EFFECT OF PLANT DENSITY AND ROW SPACING ON AGRONOMIC PERFORMANCE AND ECONOMIC RETURNS OF NONOILSEED SUNFLOWER IN SOUTHEASTERN SASKATCHEWAN
Years, locations and planting density are significant factors that influence the agronomic performance of Sundak nonoilseed sunflower (Helianthus annuus L.) in southeastern Saskatchewan. As plant densities of sunflower were increased from 37 500 to 75 000 plants/ha at Indian Head from 1975 to 1977, achene (seed) yield and test weight increased linearly with density while percentages of roasting and dehulling seed categories decreased. Row spacings of 30–90 cm affected plant height and seed yield and size, but absolute amounts were not large. Based on 1984 prices of four seed-size categories, highest gross economic returns were favored by the higher plant densities. In a second test at Indian Head and Oxbow in 1979 and Areola in 1980, a range of plant densities from 22 900 to 76 400 plants/ha did not significantly affect seed yield or gross economic returns. However, yield and returns tended to be greatest for 50 000-60 000 plants/ha. Percentages of large seed decreased as plant population increased. Because markets generally favor the large-seed size categories and the price differentials among seed size categories tend to increase, plant densities of 40 000 to 50 000 plants/ha might better be recommended to allow for years with greater price differentials.Key words: Nonoilseed sunflower, Helianthus annuus L., plant density, row spacing, seed size, economic returns