Prohexadione calcium reduces vegetative growth and increases fruit set of ‘Smith’ pear trees, in Southern Brazil

Bruno Carra,Mateus Da Silveira Pasa,Cristiano Geremias Hellwig,José Carlos Fachinello,Everton Sozo De Abreu,Carina Pereira Da Silva,Daniel Spagnol

doi:10.1590/1678-4499.298

Bruno Carra, Mateus Da Silveira Pasa + Show 5 more

Open Access

https://doi.org/10.1590/1678-4499.298

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Abstract

ABSTRACT Prohexadione calcium (P-Ca) has been reported to effectively control shoot growth in several pear cultivars, but with a few reports about its efficiency under the climatic conditions of southern Brazil. Therefore, the objective of this study was to evaluate vegetative growth, production, and fruit quality of ‘Smith’ pear trees in response to the use of different rates of P-Ca in the climatic conditions of southern Brazil. The experiment was conducted during the 2013/2014 and 2014/2015 seasons, in a 6-year-old ‘Smith’ pear orchard, trained to a central-leader system, with spacing of 1.5 × 4.8 m, grafted onto Pyrus calleryana Decne. Different P-Ca rates were applied (100, 200, 300, and 400 mg∙L–1) in different stages: first, in early spring for all treatments, and the others when shoot growth resumed (GR), but only for some treatments. Variables for vegetative growth, yield components and fruit quality at harvest and post-harvest were evaluated. The use of P-Ca was effective to control vegetative growth in both seasons, at different rates. Yield components were not affected by P-Ca applications in 2013/2014, except return bloom and return yield. In 2014/2015 season, P-Ca applications positively affected yield components, except average fruit weight and return bloom. P-Ca applications did not alter the qualitative attributes of the fruits of ‘Smith’ pear trees at harvest and after a period of cold storage. These results implicate P-Ca as a potential tool to manage vigor of ‘Smith’ pear trees in climatic conditions of southern Brazil.

Highlights

The pear (Pyrus spp.) is the most imported fruit in Brazil, according to the FAO (2016)
In studies about fruiting habit and production of pear trees on different rootstocks, it was observed that formation of flower buds, production structures, and production efficiency are inversely proportional to the vigor induced by the rootstocks in most of the time (Pasa et al 2011)
According Köppen climate classification, the studied region has a Cfb climate, marine, with annual averages of rainfall, temperatures, and humidity of 1,736 mm, 17.2 °C, and 76%, respectively. It accumulates an average of 410 chill hours (CH) below 7.2 °C, during the winter, according to data provided by Bento Gonçalves Agro Climatic Station

Summary

Introduction

The pear (Pyrus spp.) is the most imported fruit in Brazil, according to the FAO (2016). It is clear that the culture of pear is an important opportunity for Brazilian producers, some obstacles that prevent economically satisfactory productions must be solved. The pear is one of the less productive temperate fruit trees in Brazil. Hawerroth et al (2012) attribute the reduced cultivation of the pear to problems related to low productivity, like low fruit set and long juvenile period in the climatic conditions of the country. In southern Brazil, these conditions are characterized by high rainfall, high temperatures in the growing season, short wintry periods, and insufficient accumulation of chilling hours. This favors the higher vegetative growth, especially when vigorous rootstocks are used. In studies about fruiting habit and production of pear trees on different rootstocks, it was observed that formation of flower buds, production structures, and production efficiency are inversely proportional to the vigor induced by the rootstocks in most of the time (Pasa et al 2011)

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