The Effect of Nitrogen and Phosphorus Fertilization on the Nitrogen Absorption by Sunflowers |
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| Authors: | H L Loubser JJ Human |
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| Institution: | Contribution from the Grain Crops Research Institute, Potchefstroom, Republic of South Africa |
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| Abstract: | Little is known about the effect of fertilization on the N uptake of sunflowers. A 42 factorial trial with 0, 60, 120 and 180 kg N ha?1 and 0, 15, 30 and 45 kg P ha?1 was conducted over three years. The N content and concentration of leaves, stems and capitula were determined at three growth stages. High N levels increased the N content and concentration of all plant parts at all growth stages sharply. High P levels increased the N content of all plant components through better growth. P has an inconsistent effect on N concentration but tended to decrease it. After flowering the crop assimilated 20 to 25 % of the total N. This implies that N applied can still be applied and utilized by the crop at a late stage. This should be substantiated by further research. |
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| Keywords: | Sunflower nitrogen uptake |
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