Effect of benzyladenine and gibberellins on yield components, yield and the postharvest shelf life of french beans (Phaseolus vulgaris L.)

Abstract

The objective of this study was to investigate the effect of exogenous gibberellins (G~+7) and Accel on yield components, yield and postharvest shelf life of French beans. The plants were sprayed to run-off with four concentrations ofGA4+7 (1.25, 2.50, 3.75 or 5.0 mg/litre), Accel (12.5,,25.0, 37.5 or 50.0 mg/litre) and a control (plain water) just before flowering. Both G~+7 and Accel significantly increased the pod number, fresh pod yield, pod length and water content of the pods. Independently BA did not have any significant effect on pod length, pod number per plant or fresh pod yield, suggesting that the effect of Accel on pod length, pod number, fresh pod yield and water content of the pods was a GA4+7 effect rather than a BA effect. Accel in experiment 1 andG'A4+7 in experiment 2 reduced wilting of the pods. Both Accel and G~+7 reduced the rate of post storage water loss by the pods; thus slowing down wilting which is characteristic of fresh produce such as French beans. Accel increased the chlorophyll content of French bean pods and leaves and enhanced chlorophyll retention by the pods after storage thereby slowing down yellowing or senescence of the pods. Gibberellins (G~+7) did not have a significant effect on the chlorophyll content of the leaves and the pods, hence the increase of both leaf and pod chlorophyll content was attributed to BA. Neither GA4+7 nor accel affected the rate of water loss by the pods after cold storage and none of the two plant growth regulators imparted chilling-hardiness to French bean pods. The author concludes that Accel and GA4+7 at lower concentrations increased the yield, quality and postharvest shelf life of French bean pods. This suggests that Accel and G~+7 have the potential to be used to improve the agronomy of French beans in Kenya.