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This article in AJ

  1. Vol. 62 No. 5, p. 665-666
    Received: Mar 10, 1970

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Sunflower Date of Planting and Chemical Composition at Various Growth Stages1

  1. R. G. Robinson2



Six sunflower (Helianthus annuus L.) varieties were planted at seven dates ranging from April 24 to June 28,1967 through 1969. Early May plantings produced highest seed yields, hectoliter weights, oil percentages, and large seed percentages. Days from planting to emergence and emergence to flowering decreased from early to late planting dates. Date of planting was the variable which most consistently affected seed yield. It overshadowed both varieties variation and the interaction of dates ✕ varieties.

Whole plant samples for N, S, P, K, Ca, Mg, Fe, Na, Sr, Zn, Cu, Mo, Mn, and B analyses were taken at 13 different growth stages and separated into root, stem-leaves-receptacle, and seed. Comparative data for seedling, heaaing, flowering, and maturing periods of growth showed concentrations of most elements declined with age in stems- leaves-receptacle.

Variation in composition of stem-leaves-receptacle among growth stages was greater than among varieties, but this relationship was reversed in seed. Seed; stemleaves-receptacle, and root differed in composition and in relative rank of the elements

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