多枝柽柳幼苗生长及其根系解剖结构对水盐胁迫的响应

Response of growth and anatomical structure of roots of Tamarix ramosissima seedlings to salinity and water stress

本研究以塔里木河下游本土优势灌木多枝柽柳(Tamarix ramosissima)为研究对象,采用单因素盆栽控制试验,设置不同水分梯度(CK,75%FWC;D1,55%FWC;D2,35%FWC;D3,15%FWC;D4,水淹),不同盐分梯度(CK,基底盐的0.02%;轻盐胁迫S1,基底盐的0.2%;中盐胁迫S2,基底盐的0.5%;中高盐胁迫S3,基底盐的0.8%;高盐胁迫S4,基底盐的1.5%),研究水、盐胁迫对多枝柽柳幼苗生长、根系显微及超微结构的影响。结果表明,1)水分胁迫中,水淹处理60d后显著增加了幼苗株高、冠幅、生物量的积累(P<0.05),株高相对增长率、冠幅相对增长率分别是CK的1.9和0.9倍。盐胁迫下,随着盐浓度的增高,多枝柽柳幼苗的株高、冠幅相对增长率及生物量减小,S3处理下幼苗生物量显著下降83.42%(P<0.05)。2)盐胁迫下,随着盐浓度的增加根木质部导管孔径降低,S3处理组较对照组显著降低了64.15%(P<0.05),导管密度显著高于CK(P<0.05);水分胁迫下导管孔径和密度呈相反趋势。3)水、盐胁迫下,根细胞超微结构白色体中淀粉粒都有不同程度的肿胀变形,并伴有大量囊泡的产生。盐胁迫下细胞器有解体现象,中高盐胁迫S3下,白色体中淀粉粒膨大,膜破裂解体,细胞核核膜消失,而水分胁迫中未见解体现象,说明盐胁迫对多枝柽柳幼苗的影响大于水分胁迫。

Tamarix ramosissimais a dominate shrub in the lower reaches of the Tarim river.Using a single factor control test with indoor potted plants,five moisture gradients were employed：groups CK,D1,D2,D4,and D5（flooding）,for which soil water contents were 75%,55%,35%,15% field water capacity,and flooding treatment,respectively.For salt stress,the plant were treated with one of five salinity（CK,S1,S2,S3,S4）,soil salt contents were 0.02%,0.2%,0.5%,0.8%,1.5%.We analyzed the effects of water and salt stress on T.ramosissimaseedlings by measuring their growth,the roots of microstructure and ultrastructure.The results showed that：1）under water stress,the flooded D4,promoted the seedling height,crown diameter and biomass accumulation significantly.The relative growth rate of the seedling height and crown width were 1.9times and 0.9times of CK,respectively.With the increase of salt concentration,relative growth rates of plant height and crown width increased,and the biomass decreased.In the treatment S3,T.ramosissimaseedlings biomass decreased significantly at a rate of 83.42%.2）Under salt stress,the vessel diameter of the root xylemdecreased,and the diameter of the S3 treatment decreased by 64.5%significantly when compared with that of the control,but vessel densities were higher than that of control group.Opposite trends of the vessel variations were observed under water stress.3）There were swelling and deformation of starch grains in the root cells under different water and salt stresses,and accompanied by a large number of vesicles secreted.But there was a disintegration phenomenon of organelles under salt stress.Starch grains of the root cell in the leucoplast grew large,the membrane of leucoplast and nucleus disintegrated in the treatment S3.While it was not observed in the disintegration of root organelles under water stress.The results of the experiment proved that salt stress had more influence on T.ramosissimaseedlings than water stress.