Green Global
Foundation   Journal
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EFFECT OF HIGH TEMPERATURE AT DIFFERENT GROWTH STAGES ON PHOTOSYNTHESIS, CHLOROPHYLL STABILITY, GRAIN GROWTH AND YIELD OF AMAN RICE VARIETIES (Pages : 19 - 23)

Changing climate rises air temperature due to increasing concentration of CO2 and other atmospheric greenhouse gases. A pot experiment was conducted with five rice varieties viz., Binadhan-4, Binadhan-7, Binadhan-11, Binadhan-12 and Binasail in the plant growth chamber at Bangladesh Institute of Nuclear Agriculture, Mymensingh to assess the effects of high temperature (36°C) at different growth stages on photosynthesis, chlorophyll stability, grain growth and yield and to find out the variety tolerant to high temperature. Five temperature treatments viz., Ambient, 36°C at tillering stage, 36°C at panicle initiation stage, 36°C at booting stage, and 36°C at flowering stage were imposed for seven days at each respective growth stage and then plants were allowed to grow at ambient temperature up to maturity. For grain growth studies two temperature treatments, Ambient and 30oC were applied from fertilization to grain maturity. Ten grains were harvested from selected panicles of three plants of each treatment at 3 days interval starting from fertilization to maturity. During grain growth photosynthetic rate, chlorophyll content of flag leaf and dry weights of those grains were recorded. Photosynthetic rate, chlorophyll content of flag leaf, grain dry matter accumulation, plant height, number of total tillers and effective tillers plant-1, panicle length, filled and unfilled grains panicle-1, panicle length, 1000-grain weight and grain yield were significantly affected by temperature treatments. However, high temperature (36°C) at flowering stage affected grain yield more compared to other temperature treatments and found to be more sensitive. Grain dry matter accumulation gradually increased but photosynthetic rate in flag leaf decreased from fertilization to maturity. The rice varieties achieved physiological maturity at 24 days and chlorophyll content in flag leaves was stable up to 16 days after anthesis. The highest photosynthetic rate, grain dry matter accumulation and grain yield were found in Binadhan-7 under the treatments. So, Binadhan-7 seems to be tolerant to high temperature compared to other varieties. Download