Effects of Root Spraying Chitosan on Growth and Quality of Pakchoi in Aeroponics

Objective To explore the effects of spraying exogenous chitosan on the growth and quality of pakchoi under low temperature environment, and to screen out the appropriate concentration of exogenous chitosan, so as to provide a theoretical basis for alleviating the low temperature stress of pakchoi.

Methods In this study, different concentrations of exogenous chitosan (0, 50, 100, 150, 200 μmol·L⁻¹) were sprayed on the roots of pakchoi 'Jizao 30' under low temperature conditions. The growth, photosynthetic pigments, antioxidant enzyme activities, osmotic adjustment substances, quality and mineral nutrient contents of pakchoi were determined.

Results Under low temperature stress, at 28 days, the leaf length of the CTS50 treatment reached a relatively high level and was significantly increased by 10.4% compared with the control (CTS0). Regarding the content of photosynthetic pigments,compared with the control, the contents of chlorophyll a,chlorophyll b, carotenoids, and total chlorophyll were increased by 1.9%, 106%, 91.7%, and 19.4% respectively. As for antioxidant enzyme activities, compared with the control,the activities of superoxide dismutase, peroxidase, and catalase were increased by 1.4%, 84.6%, and 166% respectively. In terms of quality, the contents of soluble sugar and soluble protein were increased by 79% and 17.9% respectively compared with the control.

Conclusion Spraying 50 μmol·L⁻¹ chitosan on roots can promote the growth, photosynthetic pigment and antioxidant enzyme activity of pakchoi in aeroponics under low temperature environment, improve the quality and mineral nutrition absorption of pakchoi.