Soil and rootstock influence on fruit quality of plums (Prunus domestica L.)

Soil and rootstock can particularly affect the 'Rainha Claudia Verde' (Prunus domestica) fruit quality, mainly its firmness characteristics. To investigate the variation in fruit quality, plums were harvested at commercial maturity from trees grafted on Marianna GF8-1 (Prunus cerasifera x munsoniona) and Marianna GF10-2 (P. cerasifera x munsoniana) rootstocks on two different soils: Haplic Luvisol and Vertic Luvisol. After harvest fruits were stored at 2 degrees C for 3 weeks. At the harvest day a small group of fruits were analysed without cold storage. During storage fruits were tested for firmness, soluble solids content, titratable acidity and fruit mineral content. Tree vigour was evaluated from trunk cross-sectional areas values. The GF8-1 rootstock promoted the highest vegetative development, comparing to GF10-2. This rootstock promoted the largest fruits size and the higher calcium fruit level. Positive correlations were found between higher concentrations of calcium in the pulp fruits and firmness. Fruits from two different rootstocks showed the same firmness at harvest but during cold storage, fruits from GF10-2 rootstock exhibited the highest firmness pulp values. There weren't significant differences in fruit nitrogen and potassium levels for any studied factor. At harvest solids soluble content and solids soluble content/titratable acidity ratio weren't affected by soil type or rootstock. As expected, solids soluble content during cold storage increased and Solids Soluble content/titratable acidity had a slight increase. GF10-2 revealed to be a good option as a 'Rainha Claudia Verde' rootstock for plums growers due to its intermediate-vigour. Also GF10-2 fruits presented better quality during storage comparing with GF8-1. (C) 2008 Elsevier B.V. All rights reserved.