Interaction Effect of Growth Regulators and Irrigation Schedules on Growth and Yield of French Beans in Kiambu County, Kenya

Inadequate and unreliable rainfall distribution in Kenya has affected negatively agricultural yields and family incomes. Integration of growth regulators can stimulate favorable crop growth under limited moisture, but there has been scarce research and documentation on them. Therefore the gibberellic acid and cytokine in effect on French beans growth and yield was assessed under different irrigation schedules at Kenyatta University Field Station in two seasons of 2014/2015. The experiment was set in Randomized Complete Block Design (RCBD) in split-plot arrangement with three levels of each hormone as sub-plots and three watering regimes as main plots and replicated three times. The results showed that optimum rates of growth regulators positively improved the growth and yield components of French beans. Significant differences between the treatments at P<0.05 were observed on the leaf area where the 0.50ml level of cytokine in had the greatest at week nine after sowing with 1335.3 cm2 during the first season and 1343.1 cm2 during the second season at a daily watering regime. Consequently, this led to significantly the highest pod fresh yield of the French beans with 58.97 g/plant and 84.99 g/plant for the first and second seasons respectively at week nine in the same treatment combination. The highest level of gibberellic acid (0.675 ml) led to the lowest fresh pod yields at week six, seven and eight, while the highest rate of cytokine in (0.750 ml) had the least fresh pod yield at week nine showing the negative effect of excessive application of growth regulators on French beans, yield components. The study, therefore, recommends an application of cytokinin at a rate of 0.50ml to achieve maximum yields in French beans.