Influences of Main Meteorological Factors on Leaf Sunburn of Tea Cultivar 'Huangjinya'

Tian Yueyue; Zhang Lixia; Zhang Zhengqun; Li Zhi; Hou Jian; Qiao Mingming

doi:10.14083/j.issn.1001-4942.2017.07.009

Abstract：'Huangjinya', one of light sensitive tea germplasm resources, was bred from natural yellow mutant single plant in Deshi tea plantation, Yuyao City, Zhejiang Province, in 1998.It is prone to cause physical disorder and leaf sunburn when the light intensity is more than 60 klx.The occurrence and symptoms of leaf sunburn of 3-year-old tea cultivar 'Huangjinya' (HJY) were investigated in Taian area from April to July in 2016.At the same time, the leaf temperature and three main meteorological factors including light intensity, air temperature and humidity were also measured.The difference between leaf temperature and air temperature (ΔTL-A) was calculated, and the effects of main meteorological factors on leaf temperature and ΔTL-A were explored to analyze the occurrence conditions of leaf sunburn.The results were as follows.(1) The symptoms of leaf sunburn could be generally divided into three main types: white, red and necrotic, and the degree of burn injury aggravated in turn.(2) Tea cultivar 'HJY' began to show symptoms of leaf sunburn in mid May, and this phenomenon was particularly obvious from late May to June in Taian area.(3) Blaze light intensity and high leaf temperature were the two necessary conditions for causing leaf sunburn of 'HJY'.The phenomenon of leaf sunburn appeared when the daily maximum light intensity exceeded 100 klx and the daily maximum leaf temperature exceeded 38~40℃.The threshold temperature of leaf sunburn was 38℃ when the leaf temperature varied greatly throughout the day.However, it could be increased to 40℃ if the leaf temperature change was small and the leaves were exercised in high temperature.(4) The leaf temperature and ΔTL-A were significantly affected by light intensity, air temperature and air humidity, but their relevance was various in different periods.According to the above results, some technology measures such as shading, intercropping and sprinkler which could dim light, cool temperature and increase air humidity were put forward, and they could prevent 'HJY' from leaf sunburn effectively in the sensitive period.