异质低磷胁迫下马尾松家系根构型和磷效率的遗传变异

以7个马尾松(Pinus massoniana)一代种子园自由授粉家系为材料, 设置同质低磷(P)胁迫和异质低P胁迫模拟的盆栽试验, 系统研究马尾松家系对不同类型低P胁迫的适应机制和P效率变异规律。结果表明, 参试马尾松家系的苗高、地径和生物量等P效率指标均表现出显著的家系变异, 主要P效率指标的家系遗传力均较高, 干物质积累量的广义遗传力大于0.80, 揭示了马尾松P营养效率的较大遗传改良潜力。马尾松对不同类型低P胁迫的适应机制有所差异。在同质低P胁迫下, ‘3201’、‘1217’等高P效率家系的根系主要参数均高于低P效率家系, 表明整体根系参数的适应性变化是P效率和生物量形成的决定因素。在异质低P胁迫下, 高P效率马尾松家系在表层富P介质的根系分布量、分布比例均显著增加, 表层根系参数与马尾松家系P效率呈显著正相关, 揭示根系空间构型的适应性变化是决定马尾松高P效率的重要生物学基础。表层根系生物量、表层根相对比例的家系遗传力达0.88和0.72, 证实了以马尾松根构型的适应变化为突破口, 选育具有理想根构型和较高P效率的马尾松家系。

Genetic variation in root architecture and phosphorus efficiency in response to heterogeneous phosphorus deficiency in Pinus massoniana families

Aims Our aim was to investigate the genotypic variations among semi-sib families of Pinus massoniana for adaptive changes in root morphology and architecture in response to different types of low soil phosphorus (P) availability and their relationships to plant growth and P efficiency.
Methods Pot experiments were conducted during the 2010 growing season in a nursery located in Chun’an County of Zhejiang Province, China. Seven semi-sib families of P. massoniana contrasting in root architecture and P efficiency were compared for their root morphological and architectural traits and their relationships to plant growth and P efficiency under both heterogeneous and homogeneous low P conditions.
Important findings Large genotypic variations were observed under different types of low-P conditions. The adaptive mechanism for P deficiency was different under heterogeneous and homogeneous low-P conditions. Under homogeneous low-P conditions, adaptive responses of root growth parameters were present in genotypes with high-P efficiency such as ‘3201’ and ‘1217’, while it was not observed in genotypes with low-P efficiency. Root architecture was not closely related to plant P efficiency under homogeneous low-P conditions. Under heterogeneous low-P conditions, root architecture was found to closely related to P efficiency. Genotypes with shallow root architecture had optimal root parameters including root length, surface area and biomass in the top layer of soil, thus having the greater ability for P absorption and having higher P efficiency and biomass. The heritability for the root biomass and the proportion of root in the top soil layer was 0.88 and 0.72, respectively. A significant interactive effect between patterns of low-P conditions and P efficiency was observed. Given that P. massoniana has great genetic potential for adaptation to low-P soils, the selection of high-P efficiency genotypes with optimal root architecture may significantly increase wood production of P. massoniana under low-P conditions.