GRAFT COMPATIBILITY BETWEEN EUROPEAN PEAR CULTIVARS AND EAST MALLING “C” ROOTSTOCK

Bruno Dalazen Machado,Aike Anneliese Kreztschmar,Leo Rufato,Amauri Bogo,Maicon Magro

doi:10.1590/0100-29452017063

Abstract

ABSTRACT Graft incompatibility is one of the main factors limiting european pear production in Brazil. At present, there is no clear indication of the best combination(s) of european pear cultivars and quince rootstocks for graft compatibility. The study evaluated the graft compatibility for combinations of european Abbè Fetel, Rocha and Williams pear cultivars grafted onto the EMC quince rootstock. The experiment was performed in a commercial european pear orchard in the Urupema municipality, in State of Santa Catarina, during the 2011/12, 2012/13 and 2013/14 growing seasons. The plant growth variables comprised the section increment (mm) in the trunk diameter in the graft union region of cultivars and rootstocks; difference in the diameter of the graft for cultivars and rootstocks; “translocated” incompatibility; “located” incompatibility and the vascular connection in the graft union region, which was assessed by immersing the bases of the plants in a 0.08% succinic acid solution. There were “located” and “translocated” incompatibility between the european Williams pear cultivar and the EMC rootstock based on the vascular discontinuity in the graft union region, which prevented the translocation of succinic acid stain. Thus, the Williams/EMC combination is considered incompatible and it is not recommended for use in commercial orchards. The Rocha/EMC and Abbè Fetel/EMC are considered partially incompatible combinations and showed good development eight years after planting.

Highlights

In Brazil, the highlands of Santa Catarina State present favorable areas for european pear production with high cold demand (Pyrus communis L.) (IUCHI et al, 2008)
The european Rocha and Abbè Fetel pear cultivars grafted on to the quince East Mailing “C” (EMC) rootstock exhibited greater vigor according to the section increment in the cultivar’s trunk at the graft union region and the section increment in the rootstocks trunk at the graft union region, because partial tissue continuity existed in the graft union region between the cultivars and rootstocks
According to Mosse and Herrero (1951), the SPAD indices indicated that the Williams/EMC combination exhibited “translocated” incompatibility whereas the Abbè Fetel/EMC combination did not (Table 2)

Summary

Introduction

In Brazil, the highlands of Santa Catarina State present favorable areas for european pear production with high cold demand (Pyrus communis L.) (IUCHI et al, 2008). Brazilian pear production is not sufficient to satisfy the domestic marketand there is a significant demand for imports. Commercial pear varieties worldwide are grafted on to Pyrus and quince (Cydonia oblonga Mill.) rootstocks. Most pear cultivars exhibit graft incompatibility when grafted onto quince rootstocks because of physiological and biochemical factors (FRANCESCATTO et al, 2010). In Brazil, there is the current trend of using quince rootstock in european pear orchards with the aim of producing less vigorous plants with early fruit set, thereby allowing a high planting density (MACHADO et al, 2013). Grafting is frequently used to improve the plant propagation features, where rootstock grafting is connected to the vigor and selected features of the cultivars in terms of the trunk, stem, leaves, flowers, or fruit (JANICK, 2009)

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