Corn Responses to Post-tasseling Nitrogen Deprivation and to Various Ammonium/Nitrate Ratios
Reddy, K.S. | Mills, H.A. | Jones, J.B.
Corn (Zea mays L.) takes up more than half of its total N after tasseling. An experiment was conducted to determine how the availability of N and the N form, NH₄ or NO₃, during the post-tasseling period affect corn plant growth, ear development, and nutrient composition. In this experiment, corn hybrid ‘Pioneer 3343’ plants were grown hydroponically in pots outdoors with 50:50 NH₄:NO₃ up to the emergence of tassels and then the plants were either deprived of N or changed to various ratios of NH₄:NO₃ nutrition and grown to maturity. Nitrogen deprivation reduced both vegetative (stalk and leaf) and reproductive (cob, total kernel, and individual kernel) dry matter accumulation. Continuous supply of 50:50 ratio of NH₄:NO₃ produced greater vegetative dry matter than changing to either higher or lower ratios of NH₄:NO₃. The ratio of NH₄:NO₃ did not affect the ear dry matter production. Nitrogen deprivation decreased both leaf and kernel N concentration. While 50:50 NH₄:NO₃ ratio increased the leaf N concentration, all NH₄ increased the kernel N concentration compared to other ratios. Nitrogen deprivation also reduced the concentrations of Mg, Fe, Mn, Zn, and B in the leaves but had no effect on the kernel nutrient composition. The cation and anion concentrations in the leaves and kernels were not according to the NH₄ and NO₃ effects (viz., uptake of cations greater and anions lower with NH₄ than with NO₃ nutrition), which were previously observed before tasseling. This difference may be due to a change in the uptake capacity for these nutrients after tasseling. Research partially supported by Fluid Fertilizer Foundation.
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