基于功能性状探索磷添加下沙打旺对盐碱环境的适应策略

Phosphorus Addition Modulates Adaptation Strategies of Astragalus adsurgens to Saline-Alkaline Environments: Insights from Functional Traits

摘要:

为探究磷添加对豆科牧草缓解盐碱胁迫的机制，选取松嫩地区中度和重度盐碱土壤作为栽培介质，设置5个磷添加水平(P0、P20、P40、P80、P160和P320 mg P/kg干土)，分析沙打旺(Astragalus adsurgens)根/叶功能性状的响应及其对幼苗生物量的影响。结果显示：磷添加促使沙打旺地上生物量(AGB)与根生物量(RW)重新分配，重度盐碱处理下的沙打旺幼苗先供应根生长；而中度盐碱处理下，优先供应地上部分生长，沙打旺比叶面积(SLA)、比根表面积(SRA)、比根长(SRL)、根长(RL)、根尖数(RT)随着磷添加量呈上升趋势、叶片干物质量(LDMC)呈下降趋势，有利于提高叶片和根系对水分和养分的获取能力。方差分解结果表明，中度盐碱处理下沙打旺根功能性状和叶功能性状对磷添加AGB、RW的解释度分别为46.2%、37.7%，重度盐碱下解释度分别为66.7%、35.7%。结合经济谱分析，磷添加下根叶及全株表现出获取策略，从中度到重度盐碱处理沙打旺叶片表现出保守策略，根系表现出获取策略，全株表现出由获取向保守策略转变。

Abstract:

To study the mechanism by which phosphorus supplementation alleviates saline-alkali stress on leguminous forage, the moderately and heavy saline-alkali soils in the Songnen region were selected as the cultivation media. Five phosphorus supplementation levels(P0, P20, P40, P80, P160 and P320 mg P/kg dry soil) were set up to analyze the responses of the root/leaf functional traits of Astragalus adsurgens and their impacts on the biomass of seedlings. The results showed that, phosphorus addition induced a reallocation of aboveground biomass(AGB)and root biomass(RW) in Astragalus adsurgens seedlings. Under severe saline-alkali stress, seedlings prioritized root growth, whereas moderate saline-alkali stress triggered preferential allocation to aboveground organs. Key functional traits, including specific leaf area(SLA), specific root surface area(SRA), specific root length(SRL),root length(RL), and root tip number(RT), showed an increasing trend with phosphorus supplementation, while leaf dry matter content(LDMC) exhibited a decreasing trend. These adaptive adjustments enhanced the capacity of leaves and roots to acquire water and nutrients, reflecting a resource optimization strategy to counteract salinealkali constraints. The results of variance decomposition showed that the explanatory degrees of the root and leaf functional traits of Astragalus adsurgens on AGB and RW under the moderate salt-alkali treatment were 46.2%and 37.7% respectively, and those under the severe salt-alkali treatment were 66.7% and 35.7% respectively.Combined with the analysis of the economic spectrum, the roots, leaves and whole plants of Astragalus adsurgens showed an acquisitive strategy under phosphorus addition. From the moderate to severe salt-alkali treatment, the leaves of Astragalus adsurgens showed a conservative strategy, the roots showed an acquisitive strategy, and the whole plant showed a transition from an acquisitive to a conservative strategy.