根土微环境对早实核桃细根时空分布、养分特征的影响

Effects of Root⁃Soil Microenvironment on the Spatial and Temporal Distribution and Nutrient Characteristics of Fine Roots of Early⁃Fruiting Juglans regia L.

以长势基本一致且处于稳产期的‘新新2号’早实核桃(Juglans regia L.)后代为研究对象,按照小格子法将根土连续体划分为144个采样小区。于2022年每月采集根、土样品,测定细根生物量并构建二维空间分布图,研究细根形态指标、养分特征以及土壤水、养质量分数并分析其对早实核桃细根时空分布、养分特征的影响。结果表明:早实核桃细根主要分布在垂直方向的0~0.4 m土层和距树干水平方向1.5 m范围内,占细根分布总量的80%。细根形态参数值(生物量、根长密度、根表面积密度、根体积密度)和养分质量分数均随土层加深呈下降趋势,细根在微环境水平变异时差异不明显。夏、秋季细根形态参数值均显著高于春、冬季。土壤全氮、全磷质量分数随土层加深逐渐减少,土壤全钾质量分数在整个空间分布上无明显差异。土壤含水率随土层加深而增加,距树干距离越远含水率越低。土壤各养分质量分数的季节性差异较大,全氮质量分数在夏、秋季较高,在春季最低;全磷质量分数在春季最高;全钾质量分数在冬季最高;土壤含水率在秋、冬季最高。细根形态、养分质量分数与土壤全氮、全磷、含水率的关系更密切,相关性存在一定季节差异。细根生长在细微变异的环境下仍具有一定的趋水趋肥性。对早实核桃进行肥水精细化管理时,可根据根土的时空关系,在根区适时灌溉,季节性调整肥料养分,施肥则以氮、磷肥为主。

The study focused on the descendants of‘Xinxin 2’early⁃fruiting Juglans regia L.,which exhibited consistent growth and stable yield.The root⁃soil continuum was divided into 144 sampling plots using the grid method.Monthly collection of root and soil samples in 2022 supported the analysis of fine root biomass,construction of a two⁃dimensional spatial distribu⁃tion map,investigation of fine root morphological indicators,nutrient characteristics,and soil water and nutrient content.The goal was to analyze their impact on the spatiotemporal distribution and nutrient characteristics of early⁃fruiting J.regia fine roots.The results showed that the majority of fine roots of early⁃fruiting J.regia were distributed vertically in the 0-0.4 m soil layer and within 1.5 m horizontal distance from the trunk,accounting for 80%of the total fine root distribution.The morphological parameters(biomass,root length density,root surface area density,and root volume density)and nu⁃trient content of fine roots demonstrated a decreasing trend with increasing soil depth,and showed less variation in response to microenvironmental differences.Fine root morphological parameters in summer and autumn were significantly higher than in spring and winter.Total nitrogen and total phosphorus content in the soil decreased with increasing soil depth,while to⁃tal potassium content did not exhibit significant spatial variation.Soil moisture content increased with soil depth,and de⁃creased with distance from the trunk.Substantial seasonal variations were observed in the nutrient content of soil,with higher total nitrogen content in summer and autumn,and lowest in spring,higher total phosphorus content in spring,high⁃er total potassium content in winter,and higher soil moisture content in autumn and winter.The study identified significant seasonality in the relationship between fine root morphology,nutrient content,and soil total nitrogen,total phosphorus,and moisture content.The growth of fine roots has a certain tendency towards water and fertilizer in the environment of slight variation.When implementing precision management of fertilization and irrigation for early⁃fruiting J.regia,it is rec⁃ommended to consider the spatiotemporal relationships within the root zone,apply timely irrigation,make seasonal adjust⁃ments to fertilizer nutrients,with a focus on nitrogen and phosphorus fertilization.