南岭小坑常绿阔叶林土壤脱落酸分解特征

The Decomposition Process of Abscisic Acid in Soils from Evergreen Broadleaf Forest in Xiaokeng, Nanling

植物产生的脱落酸（ABA）可进入土壤并在土壤溶液中保持-定浓度,对植物生长、种子萌发、群落组成和演替具有重要意义.研究土壤ABA 的分解过程有助于了解ABA 在土壤中的循环过程,揭示土壤ABA 和植物生长的相互关系.以广东南岭小坑常绿阔叶林为研究对像,分析了土壤理化性质和土壤ABA 质量浓度的关系,并通过室内培养法结合灭菌处理研究土壤ABA 的分解过程和土壤微生物在ABA 分解过程中的作用.结果表明,土壤ABA 质量浓度在29.8-167.0 ng·mL^-1间,均值为91.5 ng·mL^-1,且存在较大的空间异质性;土壤全N 含量和ABA 质量浓度存在正相关关系;在培养过程中,土壤微生物能够在短时间内（7 d）快速分解掉平均33.5%的土壤ABA,之后土壤ABA 缓慢线性自然分解,分解速率平均为0.24%·d^-1;在前期快速分解过程中,土壤ABA 含量和分解速度间存在正相关关系,而在后期缓慢分解过程中则是负相关关系;土壤微生物一方面可以造成土壤ABA 的快速分解,另一方面还具有防止土壤ABA 质量浓度过低的作用.

Abscisic acid (ABA), a hormone synthesized by plants, can enter the soil solution and affect plant growth, seed germination, community composition and succession. Understanding the decomposition process of ABA in soil can help us to reveal the circulation of ABA in soils and its implication on plant growth. Soils were collected from an evergreen broadleaf forest in Xiaokeng, Nanling moutians, and soil physical and chemical properties and ABA concentration were measured. Additionally, an incubation experiment was conducted to measure soil ABA decomposition rate and the role of soil microorganism play in this process. Results showed that the concentration of ABA in soil solution was heterogeneous in space ranging from 29.8 ng·mL-1 to 167.0 ng·mL-1 (averaged at 91.5 ng·mL-1), and positively correlated with soil total nitrogen. About 33.5%of soil ABA was quickly decomposed by soil microorganisms during the first week of incubation, and then was decomposed slowly and linearly with a decomposition rate of about 0.24% per day afterwards. Soil ABA concentration and decomposition rate was positively correlated during the initial fast-decomposition period but was negatively correlated at the late slow-decomposition period. Soil microorganisms accelerated ABA decomposition on one hand and avoided the depletion of ABA in soil on the other hand.