N Deprivation in Maize During Grain-Filling. I. Accumulation of Dry Matter, Nitrate-N, and Sulfate-S1
- J. W. Friedrich,
- L. E. Schrader and
- E. V. Nordheim2
Maize (Zea mays L.) has a noted propensity for accumulating large amounts of nitrate-N (NO3-N). However, the availability of such NO3-N for assimilation during periods of restricted N supply has not been assessed. In addition, the availability of sulfate-S (S04-S) affects the accumulation and assimilation of NO3-N. Little is known about the effect of NO3-N supply on S04-S accumulation. Such information is vital to efforts to improve the efficiency of nutrient utilization by crops. The objective of this greenhouse experiment was to determine the effect of N deprivation during grain-filling on the accumulation of dry matter, NO3-N, and SO4-S. Maize plants were grown hydroponically in a modified Hoagland's solution. At silking the nutrient solution was replaced with fresh solution, with or without NO3-N. Plants were harvested and separated into seven fractions at silking and 1, 2, 3, 5, and 7 weeks after silking. Plants that were supplied NO3-N during grain-filling contained almost twice (1.8×) as much N at physiological maturity (7 weeks after silking) as did N-deprived plants. Ear dry weight was not affected by N deprivation. The concentration of NO3-N in all fractions declined during grain-filling; however, N deprivation enhanced this decline in the roots, lower stem, and upper stem. Lack of N did not affect NO3-N concentration in the lower leaves, upper leaves, or ear. The concentration of SO4-S in the roots nearly doubled between silking and physiological maturity when plants were deprived of NO3-N, but did not change when N was supplied. The concentration of SO4-S in all other parts was not markedly affected by N deprivation. Apparently, maize plants can compensate for a restricted N supply during grain-filling by utilizing NO3-N stored in the roots and stem.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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