Sunflower [Helianthus annuus var. marcocapus (DC.) Ckll.] acreage has been increasing rapidly in the high elevation region of the central Great Plains. Little work has been done in the region on the effect of planting date and plant population on sunflower production. This study measured the influence of three planting dates (25 May, 10-13 June, and 28 June) and four populations (11 000, 14 000, 17 000, and 20 000 plants/acre) on seed yield, oil percentage and yield components of two full season sunflower oil type hybrids ('Pioneer brand 707' and 'Sigco brand 475'). The latter is 7 to 8 d later in maturity and 4 in. taller than the Pioneer hybrid. The experiment was performed in three environments (supplemental water following corn [Zea mays L.], dryland following wheat [Triticum aestivum L. emend. Thell.], and dryland after 22 month fallow) at the High Plains Agricultural Laboratory near Sidney, NE, in 1993 and 1994. Both years showed similar seed yield across this range of plant populations. Plant populations of 11 000 resulted in 1.2 oz larger heads, 300 more seeds/head, 0.0004 oz larger seed, and 2 lb/bu lower test weight than populations of 20 000 plants/acre. Sunflower has the ability to compensate for wide population differences to maintain uniform seed yield. Sunflower planted on 25 May resulted in 200 lb higher seed yield per acre, 0.0003 oz higher weight per seed, 0.5 oz higher weight per head, 2% higher oil, 100 lb/acre more oil, and 2 lb/bu higher test weight than sunflower planted on 28 June. Gross income was reduced by $0.76/acre for each day of delay in planting after 25 May.
ASJC Scopus subject areas
- Plant Science