不同施N方式对水稻根际土壤微生物生态效应的影响

Ecological effect of different nitrogen application modes on rhizosphere microbes in soil of rice root

【目的】揭示水稻根际土壤微生物数量、微生物生物量C、N含量及酶活性的变化规律，阐明水稻一土壤一微生物之间的协同作用机理。[TY法】设总施N量为225kg／hm^2，按基肥＋分蘖肥与穗肥的施N比例设N1、N2、N3 3种处理，对应的施N比例分别为8：2，7：3和6：4，并以全生育期不施肥为空白对照（N0），对不同施N方式下水稻根际土壤微生物生态效应进行研究。【结果】（1）各处理根际土壤细菌、放线菌、氨化细菌、硝酸细菌、好气性自生固氮菌数量和微生物生物量C、N含量在水稻移栽后缓慢上升，到分蘖期达到最大；然后又逐渐下降，到孕穗期达最小值；之后随着水稻继续生长（孕穗期～齐穗期）又逐渐回升。根际土壤脲酶、酸性磷酸酶活性在水稻移栽后逐渐增强，到孕穗期达最高值；之后又逐渐下降，到成熟期达最小值。随着水稻生长，真菌、反硝化细菌、反硫化细菌数量逐渐减少，在孕穗期均达最小值；然后随着水稻继续生长，其数量又增加。（2）施肥处理水稻根际土壤细菌、放线菌数量，微生物生物量C、N含量及土壤脲酶、磷酸酶活性，均显著高于不施肥处理；不施肥处理水稻根际土壤真菌数量显著高于施肥处理。（3）在孕穗期至齐穗期，施肥处理间根际土壤细菌、放线菌、氨化细菌、硝酸细菌、好气性自生固氮菌数量，均是N1处理最大，N2处理次之，N1处理最小。【结论】适当增加水稻中、后期施N比例，有利于促进水稻中、后期的根际土壤细菌、放线菌、氨化细菌、硝酸细菌、好气性自生固氮菌生长，间接地提高根际土壤中脲酶、酸性磷酸酶的活性，为稻株的快速生长创造了良好的根际营养环境和物质基础。

[Objective] The study was to reveal mutative regularity of rhizosphere microbes, soil microbial metabolic biomass carbon and nitrogen, enzyme activity in rice,to expound concerted effect mechanism among rice, soil and microbe,and to study ecological effect of photosphere microbes in rice under the conditions of different nitrogen application modes. [Method] Total content of N supplies was 225 kg/hm2. Three treatments of N1 ,N2and N3 were designed according to nitrogen application modes between basal-tillering fertilizer and spike fertilizer,N1 was 8 ： 2,N2 7 ： 3, and N3 6 ： 4;Total content of fertilizer supplies was nought in different developmental stages of rice. that was regarded as blank check（N0）. The soil microbial flora and enzyme activity in the rhizosphere of the rice were detected. [Result] （1） The amount of bacteria, actinomycetes,ammonifier, nitric acid bacteria, aerobic azlotobacter and content of soil microbial metabolic biomass carbon and nitrogen slowly ascended after rice was transplanted, rose to peak at tillering stage in rice and then rapidly declined to the lowest at the booting stage, then went up slowly again during rice growth from booting stage to full heading stage. The activities of soil urease and acid phosphatase were gradually enhanced after rice transplanting. They were the highest at the booting stage, then declined rapidly again during rice growth,and turned to be the lowest at ripening stage. The amount of fungi and tlenitri- tier and desulphate reducer dropped after rice transplanting, and went down to the lowest at the booting stage, then increased slowly again during rice growth. （2） The amount of bacteria, actinomycetes and activity of soil urease and acid phosphatase in the application fertilizer treatments signficantly exceeded them in the control. But amount of fungi in the control signficantly exceeded the fertilizer application treatments. （3） From booting to full heading stage, the amount of bacteria, actinomycetes, ammonifier, ntric acid bacteria and aerobic azlotobacter and activity of soil urease and acid phosphatase of N3 in the application fertilizer treatments were maximum,N2 took second place,N1 minimum. [Conclusion] Properly increasing the proportion of N supplies in the middle and late growth stage promoted the growth of bacteria,actinomycetes, ammonifier,ntric acid bacteria and aerobic azlotobacter in the middle and late growth stage of the rice,thus improved activity of soil urease and acid phosphatase indirectly. All of these built up a nicer nutrition surrounding and matter basis for rapid growth of the rice.