通过田间试验研究春玉米花后氮素调控及其对叶片及根系功能和产量形成的影响。结果表明，在前期优化施氮的基础上，于花后吐丝期(R1)、乳熟期(R2)期分别设定氮素供应目标值170、140kg N ha-1(N2处理)和260、220kg N ha-1(N3处理)，并根据R1、R2期土壤Nmin确定氮素供应实际值的氮肥优化处理，与后期不追氮肥(N1)处理相比，分别平均增产13.2%、 22.0%。春玉米花后追施氮肥能显著增加玉米功能叶的SPAD值和叶面积指数(LAI)，延缓玉米衰老，在施肥后一定时间内提高了玉米的光合速率(Pn)。吐丝后28d根系取样数据表明，花后追氮对春玉米总体根系形态和总根重无显著影响，但显著增加了10-20 cm和50-60 cm土层的根长和根表面积，对玉米后期延衰和养分、水分吸收有一定的促进作用。
英文摘要:
Field experiment was conducted to evaluate the effects of applied N post-anthesis on dry matter accumulation, leaf area index (LAI), functional leaves SPAD, Photosynthetic rate (Pn) and root growth for high-yielding spring maize production. On the basis of optimizing nitrogen application in the early stage, the target values of nitrogen supply were set at silking stage (R1) and milking stage (R2), respectively 170, 140 kg N ha-1 (N2 treatment) and 260, 220 kg N ha-1 (N3 treatment), and the actual value of nitrogen supply was determined according to the soil Nmin of R1 and R2 stages. Compared with the non-topdressing nitrogen fertilizer (N1) treatment after silking stage, the average yield of N1,N2 increased by 13.2% and 22.0%. Added N application post-anthesis can increase functional leaves SPAD value, leaf area index (LAI) ,which can slowing the aging of maize and increased intensity of photosynthesis of maize. Added N application post-anthesis did not significantly increase the total of root length, root surface area and root weight; However, root length and root surface area in the 10-20 cm and 50-60 cm soil layers were significantly increased by nitrogen application post-anthises.
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