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090			_aB-13200
245	1	0	_aThe velamen of epiphytic orchids: variation in structure and correlations with nutrient absorption
490	0		_vFlora, 230, p.66-74, 2017
500			_aArtículo
520	3		_aRoots of epiphytic orchids typically possess a velamen radicum, a multiple epidermis composed of dead cells. It is largely unexplored how the structure of the velamen, the cortex and vascular cylinder facilitate the flow of water and nutrients towards the plant. Up to now, structural root features were rarely correlated with functional attributes. In this study, we compare anatomical features with nutrient uptake rates (specifically of phosphorus and rubidium) of roots of 18 taxa of epiphytic orchids. The relative proportion of the velamen of the cross-sectional area varied from 11 to 97 percent. Species with the largest relative velamen area facilitate the flow of water and nutrients, and species with larger relative proportion of vascular cylinder and cortex have a greater number of protoxylem strands and passage cells of the endodermis. The number of passage cells in the endodermis and of differential wall thickenings in cortical cells may play an important role in apoplastic and symplastic flow. The velamen pectic matrix, with negative charge, can retain cations (like Rb+), while a higher number of strands in the xylem, aligned with passage cells of the endodermis, could facilitate the entry of these ions into the vascular cylinder.
650	1	4	_aNUTRIENT UPTAKE
650	1	4	_aORCHIDACEAE
650	1	4	_aPASSAGE CELLS
650	1	4	_aPECTINS
650	1	4	_aROOT ANATOMY
650	1	4	_aVELAMEN STRUCTURE
700	1	2	_aJoca, T. A. C.
700	1	2	_ade Oliveira, D. C.
700	1	2	_aWinkler, U.
700	1	2	_aMoreira,A.S.F.P.
856	4	0	_uhttps://drive.google.com/file/d/1915QHQXOCCdgcUiQBC76zpcfnbZgX-qz/view?usp=drivesdk _zPara ver el documento ingresa a Google con tu cuenta: @cicy.edu.mx
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