Video of Current Rootstock Use and Rootstocks Needs for the future: SOUTHERN ITALY, SICILY AND ARID MEDITERRANEAN AREAS

Grapevine rootstocks have been an essential component of grape growing for over 150 years as rootstocks can impart desirable characteristics for grapevine growth. This review examined Italian and Sicilian literature on rootstocks, focusing on key issues including updates on needs for the future. Other related issues include the performance of major selection traits associated with salinity, drought, potassium uptake, vegetative growth, grape and wine quality and the propagation of grafted vines. Research on rootstocks started in Italy, and of course in other European Countries, once phylloxera was imported. In Italy, phylloxera was detected in Agrate (north Italy) in August 1879, but it may have been present since 1870. French and Italian researchers immediately understood that phylloxera resistance was common in American species of Vitis and in September 1879, the National Ampelographic Committee of Phylloxera was born in Italy. In 1880 the Italian Minister authorized the import of 0.8 tons of Vitis rotundifolia, V. cordifolia, V. aestivalis and V. riparia seeds from Unites States. In 1883 more than 0.3 tons of seeds were distributed: 185,000 scions and 11,300 vines of different biotypes of Solonis, Riparia, Rupestris, Berlandieri, Taylor, Vialla, Clinton, Cunningham, Jacquez. In 1884 another 800 Kg V. riparia seeds and 15,000 scions of different species were distributed. From 1886-95, 36 nurseries were created on a total of 67 Hectares of cultivated surface. In order to develop research expertise, Dr. Paulsen (from Portici) and Dr. Silva (from Conegliano) went to France and later became the head of “Vivai Governativi di viti americane” in Palermo and Elba Island, respectively. From this period, research was concentrated on V. riparia and V. rupestris selections and in 1889 Palermo’s governmental nursery made the first crosses. Studies were also carried out on rootstock adaptability to different calcareous soils levels and adaptability to different environmental conditions. The important rootstocks were V. riparia, gloire and grand glabre, V. riparia x V. rupestris, 3306, 3309, V. berlandieri x V. riparia, 34 EM, 420 A, 157/11, V. rupestris du Lot and Aramon x Rupestris Ganzin n.1. At the end of 1930 the national surface of replanted vineyards grafted on American rootstocks was 809,091 hectares. In Sicily, V. riparia x V. rupestris hybrids were rejected because of grafting incompatibility with the local varieties and winegrape growers used Aramon x Rupestris Ganzin n.1. After short time, vines grafted onto this rootstock showed phylloxera damage. Nevertheless this rootstock was used in California (in 1980 75% of vineyards in Sonoma and Napa county) and also failed to phylloxera. Rupestris du Lot spread around Sicily and it was called “La bonne a tout fair” (the same role that Ru140 played twenty years later) but it experienced problems with fanleaf virus (in fact today it is used as virus indicator). The next phase of rootstock use began with the introduction of 420 A, 34 EM, 157/11, 17/37 and 41B in Sicily and in Apulia. In Southern and Northern Italy, before the Second World War, the V. berlandieri x V. rupestris (Paulsen 775, 779, 1103, 1447, 771; Ruggeri 140), V. berlandieri x V. riparia (Ruggeri 225, 235, 240; 11-18); V. riparia x V. rupestris (16-107, 16-109); and V. vinifera x V. berlandieri (10-575; 11-71) started being used as rootstocks after 20 years of evaluation. After the Second World War, a significant revolution in rootstock use was made in Sicilian viticulture. The following rootstocks 17/37, 420 A, 34 EM, 157/11 and 161/49 were totally replaced by the Paulsen 1103 and Ruggeri 140 rootstocks. Although rootstock research did not end, the information available to the farmers came only from the nurseries and they focused on rootstocks with excellent nursery characteristics (i.e. strong root growth, high initial vigor, and graftability). However during that period, viticulture was becoming more mechanized and vigorous rootstocks did well in low density vineyards and wide row spacings. This was the picture of Italian viticulture until 1970. From 1980 research focused on the graftability problem, rootstock-scion interaction, and improvements in yield and quality. There was also a strong emphasis on nutrient uptake mechanisms, water use efficiency (WUE), drought tolerance, and resistance to saline, calcareous and compact soils. Finally, nursery sanitation and clean stock was also studied. Many experimental fields were created and the vegetative and fruit quality parameters of many grafting combinations were evaluated. No differences in vegetative, yield and fruit quality parameters among the grafted combinations were found when there were no climatic or soil-based limiting factors or when rootstocks with similar genetic backgrounds were investigated. Under Sicilian climatic conditions, research found that vegetative and fruit quality parameters were more influenced by cultivar and vintage than by rootstocks. However, rootstock did play an important role in water and nutrient uptake. Generally, Italian varieties are well known for their vigor and this can sometimes be a problem. This high vigor is an important characteristic given the arid summer conditions. Thus, one of the issues for breeding programs is development of a rootstock that can promote sufficient vegetative growth before veraison in order to produce a suitable and sustainable crop, and to ensure a "just right" level of vine vigor and size up to ripeness. International research has verified the secondary role that rootstocks play compared to variety and vintage in determining fruit quality, but it is also well known that the correct rootstock choice can positively affect fruit quality under limiting environmental conditions. The most important result of Italian rootstock research is, from my point of view, that the role of rootstocks in modern viticulture is no longer “a necessary evil”, but they should now be considered to be an important agronomic tool to link the goals of optimized grape quality and quantity from the vineyard.