and distal triads of the raceme. BA increased pod retention and seed yield without any significantly effect on the number of pods on other nodes, and dry matter of the stem and leaves. When BA was applied beginning at the time of anthesis and using the higher dosage (400 ppm), normally abscising fruits on the distal triad were retained with full seed development.