盐碱胁迫下AM真菌对羊草生长及生理代谢的影响

利用盆栽控制试验研究了盐碱胁迫下AM真菌对羊草生长及生理代谢的影响。结果表明,盐碱胁迫显著降低了AM真菌的侵染率与侵染强度,且具有高pH的碱胁迫的抑制效应更强。接种AM真菌一定程度上提高了胁迫下羊草幼苗的生物量及光合色素(Chl a,Chl b和Car)含量。随着盐碱胁迫浓度的增加,羊草幼苗积累了大量的Na~+,并抑制了其对K~+的吸收,接种AM真菌一定程度上降低了Na~+的积累,并缓解了胁迫下K~+含量的降低,提高NO_3~-含量从而改善羊草幼苗的离子平衡。在碱胁迫下,柠檬酸、苹果酸含量均显著提高,在盐胁迫下,仅苹果酸含量显著提高,而接种AM真菌使盐碱胁迫下有机酸含量一定程度降低。在盐碱胁迫条件下,接种AM使羊草体内超氧化物歧化酶(SOD)、过氧化物酶(POD)、过氧化氢酶(CAT)和抗坏血酸过氧化物酶(APX)的活性明显提高,增强宿主植物体内氧自由基的清除能力。接种AM真菌明显提高羊草幼苗抗盐碱能力,因胁迫类型不同,抗逆机理有所差异。研究结果为利用羊草进行生物改良退化盐碱草地以及菌肥的应用提供了科学依据,也为探求羊草-丛枝菌根共生体对盐碱胁迫的响应和反馈提供了数据支持。

Effects of arbuscular mycorrhizal fungi on the growth and physiological metabolism of Leymus chinensis under salt-alkali stress

To clarify the role of arbuscular mycorrhizal (AM) fungi in enhancing stress resistance in Leymus chinensis, the effects of AM fungi on the growth and physiological metabolism of L. chinensis under saline-alkali stress were investigated by conducting controlled pot experiments. The results showed that saline stress significantly reduced the colonization rate and colonization intensity of AM, and that the inhibitory effects of alkali stress were considerably stronger. Inoculation of Glomus mosseae enhanced the biomass and photosynthetic pigment contents (chlorophyll a and b and carotene) of L. chinensis seedlings under stresses. With an increase in saline-alkali stresses, there was a greater accumulation of Na⁺, but K⁺ uptake was suppressed. Inoculation with AM fungi reduced the accumulation of Na⁺, reduced the decreases in K⁺ content, and enhanced the content of NO₃^-, thereby improving the ion balance of L. chinensis seedlings. Under alkali stress, the contents of citric acid and malic acid were increased, and under saline stress, malic acid content was significantly increased. The activities of superoxide dismutase, peroxidase, catalase, and ascorbate peroxidase were significantly increased by inoculation with AM, thereby enhancing the scavenging of oxygen free radicals by the host plants. The research results show that due to the high pH value, the effects of alkali stress on the mycorrhizal infection were stronger. Inoculation with AM fungi significantly enhanced the stress resistance of L. chinensis seedlings. The mechanism of stress resistance also differed according to stress type. On the one hand, the results provide a scientific basis for the application of L. chinensis to saline-alkali degraded grassland and as a bacterial fertilizer. On the other hand, they also provide the necessary data for elucidating the response and feedback of the L. chinensis-AM symbiosis to saline-alkali stress.