Abstract:

Bitter gourd variety 'Jintian 188' were used as test materials in artificial climate chamber. LED pure white light 200μmol·m⁻²·s⁻¹ was taken as control (CK), and red and blue light 200, 300 and 400μmol·m⁻²·s⁻¹ treatments were set up, and the ratio of red and blue light was R7:B3. The photoperiod was day/night = 14h/10h. The purpose of this study was to explore the effects of red and blue light intensity on the growth of bitter gourd seedlings by comparing and analyzing the morphological indices, antioxidant enzyme activities, gas exchange parameters, chlorophyll fluorescence parameters and leaf tissue structure. The results showed that: (1) under red and blue light irradiation, the morphological indices, gas exchange parameters, chlorophyll fluorescence parameters and leaf tissue structure of bitter gourd seedlings were significantly improved compared with those under white light conditions. (2) With the increase of red and blue light intensity, the plant height, stem diameter, leaf area, fresh weight, dry weight and seedling index of bitter gourd seedlings increased gradually, and the plant growth became better. Pn, Gs, Ci and Tr showed increasing trends. Chlorophyll content, Y(II), qP, ETR and Fv'/Fm' were significantly increased. The thickness of leaves, palisade tissue and sponge tissue all increased significantly, and the cells of palisade tissue changed from different lengths and loose arrangement to basically the same length and neat and dense arrangement. The results showed that the morphological indices, photosynthetic efficiency and photosynthetic ability of bitter gourd seedlings were improved under red and blue light irradiation. The performance of 400μmol·m⁻²·s⁻¹ red and blue light treatment was the best, which was the suitable light intensity for bitter gourd seedlings. 

Key words: Red and blue light intensity, Bitter gourd seedlings, Morphological indices, Photoreaction index