Thidiazuron (TDZ) increases fruit set and yield of 'Hosui' and 'Packham's Triumph' pear trees.

Mateus S Pasa,André Luiz K De Souza,Alberto F Brighenti,José Luiz Petri,Bruno Carra,Carina P Da Silva

doi:10.1590/0001-3765201720170644

Abstract

The low fruit set is one of the main factors leading to poor yield of pear orchards in Brazil. The exogenous application of thidiazuron (TDZ) and aminoethoxyvinilglycine (AVG) has shown promising results in some pear cultivars and other temperate fruit trees. The objective of this study was to evaluate the effect of TDZ and AVG on fruit set, yield, and fruit quality of 'Hosui' and 'Packham's Triumph' pears. The study was performed in a commercial orchard located in São Joaquim, SC. Plant material consisted of 'Hosui' and 'Packham's Triumph' pear trees grafted on Pyrus calleryana. Treatments consisted on different rates of TDZ (0 mg L-1, 20 mg L-1, 40 mg L-1 and 60 mg L-1) sprayed at full bloom for both cultivars. An additional treatment of AVG 60 mg L-1 was sprayed one week after full bloom in 'Hosui'. The fruit set, number of fruit per tree, yield, fruit weight, seed number, and fruit quality attributes were assessed. Fruit set and yield of both cultivars are consistently increased by TDZ, within the rates of 20 to 60 mg L-1. Besides, its application increased fruit size of 'Hosui' and did not negatively affect fruit quality attributes of both cultivars.

Highlights

The low fruit set (Hawerroth et al 2011), along with the lack of knowledge about the best scionrootstock combinations, excessive vegetative growth and scarce formation of flower buds
Significant increase in fruit set induced by TDZ 10 and 20 mg L-1 sprayed at full bloom was observed in ‘Packham’s Triumph’ (Petri et al 2001) and ‘Shinseiki’ (Hawerroth et al 2011) pears, respectively
Considering the cultivar ‘Hosui’ and according to mean comparison test, the greatest fruit set was observed with TDZ 40 and 60 mg L-1

Summary

Introduction

The low fruit set (Hawerroth et al 2011), along with the lack of knowledge about the best scionrootstock combinations, excessive vegetative growth and scarce formation of flower buds Several studies have reported positive effects of gibberellins (Hawerroth et al 2011, Vercammen and Gomand 2008, Deckers and Schoofs 2002) and TDZ (Amarante et al 2002, Petri et al 2001, Bianchi et al 2000) on fruit set of apple and pear trees when applied at full bloom. The higher fruit set induced by these substances is usually due to a higher rate of parthenocarpy (Vercammen and Gomand 2008, Petri et al 2001), which in some cases may lead to misshapen fruits (Bianchi et al 2000), mainly in response to high rates of TDZ (Greene 1995). The application of gibberellins may reduce flower bud formation and return bloom (Deckers and Schoofs 2002)

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