Metamitron in the chemical thinning of ‘PS 10711’ peach trees

Abstract

Chemical thinning of fruits may be an alternative practice to hand thinning. Hand thinning must be performed in a short time during the fruiting stage, but lack of manpower and the onerous costs of the operation make it increasingly difficult to employ it at the right time and at the ideal intensity. The objective of this study was to examine the effect of different concentrations of metamitron as a chemical thinner on ‘PS 10711’ peach trees. The experiment was carried out during two harvests in an orchard in the municipality of Eldorado do Sul, in the Central Depression region of the state of Rio Grande do Sul, Brazil. Treatments consisted of the application of metamitron at the concentrations of 100, 200, 300 and 400 mg L-1; hand thinning; and no thinning. The fruits were thinned chemically and by hand 40 days after the peach trees were in full bloom. Fruit abscission, fruit set, number of fruits, production per tree and fruit quality were evaluated. Metamitron has a thinning effect on the peaches of cultivar PS 10711. The metamitron concentrations of 100 and 200 mg L-1 result in less fruit abscission as compared with hand thinning. The thinning effect of metamitron alters production per tree, but does not interfere with fruit quality.

Carbohydrate content in branches and abscission of fruit of peach trees subjected to chemical thinning

“…In the case of cultivar Sensação, in 2015, the application of metamitron resulted in a higher fruit abscission than manual thinning, but, in 2016, the obtained values were similar. Farias et al (2020a) verified that concentrations of metamitron from 100 to 200 mg L -1 applied to 'PS 10711' peach trees caused a lower decrease in fruit, compared with manual thinning. Therefore, the recommended concentration of metamitron is one that ensures a fruit load that is consistent with the fruit set and abscission obtained by manual thinning, leading to a strategically safer and easier practice.…”

“…The authors also found that negative effects of high temperatures on blooming were higher in the case of 'Granada' than in that of 'Maciel'. Likewise, Farias et al (2020aFarias et al ( , 2020b reported differences among cultivars due to chemical thinning. These results reinforce the hypothesis that the efficiency of a chemical thinning agent in peach abscission depends on the environmental conditions of the cultivation area and that further studies are fundamental to characterize the effects of this treatment on different cultivars and stages of fruit development.…”

Raleio manual de frutos na produção do pessegueiro ‘PS 10711’

“…Os frutos das plantas que receberam raleio mais intenso apresentam média de 93 g, enquanto os das plantas sem raleio, apenas 50 g (Figura 1). Com a mesma cultivar, em Eldorado do Sul-RS, também foi observada redução da produção por planta com o raleio manual ou químico, e aumento da massa média dos frutos, atingindo 97,87 g e 110,77 g com o raleio manual, nas safras de 2016 e 2017, respectivamente (Farias et al, 2020). Estes valores foram próximos aos obtidos neste trabalho, apesar da diferença na densidade de plantio, que foi de 727 plantas ha -1 no experimento destes autores e de 416 plantas ha -1 no presente trabalho.…”

“…O raleio mecânico pode ser realizado nas flores com equipamentos de vibração, reduzindo o tempo para a realização desta prática e realizando de forma antecipada à formação dos frutos (Simões et al, 2013;Barreto et al, 2019). O raleio químico consiste na aplicação de produtos químicos que inibem a formação de gemas floríferas, que causam toxidez à flor, ou que induzem a abscisão de flores ou frutos (Pavanello & Ayub, 2012;Giovanaz et al, 2016b;Gabardo et al, 2019;Farias et al, 2020).…”

“…Diversos produtos vem sendo testados para avaliar o efeito raleante, como ethephon, cianamida hidrogenada, metamitron, ácido abscísico, tiossulfato de amônio, ácido giberélico, benziladenina, óleo de soja, ureia, tioureia e tiossulfato de amônio (El-Boray et al, 2013;Meitei et al, 2013;Giovanaz et al, 2016a,b;Bauchrowitz & Maçaneiro, 2019;Farias et al, 2019;Gabardo et al, 2019;Anzanello & Tedesco, 2020;Farias et al, 2020). Entretanto, a eficiência do raleio químico depende de vários fatores ambientais e fisiológicos da planta, sendo o raleio manual mais preciso e resultando em melhor qualidade de frutos, como obtido para o pessegueiro 'Floridaprince' (El-Boray et al, 2013).…”