It is known that the rate of photosynthesis is determined by the assimilated surface area of leaves which, in its turn, depends on growing conditions. The question about the peculiarities of mineral nutrition of sunflower is important to define a theoretical foundation for the use of fertilizers and drugs of combined action. In the modern technologies rooting out is one of the best methods of fertilizer application. The article presents the results of the influence of root out nutrition of sunflower plants by the drug Khelafit Comby. It is established its stimulating effect to prolong the photosynthetic activity, a decrease of empty grains in baskets and an increase of seed weight from one basket, which leads to the increase in the level of sunflower yield by 0,27 t/ha.
At the beginning of the growing season the results showed that reducing the size of the assimilation apparatus has a similar characters in most cases, but in 15 – 20 days after the observations it was noticed a significant difference. So, by the first control on September 5 it was only 22% of the active leaf surface and after two times treatment by the drug Khelafit Comby this figure was twice as much. During the control testing of the sunflower on September 15 almost all the leaves of the plants were not capable for photosynthetic activity and with the using Khelafit Comby 16% of the area of the entire leaf surface was functional.
The treatment for sunflower plants by the drug Khelafit Comby gave the opportunity to reduce the emptiness of grains in baskets for 7 – 10% and to increase the seed weight from one basket by 8,8 – 15,4%. The result of this impact was a steady increase of the sunflower yield. Due to the low cost of this drug it can significantly increase the economic indicators of the sunflower growing.
Further use of the research results will provide the opportunity for multifaceted study and determine the impact of the new khelafit fertilizers, biological fungicides and plant growth stimulants and their further application with the technology elements improvement of sunflower cultivation in agro-climatic conditions of the Steppe zone of Ukraine.