紫花苜蓿与3种生活型多年生禾草混播的根系构型差异

Difference in root configurations of differentcombinations of alfalfa and three differentlife-type perennial grasses after mixed sowing

摘要:

【目的】 探讨豆禾混播草地牧草根系构型对混播组分和比例的响应。【方法】 以紫花苜蓿分别与3 种生活型禾草（匍匐茎型草地早熟禾、根茎型无芒雀麦和丛生型苇状羊茅）以豆禾比为7∶3、5∶5 和3∶7 建植的人工草地为研究对象，以各草种单播为对照，测定不同混播处理下各组分的根系形态和构型特征。【结果】 混播改变了牧草根系形态和构型，各草种通过增大总根长、根表面积、根体积和根尖数，减小根直径，优化拓扑结构，增强空间占有能力和提高根系发达程度等生态策略来响应竞争环境，进而使得混播草地增产。但较高比例的紫花苜蓿会阻碍苇状羊茅根系的生长和产量。较单播草地而言，混播草地牧草根系分支结构均有由叉状分支向鱼尾状分支转变的趋势。混播处理下各草种根系性状变异明显，紫花苜蓿根系性状变异主要表现在根尖数，变异系数为51. 95%，草地早熟禾匍匐茎型根系性状变异主要表现在拓扑指数，变异系数为81. 13%，无芒雀麦根茎型根系和苇状羊茅根系性状变异主要表现在根体积，变异系数分别为52. 29% 和29. 17%。【结论】 以紫花苜蓿分别与3 生活型禾草3∶7 混播时豆科牧草与禾本科牧草根系发育程度和混播草地增产率较高。

Abstract:

【Objective】 The experiment is carried out in order to explore the response of root configuration of le-gume-grass mixed pasture to mixed sowing components and proportions.【Method】 The artificial pasture constructedby alfalfa and three life forms gramineous forage （stolon type-Poa pratensis，rhizome type-Bromus inermis and bushtype-Festuca arundinacea） with mixed sowing ratios of 7∶3，5∶5 and 3∶7 was selected as the research objects，and themonoculture of each forage was chosen as the control to determine the root morphology and configuration characteris-tics of each component under different mixed sowing treatments.【Result】 Mixed sowing changed the morphologyand configuration of forages roots. The forages responded to the competitive environment by increasing the total rootlength，root surface area，root volume and root tip number，reducing root diameter，optimizing topological structure，enhancing spatial occupancy and improving root development. As a result，the mixed sowing pasture yield increased.However，the exorbitant proportion of alfalfa would hinder the growth of F. arundinacea roots. Compared with themonoculture pasture，the root branch structure of forage in the mixed pasture had the trend of changing from forkbranch to fishtail branch. Under the mixed sowing treatment，the variation of root traits of each grass species was obvi-ous. The variation of alfalfa was mainly in the number of root tips，and the coefficient of variation was 51. 95%. Thevariation of P. patensis was mainly in the topological index，and the coefficient of variation was 81. 13%. The varia-tion of B. inermis and F. arundinacea was mainly in root volume，and the coefficient of variation was 52. 29% and29. 17% respectively.【Conclusion】 When alfalfa was mixed with P. pratensis at 3∶7，with B. inermis at 3∶7，and withF. arundinaceaat 3∶7，the root system developed and the rate of increases were high. .