Effects of late time illumination delayed regulation at night on growth and photosynthetic characteristics of spring berry of Kyoho grape

【Objective】 The effects of three kinds of light quality supplemental on the growth and photosynthetic characteristics of spring berry of Kyoho grape were studied and provided theoretical basis for improving the cultivation and management techniques of spring berry of Kyoho grape in Guangxi.【Method】 Five-year Kyoho grape in facilities cultivation was selected as the research object and exposed to three different kinds of discontinuous illumination treatments at night, including white, red and blue lights for 6 h(03:00-06:00, 18:00-21:00), natural light was taken as control(CK). The treatment was prolonged from the new shoots expansion period until harvest. The effects of different supplemental light treatments on shoot growth, leaf chlorophyll content, photosynthetic physiology and fruit physiology and biochemistry indexes of spring berry of Kyoho grape were studied.【Result】 Under three different light quality conditions, the basal diameter, length of shoot from the 1^st to 10^th node, leaf length, leafwidth, petiole length and leaf thickness of spring berry of Kyoho grape was higher than the CK. The basal diameter and the length of shoot from the 1st to 10th node had the largest growth increment and significantly increased by 12.80% and 27.00% than CK under blue light treatment for 6 h(P<0.05, the same below). The leaf length, petiole length, leaf thickness and ratio of leaf length to width of 6 h white light treatment were the best, which were 11.78%, 55.90%, 12.90% and 1.85% higher than CK, respectively. The leaf width had the largest growth increment and significantly increased by 15.06% than CK under red light treatment for 6 h. Compared with CK, supplement of white light for 6 h and red light for 6 h at night could increase the chlorophyll content of Kyoho grape leaves at different growth stages. The net photosynthetic rate, stomatal conductance, transpiration rate, single berry weight, transverse diameter and soluble solids of Kyoho grape spring berry increased in different degrees under different light qualities and light supplement treatments, while the intercellular CO₂ concentration of the leaf and titratable acid content of fruit decreased in different degrees.【Conclusion】 The results show that 6 h supplemental red light and white light treatments can compensate for the lack of light in the spring Kyoho grape cultivation. The growth and development of grapes can be adjusted through artificial light supplement to improve the berry quality.