宛氏拟青霉提取物对盐胁迫下水稻幼苗的生理适应性

为探讨沙棘内生菌提取物作为生物刺激素对盐胁迫下水稻幼苗生长的影响，于沙棘内生菌宛氏拟青霉（Paecilomyces variotii）中提取了生物刺激素PVE（Paecilomyces variotii extracts），并经液相色谱对PVE的活性物质进行了富集纯化。通过水稻液培试验，设无盐（CK）、添加NaCl（NS）、添加PVE和NaCl（PN1）、添加PVE纯化物和NaCl（PN2）4个处理，研究生物刺激素对水稻的耐盐效应。结果表明，施用生物刺激素能够缓解盐胁迫对水稻生长造成的严重抑制。PN1、PN2处理较NS处理提高了叶片与根系的干质量，减少了植株体内的水分流失，增加了根系的直径和吸收面积，但根长相较于CK处理无显著差异；PN2处理叶片鲜质量、叶片含水量、根系含水量较PN1处理分别增加了12.44%、1.13%和0.42%。与NS处理相比，PN1和PN2处理叶片光合速率分别提高了34.08%和40.82%，蒸腾速率分别提高了23.90%和18.86%，PN1和PN2处理还显著提高了叶片中的超氧化物歧化酶（SOD）和过氧化物酶（POD）活性，使丙二醛（MDA）含量分别降低了28.36%和20.97%。PN2处理叶片和根系中的Na⁺含量较NS处理分别降低了36.31%和10.85%，从而降低了Na⁺/K⁺，保证了植株体内的离子平衡。研究表明，PVE及PVE纯化物在极低的浓度下具有较高的生理活性，并通过减少水分流失、促进根系生长、提高光合速率来减轻氧化损伤，同时以降低Na⁺流入的方式缓解盐胁迫对水稻幼苗的影响。

Effects of Paecilomyces variotii extracts on the physiological adaptability of rice seedlings under salt stress

To investigate the effects of sea-buckthorn(Hippophae rhamnoides L.) endophytic bacteria extracts as biostimulants on the growth of rice seedlings under salt stress, PVE(Paecilomyces variotii extract) was obtained from the fermentation of Paecilomyces variotii strains; The purified PVE, the active substance, was concentrated by liquid chromatography from PVE. There were 4 treatments with three replicates in the nutrient liquid culture experiment including no NaCl stress(CK), NaCl stress(NS), PVE+NaCl stress(PN1), purified PVE+NaCl(PN2). The antioxidant enzymes(including SOD, POD, and CAT) activity, photosynthetic parameters, Na⁺/K⁺, as well as the growth index were measured to evaluate the tolerance of rice seedlings under 100 mmol·L^-1 NaCl. The results showed that biostimulants could alleviate the severe inhibition of rice growth by salt stress. Compared with NS, PN1 and PN2 increased leaf and root dry weights. In addition, PN1 and PN2 led to lower loss of water under salt stress than that with NS. Both PN1 and PN2 significantly increased the total root length, root surface area, root volume, and root mean diameter of rice root; The root lengths of PN1 and PN2 did not differ significantly from those under the CK treatment. Compared with the PN1 treatment, PN2 led to higher leaf fresh weight, leaf water content, and root water content by 12.44%, 1.13%, and 0.42%, respectively. PN1 and PN2 also led to higher leaf photosynthetic rate by 34.08% and 40.82% and transpiration rate by 23.90% and 18.86% than that with the NS treatment, respectively. PN1 and PN2 led to higher leaf SOD and POD activity while leaf MDA content was significantly lower in comparision to NS. Moreover, PN2 led to lower Na⁺ content of 36.31% and 10.85% in leaves and roots than that under NS, and ensured the ion balance in rice to a greater extent than did NS. In conclusion, PVE and purified PVE had high biological activity at very low concentrations and alleviated salt stress in rice seedlings by reducing water loss, promoting root growth, increasing photosynthetic rate, increasing antioxidant enzyme activity, and reducing Na⁺ inflow.