Using remotely sensed (UAV) and in situ field measurements to describe grapevine canopy characteristics

Rootstocks were the first sustainable and environmentally friendly strategy to cope with a major threat for Vitis vinifera cultivation. In addition to providing Phylloxera resistance, they play an important role in protecting against other soil-borne pests, such as nematodes, and in adapting V. vinifera to limiting abiotic conditions. Today viticulture has to adapt to ongoing climate change whilst simultaneously reducing its environmental impact. In this context, rootstocks are a central element in the development of agro-ecological practices that increase adaptive potential with low external inputs. Despite the apparent diversity of the Vitis genus, only few rootstock varieties are used worldwide and most of them have a very narrow genetic background. This means that there is considerable scope to breed new, improved rootstocks to adapt viticulture for the future. However, in comparison to the extensive research effort devoted to fruit varieties, there is little scientific knowledge to support grapevine rootstock breeding. Since grafting became widespread in viticulture, very few studies have been done on the genetic architecture of the relevant traits in rootstocks, even for resistance to Phylloxera or grafting ability. The current presentation will provide an overview of our knowledge on the genetics of specific rootstock traits, covering resistance to Phylloxera and nematodes, rooting and grafting abilities, and adaptation to drought and salinity. An attempt to list the resources and initiatives at the international level will be made. Acknowledgements: The research for rootstock breeding in Bordeaux has been supported over the years by numerous funding agencies and has benefited from the support of the wine industry. Louis Bordenave, Bernard Douens, Jean-Pierre Petit, Cyril Hévin and Nicolas Hocquard are to be acknowledged for their great involvement in the management of genetic resources and the monitoring of plant material.