Variation in rhizosphere priming and microbial growth and carbon use efficiency caused by wheat genotypes and temperatures. (July 2019)

• Record Type: Journal Article
• Authors: Yin, Liming; Corneo, Paola E.; Richter, Andreas; Wang, Peng; Cheng, Weixin; Dijkstra, Feike A.
• Is Part Of: Soil biology and biochemistry. Volume 134(2019)
• Page Start: 54
• Page End: 61
• Publication Date: 2019-07
• Subjects: Soil organic matter turnover -- Rhizosphere priming effect -- Net C balance -- Wheat genotype -- Warming; Soil biochemistry -- Periodicals; Soil biology -- Periodicals; Sols -- Biochimie -- Périodiques; Sols -- Biologie -- Périodiques; Sols -- Microbiologie -- Périodiques; Bodembiologie; Biochemie; 631.46
• DOI: 10.1016/j.soilbio.2019.03.019
• Languages: English
• ISSNs: 0038-0717

Abstract

Abstract: Living roots can influence microbial decomposition of soil organic matter, which has been referred to as the rhizosphere priming effect (RPE). Both microbial carbon efficiency (CUE) and microbial growth and turnover rates are associated with microbial decomposition and respiration of soil-derived C, but their linkage to the RPE remains poorly understood. Here we used a natural 13 C tracer method to determine the RPE in soils planted with two wheat genotypes (249 or IAW2013) grown at high (30/24 °C during day/night) and low temperature (25/17 °C during day/night). We also determined microbial CUE, growth and biomass turnover rate using a substrate-independent H2 18 O labeling method. The RPE varied from −2 to +455%, with significant effects of genotype, sampling date and their interaction with temperature. Compared to the unplanted control, microbial biomass C and growth/turnover rate were both enhanced in planted pots, with an average increase of 17% and 70%, respectively. Microbial CUE was lowest in pots planted with IAW2013 at low temperature, but there were no significant main effects of planting and temperature. Microbial biomass growth/turnover rate together with CUE accounted for 83% of the variation in soil-derived CO2, with a relatively larger contribution of microbial biomass growth/turnover rate (52%) than CUE (31%). Furthermore, using linear regression, we demonstrated that the RPE was significantly positively related to microbial biomass growth/turnover rate. No net soil organic C (SOC) loss or gain was detected, indicating that any increase in SOC due to increased microbial growth/turnover was counteracted by C loss caused by a higher RPE during the relatively short time of planting. These findings suggest that microbial biomass turnover associated with growth could control the loss of SOC with planting. We highlight the importance of plant-induced changes in microbial CUE and biomass growth/turnover for long-term soil C dynamics. Graphical abstract: Image 1 Highlights: The rhizosphere priming effect (RPE) ranged from −2% to +455%. Microbial biomass turnover rate was significantly accelerated by planting. Microbial C use efficiency was not significantly affected by planting. RPEs were predominantly associated with increases in microbial biomass turnover.