Plant growth regulators to increase fruit set and yield of ‘Rocha’ pear trees in Southern Brazil

Bruno Carra,Everton S Abreu,Mateus S Pasa,Carina P Pasa,Paulo Mello-Farias,Marlise N Ciotta,Flavio G Herter,Maximiliano Dini

doi:10.1590/0001-3765202120180860

Abstract

The aim of this study was to evaluate the effect of different aminoethoxyvinilglycine (AVG), thidiazuron (TDZ) and prohexadione calcium (P-Ca) rates sprayed at different timings on fruit set, yield, and fruit quality of 'Rocha' pear trees in different climatic conditions of Southern Brazil. The study was performed in two commercial orchards located in São Joaquim, SC (2015/2016) and Antônio Prado, RS (2016/2017). Plant material consisted of 'Rocha' pear trees grafted onto Pyrus calleryana and quince rootstock 'BA29' in São Joaquim and Antônio Prado, respectively. Treatments consisted of AVG, TDZ and P-Ca sprayed at different rates and timings. Trunk cross-sectional area increase, fruit set, thinned fruit, fruit per tree, yield, average fruit weight, projected yield, yield efficiency, fruit length, fruit diameter, L/D ratio, seed number, flesh firmness, and soluble solids content were assessed. Fruit set and yield were consistently increased by AVG in all experiments. Fruit set was not affected by P-Ca and was significantly decreased by TDZ. However, yield was positively affected by P-Ca 100 mg L-1 sprayed at full bloom + 7 days after full bloom and TDZ 10 mg L-1 at full bloom. Fruit size was consistently increased by TDZ.

Highlights

Pear (Pyrus spp.) is widely cultivated in the world, with an estimated production of 27.4 million tons in 2016
The aim of this study was, to evaluate the effect of different AVG, TDZ and prohexadione calcium (P-Ca) rates sprayed at different timings on fruit set, yield, and fruit quality of ‘Rocha’ pear trees in different climatic conditions of Southern Brazil
No differences in fruit set and yield between rates were observed when AVG as sprayed at 7 DAFB, indicating that the lowest AVG rate would be recommended by economic reasons

Summary

Introduction

Pear (Pyrus spp.) is widely cultivated in the world, with an estimated production of 27.4 million tons in 2016. Achieving high yields in pear orchards is dependent on the successful achievement of many sequential processes; those associated with floral induction, flower development, pollination, flower fertilization and fruitlet retention (fruit set), and fruit growth (Webster 2002). Among these factors, problems related to fruit set seems to be one of the most important, as it has been reported for some pear cultivars worldwide (Carra et al 2018, Hawerroth et al 2011, Pasa et al 2017a, b, Sánchez et al 2011). Flowers are pre-programmed to abscise after anthesis unless they receive a new stimulus to continue growing, which is commonly associated with

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