Chitosan Spraying Enhances the Growth, Photosynthesis, and Resistance of Continuous Pinellia ternata and Promotes Its Yield and Quality

The continuous cropping obstacle has become the key factor that seriously restricts the growth, yield, and quality of Pinellia ternata. In this study, the effects of chitosan on the growth, photosynthesis, resistance, yield, and quality of the continuous cropping of P. ternata were investigated by two field spraying methods. The results indicate that continuous cropping significantly (p < 0.05) raised the inverted seedling rate of P. ternata and inhibited its growth, yield, and quality. Spraying of 0.5~1.0% chitosan effectively increased the leaf area and plant height of continuous P. ternata, and reduced its inverted seedling rate. Meanwhile, 0.5~1.0% chitosan spraying could notably increase its photosynthetic rate (Pn), intercellular carbon dioxide concentration (Ci), stomatal conductance (Gs), and transpiration rate (Tr), and decrease its soluble sugar, proline (Pro), and malonaldehyde (MDA) contents, as well as promoting its superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) activities. Additionally, 0.5~1.0% chitosan spraying could also effectively enhance its yield and quality. This finding highlights that chitosan can be proposed as an alternative and practicable mitigator for alleviating the continuous cropping obstacle of P. ternata.