Acta Agrestia Sinica ›› 2016, Vol. 24 ›› Issue (6): 1290-1295.DOI: 10.11733/j.issn.1007-0435.2016.06.020

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Effects of Nitrogen on Root Morphology and Anatomical Structure of Alfalfa

ZHU Tian-qi, LIU Xiao-jing, ZHANG Xiao-ling   

  1. College of Grassland Science, Gansu Agricultural University, Key Laboratory of Grassland Ecosystem of Ministry of Education, Sino-U. S. Centers for Grazing land Ecosystem Sustainability, Lanzhou, Gansu Province 730070, China
  • Received:2016-06-21 Revised:2016-08-08 Online:2016-12-15 Published:2017-03-18

氮营养调控对紫花苜蓿根系形态及其解剖结构的影响

朱天琦, 刘晓静, 张晓玲   

  1. 甘肃农业大学草业学院/草业生态系统教育部重点实验室/中美草地畜牧业可持续发展研究中心, 甘肃 兰州 730070
  • 通讯作者: 刘晓静
  • 作者简介:朱天琦(1992-),男,甘肃天水人,硕士研究生,研究方向为牧草营养生理,E-mail:zhutq1992@163.com
  • 基金资助:

    国家自然科学基金项目(31460622);甘肃省科技支撑计划项目(1504NKCA003);公益性行业(农业)科研专项(201403048-8)资助

Abstract:

This paper is to explore the effects of regulation of exogenous nitrogen on early root external morphology and internal structure of alfalfa. In order to simulate soil nutrient that could be absorbed by plants, the study was based on two nitrogen forms (nitrate nitrogen and ammonium nitrogen) and five nitrogen levels (0,105,210,315,420 mg·L-1). ‘Gannong No.3’ alfalfa was used as the experimental material by using sand culture supplied with different nutrient solutions,and observation of paraffin section and the photomicrography of roots. The results showed that under each level of two kinds of nitrogen forms, the root biomass, length, surface area and volume, average diameter were significantly higher than that of controls (P <0.05). With the levels of nitrogen increase, each root indexes were increased at the beginning and then decreased. When two kinks of nitrogen forms were 210 mg·L-1, the root growth and morphological indexes were maximum, and NH4+-N treatments were better than NO3--N. Root conduction tissue anatomy also showed the same trend as root morphology. When NH4+-N treatment was 210 mg·L-1, the root anatomy of conducting tissue (vascular area, xylem area, phloem area and the number of catheter) showed the best performance. The result showed that NH4+-N 210 mg·L-1 level can effectively promote roots outside morphogenesis, improve internal conducting tissue structure.

Key words: Alfalfa, Nitrogen, Root morphology, Conducting tissue, Anatomical structure

摘要:

为探究外源氮调控对紫花苜蓿(Medicago sativa L.)生长早期根系外部形态及内部结构的影响,本研究模拟自然条件下土壤中可供植物吸收利用的不同浓度水平(0,105,210,315,420 mg·L-1)的2种氮素形态(NO3--N,NH4+-N),以‘甘农3号’紫花苜蓿为材料,经营养液砂培,采用石蜡切片技术和根系扫描系统,展开试验研究。结果表明:2种氮形态各水平处理下根系生物量、总长度、表面积、体积、平均直径显著高于对照(P<0.05),根系各指标均随氮素水平的增加呈先上升后下降的趋势,并在210 mg·L-1处理下达到最大值,NH4+-N处理好于NO3--N。根系输导组织解剖结构也表现为相同的变化趋势,在NH4+-N 210 mg·L-1时根系维管束面积、木质部面积、韧皮部面积、导管数达到最大值。由此可见,210 mg·L-1水平NH4+-N可有效促进其根系外部形态建成及改善其内部输导组织结构。

关键词: 紫花苜蓿, 氮营养, 根系形态, 输导组织, 解剖结构

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