不同盐分水平对柽柳扦插苗根系生长及生理特性的影响

摘要

Tamarix chinensis is a dominant shrub in the Yellow River Delta region.Salt glands occur on the leaves of T.chinensis,which can effectively exclude salt from the plant.However,due to the effects of global climate change and human over-exploitation of seawater resources,soil salinization and degradation has occurred in this region.The growth of T.chinensis has gradually decreased under conditions of high soil osmotic pressure,poor aeration and moisture,low nutrient availability,and high soil salinity.However,the roots can directly sense soil salinity changes,which mean that the effect of differing salinity on the eco-physiological characteristics of roots of T.chinensis cuttings is very important for the ecological restoration of coastal wetlands.In the present study,we studied the effects of different salinities (0.0,0.4％,0.8％,1.2％,2.4％,3.6％ NaCl solutions) on the eco-physiological characteristics of roots of 1-year old T.chinensis.To explore the response of T.chinensis root growth and eco-physiological characteristics to different salinity levels,the rooting rate of T.chinensis cuttings,root lifespan,root number,root length,aboveground biomass,root biomass,hydrogen peroxide enzyme (CAT) activity,adenosine triphosphate (ATP) synthase,and the content of abscisic acid were determined.The results revealed that (1) the rooting rate was approximately 83％ in the 0.8％ NaCl treatment,and the rooting rate and life of the root decreased significantly when the salinity increased to greater than 0.8％;(2) the root length gradually decreased with increasing salinity,while the root quantity initially increased and then decreased with increasing salinity once the salinity was greater than 1.2％;(3) examining the biomass allocation pattern of T.chinensis adjustment to acclimate to salinity conditions,the aboveground biomass was higher than root biomass at lower salinity and the proportion of root biomass increased gradually;however,was still less than the aboveground biomass;and (4) the activity of ATP synthase and CAT increased when salinity was less than 0.8％,and the activities decreased when the salt content was greater than 0.8％.In addition,the content of abscisic acid increased with increasing salinity and then decreased when the salinity increased to greater than 1.2％.%柽柳(Tamarix chinensis)作为黄河三角洲湿地的优势种之一,对盐渍化环境具有较好的适应性.根系作为植物直接感受盐分变化的器官,其对盐分条件的响应特征对研究植物生存、湿地恢复、土壤改良等具有重要意义.以一年生柽柳插穗为研究材料,采用水培法,设置6个盐分水平:CK(空白对照)、0.4％、0.8％、1.2％、2.4％、3.6％进行试验,测定柽柳生根率、根寿命、根系生物量等生长指标及根中ATP合成酶和过氧化氢酶(CAT)活性及脱落酸(ABA)含量,研究柽柳根系生长及生理特性对不同盐分水平的响应.结果表明:(1)柽柳适合扦插繁殖的培养溶液含盐量低于0.8％;含盐量超过0.8％后,扦插生根率显著降低,根系寿命减短.(2)柽柳根长生长随含盐量升高呈下降趋势;主根数随含盐量升高先增加,至含盐量超过1.2％后逐渐减少.(3)柽柳可通过调整生物量的分配模式来适应盐环境,低盐时地上部生物量高于地下,高盐时根系生物量比例逐渐增加,但生物量仍低于地上部分.(4)ATP合成酶活性、CAT活性在含盐量低于0.8％时增加;含盐量超过0.8％时,活性降低;脱落酸(ABA)含量随含盐量增加先增加,含盐量超过1.2％时减少.