盐雾胁迫对肯氏南洋杉幼苗生长及离子分布的影响

Effects of salt spray stress on growth and ion distribution of Araucaria cunninghamii seedlings

盐雾是限制滨海地区植物生长发育的主要因素之一。本文探讨了盐雾对肯氏南洋杉生长的影响,及其耐盐雾的能力和机理。实验选取生长一致(树龄为1年)的肯氏南洋杉幼苗进行Na Cl盐雾胁迫实验,设置0、0.7%、1.4%、2.1%、2.8%、3.5%6个Na Cl质量分数处理,胁迫第30天统计其盐害情况,并测定K^(+)、Na^(+)、Cl^(-)3种离子在根、茎、叶以及新叶、成叶、老叶中的含量。研究表明:肯氏南洋杉幼苗具有较强耐盐雾能力,在30 d(每次50 m L,每天2次)的盐雾胁迫下,其耐盐阈值在1.4%~2.1%之间。肯氏南洋杉的针叶小且革质,气孔上方覆盖着不透水的蜡质原纤维厚层,抑制盐雾进入植物体,随着叶片的老化,蜡质原纤维风化融合后形成气孔塞,进一步阻断盐雾进入植物体的途径,故老叶抵御盐雾的能力更强。通过叶片进入植物体的盐分,被分隔到特定的区域(Na^(+)运往茎,Cl^(-)积累在叶),从而减轻盐分对地上部分的伤害;同时根选择性地向地上部分运输K+,提高K^(+)/Na+比值以减缓盐分对地上部分生理代谢的伤害。肯氏南洋杉具有良好的抗盐性及抗风性,可作为我国华南滨海地区的城市园林绿化树种,以及沿海风景林、防风林树种。

Salt spray is one of the main factors limiting the growth and development of plants in coastal ar-eas.In this study,the effects of salt spray on the growth of Araucaria cunninghamii and its ability and mechanism of salt spray tolerance were explored.One-year-old seedlings with the same growth state were selected,and six NaCl concentration gradients(0%,0.7%,1.4%,2.1%,2.8%and 3.5%)were set up in the test.The salt damage was calculated on the 30th day of stress.The contents of Kt,Na*and Cl^(-)in roots,stems and leaves,as well as in new,mature and old leaves were determined.The results showed that A.cunninghamii seedlings had strong tolerance to salt spray,and the salt tolerance threshold was between 1.4%-2.1%under 30 days of salt spray stress(50 mL each time,twice a day).The needles of A.cunninghami are small and leathery,and the pores are covered with thick layer of impervious waxy fibril,which inhibits the entry of salt spray.With the aging of leaves,the waxy fibril is weathered and fused to form stomata plug,blocking the way of salt spray entering the plant,so the old leaves have a stronger ability to resist salt spray.The salt that enters the plant through the leaves is separated into specific areas(Na^(+)mainly stored in the stem,Cl^(-)is mainly accumulated in the leaves),so as to reduce the damage of salt to the above-ground part.At the same time,the root selectively transports K*to the above-ground part and increases K^(+)/Na^(+)mass ratio to slow down the damage of salt to its physiological metabolism of aboveground part.Due to the excellent resistance to salt and wind,A.cunninghami can be used as urban landscaping tree,coastal landscape forest tree and windbreak forest tree in coastal areas of South China.