低磷胁迫下不同种源马尾松的根构型与磷效率

以浙江淳安、福建武平、广西岑溪和广东信宜4个代表性的马尾松种源为试材,设置异质低磷胁迫、同质低磷胁迫等不同磷素处理,研究马尾松种源感知不同类型低磷胁迫的根构型及磷效率变异规律.结果表明:无论在异质低磷还是同质低磷胁迫下,参试种源马尾松的主要生长性状和磷效率指标均存在极显著的种源间变异.异质低磷胁迫下,广东信宜、福建武平种源马尾松表现出较高的磷效率和干物质积累量,根构型发生适应性变化,富磷表层介质中的根系参数显著高于低磷效率的广西岑溪和浙江淳安种源.这是磷高效种源具有较高的磷素吸收效率和磷效率的重要机制.不同种源的表层富磷介质根系参数与其整株干物质积累量相关系数在0.95以上.同质低磷胁迫下,高磷效率种源马尾松的磷吸收率显著高于低磷效率种源,但表层介质中的根系参数和整株根系参数与整株干物质积累量的相关性较低.不同种源马尾松适应同质低磷胁迫和异质低磷胁迫的生物学机制有所差异,应有针对性地选择不同土壤磷素的森林立地并推广磷营养高效的马尾松种源.

Root architecture and phosphorus efficiency of different provenance Pinus massoniana under low phosphorous stress

Taking four representative provenances of Pinus massoniana from Chun’an of Zhejiang,Wuping of Fujian,Cenxi of Guangxi,and Xinyi of Guangdong in East and South China as test materials,a pot experiment was conducted to study their variations in root architecture and phosphorus(P) efficiency under heterogeneous and homogeneous low P stress.Large variations were detected in the major growth traits and the indices of P efficiency among the P.massoniana provenances under both heterogeneous and homogeneous low P stress.Under heterogeneous low P stress,the provenances from Xinyi of Guangdong and Wuping of Fujian exhibited higher P efficiency and greater dry matter accumulation,and their root architecture presented large adaptive changes,with the values of root parameters in P-rich soil surface layer being significantly higher than those of the P inefficient provenances from Chun’an of Zhejiang and Cenxi of Guangxi,which should be responsible for the higher P absorption efficiency and high P efficiency of the provenances from Xinyi and Wuping under heterogeneous low P condition.The root architecture parameters in P-rich soil surface layer and the plant dry matter accumulation of different provenance P.massoniana under heterogeneous low P stress had a correlation coefficient >0.95.Under homogeneous low P stress,the provenances with higher P efficiency had a significantly higher P uptake efficiency than the provenances with lower P efficiency,but the root parametres of the provenances with higher P efficiency had no significant correlation with the P efficiency of the provenances.There existed differences in the adaptive mechanism for the heterogeneous and homogeneous low P stress among the the P.massoniana provenances,and thus,different strategies should be adopted in the selection of P-efficient provenances for different forest stands.