PHOTOSYNTHETIC ACTIVITY OF ALFALFA IN DEPENDENCE OF MINERAL NUTRITION

The tests were performed in field conditions. The test variants were different quantities of NPK mineral fertilizens. The following conclusions can be drawn: The chlorophyll content was higher at the stage of budding in some nutrition variants; in another, it was higher at the stage of flowering. The carotenoid content was higher at the stage of budding in all the variants. This confirms the statament that it is justifiable to mow alfalfa at these stages of development because the it has an increased biological alue. The assimilation area size grows significantly with the application of increased quantities of NPK ,mineral and organic fertilizers at both stages. The volume of photosynthetic productivity (net assimilation) increases with the application of increased quantities of fertilizers.Also, an increase of biological yield was registered. In most cases there is a high positive correlation between the two indicators of photosynthetic productivity, the assimilation, area size and biological yield. The intensity of photosynthesis depends on the NPK uptake; on the other hand, the sunlight absorbed in the process of photosynthesis is necessary for the absorption of these elements from the soil