Early spring inhibition of ethylene synthesis increases fruit set and yield of 'Rocha' pear trees in Southern Brazil

Low fruit set is one of the main factors leading to poor yield of pear orchards in Brazil. Early spring exogenous application of aminoethoxyvinilglycine (AVG) has shown promising results to increase fruit set and yield in some pear cultivars. Therefore, the objective of this study was to evaluate fruit set, yield and fruit quality of 'Rocha' pear trees in response to different rates of AVG (0, 60, 80 and 100 mg L-1) sprayed seven days after full bloom (DAFB). The study was performed during the 2016/2017 growing season, in an eight-year-old 'Rocha' pear orchard grafted onto quince rootstock 'BA29'. Flowers were collected in the field two days after AVG application and assessed for ethylene production rate. Fruit set, number of fruits per tree, average fruit weight, yield, projected yield, number of thinned fruits, fruit quality, seed number and return bloom were also assessed. AVG significantly reduced ethylene production rate while fruit set and yield were increased in a rate-dependent manner. Fruit weight was reduced but as a direct effect of higher crop load induced by AVG. Return bloom was negatively affected only in response to AVG 100 mg L-1. These results implicate AVG as a potential tool to increase fruit set and yield of 'Rocha' pear trees in the climatic conditions of Southern Brazil.