遮光对光照敏感型新梢白化茶春梢化学成分含量的影响

以光照敏感型新梢白化茶树‘黄-2’、‘黄-8’和‘黄-13’为供试材料,在春季一芽一叶期采用30%透光度的黑色遮阳网覆盖遮光处理7天,HLPC法检测一芽二叶新梢咖啡因、儿茶素类、氨基酸类和色素类化合物含量。结果显示,遮光处理对茶叶咖啡因含量无显著影响;遮光对儿茶素类总含量的影响因品种而异,在品系‘黄-2’显著提高,而品系‘黄-8’和‘黄-13’则显著降低;遮光显著提高品系‘黄-13’的氨基酸总含量,降低品系‘黄-8’氨基酸总含量,但对品系‘黄-2’无显著影响;遮光显著提高β-胡萝卜素、叶绿素a、叶绿素b和新黄质的含量,显著降低紫黄质含量。具有热耗散作用的黄体素在光照敏感新梢白化茶品种的含量很低,是其容易受到强光胁迫伤害的原因。在强光照条件下,光照敏感型新梢白化茶叶片呈现黄色,主要是叶绿素含量显著降低,而不是因为胡萝卜素和叶黄素含量提高所致。根据这些研究结果,作者认为:在高温强光季节采取适度遮光,将有助于光照敏感型新梢白化茶提高叶片叶绿素含量,增强光合作用,进而提高茶苗生长势和抗性,有助于提高茶苗移栽成活率。

Effect of light-shading on chemical composition of spring shoots on light-sensitive albino tea plants

Light-sensitive albino tea cultivars ‘Huang -2’,‘Huang -8’and ‘Huang -1 3’were used as tested cultivars in the present study.At the growing stage of spring shoots with one leaf and a bud,the plants were covered using black shading net with 30% light transmittance for 7 days,and then tea shoots with two leaves and a bud were sampled for HPLC analysis of caffeine,catechins,amino acids and pigments.The results showed that shading treatment had no significant effect on the caffeine content of the tea shoots.The effect of shading on the total content of tea catechins varied with tea cultivars,with significant increase in cultivar ‘Huang-2’,but significant decrease in cultivars ‘Huang -8’and ‘Huang-1 3’.Total content of amino acids was significantly reduced in the shaded cultivar ‘Huang-8’,but was significantly increased in the shaded cultivar ‘Huang-2 ’,while it showed no significant differences between light-shading treatment and control in cultivar ‘Huang-2 ’.The light-shading treatment significantly increased the contents of carotenoid,chlorophyll a,chlorophyll b and neoxanthin,but significantly decreased the content of violaxanthin.Under strong light condition,the new shoots on plants of light-sensitive albino tea cultivars showed yellow color,which was induced by the significant decrease in chlorophyll content,instead of the increase in carotenoids and lutein contents.Content of lutein,a pigment with heat dissipation function,was very low in the light-sensitive albino tea cultivars,which is considered to be a reason why they were easily injured by strong light stress.In the seasons with high temperature and strong sun-light,appropriate light shading will be beneficial to promoting chlorophyll biosynthesis and photosynthesis in the tea leaves,resulting in improvement of the growing vigor and resistance to environmental stress of tea plants,which will contribute to increase in survival rate of the transplanted young tea plants.