Performance of 'Rocha' pears on three rootstocks planted in high-density

The objective of this study was to evaluate the effect of different rootstocks on the performance of ‘Rocha’ pears planted in high-density. Single-axis trees of ‘Rocha’ pears grafted on Pyrus calleryana (PC), quince BA29 and quince EMA were planted (1×4 m; 2500 trees ha^‑1) in the winter of 2008 in São Joaquim, Santa Catarina State (southern Brazil). The experiment was arranged in a randomized block design, with four replications (five trees each). Adjacent rows of ‘Packham’s Triumph’ were planted for pollination. Yield components, trunk cross sectional area (TCSA) and fruit quality attributes were assessed from 2014/15 to 2017/2018. The trees on quince ‘BA29’ showed the greatest yield components (yield and yield efficiency), although in some cases not differing significantly from trees on ‘EMA’ while PC showed the lowest values. Trees on PC had larger TCSA than both quinces. Fruit of ‘EMA’ were smaller than PC, whereas ‘BA29’ was intermediate and did not differ from the other rootstocks. Flesh firmness was lower from both quinces, but soluble solids was higher when compared to PC. Growing pear trees in high-density systems requires an adequate control of vegetative growth, which is primarily provided by the right choice of rootstock. Our results show that the vigorous PC is not a suitable rootstock choice for such systems in southern Brazil, due to low yields and excessive vigor induced. The quince BA29 seems to be the best choice for high-density plantings in São Joaquim, since it induces a moderate vigor (greater TCSA than EMA and lower than PC), acceptable yields, and good fruit size. Considering that there is a wide range of soil types in southern Brazil and rootstock performance is closely related to soil type, the rootstock choice should carefully consider representative research results of a given region.