遮阴和磷限制下胡桃楸1级根养分吸收策略选择

Nutrient uptake strategy selection by first-order roots of Juglans mandshurica under shading and phosphorus limitation

本研究探讨了1年生胡桃楸在不同光照环境和不同剂量磷肥下根系功能性状的变化,以了解胡桃楸根系资源获取策略与光环境和磷养分限制之间的关系。设置了4种遮阴处理(全光、65%全光、35%全光和20%全光),以及3种磷肥处理(对照、200%和500%土壤本底有效磷),并测定了1级根形态、构型特征和菌根侵染率的变化。结果表明:随着遮阴程度的增加,胡桃楸1级根的平均直径、平均根长和菌根侵染率逐渐减小,比根长、比表面积、分支比和分支强度则呈现先增加后减小的趋势。随着磷含量的减少,1级根直径逐渐变细,而菌根侵染率则逐渐升高。在遮阴环境下,胡桃楸的根系形态和构型会发生适应性变化,通过增加比根长、比表面积、分支比和分支强度等来适应遮阴环境;而在磷限制条件下,胡桃楸的根系更倾向于与菌根真菌共生以促进对磷的吸收。胡桃楸在透光度为35%的林地人工更新时,根系形态、构型会做出改变以适应遮阴环境;在磷受限的情况下,胡桃楸与菌根真菌共生能力增强,可以适当接种菌根来帮助根系吸收磷。

We investigated root growth of 1-year-old Juglans mandshurica seedlings under different light environments and varying doses of phosphorus fertilizer, to understand the relationship between root resource acquisition strategies and the variations of light and phosphorus availability. There were four shading intensities(full light, 65% full light, 35% full light, and 20% full light) along with three doses of phosphate fertilizer(0(CK), 200% soil background available phosphorus, and 500% soil background available phosphorus). We measured in root morphology characteristics, architectural characteristics, and mycorrhizal colonization rates of first-order roots. The results showed that average diameter, average root length, and mycorrhizal colonization rates of first-order roots gradually decreased, and the specific root length, specific surface area, branching ratio and branching intensity showed a trend of first increasing and then decreasing with the increases of shading degree. As the phosphorus content decreased, the first-order root diameter gradually became thinner, and the mycorrhizal infection rate gradually increased. Root morphology and architecture of J. mandshurica would undergo adaptive changes under shade, adapting to the shading environment by expanding specific root length, specific surface area, branching ratio and branching intensity. Under phosphorus limitation, root system of J. mandshurica would increase phosphorus absorption through symbiosis with mycorrhizal fungi. When J. mandshurica was artificially regenerate in forest land with a light transmittance of 35%, root morphology and architecture would adapt to the shading environment. The symbiosis between J. mandshurica and mycorrhizal fungi would be enhanced under phosphorus limitation, which could improve phosphorus absorption of roots.