Compensation of Reduced Mung Bean (Vigna radiata) Biomass due to Irrigation with Different Amounts of Zeolite Application

To evaluate compensation mechanism of biological yield reduction due to irrigation with zeolite application in mung bean (Vigna radiata L.), a factorial experiment was conducted based on randomized complete block design in Research Farm of Urmia University with three replications in 2011. Treatments were zeolite (0, 10, 20 and 30 t ha^-1) and water deficit stress (normal irrigation, irrigation disruption at flowering initiation, full flowering, pod initiation and grain filling). Results showed the significant effects of zeolite on the stem width, leaf weight per plant, total soluble carbohydrates, and significant effect of irrigation disruption on the stem width, plant height, leaf weight per plant, and harvest index. Interaction effect between irrigation and zeolite on the biological yield, the number of leaf per plant, proline and stem weight was significant, too. The plants without irrigation disruption were shown the maximum biological yield (14.51 g plant^-1) and stem weight (3.53 g plant^-1) and minimum leaf proline (0.15 mg g^-1 DW), but irrigation disruption at flowering showed the minimum biological yield (2.15 g plant^-1) and stem weight (0.56 g plant^-1), and maximum leaf proline content (0.58 mg g^-1 DW). Similar trend in plant height, leaf weight and number per plant with biomass show that leaves are important part of plant biological function. The accumulation of total soluble carbohydrates was different from proline, so the highest (267.8 mg g^-1 DW) and lowest (175.4 mg g^-1 DW) soluble sugar were respectively obtained from 0 and 10 t ha^-1 zeolite application.