Effects of Plant Densities under Two Irrigation Regimes on Leaf Water Potential, Leaf Diffusive Resistance during Drought Stress Period and Grain Yield of Grain Sorghum

Abstract

This research was carried out to determine the effect of plant densities on leaf water potential, leaf diffusive resistance during drought stress period and grain yield of grain sorghum, and also to confirm the effect of drought at three growth stages on yield as done in previous years. The results obtaincd are as follows: No consistant relationship was recognized between plant densities and leaf water potential, leaf diffusive resistance in irrigated treatment. However, high plant densities of non-irrigated treatment during drought stress period showed lower leaf water potentials and higher leaf diffusive resistances, and suffered severer water stress (Fig. 1, 2). Total evapotranspiration (consumptive water use) in both treatments during drought stress pcriod increased with increased plant densities (Fig. 3). Grain yields were the highest in 250, 000 plants density and the lowest in 400, 000 plants density per ha in irrigated treatment and in non-irrigated treatment increased as plant densities decreased. However, stover yields were higher in higher plant densities in both treatments. The effect of drought at three growth stages was the severest at boot stage and also showed the highest reduction rates of grain yields at the same stage (Table 2).