Effects Of Slow-release Nitrogen Fertilizer On Dry Matter Production,nitrogen Use Characteristics And Yield Of Machine Transplanted Rice

As a new type of value-added fertilizer,the nutrient supply of slow-release nitrogen fertilizer is influenced by many factors.It is of great significance to study the adaptability of slow-release nitrogen fertilizers for integrating the cultulation technology of machine transplanted rice.Field experiments consisted of four fertilizers [common urea conventional fertilization(FFP),sulfur coated urea(SCU),mixed slow-release fertilizer(MSRF),and resin urea(PCU)] with zero-N treatment(CK),and two rice varieties and two ecological conditions were conducted in 2016 and 2017,respectively.The results were as follows:1.Slow-release nitrogen fertilizers obviously increased the leaf photosynthesis potential of mechanically-transplanted rice by after the heading stage.Compared to FFP,8.53% to 31.80%,20.05% to 41.91%,and 8.66% to 21.49% increase in the leaf area,fresh weight,and chlorophyll content were observed by slow-release nitrogen fertilizers treatment at Pixian,respectively.And 13.17% to 22.03%,12.35% to 46.46%,and 9.09% to 19.12% increase in these indexs were recored at Shehong.Slow-release nitrogen fertilizer treatment increased chlorophyll content and net photosynthetic rate of leaves,increased fresh and dry weight of leaves,and delayed leaf senescence.By increasing single leaf area and leaf area index,the photosynthetic potential of mechanically-transplanted rice leaf was increased effectively,and the effect of "source" was achieved.2.Significant effect of slow-release nitrogen fertilizers on dry matter accumulation characteristics were observed with different varietis and ecological conditions.Compared to conventional urea,MSRF and PCU increased the dry matter quality of Fyou 498 at jointing-heading stage by 14.85% and 19.00%,respectively,while Yixiang 2115 increased 16% and 22.50%,respectively.In Pixian,compared with conventional urea,SCU,MSRF and PCU increased the dry matter accumulation at heading and maturity stage by 22.02%,15.17% and 49.92%,respectively;while the Shehong site increased by 5.88%,22.92% and 39.96%,respectively.slow release nitrogen fertilizers significantly increased the biomass of mechanically-transplanted rice by improving dry matter accumulation of rice after the jointing stage.3.Nitrogen use characteristics of machine transplanted rice were influenced by fertilizers,rice varieties,and ecological conditions.Compared to Yixiangyou 2115,Fyou 498 significantly increased nitrogen accumulation of plant and panicle from heading to maturity period,which contributied to the improvement in N redistribution and use efficiency.Unlike Shehong,leaf nitrogen transport rate,apparent nitrogen transport rate,nitrogen transport contribution rate and nitrogen fertilizer utilization efficiency is higher at Pixian.Compared to conventional fertilizer,slow release nitrogen fertilizers increased the plant N content,N accumulation before the heading stage,and N transport of stem and sheath and leaf,leading to the improvement in N uptake per 100 kg grain,partial productivity,and apparent efficiency.4.Compared to conventional fertilizer,slow-release nitrogen fertilizers markedly increased the spikelets per unit area by improviing both effective panicles and spikelets per panicle,leading to the 3.80% to 8.71% and 4.77% to 14.00% enrichment in grain yield in Pixian and Shenghong,respectively.Overall,resin urea and mixed slow-release fertilizer is suitable for using at Pixian,while resin urea and sulfur coated urea is suit at Sheing for pursuiting high yield of rice.