3种园林树木种子萌发期耐盐性研究

Study on Salt Stress of 3 Ornamental Trees during Germination Period

以杠柳、白蜡和孩儿拳3种绿化树种为材料,在室内设置5个NaCl胁迫梯度,系统测定了其种子的萌发、生长和生理生化指标及其耐盐临界值,并用隶属函数法综合评价了它们在种子萌发期的耐盐性。结果表明:随着盐胁迫浓度的增加,杠柳、白蜡和孩儿拳种子的萌发率、萌发指数、胚根生长速率、胚轴生长速率、种子活力指数和相对含水量均呈逐渐下降趋势,且相同盐处理的指标值及各指标的耐盐临界值均表现为杠柳>白蜡>孩儿拳;随着盐胁迫浓度的增加,杠柳和白蜡的SOD活性、POD活性和MDA含量分别呈现先降后升、先升后降和保持较低水平的趋势,而孩儿拳则分别表现出先升后降、持续下降和大幅先降再升的趋势;各树种隶属函数法综合评价的耐盐性依次为杠柳>白蜡>孩儿拳。可见,各树种种子萌发和生长均受到不同程度盐胁迫伤害,杠柳的耐盐性明显强于白蜡和孩儿拳。

With the controlled experiment and the grads of salt stress, the characters of physiological biochemistry of 3 ornamental trees Periploca sepiurn ,Fraxinus velutina ,Grewia biloba var. parvi flora were studied during their seeds germination. And the growth,the activity of defense enzymes, the lipid peroxida- tion and the critical salt concentration of three species had been measured systematically,and evaluated by the fuzzy subordination methods. The results showed that with the increase of salt concentration, the seed germination rate, germination index, radicle growth rate, hypocotyl growth rate, vigor index and the relative water content of the three species reduced gradually. Under salt stress,this phenomenon of P. sepium〉F. velutina〉G, biloba var. parviflora during the germination time. The critical salt concentrations for every salt tolerance index were P. sepium〉F, velutina〉G, biloba var. parviflora. With the increase of salt concentration,superoxide dismutase （SOD） activities of P. sepium and F. velutina decreased at first,increased at end;Peroxidase （POD） activities increased at first,and decreased at end;and the contents of MDA kept the lower level during stress. But SOD activities of G. biloba var. parviflora increased at first, and de- creased at end;POD activities declined continually;and the content of MDA had more variation range. The salt resistances of the three species decreased in the order of P. sepiurn〉F, velutina〉G, biloba var. parviflora by the evaluated of the fuzzy subordination methods. The seeds germination and growth of the three species were impacted by salt stress, P. sepium had stronger NaC1 tolerant ability than F. velutina had and the NaC1 tolerance of F. velutina was stronger than that of G. biloba var. parviflora.