Rootstock and soil management effects on productive characteristics of 'Princess Seedless^®' table grapes in Apulia region (southern Italy): first results

The use of rootstocks on table grape cultivars is required due to phylloxera, nematodes or soil difficulties, like high lime or salt content, drought or high ground water level. The use of inter-row cover crops (permanent or temporary) in viticulture has many advantages, such as reduction of water runoff and soil erosion, restriction of evaporation from the soil surface, improvement in soil water holding and soil organic matter, reduction of temperature fluctuations in the soil, as well as regulation of the vine growth and vigor, with influence on grape quality and quantity. The trial was carried out in 2012-2013 at an experimental vineyard, trained to “tendone trellis system” on ‘Princess^®’, (Vitis vinifera L.) a white mid-season muscat-flavored seedless table grape, grafted onto 3 rootstocks: Vitis riparia × Vitis cinerea var. helleri 161.49 C., 34 E.M. and Vitis rupestris × Vitis cinerea var. helleri 140 Ruggeri. Two different soil inter-row space management treatments, tilled cultivation and permanent resident cover crop, were applied in a split-plot design. At commercial harvest, cluster and berry mass, berry diameter, yield per vine, berry chemical composition, skin berry color and berry mechanical parameters were determined. ‘Princess^®’ vines exhibited a good performance on all three rootstocks tested. No significant interactions were detected between soil management/rootstocks with regard to cluster weight, berry weight and number per cluster. The soil management/rootstocks interaction was significant for all parameters of chemical composition and skin color coordinates. The highest and statistically different sugar juice content onto 140 Ruggeri and 161.49 rootstocks was noted. Finally, a temporary cover crop with resident vegetation had no negative effects on vine growth and productivity of ‘Princess^®’ seedless table grape, with clear benefits of the cover crops in relation to soil compaction, soil water storage and organic matter. Moreover, the rootstocks/soil management interaction affected firmness and berry detachment force.