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Acta Prataculturae Sinica ›› 2024, Vol. 33 ›› Issue (9): 1-14.DOI: 10.11686/cyxb2023380

   

Enzyme activity and microbial metabolic diversity in typical shrub rhizosphere soil in Ningxia desert steppe

Jia-ni YAO(), Shuang LIU, Jun-jie ZHANG, Ming-zhu HU, Jin-xia DAI()   

  1. College of Life Sciences,Ningxia University,Yinchuan 750021,China
  • Received:2023-10-11 Revised:2023-12-11 Online:2024-09-20 Published:2024-06-20
  • Contact: Jin-xia DAI

Abstract:

This research investigated the enzyme activity and microbial metabolic diversity of desert shrub rhizosphere soil for ecological restoration of desert soil. Four selected legume shrub species (Caragana spp., Ammopiptanthus mongolicusCaragana tibetica and Oxytropis aciphylla) within the Baijitan desert steppe in Ningxia were investigated using visible wavelength spectrophotometry and Biolog microplates, to determine if rhizosphere soil enzyme activity differed in different seasonal development periods (early season ‘nutritional’, flowering, and fruiting periods) and to determine the functional diversity of microbial metabolism. Significant differences in the enzyme activity of rhizosphere soil in the different seasonal phases of shrub growth were detected. In terms of different development periods, the rhizosphere soil urease activity of A. mongolicus was significantly higher than the other three shrubs, and the rhizosphere soil alkaline phosphatase activity of C. tibetica was significantly lower than the other shrubs. For the different development periods, during the nutritional period, rhizosphere soil urease and alkaline phosphatase activity of A. mongolicus were significantly higher than those of other periods, and rhizosphere soil urease and sucrase activity of the unidentified Caragana spp. were significantly lower than those of other periods. During the flowering period, rhizosphere soil urease and alkaline phosphatase activities ofthe Caragana spp., soil sucrase activity of A. mongolicus, and soil urease and dehydrogenase activities of O. aciphylla were significantly higher than at other periods. In the fruiting period, rhizosphere soil urease and alkaline phosphatase activities were highest in A. mongolicus and soil sucrase and dehydrogenase activities were highest in Caragana spp. Enzyme activities were generally low in the rhizosphere soils of C. tibetica during the flowering and fruiting periods. There were significant differences in the metabolic diversity of rhizosphere soil microbial communities in the different seasonal periods. Average well color development of the rhizosphere soil of the four shrub species increased gradually with the duration of incubation time, and the carbon sources utilization were mainly carbohydrates, amino acids and carboxylic acids. The microorganisms in the rhizosphere soil of the Caragana spp. had uniform distribution, strong metabolic activity and vigorous growth during the nutritional period. Principal component analysis showed that in the nutritional period, the carbon source utilization patterns of rhizosphere soil microorganisms were similar in A. mongolicusC. tibetica and O. aciphylla; in the flowering period the patterns were similar in the Caragana spp., A. mongolicus and O. aciphylla; in the fruiting period the patterns were similar in the Caragana spp. and A. mongolicus, and the patterns were similar in the C. tibetica and O. aciphylla. The soil microbial carbon source utilization pattern changed to different degrees through the three seasonal development periods. Redundancy analysis showed that enzyme activity and microbial metabolism were closely related to soil physicochemical properties. Urease was positively correlated with rhizosphere ammonium nitrogen (NH4+-N) level. Alkaline phosphatase activity was significantly positively correlated with soil water content. Sucrase was positively correlated with total nitrogen (TN), NH4+-N, soil organic matter and total phosphorus (TP) (TN were also significantly positively correlated). Also, TN, available phosphorus (AP), TP, available potassium, and nitrite nitrogen (NO2--N) significantly affected dehydrogenase activity. NH4+-N, NO2--N, TP, AP and nitrate nitrogen were the main physicochemical factors affecting microbial metabolic diversity. The results of this study provide insight to and understanding of the rhizosphere soil microenvironment and the rhizosphere microbial community response characteristics to the soil environment in Ningxia desert steppe.

Key words: legume shrub, soil enzyme activity, Biolog method, carbon source utilization, metabolic diversity