4种白蜡的耐盐性响应特征与综合评价

Salt Tolerance Response and Comprehensive Evaluation for Four Kinds of Fraxinus

以1年半生绒毛白蜡、美国红梣、美国白梣和中国白蜡实生苗为材料,进行为期28d的水培试验,通过测定4种NaCl浓度(0、40、80、120mmol/L)处理下其形态、生长量、膜透性、抗氧化酶系统、叶绿素含量以及光合参数等指标的变化特征,并通过相关分析、主成分分析和隶属函数法对4种白蜡进行了综合耐盐性分析与评价,以明确盐胁迫条件下4种白蜡植物的生理响应特征及其耐盐性差异,为盐碱地绿化树种筛选提供科学依据。结果表明:(1)盐胁迫条件下,4种植物形态特征受到不同程度影响,相对株高生长量都受到抑制;叶片膜透性和丙二醛含量随盐浓度的增加而增加,而叶绿素含量随盐浓度的增加而减少。(2)不同盐浓度处理下,4个白蜡植物叶片过氧化物酶活性呈先上升后下降的变化趋势,其峰值出现在40或80mmol·L^-1NaCl,超氧化物歧化酶活性变化规律不完全相同;随着NaCl浓度的增加,4种白蜡树种叶片的平均净光合速率都呈现下降的趋势,但绒毛白蜡升降趋势较平缓,胞间CO2浓度、气孔导度和蒸腾速率变化没有明显的规律性。(3)耐盐性综合评价结果显示,4种白蜡树种的耐盐性大小为绒毛白蜡>美国白梣>美国红梣>中国白蜡,这与盐害形态症状表现的结果排序相一致。研究发现,4种白蜡树种在盐胁迫下的生长、生理响应明显不同,耐盐性存在明显差异;绒毛白蜡和美国白梣在盐胁迫下的抗氧化酶活性更强,光合能力和生长受到的影响更小,具有更优异的耐盐能力,可优先作为中国沿海地区盐碱地造林绿化树种或抗逆育种的主要试验材料。

The physiological response characteristics and salt tolerance diversity of four kinds of Fraxinus were studied under salt stress to provide scientific basis for the selection of landscaping tree species in saline-alkali land. A 28-day hydroponic experiment was conducted with one-and-a-half-year-old seedlings of Fraxinus velutina , F. pennsylvanica , F. americana a nd F. chinensis as materials. Their morphology, growth, membrane permeability, antioxidant enzyme activity, chlorophyll content and photosynthetic parameters under NaCl treatments of four concentrations (0, 40, 80, 120 mmol/L) were measured and comprehensively analyzed and evaluated by correlation analysis, principal component analysis and membership function method. The result showed that:(1) under salt stress, the morphological characteristics, relative plant height and growth of four species were inhibited. Membrane permeability and malondialdehyde (MDA) content increased with the raising of salt concentration, while chlorophyll content decreased.(2) With the rising salt concentrations, the activity of POD in leaves of Fraxinus plants first increased and then decreased, with its peak appeared at 40 or 80 mmol·L -1 , though SOD enzyme activity showed different fluctuations.(3) Average net photosynthetic rate ( P n) of leaves of four species decreased with the rising NaCl concentration, in which the rate of F. velutina decreased gently. Intercellular CO 2 concentration ( C i), stomatal conductance ( G s) and transpiration rate ( T r) were changed with no obvious regularity.(4) The comprehensive evaluation of salt tolerance of these four species reached the following conclusions: F. velutina > F. americana > F. pennsylvanica > F. chinensis which shares the same tendency of the morphologic symptoms of salt damage. Therefore, F. velutina and F. americana can be the main experimental materials for stress resistance breeding and be the important species for afforestation in saline-alkali land in coastal areas of China.