连作改变土壤性状对甜叶菊产量和品质的影响

为了解连作障碍的产生机理,对甜叶菊(Stevia rebaudiana)连作后的土壤性状变化进行了研究,并探讨土壤性状与叶片干质量和甜菊糖苷之间的相关性。结果表明,连作2 a和3 a的土壤pH值、有机质、速效磷、脲酶、过氧化氢酶、蔗糖酶、磷酸酶和甜叶菊叶片干质量及甜菊糖苷组分含量均无显著差异。连作4 a后,土壤pH值、全氮和速效钾含量显著下降,分别比对照降低了10.07%、14.38%和24.79%,土壤电导率(EC)和速效磷含量显著增加,是对照的2.57和1.70倍;土壤脲酶、蔗糖酶、磷酸酶活性、微生物量碳和微生物量氮在连作4 a降到最低,比对照分别降低了63.68%、72.03%、47.43%、78.35%和41.07;多酚氧化酶则在连作4a达到最高,是对照的4.22倍;与对照相比,连作4a的叶片干质量和甜菊苷含量降低了29.51%和16.00%,莱鲍迪苷A含量则增加了22.19%。叶片干质量及甜菊糖苷含量与土壤性状间存在着相关性。因此,连作通过改变土壤性状影响甜叶菊产量和品质,生产中最大连作年限不宜超过3 a。

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

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.