The impact of material used for minirhizotron tubes for root research

A wide variety of transparent materials are currently used for minirhizotron tubes. We tested the null hypothesis that minirhizotron composition does not influence root morphology and dynamics. Minirhizotron data were compared for glass, acrylic and butyrate tubes in apple (Malus domestica) and acrylic and butyrate tubes in a study with six forest tree species. Root phenology and morphology were generally similar among tubes. Apple root production was greatest against glass; these roots became pigmented later and lived longer than roots near acrylic or butyrate. Roots generally became pigmented faster next to butyrate than next to acrylic. Root survivorship was shorter near butyrate tubes in three of the four hardwood species; however, survivorship was shorter near acrylic tubes for the three conifer species. Comparison of minirhizotron standing crop data with root standing crop from cores showed that the acrylic data matched more closely than the butyrate data. This study reveals that the transparent material used often has little effect on root production but can substantially influence root survivorship in some plants.