干旱胁迫对茶树幼苗生长及叶绿素荧光特性的影响

在全球变暖的气候背景下,干旱已成为限制作物生产发展的重要因素,但目前关于干旱胁迫下不同茶树的生理生化响应研究相对较少。以黄金茶1号（HJC-1）、壶瓶山8号（HPS-8）和壶瓶山15号（HPS-15）等10个茶树品种（系）的一年生幼苗为材料进行盆栽控水试验,对持续性干旱胁迫处理下茶树幼苗的表型、叶片结构、叶绿素含量、叶绿素荧光参数和可溶性糖含量进行研究。结果表明,干旱胁迫使其叶长、叶宽缩短,叶片数减少,侧根数增多,植株矮化;叶片厚度、上表皮厚度、栅栏组织厚度、海绵组织厚度、下表皮厚度、栅栏组织与海绵组织比值均呈现下降趋势。叶绿素a、叶绿素b和总叶绿素含量与对照组相比均有所增加,且叶绿素a含量存在极显著性差异（P<0.000 1）。10个茶树品种（系）在干旱胁迫下均受到光抑制,与对照组相比,Fo、Fv/Fm和Fv/Fo值减少,而Fm值增大。叶片可溶性糖含量在干旱胁迫下与正常水分环境相比有所增加,除湘农1号（XN-1）外,其他品种（系）的增加量均有显著性差异。通过耐旱性隶属函数值法比较得出,茶树HPS-8、湘农18号（XN-18）、湘农9803号（XN-9803）、湘农9810号（XN-9810）和湘农9809号（XN-9809）的抗旱能力较弱,HJC-1、HPS-15、XN-1、湘农9802号（XN-9802）和壶瓶山20号（HPS-20）的抗旱能力相对较强。

Effects of Drought Stress on Growth and Chlorophyll Fluorescence Characteristics of Tea Seedlings

In the context of global warming, drought has become an important factor restricting the development of crop production, but there were relatively few studies on the physiological and biochemical responses of different tea cultivars to drought stress. Here, a pot water control experiment was conducted using annual tea seedlings of 10 tea cultivars (strains) such as Huangjincha 1 (HJC-1), HPS-8, and HPS-15 as materials. The chlorophyll content, chlorophyll fluorescence parameters and soluble sugar content were studied. The results show that: drought stress shortened the leaf length and width, reduced the number of leaves, increased the number of lateral roots, and dwarfed the plant. Furthermore, leaf thickness, upper epidermal thickness, fence tissue thickness, sponge tissue thickness, lower epidermal thickness and ratio of fence tissue to sponge tissue also decreased under stress. Chlorophyll a, chlorophyll b, and total chlorophyll contents increased compared to the control group, and the increase of chlorophyll a content was significant. Photoinhibition was observed in all tea cultivars (strains) under drought stress. The values of Fo, Fv/Fm and Fv/Fo of tea cultivars under stress were lower than the control group, but the Fm values showed an opposite trend. The soluble sugar content of leaves significantly increased under drought stress compared with the control, except tea cultivar XN-1. Further analysis shows that HPS-8, XN-18, XN-9803, XN-9810 and XN-9809 have low drought tolerance but HJC-1, HPS-15, XN-1, XN-9802 and HPS-20 have relatively strong drought tolerance.