Comparison of Bearing and Yield Efficiency of Commercial Pear Cultivars on Pyrodwarf Semi-dwarfing Rootstock

Despite adaptability of Pyrodwarf semi-dwarf pear rootstock in Iran, the final yield and yield efficiency of different commercial pear cultivars on this rootstock have not been studied and analyzed in detail. Therefore, in recent study, the yield, yield potential and yield efficiency of four commercial pear cultivars including Louis Bonne, Spadona, Dargazi and Beyrut cultivars were evaluated on Pyrodwarf rootstock during four years (2017 to 2020) in commercial bearing phase. Growth traits according to high vigor of Dargazi and Spadona cultivars were higher than Louise Bonne cultivar and all cultivars in 2020 (8 years old) had a height between 294.4 to 352.7 cm, which indicates semi-dwarf habit of this rootstock. The highest yield per tree was in Dargazi cultivar and then at a lower level in two cultivars Spadona and Louise Bonne. In spite of increase in tree yields with increasing age of the trees, the yield per trunk cross-sectional area (TCSA) decreased consistently, so this index in 2017 was more than 0.2 in most cultivars and decreased to about 0.05 kg per cm2 TCSA in two years 2019 and 2020. A similar situation was observed in terms of fruit number and yield per unit volume of canopy and the highest efficiency of canopy volume unit was observed in Louise Bonne cultivar. It can be concluded that for higher yield efficiency of pear cultivars on Pyrodwarf rootstock, evaluation of training forms that decrease the canopy shading in the internal parts of canopy is essential.