运用微根管技术研究草地植物细根的进展

Review of minirhizotron applications for study of fine roots in grassland

微根管(minirhizotron,MR)技术自出现以来,因其方便、简洁、省时省力和能够原位观察的特点而在植物细根(直径<2mm)研究中发挥重要作用。草地植物细根在土壤养分循环和草地可持续发展中起到关键作用。本研究综述了国内外学者运用微根管技术研究草地植物细根的进展,主要集中在草地植物根系产量、寿命及周转速率对气候变化、草地管理与利用以及土壤生物的响应等方面。多数研究认为CO2浓度升高和气候变暖会增加植物细根根长、根数量或生物量,降低根系寿命;春季发生的细根寿命相对秋季发生的细根较短。刈割和人工施加氮肥对天然草地植物根系没有显著影响,但会成倍增加草地地上生物量,减少物种丰富度。植物细根寿命与直径呈正相关关系,周转速率与直径呈负相关关系。微根管技术在今后研究的重点可围绕4个方面:1)放牧、草地利用与管理以及土壤生物与草地植物细根的相互关系;2)根系寿命或周转速率对土壤碳库或养分库的影响;3)气候变化或人类活动引起草地植物根系发生变化的机制。通过综述,以期更好地利用微根管技术服务于草地根系研究,促进草地农业生态系统根系研究的发展。

Minirhizotron（MR）devices are playing an important role in fine root study due to their convenience,low time-input requirement,also because they can be used in situ.The fine roots of grassland plants are important in the soil nutrient cycle and in the sustainable development of grassland.Therefore,this review summarized the progress of research into fine root dynamics of plants in grassland.Aspects covered include the effect of global climate change,land use,land management and soil organisms on root longevity and root turnover rate.Most studies indicated that high CO2 concentration,and also global warming,increased root length,root number or biomass,but decreased root longevity.Fine roots developed in spring tend to have greater longevity than those developed in autumn.Additionally,grazing and nitrogen fertilizer have no effect on plant root growth,but increase shoot biomass,and decrease the species diversity in natural grassland.Plant fine root longevity is positively correlated with root diameter,whereas root turnover rate is negatively correlated with root diameter.The future research directions for MR research include study of：1）the relationship between grazing,land-use change,soil organism populations and plant root dynamics in grassland;2）the effect of root longevity and root turnover rate on the soil carbon and soil nutrient pool;3）the mechanisms where by interaction between climate change and human activity affect plant root systems;and 4）how external factors influence the relationship between plant roots and soil organisms.We expect to raise awareness of the application of MR technology in the grassland agro-ecosystem research,and to advance the development of fine root research in grasslands.