Features of sunflower bioproductivity in influence zone of forest belts
Sunflower occupies considerable acreages and is one of the principle species for vegetable oil production in Russia, so the specificities of its growing in the systems of forest belts with the use of no-till technology are to be studied. The research was conducted in Mikhailovsky and Ilovlinskyareas, the Volgograd region. The main research object was the sheltered sowings of sunflower hybrid LG-5456 on southern chernozems with the use of no-till technology in different vegetation phases. The comparative data on sunflower variety Rodnik grown on light-chestnut soils by the common technology is presented. The unique scheme of fields observation was used which was based on the system analysis and study of the patterns of agrophytocenoses functioning in the zone of forest belts influence. The data on leaves area, assimilating surface, and photosynthetic activity were obtained. The leaves area during the three years of research has reached its maximum values in 2016, wherein there was its burst caused by abundant rainfalls and registered in July, 12, 2017, in the zone of depression at a distance of one height (1H) of the forest belts. In the droughty 1999 the maximum quantity of leaves of the variance Rodnik in the phase of full ripeness was at a distance of 5H and equaled 21, and decreased up to 16 in control site. The analysis of assimilating surface in timing displayed its changes in logistic dependence. The photosynthetic potential of sunflower in space at a different distance from forest belts changes in exponential dependence. The said characteristics provide the prediction of species development. The harvest quality indices of sunflower hybrid LG-5456 grown by dry farming in the zone of windbreaks influence were obtained. The weight of 1000 grains reached the maximum value of 59.27 g in 2016 at a distance of 15H and 45.06 g in 2017 at a distance of 30H. The diagnosis of mineral nutrition in sunflower plants was carried out. The insufficiency in boron content at a distance of 10H in 2017 resulted in the stopping of the development of flowers and decrease in weight of calathides, number of grains per calathide, weight of 1000 grains which affected the indices of oil content and seeds fullness.