欧美108杨细根形态及垂直分布对水氮耦合措施的响应  

Responses of the fine root morphology and vertical distribution of Populus × euramericana ‘Guariento' to the coupled effect of water and nitrogen

作　　者：闫小莉[1] 戴腾飞[1] 贾黎明[1] 戴丽莉[1] 辛福梅[2] 

机构地区：[1]北京林业大学省部共建森林培育与保护教育部重点实验室,北京100083 [2]西藏大学农牧学院,西藏林芝860000

出　　处：《植物生态学报》2015年第8期825-837,共13页Chinese Journal of Plant Ecology

基　　金：国家林业公益性行业科研专项经费重大项目(201004004)

摘　　要：合理高效的水肥集约经营是有效地提高速生丰产林生产力的重要途径。细根是植物吸收水肥和维持生长的主要器官,了解细根形态及其分布对水肥耦合措施的响应机制有助于解释树木生长和吸收水肥能力的差异性。该文基于水氮耦合措施对欧美108杨(Populus×euramericana‘Guariento’)幼林表土层(0–30 cm)细根形态及分布的影响研究,在连续两年的水氮管理后,开展了欧美108杨0–60 cm土层细根形态及垂直分布对水氮耦合响应的研究。田间设计3个灌溉水平(灌溉土壤水势起始阈值为–75 k Pa、–50 k Pa、–25 k Pa)和3个养分水平(施N 150 g·tree–1·a–1、300 g·tree–1·a–1、450 g·tree–1·a–1),组合成9个水氮耦合处理,另设1个对照处理(CK)。研究结果表明:(1)垂直方向上,各处理细根生物量密度、表面积和平均直径均表现为10–20 cm土层最大(该层生物量密度占0–60 cm土层总生物量的27%–37%),随后在30–60 cm土层逐层递减;根长密度则随土壤深度的加深而逐层递减,0–10 cm土层显著大于其他土层(该层根长密度占0–60 cm土层总根长密度的33%–45%)。(2)6个土层的细根生物量密度、根长密度和平均直径均表现为高水高氮(D3F3)和中水高氮(D2F3)2个处理间差异不显著,但均显著高于其他处理,其中,D3F3处理6个土层生物量密度是对照的3.12–47.74倍;细根表面积则是D3F3处理显著高于其他处理,是CK的4.36–30.57倍。(3)连续的水氮耦合管理措施不会改变细根的垂直分布格局(各处理均具有与CK一致的分布格局),但在第二个生长季,欧美108杨细根的整体分布随着林龄的增加趋于深层化;另外,中水高氮的耦合处理也可有效地促进细根的生长,这种水氮需求水平与第一个生长季内需高水高氮才可显著促进其生长的特性不同。欧美108杨细根在第2个生长季主要分布于0–20 cm土层,9个水氮耦合处理中,除低水低氮处Aims Irrigation and fertilization have great potentials to enhance yield in forest plantations. The integrated effect of water and nitrogen management on fine roots morphology and distribution of Populus × euramericana ‘Guariento’, however, remains unclear. The objective of this study was to evaluate the effect of water and nitrogen addition on fine root morphology and distribution in poplar plantations for developing the best water and nitrogen strategy for promoting fine root.Methods The soil core method was used to quantify the morphology and distribution of fine roots in the 0-60 cm in a poplar plantation with surface dripping irrigation and fertilization technologies. The experiment included nine treatments, which were a combination of three irrigation treatments where dripping irrigation was applied when soil water potential （ψsoil） reached -75, -50, or -25 kPa, and three fertilization treatments at nitrogen additions of 150, 300, or 450 g·tree^-1·a^-1, respectively）. A control plot with non-irrigation and non-fertilization treatment in growing season （CK） was also included in the study.Important findings The fine roots biomass density, fine root surface area density, average root diameter in all treatments were mainly found at 0-10 cm and 10-20 cm depths, with root biomass density in the 10-20 cm of 1.03 to 1.21 times of that in the 0-10 cm, 1.25 to 1.80 times of that in the 20-30 cm, 1.62 to 22.10 times of that in the 30-40 cm, 2.77 to 54.35 times of that in the 40-50 cm, and 6.48 to 293.09 times of that in the 50-60 cm. The root biomass density in the 10-20 cm accounted for 27%-37% of the total biomass density in the top 60 cm. For root biomass density and average diameter, there were no significant differences between 0-10 cm and 10-20 cm depths, and between 40-50 cm and 50-60 cm depths. Fine roots in the irrigation and fertilization treatments were significantly higher than that of the CK, except the D1F1 treatment （i.e., with low water and low nitrogen level）. Additionally, fine

关 键 词：水氮耦合 细根 形态 垂直分布 

分 类 号：S792.11[农业科学—林木遗传育种]