Effect of Low Light Stress at Different Phases of Grain Filling on Rice Seed Germination and Seed Vigour

Abstract

The different phases of grain filling on rice (Oryza sativa L.) seed germination and seed vigour can be affected by environmental factors at the different growth stages. The study was attempted to identify the effects of shading stress on grain filling on rice seed germination and seed vigour. The shading type treatments were applied at 0.60 and 0.90  on the hybrid and inbred respectively compared to the control, The results indicated that, the hybrid varieties have a higher potential in germination index and vigor index, compared to the inbred varieties were interacted better in the grain filling rate, germination rate and grain weight. Although, it resulted the shading 0.90 showed higher significant negative effects in comparison with the shading at 0.60 and no shading. The maximal fluorescence intensity and variable fluorescence of the studied genotypes significantly increased under shading stress. The ratio of maximum quantum yields under shading treatments 0.60 and .090 decreased by 1.34% and 2.79% compared to the no shading respectively, and maximum primary yield of photochemistry (PSII) increased, whereas, Non photochemical quenching (qN) value decreased comparing with the control (no shading treatment). Therefore, the results indicated a lower significant difference effects on protein, soluble sugar, amylose content and starch content at each stage were lower contents in comparison to that of the control.