HIGH DENSITY PEAR PRODUCTION WITH PYRUS COMMUNIS ROOTSTOCKS

Abstract

A field trial at Geneva, New York, United States compared four training systems/densities [Central Leader (598 trees/ha), Vertical Axis (1281 trees/ha), Tall Spindle (2243 trees/ha) and Super Spindle (5382 trees/ha)] on 6 rootstocks (seedling, OHF97, OHF87, Pyrodwarf, Pyro2-33 and Quince A) with 3 cultivars (‘Bartlett’, ‘Bosc’ and ‘Taylor’s Gold Comice’). After eight years, tree density had a negative effect on tree size with trees at the highest planting density being only 60% the size of the trees at the lowest planting density. With ‘Bartlett’, the largest trees were on OHF97 followed by OHF87, Pyro2-33, Pyrodwarf and the smallest trees were on Quince A. With ‘Bosc’ the largest trees were on OHF87. Trees of ‘Taylor’s Gold’ on OHF97 and on seedling were damaged in the winter of 2004/05 with 37% of the scions killed. None of the other rootstocks were damaged. Tree density had a large positive effect on cumulative yield, while rootstock genotype had a much smaller effect. The high-density Super Spindle system had 5 times the cumulative yield as the low-density central leader system. With ‘Bosc’ there was little effect of rootstock, but with ‘Bartlett’, OHF97 and OHF87 had the highest cumulative yield at each density. Quince A had the lowest yield at all densities. Pyrodwarf and Pyro 2-33 had similar intermediate yields at all densities, but Pyrodwarf had numerous root suckers. Yield efficiency was not largely affected by planting density or rootstock genotype although there was a slight negative relationship between planting density and yield efficiency. Fruit size was negatively related to planting density with the Super Spindle system producing significantly smaller fruit size than other systems. Part of the effect was due to greater crop loads on the Super Spindle system. However, when fruit size was adjusted for crop load there was still a negative effect of planting density on fruit size. With ‘Bartlett’, Quince A produced the largest fruit size, while Pyrodwarf and seedling had significantly smaller size. With ‘Bosc’ and ‘Taylor’s Gold’ there was no effect of rootstock on fruit size.