Abstract: Factors affecting the alfalfa rooting depth and the rooting depth in several natural regions were reviewed in this paper.Factors affecting the alfalfa rooting depth include the depth of the soil layer,underground water level,the soil characteristics,ploughing,fertilization,irrigation,defoliation,growth regulators,cultivars and growing year.Depth of soil layer,underground water level,soil characteristics and growing year had a great influence on the alfalfa rooting depth.Thinner the depth of soil layer,higher the underground water level,severer the soil obstacle,shorter the growing year,the rooting depth was shallower.Deep tillage,fertilization,application of plant growth regulators could promote the root penetration.Under different irrigation patterns,the rooting depth was slightly different.The more frequent the clipping,the shallower the rooting depth was.There was a certain degree difference with the rooting depth between different varieties.Among the different natural regions and growing year,there was great difference with the rooting depth.In some situations which the depth of soil layer was thin and the underground water level was high,the rooting depth depended on the depth of the soil layer and underground water level.When the soil obstacle was severer,the rooting depth was always below 1 m,generally less than 2 m.In some situations without obvious soil obstacle,the rooting depth of one growing year alfalfa was about 1～2 m,that of 2 to 5 growing year’s was about 2～5 m.

Key words: Alfalfa, Root system, Rooting depth, Growing year

摘要： 综述了紫花苜蓿(Medicago sativa L.)根系入土深度的影响因子和若干自然区域的紫花苜蓿根系入土深度,为其根系的深入研究及栽培管理提供依据.影响紫花苜蓿根系入土深度的因子包括土层厚度、地下水位、土壤特性、耕作、施肥、灌溉、刈割、生长调节剂、品种和生长年限,其中土层厚度、地下水位、土壤特性和生长年限对紫花苜蓿根系入土深度的影响较大;土层越薄、地下水位越高、土壤障碍(酸、碱、盐、粘重、紧实和贫瘠)越重、生长年限越短,根系入土深度越浅;深耕、施肥和应用生长调节剂皆可促进苜蓿根系下扎;不同灌溉模式根系入土深度略有不同;刈割频率越高,根系入土深度越浅;不同品种根系入土深度存在一定差异;不同自然区域和生长年限紫花苜蓿根系入土深度差异很大;在土层薄及地下水位高的情况下,紫花苜蓿根系入土深度取决于土层厚度和地下水位;当土壤障碍较为严重时,紫花苜蓿根系入土深度常可浅至不足1 m,一般不超过2 m;在无明显土壤障碍因子的情况下,生长1年紫花苜蓿根系入土深度约为1~2 m,生长2-5年者多在2~5 m之间.

关键词: 紫花苜蓿, 根系, 入土深度, 生长年限