Ecophysiological and agronomic response of two 'Nebbiolo' clones to different leafroll virus infection

Viral diseases are reported to cause several detrimental effects on grapevine. Leafroll, due to single or mixed infection of GLRaV-1 and GLRaV-3, and Rugose wood associated to GVA, are considered the most widespread and dangerous. The virus influence on grape qualitative (i.e enological) aspects is still controversial and the grapevine response may vary depending on the specific virus involved or the environmental conditions. The aim of the present study was to deeply investigate the effect due to specific viruses. For this purpose the healthy and the infected descendants of two clones of Nebbiolo (Vitis vinifera L.) were compared in a vineyard. The viruses present in the infected lines were GLRaV1+GVA in the clone 'A' and GLRaV3+GVA in the clone 'B'. During 2008 and 2009, canopy physiological efficiency was investigated as well as field performances, juice composition, berry phenols amount and berry anthocyanin profile. The results indicated the infected plants showed alternate field performances, lower canopy efficiency and an anthocyanin profile poorer of malvidine-3-gucoside.