水分胁迫对油松抗旱生理特征的影响

Effects of Water Stress on Drought Resistance Physiological Characteristics of Pinus tabulaeformis

[目的]探究水土保持主要造林树种油松(Pinus tabulaeformis)在水分胁迫下的抗旱生理特性,为该地区油松人工林管理提供科学依据。[方法]以1年生油松幼苗为研究对象,设置4个水分胁迫处理,分别为对照组(CK)、轻度胁迫(RE25%)、中度胁迫(RE50%)和重度胁迫(RE75%),分析不同水分胁迫处理后油松幼苗的生长特性、水力功能及渗透调节物质含量的变化及其之间的相关关系。[结果](1)与CK相比,经过20个月的RE50%和RE75%处理后油松地上生物量分别显著降低19.1%和37.0%,地下生物量分别显著增加13.7%和23.9%。(2)CK、RE25%、RE50%和RE75%处理后油松幼苗新枝的抗栓塞水势阈值分别为-1.43,-2.04,-0.91,-0.58 MPa。(3)与CK相比,经过RE50%和RE75%处理后粗根内的可溶性糖分别显著增加123.3%和121.9%,淀粉分别显著增加15.0%和58.0%,非结构性碳水化合物(NSC)总量分别显著增加104.0%和83.2%。与CK相比,经过RE75%处理后新枝内脯氨酸显著降低43.0%,K^(+)显著降低23.7%。(4)不同水分胁迫处理下各器官内渗透调节物质对水力功能变化的贡献依次为NSC、淀粉、可溶性糖、K^(+)、管胞汁液内的脯氨酸和管胞汁液内的可溶性糖。[结论]轻度水分胁迫提高新枝的抗栓塞能力,而中度和重度水分胁迫下油松幼苗通过增加根内碳储存维持油松的生长代谢。油松各器官通过积累渗透调节物质提高细胞浓度,降低渗透势以适应水分胁迫环境。研究结果加深对油松抗旱机制的认识,为黄土高原油松人工林管理提供科学依据。

[Objective]Exploring the drought resistance characteristics of Pinus tabulaeformis,a major afforestation tree species for soil and water conservation,under different water stress to provide a scientific basis for the management of P.tabulaeformis artificial forests in the region.[Methods]Using one-year P.tabulaeformis seedings as the research subject,four levels of water stress treatments were set up,which were control group(CK),mild stress(RE25%),moderate stress(RE50%)and severe stress(RE75%),respectively,the growth characteristics,hydraulic function and osmotic regulatory substance content of P.tabulaeformis seedlings were analyzed after different water stress treatments,and their correlation was analyzed.[Results](1)Compared with the CK treatment,after twenty months of RE50%and RE75%treatment,the aboveground biomass of P.tabulaeformis significantly decreased by 19.1%and 37.0%,respectively,while the underground biomass significantly increased by 13.7%and 23.9%,respectively.(2)In the CK,RE25%,RE50%and RE75%treatments,the water potential threshold for embolism resistance of P.tabulaeformis new branches was-1.43,-2.04,-0.91 and-0.58 MPa,respectively.(3)Compared with CK,in the RE50%and RE75%treatments,the soluble sugar content in the coarse roots significantly increased by 123.3%and 121.9%,respectively,the starch content significantly increased by 15.0%and 58.0%,respectively,and the total nonstructural carbohydrate(NSC)content significantly increased by 104.0%and 83.2%,respectively.In the RE75%treatment,the proline content in the new branches significantly decreased by 43.0%,while the K^(+)content decreased by 23.7%compared with the CK group.(4)The contribution rates of various osmotic regulating substances in various organs to hydraulic function under different water stress were as follows:NSC,starch,soluble sugars,K^(+),proline and soluble sugars in tracheid sap.[Conclusion]Mild water stress could enhance the embolism resistance of new branches.P.tabulaeformis seedlings maintained their metabolism by increasing root carbon storage.Meanwhile,the numerous organs of P.tabulaeformis improved cell concentration,reduced osmotic potential,and preserved hydraulic function to adapt to water stress environment by coordinating the accumulation of osmotic regulating substances.This study advanced the understanding of P.tabulaeformis'drought resistance mechanism and provided a scientific basic for the management of P.tabulaeformis artificial forests on the Loess Plateau.