Dynamics of nutrient accumulation in maize plants under different water and nitrogen supply conditions

A field experiment with microplots was conducted under rainpreventing condition for studying the effects of water and N supply on the dynamics of nutrient uptake and accumulation in summer maize plants. The results showed that the shoot dry matter and N, P, K consumption was increased with growth stage while the percentage of their content tended to decrease. The dry matter and the absolute amount of the nutrients could be described by S curve. The rate of dry matter accumulation and that of nutrient uptake was not in the same way at all time, but changed from one time to another. Usually, the rate was increased fast at early stages, and gradually decreased after reaching their peak. Of N, P and K, the uptake rate for N and K was higher, and their increase and decrease were both fast while P was in reverse case. The time for the maximum absorptive rate appeared earlier for K, followed by N, and then by P. In any case, the time of maximum nutrient uptake rate appeared earlier than did the dry matter. Supply of water and N increased nutrient uptake amount, maximum nutrient uptake rate and the nutrient percentage at early stage but the trends of nutrient accumulation and uptake rate were not changed. Since water and N supply promoted transfer of nutrients from vegetative organs to grains and raised the proportion of nutrients, crop yield was thereby greatly increased. 