舟山新木姜子(Neolitsea sericea)幼苗对不同盐胁迫的光合生理响应

Responses of photosynthetic physiological characteristics of Neolitsea Sericea seedlings to different salt stress

为评价舟山新木姜子(Neolitsea sericea)的耐盐性, 对其在不同盐胁迫下的光合生理特性进行实验研究。以舟山新木姜子 2 年实生幼苗为试验材料进行盆栽实验, 通过添加不同浓度的 NaCl 溶液, 设置 4 个不同土壤盐分处理(土壤含盐量分别为 0、0.3%、0.6% 和 0.9%)。分别在第 10 d、20 d、30 d、40 d, 测定舟山新木姜子幼苗在不同处理条件下的叶片叶绿素含量(Chl)、净光合速率(P)和最大光化学效率(Fv/Fm)等指标。结果表明:在不同处理之间, 在相同的胁迫阶段, 叶片 Chl 无显著性差异(P>0.05);在各胁迫阶段, 随着土壤含盐量的增大,叶片 P、最大光合速率(P)和光饱和点(LSP)都呈现下降趋势。在轻度盐胁迫(0.3%)舟山新木姜子幼苗叶片 Fv/Fm 介于 0.74—0.78 之间, 与对照无显著性差异(P<0.05), 中度(0.6%)和重度盐胁迫(0.9%)最终都显著降低了叶片 Fv/Fm;在胁迫初期, 0.3%、0.6%和 0.9%土壤盐分处理条件下 P与 CK 相比分别下降了 29.46%、52.51%、97.91%;在胁迫初期, LCP 随土壤含盐量的增加而升高, 0.3%土壤盐分处理条件下叶片 LCP 随胁迫时间的延长呈现先下降后上升的趋势。研究表明, 舟山新木姜子幼苗在轻度盐胁迫下(土壤含盐量 0.3%)生长受到了一定程度的抑制, 但仍能正常存活, 表现出一定的耐盐性;在中度(土壤含盐量 0.6%)和重度盐胁迫下(土壤含盐量 0.9%)则无法存活。该研究结果为该物种迁地保护和滨海盐碱地造林树种选择提供了理论科学依据。

The photosynthetic physiological characteristics of Neolitsea sericea seedlings stressed by soil salt were studied, in order to evaluate its salt tolerance. 2-year-old seedlings were used for the pot experiment. Four treatments of soil salt content (0, 0.3%, 0.6%and 0.9%) were set by adding sodium chloride solute with different concentrations. Determinations were implemented on chlorophyll content (Chl), net photosynthetic rate (P), and maximum photochemical efficiency (Fv/Fm) of the treated seedlings on the10, 20, 30and 40day. The results showed that there were no significant differences in Chl at the same stress period among all treatments (P>0.05). P, Pand light saturation point (LSP) decreased with increasing intensity of soil salt stress. Under 0.3% of soil salt content, Fv/Fm ranged from 0.74 to 0.78, being non-significantly different with CK, but both moderate (0.6%) and severe (0.9%)salt stress significantly reduced Fv/Fm. At the early stage of stress, Pof treatments under 0.3%, 0.6% and 0.9% of soil salt content were decreased by 29.46%, 52.51% and 97.91%, respectively, compared with those of CK. At the early stage of stress, LCP increased with increasing intensity of soil salt stress. Under 0.3% of soil salt content, LCP had the tendency of declining at the beginning and rising by the end of the duration of salt stress. The research showed that Neolitsea sericea had certain tolerance to light soil salt stress(soil salt content was no more than 0.3%) and survived, but it could not survive in the conditions of moderate and severe soil salt stresses. The results provided a scientific basis for its ex-situ conservation and afforestation in coastal saline-alkali soil.