Influence of low light intensity on growth and productivity in relation to population pressure and varietal reaction in irrigated rice (Oryza sativa L.)

Studies on shading effect (40-50% of natural light) were conducted with Sona and RP 4-14 under field conditions at different growth phases with two densities of population (50 and 100 hills/m²) and assessment of varieties (6 of early duration and 9 of medium duration group) was done. Although yield losses were maximum at reproductive and ripening phases, higher population density compensated the loss in some measure. Varietal responses differed for total dry matter, panicle number and grain yield under shade suggesting the need for further screening of varieties to identify plants with relative tolerance to reduced light conditions. Slow complex heritable approach was considered desirable in breeding programmes to synthesise plants to suit to low light intensity stress situations.