黄土高原丘陵区柠条根系生长发育特性研究

Development of Caragana Microphylla Seedling Root System in Hilly Regions of Loess Plateau

以陇西黄土高原丘陵沟壑区1～3a柠条荒山直播苗为研究对象,应用挖掘法对其根系的形态、生长发育、分布及根瘤特性进行了观测分析。结果表明,幼龄期柠条主根生长速度远大于株高生长,根冠比值在4～6之间;侧根主要发生在主根的5～15cm段;柠条胚根平均向上伸长5cm,合理的播种深度为3cm;根瘤主要集中在10—30cm土层中主根及一级侧根上;速生、发达的根系和根瘤,使得柠条具有超强的抗旱、耐瘠薄能力和蓄水保土、改良土壤的生态功能。柠条秋播较春播能更大程度地与当地的光、热、水等资源相拟合,应大力倡导秋季直播造林。

The major objective of this study was to characterize the root system of the 1～3 year old seedlings of Caragana microphylla,an important shrub species in Longxi hilly region of the Loess Plateau,China.Root morphology,growth and development,distribution and nodule characteristics were determined after excavation.The results show that the growth rate of the major root of Caragana microphylla was much greater than that of the stem.The ratio of root to shoot ranged from four to six.The lateral roots were found mainly on the 5～15 cm section of the major root.The radicles of Caragana microphylla in average elongated 5 cm upward,implying a reasonable sowing depth of 3 cm.The nodules concentrated mainly on the major root and the first-division lateral roots in the 10—30 cm soil layer.The fast-growing,well-developed root system and nodules provided the plant with superior drought resistance and ecological functions of improving soil quality and conserving soil and water.Compared with spring sowing,fall sowing agreed to local light,heat,and water resources better and should be promoted to a higher level.