Effect of plant bio-regulators on photosynthesis, growth and yield efficiency of pear trained on Y-trellis system

Patharnakh' and 'Punjab Beauty' are major pear cultivars grown under the subtropical conditions of northwestern India. These pear cultivars tend to put up profuse vegetative growth under the high density planting that leads to excessive shading of bearing zone of canopy. To facilitate light penetration into inner plant canopy, there is a need to contrive an efficient approach for vegetative growth management. The foliar applications of varying concentrations of plant bio-regulators viz. Prohexadione calcium (Pro-Ca) (100, 200, 400 mg L-1) and Paclobutrazol (PBZ) (100, 250, 500 mg L-1) were done at 10 days after full bloom (DAFB) 'Patharnakh' and 'Punjab Beauty' pear plants trained on the Y-trellis training system. Shoot length, leaf area index and trunk cross-sectional areas (TCSA) were greatly reduced by Pro-Ca 200 and 400 mg L-1 concentrations. Treatments enhanced light penetration and photosynthesis. Fruit weight improved with plant bio-regulator treatments resulting in increased yield efficiency of pear plants. This study exhibited a strong positive correlation between light availability and yield efficiency of pear plants.