Na2SO4胁迫对沙枣幼苗生长和光合生理的影响

采用盆栽控制试验,研究了不同浓度(0、60、120和180 mmol·L-1)Na2SO4胁迫对沙枣幼苗生长和光合特性的影响。结果表明:(1)盐胁迫对沙枣幼苗生长具有显著的抑制效应。不同浓度Na2SO4胁迫沙枣的株高、侧枝数、总叶面积、单株叶片数、比叶面积以及各组织(除根)生物量均显著低于对照,且均随盐胁迫浓度的升高呈下降趋势,而根冠比值则由对照的0.153 1显著增加到180 mmol·L-1Na2SO4胁迫幼苗的0.348 7。(2)盐胁迫显著降低了沙枣幼苗的光合能力。随着Na2SO4胁迫的加剧,净光合速率(Pn)、气孔导度(Gs)、胞间CO2浓度(Ci)和蒸腾速率(Tr)均呈下降的趋势,而气孔限制值(Ls)和水分利用效率(WUE)则依次增加,且Pn下降主要受气孔限制;180 mmol·L-1Na2SO4胁迫沙枣幼苗的Pn、Gs、Ci和Tr分别为对照的71.57%、30.85%、67.15%和51.65%,而Ls和WUE则分别为对照的1.91、1.38倍。(3)盐胁迫强度与幼苗株高、总叶面积、单株叶片数、比叶面积、茎生物量、叶生物量、总生物量等生长指标以及Pn、Gs、Ci、Tr等光合参数呈极显著负相关,叶片的光合参数与总叶面积、单株叶片数呈显著或极显著正相关,而叶片的生长指标、光合参数与幼苗的株高生长和生物量累积也呈显著或极显著正相关。

Effects of Na2SO4 Stress on Growth and Photosynthetic Physiology of Elaeagnus angustifolia Seedlings

A pot experiment was conducted to investigate the effects of salt stress (0, 60, 120 and 180 mmol·L^-1 Na₂SO₄) on the growth and photosynthetic characteristics of Elaeagnus angustifolia seedlings. The results showed that: (1) the plant growth was significantly inhibited by salt treatment. The tree height, number of branches, specific leaf area, total leaf area, leaf number per plant, and the biomass accumulation of stem, leaf, shoot and whole-plant of Na₂SO₄-stressed seedlings were all significantly lower than those of the control (no salt-stressed). With the salt concentration elevated, the above-mentioned growth parameters generally exhibited a decreasing trend, while the root-shoot ratio increased significantly from control's 0.153 1 to 180 mmol·L^-1 Na₂SO₄-stressed seedlings' 0.348 7. (2) The photosynthetic capacity decreased by salt stress significantly. The net photosynthetic rate (P_n), stomatal conductance (G_s), intercellular CO₂ content (C_i) and transpiration rate (T_r) of seedlings treated by 180 mmol·L^-1 Na₂SO₄ were only 71.57%, 30.85%, 67.15% and 51.65% of the corresponding control, while the stomatal limitation value (L_s) and water use efficiency (WUE) of 180 mmol·L^-1 Na₂SO₄-stressed seedlings were 1.91 and 1.38 times that of the control seedlings, respectively. With the salt stress aggravated, the P_n, G_s, C_i and T_r, and L_s and WUE generally exhibited a decreasing, and increasing trend, respectively. The decreased P_n of stressed seedlings was mainly attributed to stomatal restrictions. (3) The various growth parameters of height, total leaf area, leaf number per plant, specific leaf area, stem biomass, leaf biomass and whole-plant biomass accumulation, and photosynthetic parameters of P_n, G_s, C_i and T_r had all extremely significant and negative correlation with salt stress intensity. The total leaf area and leaf number per plant were significantly or extremely significantly correlated with leaf photosynthetic parameters. There was also significant or extremely significant correlation between parameters of growth and photosynthesis and parameters of seedling height and biomass accumulation.