【目的】 了解沼泽小叶桦(Betula microphylla var. paludosa)在海水处理土壤和海水处理叶片两种条件下的生长和生理响应,为耐盐树种的选择与应用提供依据。【方法】 用稀释成不同盐度(含盐量)的海水对1.5年生的沼泽小叶桦扦插苗进行根系浇灌和叶片喷雾处理。根系浇灌处理的盐度为盆栽基质质量的0%(CK)、0.2%、0.4%、0.6%(质量分数,下同);叶片喷雾处理的盐度为0(CK)、3.07、6.14、15.35 g/L。观察苗木的形态变化,并测定其生长和生理指标。【结果】 当用海水处理土壤(根系浇灌)的盐度在0.6%以下、处理叶片(叶片喷雾)的盐度在6.14 g/L以下时,沼泽小叶桦苗所受盐害较小,存活率均为100%。低盐度的海水处理(0.2%)土壤能提高沼泽小叶桦叶片叶绿素含量和可溶性蛋白含量,并促进苗木生长。海水处理土壤和海水处理叶片均导致叶片相对电导率升高,且海水处理叶片的涨幅更大。海水处理土壤条件下的苗木叶片丙二醛(MDA)含量低于CK,海水处理叶片条件下的MDA含量高于CK,但差异均不显著。除高盐度的海水处理(15.35 g/L)叶片外,其他海水处理的苗木叶片SOD活性总体上均低于CK。海水处理后,苗木叶片过氧化物酶(POD)活性在处理早期高于CK,在处理后期低于CK。【结论】 沼泽小叶桦能耐受盐度为0.6%的土壤海水浇灌处理或盐度为6.14 g/L的叶片海水喷雾处理,表现出较强的耐盐特性,在滨海盐碱地绿化中具有一定的应用潜力。

【Objective】 The aim of this research is to study the growth and physiological responses of Betula microphylla var. paludosa exposed to salt stress in seawater and provide the basis for the selection of seawater-tolerant tree species. 【Method】 Seawater diluted to different salinities (salt content) was used for root irrigation and leaf spray treatment of 1.5-year-old B. microphylla var. paludosa cutting seedlings. The root irrigating salinity was 0% (CK), 0.2%, 0.4% and 0.6% (mass fraction, same as below), respectively. The salinity of spray treatment on the leaves was 0 (CK), 3.07, 6.14, and 15.35 g/L, respectively. We observed morphological changes in the cutting seedlings and measured their growth and physiological indexes. 【Result】 When the salinity of the soil seawater treatment was below 0.6%, and the salinity of the leaf seawater treatment was below 6.14 g/L, the cutting seedlings suffered less salt damage and survived completely. Low salinity (0.2%) of seawater treatment on the soil could increase the content of chlorophyll and soluble protein in leaves to a certain extent and promote the growth of cutting seedlings. Both seawater treatments on the soil and the leaves could lead to an increase in the relative conductivity of leaves, but the increase in seawater treatment on the leaves had a more significant effect than that on the soil. The malondialdehyde (MDA) content of leaves under seawater treatment on the roots was lower than that of the control treatment (CK), and the MDA content of leaves under the seawater treatment on the leaves was higher than that of CK, but the difference between them was not significant. In addition to the high salinity (15.35 g/L) of seawater treatment on the leaves, the activity of superoxide dismutase in the leaves of other seawater treatments was lower than that of CK. After seawater treatment of the soil and leaves, the peroxidase activity of cutting seedling leaves was higher than that of CK in the early stage and lower than that of CK in the later stage. 【Conclusion】 B. microphylla var. paludosa could withstand soil seawater treatment with a salinity of 0.6% or leaf seawater treatment with a salinity of 6.14 g/L, showing a strong tolerance to seawater, and had substantial application potential in saline land greening.