EFFECT OF PLANT DENSITY AND SOIL FERTILITY ON OILSEED SUNFLOWER GENOTYPES

Abstract

Field experiments were conducted in the 1979 to 1982 seasons to determine the response of sunflower (Helianthus annuus L.) genotypes with different growth habits to different plant densities at two levels of soil fertility in the Morden, Manitoba area. Treatments included hybrids and an open-pollinated cultivar, no fertilizer and 250 kg ha−1 of 27-14-0 and plant densities of 30 000, 45 000, 60 000 and 75 000 plants ha−1. Hybrids and open-pollinated cultivar responded similarly to the fertility and plant density levels. An increase in plant density did not affect yield, but slightly delayed flowering time, increased plant height, test weight and oil concentration and decreased achene weight. A plant density of about 45 000 plants ha−1 was required to ensure optimum yield.Key words: Sunflower, Helianthus annuus L., plant density, soil fertility