中文摘要：

在大田栽培条件下，以郑单958和丰单3号为材料，于六叶期喷施玉米专用抗冷剂聚糠萘水剂（PKN），研究PKN对黑龙江省3个积温带上花后玉米穗位叶衰老生理及籽粒灌浆速率的影响。结果表明，从第1积温带到第1II积温带，气温逐渐降低；两玉米品种穗位叶的超氧化物歧化酶（SOD）、过氧化物酶（POD）、过氧化氢酶（CAT）活性及叶绿素（Chla＋Chlb）含量均呈逐渐下降趋势，而MDA含量呈逐渐升高的趋势。同一积温带，两品种不同处理的穗位叶SOD、POD、CAT的活性随生育期呈“先升高后下降”的单峰变化趋势，而MDA含量呈“先降低后升高”的趋势；PKN处理后3个积温带的两品种穗位叶SOD、POD、CAT的活性及叶绿素含量较对照均有不同程度的提高。而MDA的含量与对照相比呈下降趋势。从第1积温带到第III积温带，两品种籽粒的干重均随籽粒的发育呈“慢-快-慢”的S型变化，而灌浆速率呈“先升高后降低”的单峰曲线变化趋势，且两品种籽粒干物重和灌浆速率呈下降趋势；PKN处理后两品种的籽粒干物重和灌浆速率较对照均有不同程度的提高。2010年和2011年PKN处理后3个积温带两品种的产量均增加。2010年第III积温带的ZDTR和FDTR的增产幅度比第I、第II积温带高2．58％、1．17％和2．04％、1．48％。2011年第III积温带的ZDTR和FDTR的增产幅度比第I、第II积温带高8．2％、5．1％和3．4％、0．8％。由此可见，PKN处理后延缓玉米叶片衰老，提高籽粒的灌浆速率，最终增加玉米的产量。

英文摘要：

A field experiment was performed to investigate the effects of the chemical regulation of PASP-KT-NAA （PKN） on leaf senescence physiology and grain filling rate under different temperatures. The result showed that the activities of superoxide disnmtase （SOD）, peroxidase （POD）, catalase （CAT）, chlorophyll concentration in ear leaves of two maize cultivars were declined, while malondialdehyde （MDA） content increased in three accumulate temperature zones with low temperature. In the same accu- mulated temperature zone, and in process of growth, SOD, POD, CAT activities showed the trend of a single peak curve with ＂first increase and then decrease＂, and MDA content showed an opposite trend. PKN treatment increased SOD, POD, CAT activi- ties and chlorophyll contents of ear leaves, while declined MDA content in ear leaves of Zhengdan 958 and Fengdan 3. From the first accumulated temperature zone to the third accumulated temperature zone, the grain weight of two maize cultivars show a S-shape increase in the ＂low-fast-low＂ type and the grain filling rate showed an ＂increased and then declined＂ trend. The grain weight and the grain filling rate of the first accumulated temperature zone were higher than those of the second and the third ac- cumulated temperature zones. PKN treatment had higher grain weight and the grain filling rate compared with the control. In 2010 and 2011, the yield of two varieties of maize increased in the PKN treatment. The yield of Zhengdan 958 and Fengdan 3 in the third accumulated temperature zone were 2.58%, 1.17% and 2.04%, 1.48% higher than those in the first and second accumulated temperature zones, in 2010 and 8.2%, 5.1% and 3.4%, 0.8% higher than those in the first and second accumulated temperature zones in 2011. Thus, the chemical regulation was proved to be useful to delay the leaf senescence, improving the grain filling rate, and ultimately increasing the yield in maize.