scholarly journals Rhizobium Inoculation Enhances the Resistance of Alfalfa and Microbial Characteristics in Copper-Contaminated Soil

2022 ◽  
Vol 12 ◽  
Author(s):  
Chengjiao Duan ◽  
Yuxia Mei ◽  
Qiang Wang ◽  
Yuhan Wang ◽  
Qi Li ◽  
...  

Some studies have reported the importance of rhizobium in mitigating heavy metal toxicity, however, the regulatory mechanism of the alfalfa-rhizobium symbiosis to resist copper (Cu) stress in the plant-soil system through biochemical reactions is still unclear. This study assessed the effects of rhizobium (Sinorhizobium meliloti CCNWSX0020) inoculation on the growth of alfalfa and soil microbial characteristics under Cu-stress. Further, we determined the regulatory mechanism of rhizobium inoculation to alleviate Cu-stress in alfalfa through plant-soil system. The results showed that rhizobium inoculation markedly alleviated Cu-induced growth inhibition in alfalfa by increasing the chlorophyll content, height, and biomass, in addition to nitrogen and phosphorus contents. Furthermore, rhizobium application alleviated Cu-induced phytotoxicity by increasing the antioxidant enzyme activities and soluble protein content in tissues, and inhibiting the lipid peroxidation levels (i.e., malondialdehyde content). In addition, rhizobium inoculation improved soil nutrient cycling, which increased soil enzyme activities (i.e., β-glucosidase activity and alkaline phosphatase) and microbial biomass nitrogen. Both Pearson correlation coefficient analysis and partial least squares path modeling (PLS-PM) identified that the interactions between soil nutrient content, enzyme activity, microbial biomass, plant antioxidant enzymes, and oxidative damage could jointly regulate plant growth. This study provides comprehensive insights into the mechanism of action of the legume-rhizobium symbiotic system to mitigate Cu stress and provide an efficient strategy for phytoremediation of Cu-contaminated soils.

2021 ◽  
Author(s):  
Chengjiao Duan ◽  
Yuxia Mei ◽  
Qiang Wang ◽  
Yuhan Wang ◽  
Qi Li ◽  
...  

Abstract Although some studies have reported an important role of rhizobia in mitigating heavy metal toxicity, the regulatory mechanism of the alfalfa-rhizobium symbiosis system to resist copper (Cu) stress through biochemical reactions in the plant-soil system is still unclear. Hence, this study assessed the effects of rhizobium inoculation (i.e., Sinorhizobium meliloti CCNWSX0020) on the growth of alfalfa and soil enzyme activities under Cu stress. Our results showed that rhizobium inoculation markedly alleviated Cu-induced growth inhibition by increasing chlorophyll content, height and biomass and the contents of nitrogen and phosphorus in alfalfa. The content of malondialdehyde (MDA) was increased in both shoot and root of alfalfa under Cu stress. The application of rhizobium alleviated Cu-induced phytotoxicity by increasing the activity of antioxidant enzymes and soluble protein content of tissues and inhibiting the level of lipid peroxidation (i.e., MDA level). In addition, rhizobium inoculation improved soil nutrient cycling, increased soil enzyme activities (i.e., β-glucosidase activity and alkaline phosphatase) and microbial biomass nitrogen. Both Pearson correlation coefficient analysis and partial least squares path modeling (PLS-PM) identified that the interactions between soil nutrient content, enzyme activity, microbial biomass and plant antioxidant enzymes and oxidative damage could jointly regulate plant growth. This study provides comprehensive insights into the mechanism of action of the legume-rhizobium symbiosis system to mitigate Cu stress and provide an efficient strategy for phytoremediation of Cu-polluted soils.


2015 ◽  
Vol 45 (4) ◽  
pp. 394-401 ◽  
Author(s):  
Yong-Sheng Wang ◽  
Shu-Lan Cheng ◽  
Gui-Rui Yu ◽  
Hua-Jun Fang ◽  
Jiang-Ming Mo ◽  
...  

Nitrogen (N) deposition has been shown to affect soil carbon (C) and N cycling in subtropical forests; however, the underlying microbial mechanisms are poorly understood. We used patterns of community-level physiological profiles and enzyme activities to assess the relative effects of the addition of four N levels (0, 50, 100, and 150 kg·ha−1·year−1) on the soil microbial community in three forest stands (pine, mixed, and broadleaf forests) in southern China, where the forests have been experimentally manipulated for over 8 years. In pine forests, N50 addition significantly increased microbial biomass carbon (MBC) concentration but decreased soil pH levels. N100 addition significantly increased soil peroxidase activity but decreased soil β-1,4-glucosidase activity. In broadleaf forests, N addition increased soil dissolved organic carbon (DOC) concentration and polyphenol oxidase activity but decreased soil MBC concentration and soil pH levels. N addition also significantly increased soil microbial metabolism activity (expressed as average well color development) in pine forest and broadleaf forest soils. However, the mixed forests responded slowly to N additions and exhibited no significant response of C-utilization profiles and soil enzyme activities. Principal component analysis of C-utilization data separated microbial communities with respect to N addition and forest successional stage. In addition, microbial C utilization was driven by soil pH levels. Although enzyme activities were correlated with soil MBC and microbial biomass nitrogen concentrations, stepwise regression results indicated that soil total carbon contents that were integrated with soil pH levels were key integrators of soil enzyme activities. Our results suggest that soil acidification due to N addition increased soil bacterial C utilization and enzyme activities.


2011 ◽  
Vol 2011 ◽  
pp. 1-10 ◽  
Author(s):  
Changting Wang ◽  
Genxu Wang ◽  
Wei Liu ◽  
Pengfei Wu

Four different alpine meadow communities were studied to examine the effects of plant-soil-enzyme interactions on plant composition and diversity. Enzyme activities differed by meadow type, and in general were higher in the upper soil layers (0–10 and 10–20 cm) than in the 20–40 cm layer. Community differences in plant composition or functional group composition were reflected in plant biomass distribution. The identity of a species (or a functional group) was a greater determinant of ecosystem function than the number of plant species. A significant correlation was found between the coverage per functional group and the aboveground biomass of functional groups in four alpine meadows. Soil microbial biomass carbon (Cmic) and enzyme activity were each affected by both functional group biomass andCABin the different meadow types. The negative correlation between diversity andCABin theKTSmay be influenced by a high soil nutrients input as a result of a higher litter input because of high aboveground biomass. Soil enzyme activities have been related to soil physio-chemical characters and plant primary production to change in vegetation. The original soil conditions, plant community composition, and community productivity are very important in regulating plant community productivity and microbial biomass and activity.


2019 ◽  
Vol 56 (3) ◽  
pp. 305-311
Author(s):  
Debasis Purohit ◽  
Mitali Mandal ◽  
Avisek Dash ◽  
Kumbha Karna Rout ◽  
Narayan Panda ◽  
...  

An effective approach for improving nutrient use efficiency and crop productivity simultaneously through exploitation of biological potential for efficient acquisition and utilization of nutrients by crops is very much needed in this current era. Thus, an attempt is made here to investigate the impact of long term fertilization in the soil ecology in rice-rice cropping system in post kharif - 2015 in flooded tropical rice (Oryza sativa L.) in an acidic sandy soil. The experiment was laid out in a randomized block design with quadruplicated treatments. Soil samples at different growth stages of rice were collected from long term fertilizer experiment.The studied long-term manured treatments included 100 % N, 100% NP, 100 % NPK, 150 % NPK and 100 % NPK+FYM (5 t ha-1) and an unmanured control. Soil fertility status like SOC content and other available nutrient content has decreased continuously towards the crop growth period. Comparing the results of different treatments, it was found that the application of 100% NPK + FYM exhibited highest nutrient content in soils. With regards to microbial properties it was also observed that the amount of microbial biomass carbon (MBC) and microbial biomass nitrogen ( MBN) showed highest accumulation in 100 % NPK + FYM at maximum tillering stage of the rice. The results further reveal that dehydrogenase activity was maximum at panicle initiation stage and thereafter it decreases. Soil organic carbon content, MBC, MBN and dehydrogenase activity were significantly correlated with each other. Significant correlations were observed between rice yield and MBC at maturity stage( R2 = 0.94**) and panicle initiation stage( R2 = 0.92**) and available nitrogen content at maturity stage( R2 = 0.91**).


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