Role of the variety and some environmental factors on grape stilbenes

V. vinifera L. 'Barbera', 'Croatina', 'Malvasia di Candia aromatica', growing in the Piacenza viticultural area (North-West Italy) at four elevations (150, 240, 320, 420 m a.s.l.), were tested at harvest for grape stilbene (trans-resveratrol, trans-piceid, cis-piceid) synthesis over three years (2000-2002). Meteorological data were recorded, as well as vine production and fruit quality parameters. The most significant findings were: (i) trans-piceid was the most abundantly produced stilbene compound (103 μg·kg-1 berry FW), while trans-resveratrol was the least produced (57 μg·kg-1 berry FW); (ii) 'Barbera' and 'Croatina' had similar trans-resveratrol berry levels (71 μg·kg-1 berry FW and 76 μg·kg-1 berry FW respectively), higher than 'Malvasia di Candia aromatica' (24 μg·kg-1 berry FW); (iii) 'Barbera' had the highest trans-piceid and cis-piceid concentrations (235 and 136 μg·kg-1 berry FW, respectively) while 'Malvasia di Candia aromatica' had the lowest levels (13 and 1 μg·kg-1 berry FW, respectively); (iv) stilbenes increased with elevation up to 320 m, while decreasing at the highest altitude; (v) the vintage year only significantly affected the cis-piceid berry concentration which was positively related to the relative humidity at the end of ripening, and negatively related to degree-days at the end of ripening.