磷胁迫和不同栽植方式下云南松幼苗生物量及其分配的变化

摘要

研究云南松与旱冬瓜混栽对磷胁迫的反应.通过温室砂培试验研究了云南松与旱冬瓜2树种不同栽植方式下云南松幼苗的生长、生物量及其分配.供试营养液为Hoagland营养液,设置了缺磷(0 mg·L-1)、低磷(31 mg·L-1)和适磷(62 mg·L-1)3个水平.结果表明:(1)磷胁迫下,纯栽植或与旱冬瓜混栽,云南松幼苗的苗高、地径、根长、地上、地下和全株干重均低于对照,在低磷胁迫时差异不显著,缺磷时差异显著(P＜0.05)；随着磷胁迫程度增加云南松幼苗根冠比增加.(2)不同栽植方式对云南松幼苗的影响表现为,磷胁迫下,随着旱冬瓜混栽比例(0、1、2株)增加,云南松幼苗的苗高、地径、根长、根尖数、地上、地下、全株生物量、根冠比减少.磷胁迫可降低云南松幼苗的生物量,但它可通过地上部与地下部干物质分配来适应磷营养的胁迫；苗期混交旱冬瓜对云南松幼苗的生长有一定影响,但对旱冬瓜的生长是有利的；云南松幼苗以降低地下部分的生长来适应磷胁迫下地上部分与旱冬瓜幼苗对光照和空间的竞争.%To reveal responses of mixed plantation of Pinus yunnanensis and Alnus nepalensis to phosphorus stress, growth, biomass and allocation of P. Yunnanensis seedlings were measured through sand culture experiments in green house. Hoagland nutrient solution was used and 3 levels of P concentrations (0 mg· L-1, 31 mg·L-1 and 62 mg·L-1) were designed. The results were as follows. (1) Under P stress, height, diameter, root length, shoot biomass, root biomass and total biomass of P. Yunnanensis seedlings were lower than those of the control when mixed or not mixed with A. Nepalensis. Differences, with the control were not remarkable (P>0. 05)under low P stress (31 mg·L-1) , and remarkable (P<0. 05) under the absence of P (0 mg·L-1). With the increase of P stress, root mass/shoot mass ratio of P. Yunnanensis seedlings increased. (2) Under P stress, the height, diameter, root length, shoot biomass, root biomass, total biomass and root mass/shoot mass ratio of P. Yunnanensis seedlings decreased with the increase of individuals of A. Nepalensis mixed. It was concluded that biomass of P. Yunnanensis seedlings would decrease under P stress. Besides, shoot and root mass would be re-allocated to adapt the stress. In the re-allocation, the decrease of root mass would strengthen competition of shoots growing with those of A. Nepalensis. Mixed A. Nepalensis in seedlings would affect the growth of P. Yunnanensis seedlings, butbenefit to the growth of A. Nepalensis.