Effect of early and late planting on sunflower performance in the southeastern United States
1989
Sojka, R.E. | Arnold, F.B. | Morrison, W.H. III. | Busscher, W.J.
Sunflower hybrids (Helianthus annuus L.) which mature in fewer than 100 days can facilitate double cropping in the humid subtropic climatic area of the United States (which has greater than 210 frost free days and 1.2 m or 47 in. annual rain-fall) and in other countries with similar climates. Little information is available for the very early or very late planting dates needed for this strategy. From 1981 to 1984 sunflowers were grown as a double crop either before soybean [Glycine max (L.) Merrill] or after corn (Zea mays L.). Yield and oil content of hybrids declined only slightly by delaying planting from mid-March to late April, but yield and oil content declined sharply with delayed planting from 7 August to 2 September. Flowering interval was planting-date dependent and was estimated shortest for planting dates near the summer solstice. Yields were not satisfactory for planting after 18 August. Supplemental irrigation and early desiccation did not affect yield. Bird damage was significant if harvesting was not prompt. Yield and oil production potential of sunflower was very good for the planting dates before 18 August, suggesting a good potential for double cropping with sunflower in this climatic zone.
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