关键词: 紫花苜蓿, 根系, 入土深度, 生长年限

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