南方红壤丘陵区土壤细菌对土壤水分和温度的响应差异

Difference in Response of Soil Bacteria to Soil Moisture and Temperature in the Hilly Red Soil Region of Subtropics of Southern China

红壤丘陵区稻田不同时期进行的水分管理导致土壤水分和温度同时变化,继而影响土壤微生物群落结构,二者对土壤微生物的影响机制目前还不清楚。本研究以中国科学院桃源农业生态实验站长期定位试验的稻田作为研究对象,同时以旱地农田作为对照,利用末端限制性酶切片段长度多态性分析(T-RFLP)和荧光定量PCR(qPCR)方法,研究不同水分管理时期细菌群落结构与丰度的变化特征,进而分析其变化的影响因素,阐明水分和温度的相对贡献。结果表明,稻田土壤细菌受土壤水分状况的显著影响,淹水期土壤细菌群落结构明显区别于其他时期,且淹水期土壤细菌丰度和多样性指数均显著低于晒田期。稻田土壤细菌群落结构和多样性指数均受到土壤含水量和土壤温度的显著影响,但土壤含水量的相关性大于土壤温度。而作为对照的旱地农田土壤含水量在不同时期没有差异,土壤细菌群落结构也没有差异,仅土壤细菌丰度和多样性指数发生一定变化,但这种变化并不与土壤温度呈现相关性。因此,本研究认为,南方丘陵区农田土壤细菌对土壤水分的响应比对土壤温度更敏感。

Water management in paddy fields in the red soil hilly region results in the simultaneous change of soil moisture and soil temperature, and then induces the variation of the community structure of soil microbes. However the action mechanisms of soil moisture and temperature are not fully clear by now. The long-term paddy fields at the Taoyuan Agro-ecological Experimental Station of the Chinese Academy of Sciences was taken as the research object, and the selected dryland fields was taken as the control. Soil samples were collected in different water management periods of paddy fields. Terminal restriction fragment length polymorphism(T-RFLP) and fluorescence quantitative PCR(qPCR) were used to disclose the characteristics of bacterial community structure and abundance in different periods, and the influencing factors were further analyzed. The results showed that bacterial community structure in paddy field was affected by soil moisture variation in different periods. The bacterial community structure in flooding period was quite different, and the bacterial abundance and diversity index were lower compared to other periods. The bacterial community structure and diversity were affected by soil moisture and soil temperature, however the former made greater contribution. In contrast, the soil moisture and bacterial community structure showed no significant difference among different periods in the dryland field. Though the bacterial abundance and diversity index showed a little change, which was not related to soil temperature. Therefore, soil bacteria variation in the hilly red soil region of subtropics was more sensitive to soil moisture than soil temperature.