Table_5_Abscisic acid-polyacrylamide (ABA-PAM) treatment enhances forage grass growth and soil microbial diversity under drought stress.xlsx

Drought restricts the growth of alpine grassland vegetation. This study aimed to explore a new technical system to improve the drought resistance of forage grass. Qinghai cold-land Poa pratensis seedlings were used in the drought stress experiment. A combination of abscisic acid (ABA) and polyacrylamide (PAM) were used to affect the growth, leaf physiology, soil enzyme activity, and rhizosphere microbial diversity of P. pratensis. The fresh leaf weight and root surface area were significantly increased after ABA-PAM combined treatment, while root length was significantly reduced. Besides, the leaf catalase (CAT) and superoxide dismutase (SOD) enzyme activity, proline and chlorophyll content, increased after the treatment, while malondialdehyde (MDA) content decreased. The treatment also increased sucrase, urease, and alkaline protease activities in rhizosphere soil, while decreasing acid phosphatase and neutral phosphatase enzyme activities. ABA-PAM combined treatment enhanced the rhizosphere microbial community and forage drought resistance by altering the abundance of various dominant microorganisms in the rhizosphere soil. The relative abundances of Actinobacteria, Chloroflexi, and Acidobacteria decreased, while Proteobacteria, Firmicutes, and Ascomycota increased. Unlike the relative abundance of Gibberella that decreased significantly, Komagataeibacter, Lactobacillus, Pichia, and Dekkera were significantly increased. Single-factor collinearity network analysis revealed a close relationship between the different rhizosphere microbial communities of forage grass, after ABA-PAM treatment. This study implies that ABA-PAM combined treatment can improve the drought resistance of forages. Therefore, it provides a theoretical and practical basis for restoring drought-induced grassland degradation.

干旱胁迫会抑制高寒草原植被的生长。本研究旨在探索一套提升饲草抗旱性的新型技术体系，以青海冷地型草地早熟禾（Poa pratensis）幼苗为试验材料开展干旱胁迫实验，采用脱落酸（abscisic acid, ABA）与聚丙烯酰胺（polyacrylamide, PAM）复配处理，探究其对草地早熟禾生长、叶片生理特性、土壤酶活性及根际微生物多样性的调控效应。结果显示，ABA-PAM复配处理后，供试材料的叶片鲜重与根表面积显著提升，但根长显著降低。此外，该处理可显著提升叶片过氧化氢酶（catalase, CAT）与超氧化物歧化酶（superoxide dismutase, SOD）活性，以及脯氨酸与叶绿素含量，同时降低丙二醛（malondialdehyde, MDA）的积累量。该处理还可提升根际土壤中的蔗糖酶、脲酶与碱性蛋白酶活性，却抑制了酸性磷酸酶与中性磷酸酶的活性。ABA-PAM复配处理通过改变根际土壤中各类优势微生物的相对丰度，优化根际微生物群落结构，进而增强饲草的抗旱性。其中，放线菌门（Actinobacteria）、绿弯菌门（Chloroflexi）与酸杆菌门（Acidobacteria）的相对丰度显著下降，而变形菌门（Proteobacteria）、厚壁菌门（Firmicutes）与子囊菌门（Ascomycota）的相对丰度显著升高。与赤霉属（Gibberella）相对丰度显著下降不同，葡糖醋杆菌属（Komagataeibacter）、乳杆菌属（Lactobacillus）、毕赤酵母属（Pichia）与德克酵母属（Dekkera）的相对丰度均显著升高。单因素共线性网络分析结果显示，经ABA-PAM处理后，饲草根际不同微生物类群间存在紧密的关联网络。本研究证实ABA-PAM复配处理可有效提升饲草的抗旱性，为干旱诱导的草原退化修复工作提供了坚实的理论与实践依据。