The impact of seed sowing rates on the filling, volume weight and thousand-seed weigh of new and promising sunflower varieties and hybrids

Research on the effect of seed sowing rate on the filling, volume weight and thousand-seed weight of sunflower was carried out in 2016-2017 in VNIIMK (Krasnodar). The new and promising sunflower varieties (Skormas, Umnik, Master) and hybrids (Mercury, Typhoon, Imidzh, Oksi, Natalie) of VNIIMK breeding were used as the objects. They were cultivated at various seed sowing rates that provided the plant population of 40, 60 and 80 thousand plants per ha. It was established that the seed filling of sunflower varieties and hybrids was at the same level and did not depend on the seed sowing rate. The highest volume weight of seeds was observed in hybrids Imidzh, Typhoon, Natalie (429.8-435.0 g per liter), an increase of seed sowing rate from 40 to 80 thousand plants per ha contributed to its significant increase - from 406.3 to 423.0 g per liter, respectively. The highest thousand-seed weight was observed in the hybrids Mercury (72.0 g), Oksi (71.0 g) and Umnik (68.9 g) in the conditions of 2016, in the variety Master (58.9 g) and hybrid Oksi (57/3 g) in 2017, and the decrease of seed sowing rate from 80 to 40 thousand pcs. per ha contributed to its significant increase on average for these years for varieties and hybrids from 55.8 to 62.1 g. The dependence between the seed sowing rate and volume weight of seeds was positive and varied from the weak in 2016 for Mercury (r = 0.283) and in 2017 for Oksi (r = 0.041) to the strong in 2016 for Natalie (r = 0.892) and in Master (r = 0.723) and in 2017 for Typhoon (r = 0.852) and Mercury (r = 0.847). In 2016, the correlation between the seed sowing rate and thousand-seed weight was negative: strong for Umnik, Typhoon and Natalie (from r = -0.907 to r = -0.744); average in Skormas, Mercury and Imidzh (from r = -0.399 to r = -0.570). In 2017, it was strong in all samples (from r = -0.768 to r = -0.954), with the exception of Oksi - it had an average correlation dependence (r = -0.469). The dependence between the studied traits and the yield was weak. Therefore, the growing conditions, genotype and seed sowing rate have an impact on volume weight and thousand-seed weight.