This study aims to compare the leaf morphoanatomical characteristics of seven Vitis vinifera subsp. vinifera white cultivars with different geographical origin, grown side by side at the same "terroir". The leaf morphoanatomical traits analyzed under light and scanning electron microscopy (SEM) showed large variability among genotypes. Significant differences between cultivars were observed in single leaf area, specific leaf area, leaf density and in the thickness of cuticle, upper and lower epidermal cells and mesophyll. Leaf dry mass per area presented a significant positive correlation with leaf density but showed no correlation with leaf thickness, results that can be explained by the quite different mesophyll structure, epidermal cells and cuticle thickness. 'Alvarinho', 'Encruzado', 'Macabeu' and 'Viosinho' were the cultivars with the highest thickness of cuticle and mesophyll tissues. Under SEM magnification three types of stomata were identified: sunken, at the same level and raised above, with the same level type presenting the higher percentage in all cultivars. Stomata density presented significant differences between cultivars, with 'Macabeu' showing the highest value and 'Alvarinho' and 'Arinto' the lowest ones. The hairs on the lower surface presented a similar woolly aspect in all cultivars. Calcium oxalate crystals, raphids and druses were visible and widely distributed in the parenchyma tissues. The observed differences in leaf traits among genotypes suggest a major role of leaf anatomy in determining grapevine capacity for coping with different environmental conditions. RESUMOEste estudo teve por objetivo comparar as características micromorfoanatómicas foliares de sete cultivares brancas de Vitis vinifera subsp. vinifera, com diferente origem geográfica, cultivadas lado a lado no mesmo "terroir". Os parâmetros foliares analisados, com recurso à microscopia ótica e eletrónica de varrimento, evidenciaram uma grande variabilidade entre genótipos. Observaram-se diferenças significativas entre cultivares na área foliar, área específica da folha, densidade foliar, espessura da cutícula e das células epidérmicas da página superior e inferior e do mesófilo. O peso seco por unidade de área apresentou uma correlação significativa e positiva com a densidade da folha mas não com a espessura do mesófilo, resultados que se podem explicar pelas diferenças na estrutura do mesófilo e espessura da epiderme e da cutícula. As cultivares 'Alvarinho', 'Encruzado', 'Macabeu' e 'Viosinho' foram as que apresentaram os maiores valores de espessura da cutícula e dos tecidos do mesófilo. Com recurso à microscopia eletrónica identificaram-se três tipos de estomas -enterrados, ao mesmo nível e elevados, estando o tipo de estoma ao mesmo nível presente em maior percentagem em todas as cultivares. A densidade estomática apresentou diferenças significativas entre cultivares tendo sido obtido o maior valor na cultivar 'Macabeu' e o menor nas cultivares 'Alvarinho' e 'Arinto'. O indumento da página inferior evidenciou caracterís...

This study compare leaf morphoanatomical characteristics of four red cultivars - ‘Touriga Nacional’, ‘Trindadeira’, ‘Cabernet Sauvignon’ and ‘Syrah’ -, grown side by side at the same terroir. The analyzed leaf traits, under light and scanning electron microscopy, showed large variability among genotypes. ‘Trincadeira’ has the biggest single leaf area and ‘Cabernet Sauvignon’ the smallest one. ‘Touriga Nacional’ showed the lowest leaf dry weight and ‘Trincadeira’ the highest one, nonetheless there was no significantly differences in leaf dry mass per area and in leaf density. Leaf dry mass per area was positively correlated with leaf density but showed no correlation with leaf thickness. The French genotypes presented higher thickness of the leaf anatomical traits than the two Portuguese ones. ‘Trincadeira’ showed significantly highest stomata density while the other cultivars showed no significant differences among them. The analyses of the three types of stomata revealed that ‘Trincadeira’ has the lower percentage of raised above and the highest percentage of sunken stomata while ‘Cabernet Sauvignon’ showed the opposite behaviour. The hairs on the lower surface presented a similar woolly aspect in all cultivars. The possible role of leaf morphoanatomical characteristics in determining the cultivars adaptation to abiotic stresses is suggested and discussed.

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