玉米生长量、养分吸收量和及氮肥利用率的动态变化

在不同水、氮供应条件下，研究了玉米干物质累积、养分吸收及氮肥利用率的变化动态。结果表明，植株干物质和养分吸收量，随生育期延长而持续增加，变化动态可用S曲线方程拟合。对干物质和养分累积方程求导，得到了干物质累积和养分吸收速率。玉米生长期间干物质累积速率前期上升快，至高峰后缓慢下降。在氮、磷、钾三要素中，氮、钾吸收速率高，上升快，下降也快；磷吸收速率低，上升慢，下降亦慢。养分最大吸收速率出现的时间，钾最早，氮次之，磷最晚，但均早于干物质最大累积速率出现时间。氮肥利用率与干物质累积、养分吸收速率有类似变化趋势；氮肥最高瞬时利用率与氮素最大吸收速率出现的时间基本一致。灌水明显提高了氮肥累积利用率和瞬时利用率；水分和氮素供应虽然增加了养分吸收速率和干物质累积速率，但未改变其变化趋势。

Dynamics of Nutrient Accumulation in Maize Plants Under Different Water and N Supply Conditions

The dynamics of accumulations of plant dry matter, nutrient uptake and N fertilizer recovery were studied under different water and N supply, using summer maize(Zea mays L.var. Shandan9)as an indicating crop. The total dry matter (including roots) and N, P, K uptake amounts were continuously increased with plant growth, and their accumulations with time during plant growing period were shaped in S curves that could be described by exponential regression equations. Differentiating the regression equations fitting the curves over time for first derivatives, the momentary rate of the dry matter and nutrient uptake was obtained. Results show that the rate of dry matter accumulation and nutrient uptake were not in the same 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 of N and K was higher, and their increase and decrease were both fast while P was in reverse case. The time of 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. The momentrary N recovery rate was similar in trend to those of dry matter and N uptake, and its maximum momentary recovery rate occurred almost at the same time as its maximum uptake rate. Supplemental irrigation raised the accumulative and momentary rates of N. Although water and N supplies increased dry matter and nutrient uptake rates, they did not alter their changing trends during the plant growing period.