EFFECTS OF SEEDING AND HARVESTING DATES ON YIELD AND OIL QUALITY OF SUNFLOWER CULTIVARS

Abstract

Several sunflower cultivars were seeded at approximately weekly intervals from early May to 20 June from 1978 to 1981. In another experiment the plots were harvested at different dates to study the effects on yield and oil quality. In general the yield was highest for all cultivars at the earliest seeding, with the late maturing cultivars performing the best. In late plantings, the yields were in general lower and early maturing cultivars performed better than the later ones. The cross-over point varied from year to year ranging from 16 May to 7 June except in 1981 when there was no cross-over. The oil content was similarly affected, declining more rapidly with delay in seeding in the later maturing hybrids than in the early hybrids. In the separate study on harvest dates, maximum oil content was reached when seed moisture content had declined to 45%. This occurred approximately 1 wk earlier in the early cultivars than in the late ones. Maximum linoleic acid level was reached approximately a week after the maximum oil content was obtained.Key words: Seeding date, sunflower, oil content, yield, linoleic acid, harvesting date