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    宽窄行栽植模式下三倍体毛白杨−小麦复合系统的细根分布及形态特征

    Fine root spatial distribution and morphology of triploid Populus tomentosa-wheat agroforestry system under wide- and narrow-row spacing planting schemes

      摘要
    • 摘要:
        目的  探讨宽窄行栽植模式下毛白杨−小麦复合系统中的细根根长密度(FRLD)分布及形态特征，为优化该系统的集约栽培措施提供了理论依据。
        方法  在宽窄行栽植模式下的4年生三倍体毛白杨−小麦复合系统中，于小麦收获后，采取根钻法在3株平均标准木周围进行根系取样，取样位点为窄行距树75 cm、树行距树75 cm、宽行距树100、200、300、400 cm，取样深度为80 cm，共取得根样288个。对所有样品进行形态扫描和烘干称质量，得到不同深度、位点处的毛白杨和小麦细根的分布及形态数据。
        结果  垂直方向上，毛白杨和小麦的细根均主要聚集在0 ~ 20 cm的浅土层，其中FRLD分别占总根长密度的68%和45%。毛白杨（R2 = 0.679 3，P < 0.05）和小麦（R2 = 0.922 9，P < 0.05）细根均随土层指数递减；两个物种的FRLD在浅土层没有显著差异（P > 0.05），在深土层中则表现出小麦的FRLD显著高于毛白杨的特征（P < 0.05）。水平方向上，毛白杨细根主要聚集在窄行的浅土层中，而小麦细根则在宽行中大量分布。二维根系分布结果显示，毛白杨和小麦有各自的细根密集分布区域且总体上互不干涉。毛白杨的平均细根直径显著高于小麦（P < 0.05），其比根长则显著低于小麦（P < 0.05）。
        结论  在宽窄行栽植模式下的三倍体毛白杨−小麦复合系统中，毛白杨和小麦的细根分布产生了空间分离，密集分布区域重叠较少；此外，为了更有效地吸收土壤资源以占据竞争优势，小麦会生产更多吸收效率更高的细根。以上结果可为优化该栽植模式下农林复合系统的集约经营技术提供理论支撑。

       

      Abstract:
        Objective  To provide a theoretical basis for optimizing the intensive management technology in Populus tomentosa-wheat agroforestry system under wide- and narrow-row spacing planting schemes, the distribution and morphological characteristics of fine root length density (FRLD) in this system were studied.
        Method  In a four-year-old triploid P. tomentosa-wheat agroforestry system under wide- and narrow-row spacing planting schemes, a soil coring method was adopted for root sampling around three average standard trees after wheat harvest. The sampling locations were 75 cm away from tree lines for narrow row and 75 cm away from trees for tree row, while 100, 200, 300, and 400 cm away from tree lines for the wide row, sampling depth was 80 cm. A total of 288 root samples were obtained. All fine root samples were scanned, dried and weighed to obtain the distribution and morphological data in different depths and horizontal distances.
        Result  Vertically, the fine roots of P. tomentosa and wheat were mainly concentrated in the shallow soil layer. The FRLD in 0–20 cm soil layer accounted for 68% and 45% of the total FRLD, respectively. The FRLD decreased exponentially with depth for both P. tomentosa (R2 = 0.679 3, P < 0.05) and wheat (R2 = 0.922 9, P < 0.05). There was no significant difference in FRLD between the two species in the shallow soil layer (P > 0.05). However, in the deep soil layer, the FRLD of wheat was significantly higher than that of P. tomentosa (P < 0.05). Horizontally, fine roots of P. tomentosa were mainly concentrated in narrow row and tree row, while fine roots of wheat were widely distributed in wide row. On a two-dimensional scale, two species had their own dense distribution zones of fine roots and did not interfere with each other. The fine root diameter of P. tomentosa was significantly higher than that of wheat, while its specific root length was significantly lower than that of wheat (P < 0.05).
        Conclusion  In P. tomentosa-wheat agroforestry system under wide- and narrow-row spacing planting schemes, the spatial distribution of the fine roots of P. tomentosa and wheat was separated, and the dense distribution area overlapped less. Also, in order to absorb soil resources more effectively and occupy a competitive advantage, wheat would produce more fine roots with higher absorption efficiency. The results can provide a theoretical basis for optimizing the intensive management technology in agroforestry system under this planting schemes.

       

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