干旱胁迫对喀斯特地区野生茶树幼苗生理特性及根系生长的影响

以贵州喀斯特地区4种野生茶树(Sect Thea(L.)Dyer)无性系幼苗为材料,采用盆栽控水方法研究其对干旱胁迫的生理生长响应,初步评价其抗旱性,并采用田间模拟持续干旱试验进行验证。结果表明:(1)随着干旱胁迫程度的加强,4种野生茶树叶片的相对含水量逐渐降低;细胞质膜透性、丙二醛(MDA)含量和可溶性糖含量均呈上升趋势;游离脯氨酸含量和超氧化物歧化酶(SOD)活性先升后降;过氧化物酶(POD)活性除秃房茶随胁迫程度加强呈上升趋势外,其他种均呈先升后降趋势。(2)随着干旱胁迫程度的加强,4种茶树幼苗总生物量干重均逐渐下降,根冠比先升后降;根系总长除在秃房茶中呈先升后降趋势外,在其他3个种中均逐渐下降;根系总表面积、根系总体积在大理茶和茶中逐渐下降,而在大厂茶和秃房茶中先升后降;根系平均直径在秃房茶中逐渐降低,大厂茶中先升后降,茶中逐渐升高;根系活力在大理茶中逐渐下降,在其他3种中均先升后降;而比叶面积则在大厂茶中呈下降趋势,在其他3种中均先升后降。(3)基于生长生理指标的隶属函数抗旱性评价结果表明,MDA含量和细胞质膜透性与野生茶树抗旱性密切相关,4种野生茶树幼苗的抗旱顺序为秃房茶(Camellia gymnogyna Chang)大厂茶(Camellia tachangensis F.C.Zhang)茶(Camellia Sinensis(L.)-O.Kuntze)大理茶(Camellia taliensis(W.W.Smish)),田间持续干旱试验验证了基于隶属函数抗旱性评价方法的准确性和可靠性。

Effects of drought stress on leaf physiological characteristics and root growth of the clone seedlings of wild tea plants

Physiological characteristics and root growth of clone seedlings from four species of wild tea plant were investigated under varying conditions of water stress (regular soil water content CK], mild drought stress T1], medium drought stress T2],and severe drought stress T3]) in the Karst region of Guizhou Province to understand the physiological response of the seedlings to drought stress and to screen out the drought-resistant germplasms. The results were verified by duplicating the field experiment over two years. The results of increasing drought stress were as follows: (1) The relative water content of the plants decreased gradually, while membrane permeability, malondialdehyde content (MDA), and soluble sugars all increased. The content of free proline and the activity of superoxide dismutase (SOD) increased with mild water stress and then decreased with increasing stress. The peroxidase activity (POD) in Camellia taliensis, Camellia tachangensis, and Camellia sinensis showed the same trend as SOD, but continued to increase in Camellia gymnogyna. (2) With increasing drought stress, the total dry weight of biomass decreased, and the root-shoot ratio increased under mild water stress and then decreased with increasing water stress for all four species. The root length of Camellia gymnogyna increased under mild stress and then decreased under increasing water stress, but those of the other three species decreased gradually with increasing water stress. The total surface area and volume of the roots of Camellia taliensis and Camellia sinensis showed a gradual decrease; but increased under mild water stress and then decreased under stress for Camellia tachangensis and Camellia gymnogyna. The root activity of Camellia taliensis declined gradually, whereas in the other three species, it increased under mild water stress and then declined under increased stress. Specific leaf area in Camellia tachangensis decreased with increasing water stress, whereas in the other three species it increased with mild water stress and then decreased with greater stress. (3) The MDA content and membrane permeability were closely related to the drought resistance of wild tea plants. The order of drought resistance was Camellia gymnogyna > Camellia tachangensis > Camellia sinensis > Camellia taliensis. The accuracy and reliability of the evaluation method based on membership function were validated by the duplication of the experiment over two years.