Seed production of bush snap beans (Phaseolus vulgaris L.) in unheated greenhouses following tomato cultivation in relation to the duration of irrigation at various fertilizer levels
Bush snap beans (Phaseolus vulgaris L.) cv. Larma and Montano were grown in the soil of two unheated glasshouses after tomato cultivation, and irrigated with the following nutrient media: (1) control of water only (0:0), (2) N:K (1:1), (3) N:K (1:3) and (4) N:K (3:1). Each of these irrigation treatments was applied twice a week from planting until four stages of plant growth: (1) until the start of flowering, 17 days after transplanting, (2) until 50% of the pods had filled, 28 days after transplanting, (3) until the first-formed pods were dry, 58 days after transplanting, and (4) until harvest, 88 days after transplanting. The results of this study showed that due to a high concentration of N and K in the soil from the preceding crop, plants that were irrigated solely with water (0:0) had a higher number of pods, seed weight, seed size and dry weight per plant than those of the three fertilizer treatments. Irrigation of plants after 50% of the pods had filled (28 days after transplanting) did not increase seed yield. This means that when beans are grown for seed after a fertilizer-demanding crop (e.g. tomato) and irrigation is stopped at 50% pod-filling, significant savings of water and fertilizer may be achieved. Continuation of irrigation and nutrient application until the fourth stage (i.e. 88 days after transplanting) would seem to result in significant water and nutrient waste leading to soil and underground contamination as well as a waste of energy.