花前光照亏缺对水稻根际土壤微生物生态效应的影响

Ecological Effect of Pre-flowering Light Deficit on the Rhizosphere Soil Microbes of Rice

在大田条件下,以超级稻"II优航2号"为试验材料,水稻拔节期至始穗期设置55%和85%两个遮光强度,以全生育期正常自然光为对照,研究花前光照亏缺对水稻根际土壤微生物生态效应的影响,为光贫乏区土壤良性生态循环和超级稻栽培技术研究提供依据。结果表明,水稻拔节期至始穗期弱光胁迫条件下,在水稻生长的孕穗期、始穗期、灌浆期、收获期,显著降低了水稻根际土壤微生物细菌、放线菌、氨化细菌、硝酸细菌、好气性自生固氮菌数量,增加了真菌、反硝化细菌、反硫化细菌数量,从而导致土壤微生物生物量C和N含量减少,抑制了根际土壤中脲酶、磷酸酶的活性。而且,随着弱光胁迫强度和时间的增加,水稻根际土壤微生物细菌、放线菌、氨化细菌、硝酸细菌、好气性自生固氮菌的生长和土壤微生物生物量C、N的含量和土壤中脲酶、磷酸酶的活性受抑制程度加重,真菌、反硝化细菌、反硫化细菌生长的促进作用增强。说明花前光照亏缺降低了稻田根际微生物生物量和土壤酶活性,改变了根际微生物群落结构,破坏了稻株生长的根际微生态环境。

The aim of this study is to investigate the ecological effect of pre-flowering light deficit on the rhizosphere soil microbes of rice and provide the guidelines for the benign ecological cycle of soil and for the cultivation practice of super rice in light-poor areas.A super hybrid rice combination,＂II Youhang 2＂,was used in the experiment under the field condition.Two shading intensities of 55% and 85% were set from jointing stage to initial heading stage in the experiment.The natural light condition was taken as the control.The results show that the amount of bacteria,actinomycetes,ammonifier,nitric acid bacteria,and aerobic azlotobacter has significantly declined with light deficient treatments at booting,initial heading,grain-filling,and harvest;in the meantime,the amount of fungi and denitrifier as well as desulphate has enhanced,and it results in the descent of the content of soil microbial metabolic biomass carbon and nitrogen.The factors inhibit the activities of soil urease and acid phosphatase.Moreover,the amount of bacteria,actinomycetes,ammonifier,nitric acid bacteria and aerobic azlotobacter is going down with the increasing intensity of light stress,and mutative trend of soil microbial metabolic biomass carbon and nitrogen,soil urease,and acid phosphatase is the same.However,the behavior of fungi and denitrifier as well as desulphate reducer are quite opposite to bacteria and actinomycetes.It is implied that pre-flower light deficit drops drown soil microbial metabolic biomass,alters soil microbial community,and undermines rhizosphere micro-ecological environment of the growth of rice.