盐胁迫下根瘤共生豌豆植株对外源钙的生理响应

为明确外源钙对根瘤共生豌豆植株耐盐性的影响机制,本试验采用盆栽方式研究了NaCl (170 mmol·L^-1)胁迫下,外源施加CaCl₂(0、5、15 mmol·L^-1)对接种根瘤菌(菌株15657、15735、Ca66)的两种耐盐性不同品种豌豆(定豌8号、陇豌6号)植株生理指标的影响。结果表明: 接种根瘤菌、施加CaCl₂或接种根瘤菌后施加CaCl₂均提高了豌豆植株的生物量、超氧化物歧化酶(SOD)和过氧化物酶(POD)活性、脯氨酸(Pro)和可溶性糖(SS)含量,降低了丙二醛(MDA)含量;接种根瘤菌后施加15 mmol·L^-1 CaCl₂显著提高了豌豆植株的生物量、POD活性和Pro含量。接种与豌豆植株匹配性较好的15735菌株并施加CaCl₂对豌豆在盐胁迫下各指标的影响相对较小,接种匹配性差的菌株(156567、Ca66)并施加CaCl₂影响较大。经隶属函数综合分析表明,接种根瘤菌后施加CaCl₂的豌豆植株表现出较强的耐盐性,接种15735菌后施加15 mmol·L^-1 CaCl₂的定豌8号隶属函数值为0.814,耐盐性最强。本研究表明,相比接种根瘤菌和施加CaCl₂处理,接种根瘤菌后施加CaCl₂可更有效地提高盐胁迫下豌豆植株的抗氧化酶活性,增强渗透调节能力,降低膜脂过氧化伤害,从而提高豌豆植株的耐盐性。

Physiological responses of symbiotic rhizobium pea to exogenous calcium under salt stress

To clarify the effects of exogenous calcium on salt tolerance of nodule symbiotic pea, a pot experiment was conducted under salt stress (170 mmol·L^-1) to examine the effects of exogenous CaCl₂(0, 5 and 15 mmol·L^-1) on physiological parameters of two pea cultivars, ‘Dingwan 8’ (salt tolerant) and ‘Longwan 6’ (salt sensitive), inoculated with rhizobium strains 15657, 15735 and Ca66. The results showed that plant biomass, the activities of superoxide dismutase (SOD) and peroxidase (POD), and the contents of proline (Pro) and soluble sugar (SS) were enhanced, but malondialdehyde (MDA) content was decreased, with rhizobium inoculation, CaCl₂ application or CaCl₂ application after rhizobium inoculation. Plant biomass and activities of SOD and POD and Pro content were increased significantly by the application of 15 mmol·L^-1 CaCl₂ after rhizobium inoculation. The application of CaCl₂ after inoculation of rhizobium strain 15735 suitable for pea had limited effects on physiological parameters of pea plants, whereas the application of CaCl₂ after inoculation of rhizobium (15657, Ca66) unsuitable for pea had obvious effects. The comprehensive analysis of membership function showed that pea treated with CaCl₂ after rhizobium inoculation exhibited stronger salt tolerance, and ‘Dingwan 8’ plants treated with 15 mmol·L^-1 CaCl₂ after inoculation of rhizobium strain 15735 showed the strongest ability of salt tolerance with the highest membership function value of 0.814. In summary, compared with CaCl₂ application or rhizobium inoculation alone, CaCl₂ application after rhizobium inoculation could effectively enhance the activities of antioxidant enzymes and osmotic regulation ability, reduce the damage of membrane lipid peroxidation, and consequently improve the salt tolerance of pea.