水稻和稗草共生土壤微生物生物量碳及酶活性的变化

以稻田稗草、化感水稻PI312777和普通水稻辽粳9为试材，研究了田间稗草和水稻1∶1共生条件下，土壤微生物生物量碳及脱氢酶、脲酶和转化酶活性的变化.结果表明：在稗草 的干扰下，化感水稻PI312777根区土壤微生物生物量碳含量比单作减少了 50.52％（P<0.01），而行间土壤微生物生物量碳含量增加；普通水稻辽粳9根区土壤 微生物生物量碳含量比单作减少了38.99％（P<0.01），但其行间土壤微生物生物量碳含量无明显变化.两个水稻品种根区土壤脱氢酶活性均被显著抑制（P<0.05），下降率都在20％以上；PI312777根区土壤脲酶和转化酶活性均被显著促进（P<0.01）；而辽粳9根区土壤转化酶活性也被显著抑制（P<0.01），但脲酶活性无明显变化.化感水稻根区土壤微生物生物量碳含量的显著减少及脲酶、转化酶活性的增加是其化感特性的表现，表明土壤微生物和酶均参与了水稻和稗草的种间作用，化感水稻具有抗稗草干扰的明显优势.

Changes of microbial biomass carbon and enzyme activities in rice-barnyard grass coexisted soils.

Taking barnyard grass (Echinochloa crus-galli), allelopathic rice (Oryza sativa) PI312777, and non-allelopathic rice Liaojing-9 as test materials, this paper studied the changes of microbial biomass C and of dehydrogenase, urease and invertase activities in soils under 1∶1 rice-barnyard grass coexistence. The results showed that with the coexistence of barnyard grass, the microbial biomass C in rhizosphere soil of PI312777 was decreased by 50.52% (P<0.01), while that in inter-row soil was increased. The microbial biomass C in rhizosphere soil of Liaojing-9 was also decreased by 38.99%(P<0.01), but no significant difference was observed in inter-row soil. The dehydrogenase activity in rhizosphere soils of the two rice varieties were decreased by 20% or more (P<0.05), but the urease and invertase activities in rhizosphere soil of PI312777 were significantly stimulated (P<0.01). The invertase activity in rhizosphere soil of Liaojing-9 was inhibited by coexisting barnyard grass, but urease activity had less change. As a result, the allelopathic traits of rice variety led to a significant decrease of microbial biomass C and an increase of urease and invertase activities in rhizosphere soil under barnyard grass coexistence, implying that soil microbial biomass and enzymes might play essential roles in species interactions between rice and barnyard grass, and allelopathic rice had its advantage in resistance to barnyard grass.