Varia？？es na anatomia foliar de videira Niagara em diferentes sistemas de condu？？o

variations in leaf anatomy are caused by several environmental factors, mainly the availability of solar radiation, leading to possible changes in photosynthetic capacity and crop yield. this paper aims to identify alterations in grapevine 'niagara rosada' and 'niagara branca' leaf anatomy grown in three different training systems: double cordon (esp), lyre (y) and lyre with plastic (ypla). the anatomical studies were made using mature leaves, external in relation to the canopy, collected in distinct regions of vine plants (lower, middle and upper). for anatomical characterization the samples were fixed in faa, embedded in paraffin, sectioned in microtome and stained with safranin-alcian blue. slides were examined with an optical microscope with the aid of the image analysis software motic and the video image was acquired by using a jvc video camera attached to the same optical microscope. leaf anatomy parameters were measured for ten leaves collected in each treatment: thickness of the leaf blade, of the palisade and of the spongy parenchyma, of the adaxial and abaxial epidermis and the ratio of palisade and spongy parenchyma. analyses of variance were performed by f test and the means were compared by the tukey test at 5% probability. the results indicate that the niagara branca and niagara rosada cultivars conducted in esp had a greater average leaf blade thickness, but they were less productive when compared with y and ypla. leaves grown under sunlight showed higher leaf thickness due to a greater development of palisade parenchyma, irrespective of the conduction system.