Microalgae as a potential conditioner for continuous cropping obstacles for taro (Colocasia esculenta L. Schott) production

Continuous cropping of Fenghua taro leads to poor quality. In this research, two pollution tolerant algae, Spirulina platensis and Chlorella vulgaris, were selected as conditioners for continuous cropping obstacles of taro production. The composition, abundance, and biodiversity of the bacteria and fungi communities in soil rhizosphere of continuous cropping were compared to non-continuous cropping, and studied in-depth. These results showed that the growth of taro during continuous cropping, when irrigated with Chlorella vulgaris and Spirulina platensis, was significantly better than the control group without algal cell irrigation. Accordingly, the plant height, leaf length, leaf area, moisture, carbohydrate, and protein in continuous cropping were 128 cm, 69 cm, 56 cm, 72 g/100 g, 10.8 g/100 g and 2.4 g/100 g, respectively, when watered with Chlorella vulgaris. Furthermore, compared with continuous cropping, the abundance of plant pathogens in the taro rhizosphere, fertilized with Spirulina platensis, were significantly reduced, while the corresponding abundance of soil beneficial bacteria was significantly increased. Specifically, the abundance of beneficial bacteria Ceratobasidium and Pulveroboletus increased, and the pathogens such as Curvularia, Erysiphe, and Clonostachys decreased, during continuous cropping when irrigated with Spirulina platensis. Live microalgae, after wastewater treatment, could be used as potential conditioners to avoid obstacles during continuous cropping of taro production.