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Plant Growth‐Promoting Rhizobacteria (PGPR) Reduce Evaporation and Increase Soil Water Retention
Author(s) -
Zheng Wenjuan,
Zeng Saiqi,
Bais Harsh,
LaManna Jacob M.,
Hussey Daniel S.,
Jacobson David L.,
Jin Yan
Publication year - 2018
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/2018wr022656
Subject(s) - rhizobacteria , water retention , hydraulic conductivity , soil water , environmental science , water potential , agronomy , soil science , rhizosphere , biology , bacteria , genetics
Abstract Enhancement of plant drought stress tolerance by plant growth‐promoting rhizobacteria (PGPR) has been increasingly documented in the literature. However, most studies to date have focused on PGPR‐root/plant interactions; very little is known about PGPR's role in mediating physiochemical and hydrological changes in the rhizospheric soil that may impact plant drought stress tolerance. Our study aimed to advance mechanistic understanding of PGPR‐mediated biophysical changes in the rhizospheric soil that may contribute to plant drought stress tolerance in addition to plant responses. We measured soil water retention characteristics, hydraulic conductivity, and water evaporation in soils with various textures (i.e., pure sand, sandy soil, and clay) as influenced by a representative PGPR ( Bacillus subtilis strain UD1022) using the HYPROP system. We found that all PGPR‐treated soils held more water and had reduced hydraulic conductivity and accumulative evaporation, compared to their corresponding controls. We discuss three mechanisms, due to B. subtilis incubation or production of extracellular polymeric substances (EPS), that are potentially responsible for the changes in hydraulic properties and soil evaporation: (i) EPS have a large water holding capacity; (ii) EPS alter soil matrix structure and connectivity of pore space; (iii) EPS modify the physicochemical properties of water (surface tension and viscosity). These results clearly demonstrate PGPR's ability to increase water availability to plants by slowing down evaporation and by increasing the time available for plants to make metabolic adjustments to drought stress.