川西北沙化草地7种牧草根系构型及根鞘特征分析

以川西北沙化草地7种禾本科牧草为研究对象,通过测定并分析牧草根系的几何形态指标、分形维数、拓扑指数和根鞘重,探讨了影响根系构型和根鞘重的主要根系形态因子,确定了牧草根系的综合评分。结果表明:(1)根表面积、总根长和分叉数是影响供试牧草根系构型的主要几何形态指标,决定了牧草根系的空间分布属性;(2)7种牧草的根系拓扑指数都接近于1,属于鱼尾形分支模型;根系的综合得分大小顺序依次为糙毛以礼草>赖草>垂穗披碱草>冷地早熟禾>■草>草地早熟禾>紫羊茅;(3)7种供试牧草的根平均连接长度、根体积、根平均直径是影响根鞘重的3个根系形态指标。糙毛以礼草、赖草和垂穗披碱草的根系空间分布更适宜于川西北高寒沙化草地的生境条件,具有更好的生态适应性,可以作为当地沙化草地治理的主要草种来利用。

Analysis of Root Architecture and Rhizosheath Characteristics of Seven Forage Species in Desertified Grassland of Northwest Sichuan

The seven forage species in desertified grassland of northwest Sichuan were used as the research objects. By measuring and analyzing the geometric parameters, fractal dimension, topological index and rhizosheath weight of forage roots, the main factors affecting root architecture and rhizosheath weight were discussed, and the comprehensive score of seven forage roots was determined. The results showed that: 1) Root surface area, total root length and number of root branches were the main geometric parameters affecting the root architecture, which determined the spatial distribution properties of forages root;2) The root topological index of seven forages got close to 1, which belonged to herringbone branch model. The order of the comprehensive score of roots system was Kengyilia hirsute>Leymus secalinus>Elymus nutans>Poa crymophila>Koeleria cristata>Poa pratensis>Festuca rubra;3) The average root link length, root volume and average root diameter of the seven forages were three root morphological indicators affecting the rhizosheath weight. The root spatial distribution of Kengyilia hirsuta, Leymus secalinus and Elymus nutans was more suitable for the habitat of desertified alpine grassland in northwest Sichuan with better ecological adaptability, which could be used as the main forage species for local desertified grassland recover.