Comparison of photosynthetic indicators in leaves of sorghum with different grains starch contents after anthesis.

Sorghum restorers with different starch content levels were planted under the same environmental condition.After anthesis,the net photosynthetic rate in sorghum leaves was measured using Li-6400 portable photosynthesis system;the chlorophyll content and specific leaf weight in leaves were measured with regular method.The starch content in grains of sorghum were measured with GB5006-85 method.The results were as follows:on 28 d after anthesis,the chlorophyll content and specific leaf weight in leaves of high starch content sorghum were significantly higher than those of low starch content sorghum;the starch content in sorghum grains had a significantly positive correlation with the chlorophyll content and specific leaf weight in leaves of sorghum.On 14 d after anthesis,the net photosynthetic rate in leaves of high starch content sorghum was significantly higher than that of low starch content sorghum;the starch content in sorghum grains had a significantly positive correlation with the net photosynthetic rate.With the use of portable photosynthesis system,the net photosynthetic rate could be measured quickly and precisely,the net photosynthetic rate could be effectively used as a selection index for high starch content sorghum breeding.