Effects of grapevine leafroll associated virus 2 infection on leaf net photosynthesis, yield and berry quality in Vitis vinifera cv. Malbec

Abstract

Grapevine leafroll associated virus 2 (GLRaV-2) is one of the most common damaging viral diseases in vines, causing significant reductions in photosynthesis, yield and grape quality. In this study, we tested the hypothesis that the leaf net photosynthesis and the transport of sugars to the berries is progressively reduced along the season in vines infected with GLRaV-2, and consequently, the yield (kg per plant) and total soluble solids (TSS) at the berry harvest-ripe stage are lower than non-infected vines. Thus, we assessed the impacts of GLRaV-2 infection on leaf net photosynthesis, yield components and berry composition (pH and TSS) of field-grown Malbec grapevines at different phenological stages. During 2016/17 season, four previously identified infected vines with GLRaV-2 and four non-infected vines were selected at the Research Station INTA, Mendoza. Diurnal dynamics of photosynthesis were determined at pre-veraison, veraison, berry harvest-ripe and post harvest. Berry samples were collected every week, after veraison, to track the Brix level. The yield (kg per plant) and number of bunches per plant were registered at harvest and the berry number, TSS and pH were determined according to different berry density categories. The main results of this work indicated that the virus infection reduced significantly the leaf net photosynthesis at the berry harvest-ripe and postharvest stages. At harvest, the infected vines had a lower yield due to a lower weight of bunches and berries relative to those non-infected. The TSS level at harvest, from all berry density categories, was reduced in infected vines.