Effects of exogenous application of GA4+7 and N-(2-chloro-4-pyridyl)-N′-phenylurea on induced parthenocarpy and fruit quality in Pyrus pyrifolia ‘Cuiguan’

Abstract

Parthenocarpy largely depends on the coordinated action of hormones produced in unpollinated ovaries, but can be induced by application of exogenous hormones. We evaluated the effects of gibberellins (GA4+7) and 1-(2-chloro-4-pyridyl)-3-phenylurea (CPPU) on induction and quality of parthenocarpic fruit in Pyrus pyrifolia Nakai ‘Cuiguan’ pear. Parthenocarpic fruit with a small core and a high edible ratio were induced by GA4+7 and/or CPPU. GA4+7 application induced normally shaped fruit with superior quality and normal size, whereas CPPU treatments resulted in abnormally shaped fruit with a larger size and an extraordinarily expanded calyx tube. Among all GA4+7 treatments, 500 mg L−1 GA4+7 induced the highest fruit set (91.88 %) and increased fruit size by 85 % compared with fruit induced by 200 mg L−1 GA4+7. In addition, the parthenocarpic fruit induced by GA4+7 accumulated considerably higher quantities of sucrose and less organic acids than pollinated and CPPU-induced fruit. The potential commercial application of CPPU and GA to pear in place of hand pollination is discussed.