盐胁迫对小报春生长及生理特性的影响

为探讨小报春对盐(NaCl)胁迫的抗性及适应机制,采用盆栽法研究不同浓度的NaCl(0、50、100、150、200、250 mmol·L^-1)对小报春生长发育和生理特性的影响。结果表明:1)不同浓度NaCl胁迫下,小报春的生长呈现低促高抑的现象。随着NaCl胁迫浓度的增加,植株的株高、冠幅、叶面积、地上和地下干重以及叶片含水量显著降低,相对电导率显著提高。2)NaCl胁迫后,小报春植株叶片净光合速率(P_n)、胞间CO₂浓度(C_i)、蒸腾速率(T_r)、气孔导度(G_s)、可溶性蛋白(SP)、游离脯氨酸(Pro)、可溶性糖(SS),以及超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性均随NaCl浓度增加呈现先上升后下降的变化趋势;丙二醛(MDA)含量呈持续升高趋势,说明植株的光合作用系统、细胞的渗透调节以及抗氧化酶系统对NaCl胁迫具有积极的响应策略。3)NaCl胁迫显著提高了小报春植株叶、叶柄、根中Na⁺的含量,根系中Na⁺含量的增幅最大;植株各器官中K⁺、Ca²⁺含量随着NaCl胁迫浓度增加呈现先上升后下降的趋势,且K⁺、Ca²⁺在叶片中保持较高的含量。综上所述,小报春具有一定的耐盐性,是盐渍土园林应用的潜力花卉。低浓度NaCl(50 mmol·L^-1)胁迫对其生长有促进作用,但NaCl浓度≥150 mmol·L^-1抑制其生长发育。

Effects of salt stress on the growth and physiological characteristics of Primula forbesii

In order to investigate the resistance and adaptation mechanism of Primula forbesii to salt (NaCl) stress, a pot experiment was conducted to determine the growth and physiological characteristics of P. forbesii under NaCl concentrations of 0, 50, 100, 150, 200, and 250 mmol·L^-1. It was found that: 1) Along the concentration gradient of NaCl, the growth of P. forbesii showed low-concentration promotion and high-concentration suppression effects. At higher NaCl concentrations, plants showed stress symptoms in that plant height, crown width, leaf area, and above-ground and underground dry weight, and leaf water content were significantly decreased. Meanwhile, the relative electrical conductivity was significantly increased. 2) The leaf net photosynthetic rate, intercellular CO₂ concentration, transpiration rate, stomatal conductance, soluble protein, free proline, soluble sugar, and the activities of superoxide dismutase, peroxidase and catalase all rose with increasing NaCl concentration and then decreased at higher concentration. Malondialdehyde content displayed continuous increase across the concentration range tested, indicating that the photosynthetic system, cell osmotic regulation and antioxidant enzyme system of plants had positive response strategies to NaCl stress. 3) Higher NaCl concentrations significantly increased the Na⁺ content in leaves, petioles and roots of the plants, with the largest increase of Na⁺ content in roots. With increasing NaCl concentration, the contents of K⁺ and Ca²⁺ in plant organs other than leaves showed a trend of initial increase and later decrease while the contents of K⁺ and Ca²⁺ in leaves remained relatively high at higher NaCl concentrations. In summary, P. forbesii has moderate salt tolerance and is a potential flower species for saline soil garden applications. In this experiment a low NaCl concentration of 50 mmol·L^-1 promoted the growth of P. forbesii, but the growth and development of plants were inhibited when the concentration of NaCl was equal to or greater than 150 mmol·L^-1.