INFLUENCE OF INTENSITY OF LIGHT ON ACTIVITY OF GAS EXCHANGE OF LEAVES AND STIPULES AT DRY PEAS

In field conditions, the influence of illumination on the rate of photosynthesis of the photosensitive surface of plants in 15 varieties of dry peas was studied for intact plants. It has been confirmed that peas are a very demanding crop for insolation conditions. With a decrease in illumination from 1000 to 300 μmol / m2s, the decrease in the rate of photosynthesis of plant leaves was 43%, and with increasing light from 1000 to 1700 μmol / m2s, the value of this indicator increased by 22%. The most responsive to the increase in illumination is the tendrils: the rate of photosynthesis increased 4,4 times, while in leaflets – 1,6 times, and stipules – 1,9 times. At the genotypic level, this is manifested in the fact that the transformation of leaflets into the tendrils, as a result of the action of the recessive gene af, leads to an increase in the photophilicity of plants. In varieties with a tendriling leaf shape, with an increase in illumination from 300 to 1700 μmol / m2s, the rate of photosynthesis of stipules increased almost 2-fold - from 6,5 to 12,8 μmol CO2 / m2s, whereas in varieties with a traditional plant morphotype, with the same lighting conditions, the rate of photosynthesis increased by only 79%, and in the morphotype "chameleon" - 62%. In this case, the nature of the dynamics of the rate of photosynthesis of the leaves did not change significantly when the lighting conditions changed, and the differences between the morphotypes were noted only in terms of the absolute value of its manifestation, that is, according to the reaction rate. With an increase in insolation from 300 to 1000 μmol / m2s, the rate of photosynthesis in leaf varieties increased 1,8-fold, tendriling – 1,9 times, and chameleon – 2-fold. With further increase in illumination, the rate of photosynthesis in the leafy morphotype was decreased by 11%, in the chameleon by 19%, while in the varieties with the tendriling form of the leaf, the value of this indicator continued to grow - on average by 10%. That is, light saturation in genotypes of peas with a traditional morphotype occurs at a lower insolation, in comparison with tendriling varieties. This confirms the conclusion that the photosynthetic apparatus of the tendriling varieties is more responsive to an increase in intensity of light than in ordinary leaf varieties.