盐胁迫对砂糖橘幼树生长、生物量积累及光合生理的影响

Effects of salt stress on plant growth,biomass accumulation and photosynthetic physiology of Shatangju saplings

【目的】明确砂糖橘对不同种类和水平的盐胁迫的适应性,为砂糖橘引种栽培和果园土壤管理提供科学支撑。【方法】分别以CaCO_(3)、NaHCO_(3)和NaCl模拟石灰质土壤、碱土和盐土的主要胁迫成分,并设0.3%和0.7%2种含盐量水平,以基质中不加盐为对照,栽培90 d后,测试分析盐胁迫对植株生长和生物量分配的影响及其基础生理响应。【结果】盐胁迫下砂糖橘单株落叶量较对照大1.85~17.66倍,盐分含量越高落叶量越大,NaCl胁迫下落叶量显著大于CaCO_(3)和NaHCO_(3)胁迫(P<0.05,下同)。盐胁迫对株高生长的抑制明显大于对地径和冠幅生长的抑制,对植株生物量积累的影响以对叶生物量的影响最明显,其次是对根生物量积累的抑制;2种含盐量水平的NaHCO_(3)、NaCl胁迫下各自植株根和叶生物量均较对照显著降低。不同种类和水平的盐胁迫均可导致砂糖橘叶片叶绿素含量降低,但0.7%CaCO_(3)胁迫与0.3%NaHCO_(3)胁迫、0.7%NaHCO_(3)胁迫与0.3%NaCl胁迫的效应相当。砂糖橘叶片光合速率、蒸腾速率和气孔导度对盐胁迫敏感,盐分含量越高3项光合生理指标的降低幅度越大;同种性质、2种水平的胁迫间植株叶片水分饱和亏缺均有显著差异,含盐量达0.3%即可使叶片丙二醛含量显著升高、细胞质膜透性显著增大。【结论】砂糖橘对CaCO_(3)含量较高的土壤具较强适应性,对NaCl为主的盐土及NaHCO_(3)为主的碱土适应性很差;对砂糖橘叶片叶绿素的破坏、光合生理的抑制及伴随的水分亏缺和膜脂过氧化是不同种类盐胁迫共同的作用特性。

【Objective】To investigate the adaptability of Shatangju sapling to salt stress,so as to provide scientific support for the introduction and cultivation of Shatangju and orchard soil management.【Method】CaCO_(3),NaHCO_(3)and NaCl were used to simulate the main stress components of calcareous soil,alkaline soil and saline soil respectively,and the content levels of 0.3%and 0.7%were set.With no salt in the substrate as the control,the effects of salt and alkali types and contents on plant growth and biomass allocation and their basic physiological responses were tested and ana-lyzed 90 days after cultivation.【Result】For Shatangju saplings under salt stress,the amount of fallen leaves per plant was 1.85 to 17.66 times larger than that of the control.The amount of fallen leaves under NaCl stress was significantly greater than that under CaCO_(3)or NaHCO_(3)stress(P<0.05,the same as below).The inhibition of salt stress on plant height growth was significantly greater than that on ground diameter and crown width growth,and the effect on plant biomass accumula-tion was the greatest on leaf biomass,followed by the inhibition on root biomass accumulation.The root and leaf biomass of each plant under the two treatment intensities of NaHCO_(3)and NaCl stress were significantly reduced compared with the control,Different types and levels of salt stress could reduce the chlorophyll content of Shatangju leaves,but the effects of 0.7%CaCO_(3)stress and 0.3%NaHCO_(3)stress,0.7%NaHCO_(3)stress and 0.3%NaCl stress were similar.The photosyn-thetic rate,transpiration rate and stomatal conductance of Shatangju leaves were sensitive to salt stress,and the higher the salt content,the greater the decrease of three photosynthetic physiological indexes.There were significant differences in leaf water saturation deficits between the same nature and two levels of stress.When the salt content reached 0.3%,the MDA content in leaves increased significantly and the membrane permeability of cytoplasm increased significantly.【Conclusion】Shatangju leaves has strong adaptability to soil with high CaCO_(3)content,but poor adaptability to saline soil domi-nated by NaCl and alkaline soil dominated by NaHCO_(3).The damage to chlorophyll,the inhibition of photosynthetic physi-ology,and the accompanying water deficit and membrane lipid peroxidation in Shatangju leaves are the common charac-teristics of different types of salt stress.