Rootstock and training system affect sweet cherry growth, yield, and fruit quality

Traditional sweet cherry (Prunus avium L.) training systems in the United States are based upon vigorous rootstocks and multiple leader vase canopy architectures. The sweet cherry research lab at Washington State University has been investigating the potential of new rootstocks and training systems to improve production efficiency and produce high quality fruit. This paper describes the effects of three rootstocks-Mazzard (P avium), 'Gisela 6', and 'Gisela 5'(P cerasus x R canescens)-and four training systems-central leader, multiple-leader bush, palmette, and y-trellis-on 'Bing' sweet cherry tree vigor, fruit yield and quality over a seven year period. Compared to trees on Mazzard, trees on 'Gisela 5' and 'Gisela 6' had 45% and 20% lower trunk cross-sectional areas after 7 seasons, respectively. Trees on 'Gisela 6' were the most productive, yielding between 13% and 31% more than those on 'Gisela 5' and 657% to 212% more than trees on Mazzard, depending on year. Both Gisela rootstocks significantly improved precocity compared to Mazzard, bearing fruit in year 3 in the orchard. Canopy architecture had only moderate effects on tree vigor and fruit yield. Across rootstocks, bush-trained trees were about 25% less productive compared to the other systems, which exhibited similar cumulative yields (102 kg/tree). Fruit weight was negatively and closely (r(2) = 0.84) related to tree yield efficiency (kg(.)cm(-2)). Crop value was related positively to fruit yield.