低磷胁迫下紫花苜蓿根系解剖结构对磷吸收效率的影响  

Effects of root anatomical characteristics on phosphorus uptake efficiency under phosphorus deficiency in alfalfa

作　　者：王鹏飞 潘新雅 卫先伟 王智[1,2,3] WANG Pengfei;PAN Xinya;WEI Xianwei;WANG Zhi(College of Grassland Agriculture,Northwest A&F University,Yangling 712100,Shaanxi,China;State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau,Northwest A&F University,Yangling 712100,Shaanxi,China;Institute of Soil and Water Conservation,Chinese Academy of Sciences and Ministry of Water Resources,Yangling 712100,Shaanxi,China)

机构地区：[1]西北农林科技大学草业与草原学院,陕西杨凌712100 [2]西北农林科技大学黄土高原土壤侵蚀与旱地农业国家重点实验室,陕西杨凌712100 [3]中国科学院水利部水土保持研究所,陕西杨凌712100

出　　处：《草业科学》2023年第7期1810-1822,共13页Pratacultural Science

基　　金：陕西省自然科学基础研究计划青年项目(2020JQ-264);陕西林业科技创新重点专项(SXLK2022-02-12);国家自然科学基金(31700335)。

摘　　要：为明确紫花苜蓿(Medicago sativa)根系解剖结构对低磷胁迫的响应特征,探明根系解剖结构变化对磷吸收效率的影响,本研究以12个紫花苜蓿品种为材料,在对照(0.5 mmol·L^(−1) NH4H2PO4)和低磷胁迫(0.05 mmol·L^(−1) NH4H2PO4)下,测定苗期根系中柱面积、皮层面积、皮层细胞层数等根系解剖结构特性。低磷胁迫抑制了各紫花苜蓿品种的生长和磷吸收效率,不同品种对低磷胁迫的响应存在显著差异;基于相对生物量和相对磷吸收效率,将供试品种划分为高产耐低磷、高产磷敏感、低产耐低磷和低产磷敏感型四大类型,这4类品种在低磷胁迫下均表现出皮层面积、中柱面积和次生木质部面积下降等趋势;与其他3种类型相比,高产耐低磷型品种的皮层细胞层数下降幅度较大,而通气组织占皮层百分比增大幅度较大,这有助于提高根系横向吸收效率,同时次生木质部面积下降幅度较低,保证了较强的轴向运输能力。逐步回归分析表明,通气组织占皮层百分比和皮层细胞层数(P<0.05)、次生木质部面积(P<0.01)与磷吸收效率显著正相关。调控次生木质部面积、皮层细胞层数和通气组织占皮层百分比是紫花苜蓿根系解剖结构响应低磷胁迫的主要途径,其中次生木质部面积是影响磷吸收效率最关键的解剖结构性状。This study aimed to determine the response characteristics of root anatomical traits under phosphorus deficiency and explore the effects of root anatomical changes on phosphorus uptake efficiency in alfalfa(Medicago sativa).In this study,12 alfalfa cultivars were selected as materials,and their root anatomical characteristics,such as stele area,cortex area,and cortical cell file,were assessed at the seedling stage under two phosphorus supply levels(control:0.5 mmol·L^(−1) NH4H2PO4;and phosphorus deficiency:0.05 mmol·L^(−1) NH4H2PO4).Phosphorus deficiency inhibited the growth and phosphorus uptake efficiency of all alfalfa cultivars.Significant differences were detected in the response of these traits to phosphorus deficiency among different alfalfa cultivars.All alfalfa cultivars were classified into four types based on their relative biomass and relative phosphorus uptake efficiency as follows:high yield and non-sensitive,high yield and sensitive,low yield and non-sensitive,and low yield and sensitive.All four types showed a decreased trend in cortex area,stele area,and metaxylem area under phosphorus deficiency.Compared to the other three types,alfalfa cultivars of the high yield and non-sensitive type not only exhibited a relatively greater decline in the cortical cell file but also a higher increase in the percentage of cortex in the aerenchyma and metaxylem areas.These performances enhanced the root horizontal phosphorus uptake efficiency and axial transport capacity and enabled this type of alfalfa cultivar with more stable and higher phosphorus uptake efficiency under phosphorus deficiency.Furthermore,stepwise regression analysis revealed that the cortical cell file,percentage of cortex that is aerenchyma(P<0.05),and metaxylem area(P<0.01)had more significant correlations with phosphorus uptake efficiency than the other root anatomical traits did.The metaxylem area,cortical cell file,and percentage of cortex that is aerenchyma were the main root anatomical characteristics that responded to phosphorus

关 键 词：低磷胁迫 耐低磷紫花苜蓿 磷敏感紫花苜蓿 根系皮层 根系中柱 次生木质部面积 磷吸收 

分 类 号：S541.9[农业科学—作物学]