Effects of stand density on yields in sunflower hybrids

Abstract

The effects of stand density of sunflower hybrids on growth dynamics, yield and certain microclimatic factors. The trial was carried out on a chernozem soil in a six-field crop rotation according to the two-factorial split-plot design. The main plot consisted of three registered or experimental hybrids (NS-Dukat, NS-H-111 and NS-H-103), while the subplots included six different stand densities: 30,000, 40,000, 50,000, 60,000, 70,000, and 80,000 plants per hectare. Because a regression analysis was to be used to calculate the optimum stand density, the stands were purposely either too sparse or too dense for our conditions. On average for all three years and all three hybrids, the seed yield increased up to the density of 60,000 plants ha-1 (the increase was significant up to 50,000 plants ha-1), while the regression maximum was at 55,000 plants ha-1. The highest seed yield significantly larger than in the other two hybrids, was detected in hybrid NS-H-111. There were significant differences in the hybrids response to different stand densities. The number of filled seeds, followed by 1000-seed weight, had the greatest direct effect on the seed yield. Since the oil yield in sunflower depends mostly on the seed yield, the highest yield of oil was recorded at densities that produced the highest seed yield as well (in a way, this was confirmed by the results of path coefficient analysis).

U radu je proučavan uticaj gustine useva na dinamiku rastenja i prinos hibrida suncokreta, kao i na neke mikroklimatske činioca. Ogled je postavljen na zemljištu tipa černozem, u šestopoljnom plodoredu, po planu dvofaktorijalnog split-plot dizajna. Glavna ili velika parcelica obuhvatala je tri priznata ili eksperimentalna hibrida: NS-Dukat, NS-H-111 i NS-H-103. Podparcelice su obuhvatale šest gustina useva: 30.000, 40.000, 50.000 60.000, 70.000 i 80.000 biljaka po hektaru. Zbog regresione obrade podataka koja omogućava izračunavanje optimalne gustine useva namerno su uzete, za naše uslove, nedovoljne i suviše velike gustine. U proseku za tri godine i sve hibride prinos semena kod suncokreta rastao je do 60.000 biljaka po hektaru, značajno do 50.000 biljaka po hektaru, a regresioni maksimum je bio pri 55.000 biljaka po hektaru. Hibrid NS-H-111 ostvario je značajno najviši prinos semena. Između pojedinih hibrida postoje uočljive razlike u reakciji na gustinu useva. Najveći direktan uticaj na prinos semena imao je broj punih semena, a zatim masa 1.000 semena. Prinos ulja kod suncokreta u najvećoj meri zavisi od prinosa semena i maksimalan prinos ulja ostvaren na onim varijantama gustine useva na kojima je ostvaren i maksimalan prinos semena suncokreta, što je na izvestan način potvrdila i analiza koeficijenata putanje.