作 者 ：石元值 方丽 吕闰强
期 刊 ：植物营养与肥料学报 2014年 20卷 5期 页码：1251-1262
Keywords:canopy microenvironment, carbon and nitrogen metabolism, tea quality,
摘 要 ：【目的】树冠微域环境对植物的生长有着显著影响，改善植物树冠环境可提升收获对象的品质。因此茶树的生长特别是其碳氮代谢及茶叶品质可能会受到树冠微域环境影响，本文拟通过覆盖遮荫的方式人为改变茶树树冠微域环境，以探明树冠微域环境对茶树碳氮代谢等的影响。【方法】采用田间小区试验，通过在茶树树冠面上分别覆盖光热透过性能不同的三种遮荫材料，人为改变茶树树冠面的微域环境，以不覆盖为对照，比较不同树冠微域环境条件下树冠面空气温度、空气湿度、光照等环境因子的变化及光合速率等的差异，并通过氨基酸组分分析及高效液相色谱等方法对不同季节茶树新梢中碳氮初级代谢产物进行分析，以比较树冠微域环境变化对茶树碳氮代谢及茶鲜叶品质等的影响。【结果】茶树树冠面经三种光热透过性能不同的遮阳网在蓬面直接覆盖后，茶树新梢的生长小环境及碳氮代谢均发生了变化： 1）树冠面的光照强度、空气温度及叶片温度均得到了不同程度的降低，空气相对湿度得到了不同程度的提高。其中覆盖隔热网的降温效果最好，降温幅度最高可达3.1℃；覆盖银色网在早晚有较好的降温效果，降温幅度可达1.6℃，但在12时、14时和16时未有明显的降温效果。而覆盖黑网后早晨的树冠面空气温度与叶片温度却显著高于其他各处理，且随着外界温度的升高，黑网下的两种温度与不覆盖比表现出了波动现象。2）茶树被覆盖后，其净光合速率表现出显著的降低趋势，其中黑网覆盖处理与不覆盖处理均在中午12点左右出现一个低谷，出现了“午睡”现象，而银色网与隔热网覆盖处理没有表现出“午睡”现象；覆盖后茶树叶片胞间CO2浓度较不覆盖表现出升高趋势，其中以隔热网处理为最高。3）在高温强光季节对茶树进行适度遮荫覆盖，能在一定程度上促进茶树氮代谢，减弱茶树碳代谢，改善各季茶树新梢的品质。主要表现为茶新梢的叶绿素含量、氮磷钾等养分含量、游离氨基酸总量显著增加；氨基酸组分如茶氨酸、谷氨酸、天冬氨酸等也均表现出显著增加趋势；茶新梢中总碳含量及茶多酚等碳水化合物含量降低；总碳、C/N、茶多酚含量等显著降低，儿茶素组分降低但儿茶素品质指数增加、苦涩味指数降低；三种茶树微域环境中，隔热网覆盖的树冠环境对茶叶品质提升方面效果最明显。4）与不覆盖相比，茶树新梢产量表现出了降低的趋势。【结论】通过遮荫覆盖等方式调控茶树树冠微域环境会影响茶树碳氮代谢等生理活动、提高茶鲜叶品质，但茶鲜叶的产量表现出降低的趋势。
Abstract:Abstract: 【Objectives】The microenvironment of tea plants affects the growth, especially the carbon and nitrogen metabolism and the tea qualities of the tea. Optimized canopy microenvironment can improve the qualities of the harvested objects. In this study, the canopy microenvironment of tea plants was changed by shading with different cover materials to explore how the carbon and nitrogen metabolism and the tea qualities of the tea plants were influenced.【Methods】Plot trials were carried out and three different kinds of shading films with different light and thermal transmittance characters were tested, with no cover as the control. The changes in the temperature and humidity of air over the canopy and tea tree leaves were measured and compared, the primary productions of the carbon and nitrogen metabolism in the tea shoots of different seasons were assayed with the amino acid components analyzer, the HPLC and so on.【Results】 After 10 days’ shading treatments, the differences in the microenvironment over tea shoots and the carbon and nitrogen metabolism have been observed. 1) The temperature of leaves and air above the canopy, the luminous intensity over the canopy of tea plants are decreased, and the air humidity is increased in different extents for all the three sheltering films. The air temperature of the canopy was decreased 3.1℃ by covering with the heat insulated net and 1.6℃ by the silver net, but the decrease was not significant at 12: 00 am, 14: 00 pm and 16: 00 pm. For the black net treatment, the temperature of air and leaves in the morning is higher than the other two cover treatments, and as the climate temperature increasing, the microenvironmental temperature and leaf surface temperature wavies. 2) The net photosynthetic rates of tea plants with covered treatments decrease significantly. Trough were shown with the black net and control treatments at 12: 00 am, named as a nap phenomenon. The nap phenomenon do not exist with the silver net and heat insulated net treatments at 12: 00 am. The intercellular CO2 concentrations in tea leaves of the covered treatments show an increasing trend compared with control, with the highest in the heat insulated net treatment. 3）During the high temperature and strong luminous intensity season, making moderate shading for the tea plants can promote the nitrogen metabolism and weak the carbon metabolism in some extent, and improve the qualities of the tea shoots in different seasons. Those mainly show as that he contents of chlorophyll, nitrogen, phosphorus, potassium, the contents of the total amino acid and so on are improved significantly, the contents of the components of amino acid, such as the theanine, glutamic acid, aspartic acid, are improved significantly, and the total carbon, C/N, the tea polyphenol are decreased significantly, the catechin fractions decreased but the index of catechin quality is increased, the index of bitter taste is decreased, also the canopy microenvironment under the heat insulated net has the best effects on improving the tea qualities among the three different shading nets. 4) The tea yields are decreased in some extents after the tea plants are covered by different shading materials.【Conclusions】The canopy microenvironment of tea plants can affect on the growth, especially the carbon and nitrogen metabolism and the tea qualities of the tea plants. But the tea yields are decreased in some extents after the tea plants are covered by different shading materials.
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