Effects of Continuous Red and Blue Light on Growth and Physiological Characteristics of Pepper Seedlings

Abstract

【Objective】In modern vegetable facility cultivation, the quality of vegetable seedlings plays a very important role in the economic benefits of subsequent agricultural production. Continuous light is a common special light mode in artificial light plant factory. Exploring the effect of continuous light combined with light quality on the growth and development of pepper seedlings could provide an important technical reference for efficiently improving the resistance of pepper seedlings.【Method】The pepper backbone parent '6421' was used as the test material, and 6 light treatment groups were set up: normal white light irradiation group (CW), normal blue light irradiation group (CB), normal red light irradiation group (CR), continuous white light irradiation group (TW), continuous blue light irradiation group (TB) and continuous red light irradiation group (TR). The effects of continuous photoperiod treatment combined with red and blue light on the growth and physiological characteristics of pepper seedlings were studied.【Result】(1) TR significantly increased the plant height and stem diameter of pepper seedlings by 20.5% and 10.6%, respectively, compared with the CW group. After TR treatment, the seedling index increased significantly by 2.38 times, while TB significantly reduced the plant height and stem diameter of pepper seedlings by 17.1% and 14.3%, and the root-shoot ratio increased significantly by 2.62 times. (2) There was no significant difference in Pn and Gs of pepper seedling leaves between TR and TB, but Tr and Ci of TB were significantly lower than those of TR. Compared with CW, Tr and Ci of TB were significantly reduced by 62.5% and 51.1%. The chlorophyll fluorescence parameters of pepper seedling leaves showed opposite results after different light treatments. The Fv/Fm, Fv/Fo, NPQ and qP values of pepper seedling leaves in TB group were significantly higher than those in TR group. The qP of TB and TR was significantly higher than that of CW, increasing by 36.1% and 26.1%, respectively. (3) The antioxidant enzyme activity and osmotic substances of pepper seedlings were significantly different after continuous red light treatment and continuous blue light treatment. TB significantly increased SOD, POD and CAT in leaves of pepper seedlings. The POD and CAT activities of pepper seedling leaves were also significantly increased after TR treatment, while the MDA content of pepper leaves after TB and TR treatments was significantly reduced by 55%-56% compared with that of CW.【Conclusion】Continuous light conditions have a positive effect on the growth and development of pepper seedlings at the seedling stage, and the antioxidant enzyme activity and osmotic substances of pepper seedlings under continuous light irradiation combined with monochromatic red and monochromatic blue light treatments increase to different degrees to better counteract the light stress environment and improve the adaptability of pepper seedlings.

Keywords

• continuous light
• light quality
• pepper
• photosynthetic characteristics
• facility cultivation
• enzyme activity