The Effects of Water Stress and Planting Date on Yield and Yield Components of Pinto Bean (Phaseolus vulgaris)

A study was conducted to determine irrigation scheduling of pinto bean and to evaluate the effect of its planting date. A split-plot with complete randomized block design with four replications was used at Isfahan University of Technology Research Station in Shervedan-Falavarjan, The main plots were three irrigation regimes of T1 to T3 (irrigation after 50±3, 70±3 and 90±3 mm evaporation from class A pan, respectively) and the sub-plots were two planting dates of May 28 and June 28. The results showed that delayed planting from May to June caused earlier flowering, physiological maturity and reduction of 29.6% in grain yield. Grain yield in T1 to T3 treatments were 3585.1, 3510.5 and 1925.8 kg/ha, respectively. The difference between grain yields of T1 and T2 with T3 treatments were significant at 1% probability level. Biological yields at May 28 and June 28 planting dates were 8257.1 and 5535 kg/ha, respectively, which were significantly different. There was no significant difference between biological yields of T1 and T2 treatments. Number of pods per square meter was the most important component of grain yield and 85% of grain yield difference was due to this part. Harvest index was affected by irrigation treatment and planting date. Mean harvest indices for T1 to T3 treatments were 45.5, 46.1 and 37%, respectively, and 42.8% and 44.9% for the two planting dates. Water use efficiencies for grain yield in T1 to T3 treatments were 0.557, 0.556 and 0.329 kg/m3, respectively. Generally, treatment T2 was shown to be the best irrigation regime.