Influence of plant population on head positions of sunflower op varieties
We studied sunflower plant population influence on formation of a head position types, a level of head inclination and sunflower Op varieties productivity. The researches were conducted in the «Federal Scientific Center «All-Russian Research Institute of Oil Crops by the name of Pustovoit V.S.» in the laboratory of sunflower OP varieties of the Sunflower department in 2012-2016 We stated the highest proportion of plants having optimal heads positions is formed at plant population up to 20-40 thousands plants per ha. While increasing the plant population from 20 to 60 thousands per ha we observed the plant height increase too. The maximal plant height was noted at plant population 60 thousand plants per ha, it was: 154 cm for a variety SUR, 170 cm for a variety Oreshek and 189 cm for an intervarietal hybrid (MSG 2205). We fixed the highest meanings for a curve of stem near head (27,1 cm, 32,0 and 34,4 cm, respectively) in the sunflower varieties SUR and Oreshek and the intervarietal hybrid MSG 2205 at plant population 20 thousands plant per ha. Overcrowding of plants population from 20 to 60 thousands plants per ha lowers a curve of a stem near a head by 3,8-7,9 cm and a level of head inclination by 4,1-5,1%. The population about 40-60 thousands plants per ha is optimal for development of plants with a low level of a head inclination and keeping of economically useful traits at a high level.