The Occurrence Conditions And The Shading Effects Of Chilling-Induced Photoinhibition Of Tea Leaves

Whether the spring tea shoots grows vigorously is related with the physical status of tea leaves in winter. The climatic factors including low temperature,strong light and drought in Shandong Province could cause tea leaves red or brown in winter and spring, and thus reduced photosynthetic efficiency and the accumulation of photosynthesis substance in tea leaves, which was disadvantage to the tea trees through winter safely and growing in spring next year. In order to resolve this practical problem, by applying the theory of chill-temperature photoinhibition, the occurrence conditions of chill-temperature photoinhibition of tea leaves were investigated under the artificial environment which the temperature and light controlled. Meanwhile, as a representative of Taian tea area, the data of temperature and light was measured and recorded, then analyzed the occurrence probability of chill-temperature photoinhibition of tea leaves in winter and spring. In addition, the effect of shading in winter on abating chill-temperature photoinhibition of tea leaves was also researched. The main results were as follows:1. The points of chill-temperature photoinhibition of tea leaves under different temperature respectively were: (0℃,4.9klx),(5℃,7.4 klx),(10℃,10.4 klx),(15℃,15.7 klx).2. Chill-temperature photoinhibition of tea leaves was easily happened in Taian city during the period of winter and spring. The occurrence probabilities of chill-temperature photoinhibition of tea leaves from November to February next year respectively were: 89.0%,89.6%,97.7%,86.3%.3. Shading in winter could reduce day-max temperature and difference temperature value between day- maximum & day- minimum in tea greenhouse. In contrast to CK, shading could make day-maximum temperature low 5℃, but day- minimum temperature differ little than 1℃.4. Fv/Fm of tea leaves, a parameter of chlorophyll fluorescence kinetics, basically maintained at 0.80 under shading treatment, but Fv/Fm of CK was below 0.60. It concluded that shading treatment could obviously abate the degree of chill-temperature photoinhibition of tea leaves. 5. Shading in winter was favourable for the growth of spring tea shoots. The weight of one hundred buds,length of tea shoots,burl interval and leaf areas by shading treatment were respectively higher 19.66%,57.10%,47.44%,82.82% than that of CK.6. Shading in winter could improve the biochemical quality of spring tea shoots. In contrast to that of CK, the content of Chlorophyll a,Chlorophyll b and the total of Chlorophyll of tea leaves by shading treatment were respectively higher 26.86%,28.89%,27.46%; the content of TP reduced 11.93%; and the content of amino acid rose14.44%, the ratio of TP&AA reduced from 9.4 of CK to 7.2, which located the best range of the ratio of TP&AA (6～8) for processing famous green tea. In addition, the content of flavonoids and caffeine respectively rose more 6.69%,6.60% than that of CK.