Exigences thermiques de quelques cepages cultives dans la region de l？Estremadura

in order to characterize the thermal exigencies of some grapevine cultivars and to determine the interanual variation, the climatic and phenological data registered in estremadura region between 1995 and 1999 were analyzed. an appreciation of the qualitative potentialities of the different vintages was carried out, which was based on precipitation data and climate indices related to the april-september period, namely the huglin and winkler indices. the characterization of the periods bud burst-flowering, flowering-veraison and veraison-harvest of four red cultivars (castel？o, aragonez, syrah e cabernet sauvignon) was performed in a vineyard located at esta？？o vitivinícola nacional, dois portos (39o 02？ lat. n; 9o 11？ long. w; 100 m a.s.l. elevation; 20% slope; south-west aspect). vines were planted in 1991 and trained to a royat cordon at 0.60 m, the planting distances between rows and plants were 1.70 m and 1.10 m, respectively. the results presented in this paper point out the difficulty of accurately predicting the date of the grape harvest from the flowering date. a minor thermal exigency in the veraison-harvest period of 1995 was observed in comparison with other years. as regards to the studied grape varieties, research has confirmed that aragonez (tempranillo) and syrah are the cultivars which present minor thermal exigencies to get a normal maturation (190 g/l of sugar content).