覆盖处理苹果细根分布与土壤物理性状响应关系研究
The relationship between root distribution of apple and soil physical properties by different ground covering approaches

以12年生红富士苹果树为试材，研究黄土高原旱塬区不同覆盖措施(覆膜、覆草、覆沙)对苹果细根（直径≤2 mm）及土壤性状的影响。结果表明：地表覆盖可有效降低土壤容重，增大土壤含水量及孔隙度，增加细根数量，增大根系吸收水肥效率。覆膜处理细根水平分布范围与清耕（CK）相似，在距干0～90 cm范围内，垂直密集分布最大深度由CK的60 cm提升至40 cm，36.05%的细根分布在0～20 cm土壤表层。与CK相比，覆草、覆沙处理的细根水平分布范围由90 cm扩展至120 cm，垂直均匀分布整个土壤剖面，利于树体对深层土壤水肥的吸收利用。土壤物理性状与细根根长、表面积、根长密度呈极显著相关，覆膜处理中根径与比根长也与土壤物理性状表现出相关性。综合分析根系分布与土壤物理性状，覆草处理是陇东旱塬区苹果园较为适宜的地表覆盖模式。
Twelve years old Red Fuji apple trees were used as materials to investigate the effects of different mulching measures (mulching, straw mulching, covering sand) on apple fine root (diameter ≤2 mm) and soil properties in rain-fed highland of the Loess Plateau. The results indicated that ground covering treatment reduced soil bulk density, increased soil moisture and porosity. Accordingly, root growth was also changed. Ground covering treatment increased number of fine roots, which implied high efficiency of nutrient absorption. The horizontal root distribution within 0～90 cm from the trunk by mulching treatment was similar to clean tillage (CK). The vertical distribution of fine roots became concentrated at the depth of 40 cm, rather than 60 cm in the CK. 36.06% of fine roots were distributed at the 0～20 cm soil layer. Straw mulching and sand covering expanded the range of horizontal distribution from 90 cm to 120 cm and vertical distribution evenly throughout the soil profile, which benefits the absorption of water and fertilizer from deep soil. A highly significant correlation was found between soil physical properties and root length, surface area and root length density of absorbing roots. Root diameter and the ratio of root length were also found to be closely related to soil physical properties in the mulching treatment. As a result, considering the root distribution and soil physical properties, straw mulching is recommended for apple orchards in dry area of eastern Gansu.