The intensity of photosynthesis and transpiration of leaves in plants of Glycine max (L.) Merr.

The article presents the results of field and vegetation experiments on the study of the relationship of photosynthetic and transpiration activity of the leaves of soybean plants. The correlation coefficient between these two indicators was quite reliable and averaged over the growing season +0.91. The closest relationship observed in the phase of 5-6 true leaves and in the period of mass ripening of seeds. It is established that the intensity of photosynthesis and transpiration of leaves of the culture increases sharply in the transition of plants to the generative period of development, reaching a maximum in the phase of mass fruit formation, when the demand for assimilate main intragenomic centers (beans) begins to grow actively. The intensity of photosynthesis of leaves in the period of development of the plant reached 17, and 21 µmol CO2/m2s, and the intensity of transpiration was 8.22 mmol H2O/m2c. The highest photosynthetic and transpiration activity was observed primarily in the upper leaves and lower leaves had the lowest activity. On the 5th node from the bottom, the intensity of photosynthesis was 3.4 times, and the intensity of transpiration 2.2 times less compared to the assimilating leaves, located in generative parts of plants at the 3-4 node from the top. Most actively functioning leaves in the daytime from 11:30 to 13:00. The intensity of photosynthesis in this period was 11 to 13 µmol CO2/m2s, and the intensity of transpiration of 6.49-of 7.64, which was 61.2 and 34.5% higher than in the morning (from 8:00 to 9:00), 24 and 30.4% in the afternoon.