Effects of Continuous Cropping on Yield and Quality of Stevia by Changing Soil Properties

Abstract:

In order to understand the mechanism of continuous cropping obstacles, the changes in soil properties after continuous cropping of Stevia rebaudiana were studied, and the correlations between soil properties and leaf dry mass and stevioside were discussed. The results showed that there were no significant differences in soil pH, organic matter, available phosphorus, urease, catalase, sucrase, phosphatase, leaf dry weight and stevioside components between 2- and 3-year continuous cropping. However, after continuous cropping for 4 years, soil pH, total nitrogen and available potassium decreased significantly, which were 10.07%, 14.38% and 24.79% lower than the control, respectively. But the soil electric conductivity (EC) and available phosphorus increased significantly with 2.57 and 1.70 times to the control. Meanwhile, the activities of urease, sucrase, alkaline phosphatase, microbial biomass carbon and microbial biomass nitrogen in soil were 63.68%, 72.03%, 47.43% and 78.35% lower than the control, while the activity of polyphenol oxidase reached the highest, which was 4.22 times to the control. Compared with the control, leaf dry weight and stevioside decreased by 29.51% and 16.00%, while the content of rebaudioside A increased by 22.19%. There were correlations between leaf dry weight and stevioside content and soil properties. Therefore, it was suggested that continuous cropping affects the yield and quality of stevia by changing soil properties, and the maximum continuous cropping period in production should not exceed 3 years.

Key words:Stevia rebaudiana;Continuous cropping;Soil property;Yield