Studies on the Seed Production of Soybean : 5. Varietal differences in photosynthetic rate of soybean.

Abstract

This study was carried out to verify the varietal difference in the activity of photosynthesis per unit of leaf area and the stability against environmental conditions. For this study, the leaves adhering to the soybean plants were used as sample and the activity of photosynthesis was measured at the stage when the leaves showed the maximum photosynthetic rate, in the laboratory under the conditions of the saturated light intensity at leaf temperature of 26 to 29°C, with ordinary atomospheric concentration of CO2. The results are as follows: 1. Coefficient of variation in photosynthesis among plants of different varieties varied as much as 5 to 25 percent. 2. Variations in photosynthetic rates among varieties were less than some ± 20 percent as against the aggregate average rate of all the different varieties. 3. Absolute vaule of photosynthesis varied with the environmental conditions, but it was verified that the varieties of high activity of photosynthesis indicated high rates of photosynthesis without exception, when all the different varieties were tested in comparison. 4. Varietal difference being found in the photosynthetic rate according to different varieties as stated above, photosynthetic rate can be taken as a target characteristic for selection in the breeding process.