缓释尿素与普通尿素不同配比对玉米氮代谢酶和氮素利用的影响

为解决我国西南地区玉米氮肥一次性施用问题,以普通尿素和包膜缓释尿素为供试材料,设置5种普通尿素与缓释尿素配比试验处理,分别为100%缓释尿素(CRU100),75%缓释尿素+25%普通尿素(CRU75),50%缓释尿素+50%普通尿素(CRU50),25%缓释尿素+75%普通尿素(CRU25)和100%普通尿素(CRU0),以不施氮肥(CK1)和常规施肥(CK2,普通尿素60%基施+40%大喇叭口期追施)为对照,研究氮肥一次底施下缓释尿素与普通尿素不同配比对玉米氮代谢关键酶、干物质积累、氮积累及氮素利用的影响。结果表明:(1)施氮显著提高了玉米叶片氮代谢关键酶(谷氨酸合成酶GOGAT和谷氨酰胺合成酶GS)活性,与常规施肥相比,普通尿素与缓释尿素配施可提高叶片GOGAT和GS活性,其中以CRU50和CRU75的缓释尿素比例处理最好。(2)CRU50和CRU75的缓释尿素比例可改善吐丝前、后物质积累和氮素积累,显著提高成熟期物质积累量和氮素积累量。(3)随缓释尿素比例增加,玉米穗粒数、千粒重和产量及氮收获指数均呈先升后降的趋势;掺施缓释尿素处理产量较常规施肥处理平均增产4.46%,其中CRU50和CRU75处理产量最高,收获指数和氮肥表观利用率显著高于其它处理。因此,普通尿素掺混50%~75%比例的缓释尿素进行一次底施,既能增加玉米产量,又可实现氮素的高效利用。

Effects of the combined application of slow release urea and urea on activities of key enzymes related to nitrogen metabolism and nitrogen utilization of maize

To solve the disposable application nitrogen fertilizer of maize in southwest China, slow-release urea ( CRU) and conventional urea ( U) were used to investigate the effects of five proportions of slow-release urea blended with conventional u-rea (100% CRU; 75% CRU +25% U; 50% CRU +50% U; 25% CRU+75% U; 100% U) and two controls ( no N fertilization; conventional fertilization) on activities of nitrogen metabolism key enzymes, dry matter accumulation, nitrogen accumulation and utilization and yield in maize. Results were as follows: (1) Nitrogen supply increased the activities of nitro-gen metabolism key enzymes ( GOGAT and GS) significantly. Compared to the conventional urea treatment, the combination applications of slow-release urea with conventional urea increased the activities of nitrogen metabolism key enzymes ( GOGAT and GS) , improvement effect of the CRU mixing ratio of 50% or 75% treatments were the most strong among them. ( 2 ) Compared to the conventional urea treatment, the CRU mixing ratio of 50% or 75% treatments improved dry matter accumula-tion and nitrogen accumulation around silking stage and also increased those of mature period. (3) With the higher ratios of CRU, the grains per spike, 1 000-kernel weight, yield and nitrogen harvest index were increased firstly and then gradually de-creased. Compared to the conventional urea treatment, the average increase of grain yield in CRU+U treatment was 4. 46%, improvement effect of the CRU mixing ratio of 50% or 75% treatments were the most strong among them, the nitrogen harvest index and nitrogen use efficiency of them were dramatically higher than those of the other treatments. Therefore, applying CRU with a mixing ratio of 50% ~75% as basal dressing should be most beneficial to increase the yield of maize and realize the effi-cient uptake and utilization of nitrogen.