四季竹耐盐能力的季节性差异

Seasonal variations in salt tolerance of Oligostachyum lubricum

以四季竹2 a生竹苗为材料,通过盆栽试验设置土壤不同NaCl含量模拟盐胁迫环境,研究其在非生理活跃期的冬季(11—12月份)和生理活跃期的夏季(5—6月份)盐胁迫下的生理响应和叶片脱落情况,以了解四季竹耐盐能力的季节性差异。结果表明,在低土壤NaCl盐分(1‰—2‰)条件下,相同浓度处理45 d的竹苗叶片脱落率和各项生理指标较对照变化在冬季和夏季间差异不大,说明在低盐分条件下四季竹耐盐能力季节性差异不明显。在高土壤NaCl盐分(3‰—5‰)条件下,相同浓度处理45 d的叶片中除可溶性蛋白含量较对照升降幅度冬夏两季基本一致外,叶片脱落率、离子渗漏率、SOD活性、POD活性、脯氨酸含量和叶绿素含量分别较对照增加或降低的幅度冬季均显著小于夏季,并且随土壤NaCl浓度的提高冬夏两季的差异逐渐加大,而丙二醛含量和叶绿素a/叶绿素b变化规律在夏冬两季间完全相反,说明在高土壤盐分(3‰—5‰)条件下相同浓度、相同时间处理的四季竹在夏季的受伤害程度显著大于冬季,即高盐条件下四季竹在生理活跃期的夏季的耐盐能力较非生理活跃期的冬季弱。土壤盐分和环境温度对四季竹生长具有较强的交互作用。

Many environmental factors affect plant growth and development.Such factors vary in their effects on plants and can interact to strengthen or weaken the effect of another factor when acting simultaneously.Air temperature and soil salt are two environmental factors that commonly influence the growth of bamboo.Air temperature may lead to differences in the salt tolerance of bamboo in different seasons.However,knowledge about seasonal variation in salt tolerance of evergreen plants is limited.Oligostachyum lubricum is an important evergreen bamboo species in subtropical regions of China with multiple uses including shoot production,protection against soil erosion in coastal areas,and water conservation.O.lubricum exhibits resistance to low temperature and salt stress,as well as rapid growth and a long shooting period from May to October.To study seasonal variations in salt tolerance of O.lubricum,a pot experiment in which plants were treated with different soil NaCl concentrations was carried out.Two-year-old seedlings of similar height and diameter at breast height were treated by incorporating NaCl（0,1‰,2‰,3‰,4‰ and 5‰） into the soil.Each treatment contained three replicates.Plants were treated from November to December（winter） and May to June（summer）.The leaf abscission rate and leaf physiological characteristics（ion leakage rate,malondialdehyde content,chlorophyll content,chlorophyll a/b ratio,superoxide dismutase activity,peroxidase activity,proline content,and soluble protein content） were recorded after 45 days salt treatment in both seasons.At a low soil NaCl concentration（1‰—2‰）,the variation in leaf abscission rate and physiological parameters compared with the control was similar in winter and summer,which indicated that no seasonal variation in tolerance to low salinity existed.At a high soil salt concentration（3‰—5‰ NaCl）,variation in soluble protein content compared with the control showed the same trend in summer and winter,whereas the variations from the control in leaf abscission rate,ion leakage rate,superoxide dismutase activity,peroxidase activity,proline content and chlorophyll content in winter were smaller than those in summer.With increasing soil NaCl concentration,the differences in the values of these physiological characteristics between summer and winter increased,whereas malondialdehyde content and chlorophyll a/b ratio showed the opposite trend.The results indicated that O.lubricum seedlings stressed by a high soil salt concentration（3‰—5‰） were injured more severely in summer than during winter under the same soil NaCl concentration.Thus,O.lubricum seedlings showed much higher salt tolerance in winter than in summer,and air temperature and soil salt acting simultaneously had a significant effect on seedling growth.