水稻不同直播方式下土壤微生物群落结构差异研究

Diversity of soil microflora structure under different direct-seed rice patterns

在人工撒播、机条播（行距25cm）和精量穴直播（行距25crn、株距14cm）3种不同水稻直播方式下，研究了稻田土壤微生物种群数量、区系、功能微生物类群间的差异，并分析了土壤微生物生态差异与土壤化学性状的相关性。结果表明：不同水稻直播方式下，土壤微生物群落结构组成有明显差异；不论是分蘖盛期还是孕穗期，人工撒播和精量机穴播处理土壤可培养微生物总量均无差异，但两个水稻生育期间土壤微生物总量变化有2个数量级差，分蘖盛期可达10^7，而孕穗期仅为10^5；机条播处理可培养微生物总量在分蘖盛期和孕穗期间波动小，始终保持在10^6，但其真菌种群数量和比例始终最高。在种群比例上，人工撒播处理B／F值（细菌种群数量与真菌数量的比值）始终最大，分蘖盛期分别是机条播和精量机穴播的2．59倍和1．69倍，孕穗期则分别是机条播和精量机穴播的1．48倍和1．22倍；在土壤微生物代谢类群多样性指数上，不论是分蘖盛期还是孕穗期，精量机穴播均优于人工撒播处理，但差异不显著。

The differences of soil microbial populations, floras and functional microorganism groups in rice fields were investigated under 3 different direct-seed rice patterns, artificial scatter, mechanical drilling at row spacing of 25 cm,and precision hill-drop drilling at seed spacing of 25 cm ~ 14 cm, and the correlations between the ecological differences of soil microorganism and the soil chemical properties were also analyzed. The results showed that the compositions of soil microflora were obviously different under the different direct-seed rice patterns; At full tillering stage or booting stage, the total quantities of soil cultivable microorganisms were nearly the same between the precision hill-drop drilling and the artificial scatter, but the total quantities varied greatly, being up to 107 at full tillering stage and only 105 at booting stage,The total quantity of cultivable microorganisms under the mechanical drilling varied little between full filleting stage and booting stage, always remaining at 10^6 , but the number and ratio of fungal population were always the highest. The B/F values（population ratio of bacteria to fungi）under artificial scatter were always the maximum, being 1.59 and 0.69 times higher than those respectively under the mechanical drilling and the precision hill-drop drilling at full filleting stage, and 48 % and 22 % higher than those respectively under the mechanical drilling and the precision hill-drop drilling at booting stage; In terms of soil microbial diversity index, the precisionhill-drop drilling was better than the artificial scatter at both full tillering stage and booting stage, though their differences were not significant.