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.

Chitosan as an Adjuvant to Enhance the Control Efficacy of Low-Dosage Pyraclostrobin against Powdery Mildew of Rosa roxburghii and Improve Its Photosynthesis, Yield, and Quality.

Powdery mildew is the most serious fungal disease of Rosa roxburghii in Guizhou Province, China. In this study, the control role of chitosan-assisted pyraclostrobin against powdery mildew of R. roxburghii and its influences on the resistance, photosynthesis, yield, quality and amino acids of R. roxburghii were evaluated. The results indicate that the foliar application of 30% pyraclostrobin suspension concentrate (SC) 100 mg L−1 + chitosan 500 mg L−1 displayed a superior control potential against powdery mildew, with a control efficacy of 89.30% and 94.58% after 7 d and 14 d of spraying, respectively, which significantly (p < 0.01) exceeded those of 30% pyraclostrobin SC 150 mg L−1, 30% pyraclostrobin SC 100 mg L−1, and chitosan 500 mg L−1. Simultaneously, their co-application could effectively enhance their effect on the resistance and photosynthesis of R. roxburghii leaves compared to their application alone. Meanwhile, their co-application could also more effectively enhance the yield, quality, and amino acids of R. roxburghii fruits compared to their application alone. This work highlights that chitosan can be applied as an effective adjuvant to promote the efficacy of low-dosage pyraclostrobin against powdery mildew in R. roxburghii and improve its resistance, photosynthesis, yield, quality, and amino acids.