Abstract:
The study on the regulation of antioxidant enzymes of greenhouse tomato by earthworm fertilizer would provide a theoretical and technical support for improving disease and stress resistance of vegetables under facility cultivation conditions. In a greenhouse pot experiment, four treatments were set up: control (CK), chemical fertilizer (CF), cow manure (CM) and earthworm fertilizer (EM). Phenotypic traits (plant height, stem diameter, SPAD value, and leaf area) were observed, and functional leaves and roots were collected at 25, 50, and 75 d after planting to determine defense enzyme activities (catalase, CAT; peroxidase, POD; polyphenol oxidase, PPO, and superoxide dismutase, SOD), root activity, and malondialdehyde content (MDA). The results showed that (1) Earthworm fertilizer significantly increased the leaf area and root activity of tomato plants, but had no significant effect on plant height, stem diameter, root fresh weight, leaf SPAD values, and root malondialdehyde content. The ratio of root to shoot in the vermicompost treatment showed an increasing trend with the tomato reproductive period. (2) Similar trends were observed between root and leaf defensive enzyme activities with reproductive period of tomato, with a downward trend in CAT, PPO and SOD activities, and an upward trend in POD activities. Earthworm fertilizer increased the CAT and POD activities during the reproductive period of tomato. The PPO activities in the EM treatment were increased by 21.63%-511.2% and by 54.6%-163.9% compared with the other treatments and CM treatment, respectively. The SOD activities in the CF treatment were decreased by 23.32%-91.67% compared with the CM and EM treatments. (3) Correlation analysis showed that leaf area was highly significantly positively correlated with root POD activities, root vigor was highly positively correlated with leaf POD, and root POD was highly positively correlated with leaf POD, PPO and SOD. The application of earthworm fertilizer at an appropriate rate in facility vegetable production can improve the plant's antioxidant defense ability, enhance crop resistance and disease resistance, and promote crop growth and development, which would lay a foundation for high yield and green pest control.