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Sunflower yield and water use as influenced by planting date, population, row spacing

Alessi, J., Power, J.F., Zimmerman, D.C.
Agronomy journal 1977 v.69 no.3 pp. 465
Helianthus annuus, oil crops, seeds, yields, seed oils, chemical concentration, plant cultural practices, water use efficiency, plant density, row spacing, air temperature, precipitation, sowing date, growing season, dryland farming, dry environmental conditions, evapotranspiration, climatic factors, correlation, United States, Great Plains region, North Dakota
Sunflower (Helianthus annuus L.) has only recently been grown commercially as an oilseed crop in the drier regions of the Northern Great Plains. This study was conducted to acquire preliminary information on seed yield, oil concentration, and water use for oil-type sunflower as affected by planting date, plant population, and row spacing; and to obtain an indication how these results were affected by yearly variation in precipitation and air temperature. Sunflower was grown at Mandan, N. Dak. at plant population of 25,000, 50,000, 75,000, and 100,000 plants/ha in 30- and 90-cm rows on Temvik silt loam (Typic haploboroll). Soil water withdrawal by sunflower was generally confined to the upper 150- soil depth. Water use by sunflower was consistently greatest for earlier plantings, and was not affected by population or row spacing. Significant positive correlations were obtained between seed yield and water use after 50% flowering. Water use before flowering was much greater in a year of high precipitation during this period than in a year when pre-flowering precipitation was lower. Seed and oil yield were usually highest for lowest populations and for 30-cm row spacing. Correlation coefficients showed that 80% of the total variation in oil concentration was accounted for by variation in water use and temperature. Oil concentration was more strongly influenced by water use than by temperature. Although late planting in 1973 increased seed yield for some of the higher plant populations, flowering was delayed until early September, increasing the frost hazard. Days from planting to flowering (50%) decreased as planting date was delayed.