Pedosphere 29(2): 259--265, 2019
ISSN 1002-0160/CN 32-1315/P
©2019 Soil Science Society of China
Published by Elsevier B.V. and Science Press
Phenological Stage, Plant Biomass, and Drought Stress Affect Microbial Biomass and Enzyme Activities in the Rhizosphere of Enteropogon macrostachyus
Kevin Z. MGANGA1,2, Bahar S. RAZAVI1, Muhammad SANAULLAH3,4, Yakov KUZYAKOV1,3,5
1Department of Soil Science of Temperate Ecosystems, Institute of Soil Science, University of Göttingen, Göttingen 37077 (Germany)
2Department of Range and Wildlife Sciences, South Eastern Kenya University, Kitui 90200 (Kenya)
3Department of Agricultural Soil Science, Institute of Soil Science, University of Göttingen, Göttingen 37077 (Germany)
4Institute of Soil and Environmental Sciences, University of Agriculture, Faisalabad 38000 (Pakistan)
5Institute of Environmental Sciences, Kazan Federal University, Kazan 420049 (Russia)
Corresponding Author:Kevin Z. MGANGA
ABSTRACT
      Indigenous grasses have been effectively used to rehabilitate degraded African drylands. Despite their success, studies examining their effects on soil bioindicators such as microbial biomass carbon (C) and enzyme activities are scarce. This study elucidates the effects of drought stress and phenological stages of a typical indigenous African grass, Enteropogon macrostachyus, on microbial biomass and enzyme activities (β-glucosidase, cellobiohydrolase, and chitinase) in the rhizosphere soil. Enteropogon macrostachyus was grown under controlled conditions. Drought stress (partial watering) was simulated during the last 10 d of plant growth, and data were compared with those from optimum moisture conditions. The rhizosphere soil was sampled after 40 d (seedling stage), 70 d (elongation stage), and 80 d (simulated drought stress). A high root:shoot ratio at seedling stage compared with elongation and reproduction stages demonstrated that E. macrostachyus invested more on root biomass in early development, to maximise the uptake of nutrients and water. Microbial biomass and enzyme activities increased with root biomass during plant growth. Ten-day drought at reproduction stage increased the microbial biomass and enzyme activities, accompanying a decrease in binding affinity and catalytic efficiency. In conclusion, drought stress controls soil organic matter decomposition and nutrient mobilization, as well as the competition between plant and microorganisms for nutrient uptake.
Key Words:  African grass,catalytic efficiency,cellobiohydrolase,chitinase,β-glucosidase,nutrient uptake,optimum moisture,soil bioindicators
Citation: Mganga K Z, Razavi B S, Sanaullah M, Kuzyakov Y. 2019. Phenological stage, plant biomass, and drought stress affect microbial biomass and enzyme activities in the rhizosphere of Enteropogon macrostachyus. Pedosphere. 29(2):259-265.
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