Vermicompost tea: Effects on pak choi (Brassica rapa cv. Bonsai, Chinensis group) growth and yield, phytonutrient content and soil biological properties.

摘要

Vermicompost tea, an aqueous extract of vermicompost has been reported to improve plant health, yield and nutritional quality. Most of the previous research on compost tea has investigated the potential of compost tea for control of plant disease. Very limited data exists on the use of vermicompost tea for improving the yield and nutritional quality of vegetable crops and altering soil biological properties. Therefore, laboratory, greenhouse and field experiments were conducted in order to identify and describe: 1) the effects of vermicompost tea extraction methods [(i) non-aerated (NCT), (ii) aerated (ACT), and (iii) aerated with additives (ACTME)], fertilizer types (Osmocote and vermicompost), and three growth media (Oxisol, Mollisol and a peat-perlite medium) on yield and nutritional quality of pak choi ( Brassica rapa, Chinensis) as well as soil biochemical properties; 2) the effects of the ratio of vermicompost to water and different fertilizers on yield and nutritional quality of pak choi as well as soil biological properties; 3) the effect of compost quality on biochemical properties of compost tea; and 4) mechanisms involved in the effects of compost tea on plant growth.;The results showed that applications of vermicompost tea, regardless of extraction method, increased plant yield, mineral nutrients and phytonutrient content of pak choi. The microbial activities of two soils and a peat-perlite medium were also increased. This effect was most prominent under organic fertilization. These findings suggest that vermicompost tea serves both as a supplemental source of plant nutrients and an enhancer of soil biological properties. Similarly, application of vermicompost tea with compost to water ratios of 1:10 - 1:100 (v:v) increased yield, total carotenoids, total glucosinolates and N content of pak choi; and microbial activities in soil. The responses of these parameters to vermicompost to water ratio was positive and linear. The results also indicated that biochemical properties of compost determined biochemical properties of compost tea, and variability in quality of tea explained differences in the magnitude of effect of compost tea on plant growth and tissue mineral nutrient. The positive effect of vermicompost tea or compost tea on plant growth was largely associated with N (NO3-) and gibberellin (GA4) present in the tea and nutrient uptake by plants.