Influence of cultivation technology elements on sunflower crops photosynthetic and seed productivity
The aim of the research is to explore the effect of presowing seed processing as well as single and double spraying sunflower crops with "Vermimag" and "Vermiodis" growth regulator on sunflower photosynthetic and seed productivity in the conditions of the Western forest-steppe. The study was performed in the 2013-2016 in the experimental field of the branch of the Department of crop production, breeding and seed production of Podilskyi state agrarian-technical University and in the fields of PF "Bogdan" located in Snyatyn district of Ivano-Frankivsk region, the Western part of the Forest-Steppe. The soil on the experimental plot is turf, podzolized medium-sandy. The seeds of hybrids NK Brio, NK Rocki were sown at the rate of 70 thousand/ha of germinated seeds. The total area of plot is 70 m<sup>2</sup>, accounting area - 50 m<sup>2</sup>. The plots location is systematical, fourfold repetition. The studies were performed according to current standard techniques. The agricultural cultivation of the crop is common for the conditions of the Western Forest-Steppe. The application of "Vermimag" and "Vermiodis" growth regulators for seeds presowing treatment as well as single and double spraying NK Brio, NK Rocki hybrids of sunflower crops had a positive impact on the growth and development of plants during the vegetation period. We found out that application of "Vermimag" and "Vermiodis" growth regulators for presowing treatment of NK Brio, NK Rocki hybrids of sunflower seeds provided the increase of the seeds energy of germination by 2.6 and 4.2 %, laboratory germination - by 2.2 and 3.6 % relative to the control. Germination of the NK Brio hybrid was 2.6-4.9 % higher, and the survival rate was 1.5-3.0 % higher than in the control; for NK Rocki hybrid these figure were, respectively, by 3.3-3.6 % and 2.3- 5.7 % higher than in the control. It is established that "Vermimag" and "Vermiodis growth regulators " affects the sixe of leaf surface and photosynthetic activity of agrocenosis of the studied sunflower hybrids and the crop productivity. The highest leaf surface growth rate of 54.8 thousand m<sup>2</sup>/ha, or 14.7 thousand m<sup>2</sup>/ha higher than in the control were noted in the flowering stage under presowing treatment of hybrid NK Brio seeds with "Vermiodis" growth regulator in a dose of 4 l/t and under double spraying of crops during vegetation with 4 l/ha of "Vermiodis" growth regulator. This variant has the highest accumulation of dry substances of 8.98 t/ha, which is 1,54 t/ha more compared with the control and photosynthetic capacity of crops reached 840 million m2/ha days, or 0,662 million m2/ha days compared to the control. The results show that, on average, for 4 years in the variants with the combined seeds pre-treatment and hybrid NK Brio sunflower crops single spraying with "Vermiodis" growth regulator the yield was 9.7-12.6 %, and 14,2-16,4 % higher under double spraying compared to the control. In the variant, where the seeds were treated with growth regulator "Vermiodis" (4 l/t) and were sprayed twice at a dose of 4 l/ha, the average for the study years, the yield of sunflower hybrid NK Brio was 3.7 t/ha, 0.52 t/ha more than in the control. The highest yield was obtained in 2016 - 4.02 t/ha, or 0.65 t/ha more than in the control, and the smallest of 3.53-3.40 t/ha under less favorable climatic conditions in 2014-2015. Consequently, high yields of NK Brio and NC Rocky sunflower hybrids - 3.54-3.70 t/ha can be obtained in the Western Forest-Steppe under pre-sowing seed treatment and the crops single and double spraying with "Vermimag" or "Vermiodis" growth regulators during vegetation.