Effects of low light intensity on different growth phases in rice (Oryza sativa L.)

Abstract

The effect of low light intensity (40 to 50% of natural light) at different growth stages and subsequent exposure to natural light was assessed on growth and productivity in 2 genotypes during kharif and 3 during rabi under 2 N levels. The dry matter accumulation was affected under shading at all stages, which was critical from primordial initiation (PI) onwards. The expression of panicle number appears to be a function of the environment particularly the light intensity within 26 to 39°C range of mean maximum temperatures. The grains/panicle were also reduced by shading from PI onwards. The yields were progressively reduced with low light intensity appearing in succession at different growth stages, particularly more critical during ripening phase. It was considered that low light intensity during monsoon season was an important constraint for higher productivity since yields as low as 3.2 to 4.4 tons/ha were recorded with varieties which yielded 8 to 10 tons/ha under high light intensity conditions as in rabi. re]19751014