Abstract
Drought stress and plant densities influence plant water relations and growth processes directly and crop performance indirectly. Growth of mung bean (Vigna radiata L. Wilczek) subjected to irrigation schedules (IS), plant densities (PD), and moisture regimes (MR) were studied in an upland silty clay loam rice soil (Tropudalf). Leaf area index (LAI), specific leaf weight (SLW), crop growth rate (CGR), per cent ground cover, dry matter (DM), leaf water potential (?L), osmotic potential (?? ) and root length density (RLD) were measured. The LAI and DM decreased with increasing soil moisture deficits while SLW, ?L, ?? and RLD increased. The LAI, SWL and RLD increased at high planting densities. Effect of IS, PD and MR on per cent ground cover was significant. Irrigation schedules had less effect on ?L, and PD affected it significantly in 1987. The effect of IS, PD and MR on ??, was not significant at all growth stages. Higher RLD was found in higher PD in both years. Per cent roots were higher in dry MR compared to wet MR in the deeper layers (60-100 cm). These findings indicate that a decrease in LAI and an increase in SLW, ?L, ?? and RLD were drought-avoidance mechanisms which help the survival of the crops during the reproductive stage for seed development when the moisture has been depleted in rice soils.
