Gas exchanges and photosynthetic pigments of ‘Tommy Atkins’ mango as a function of fenpropimorph

ABSTRACT The objective of the present study was to evaluate the influence of the application of fenpropimorph and paclobutrazol on gas exchanges and photosynthetic pigments of ‘Tommy Atkins’ mango grown in the semi-arid region in different evaluation periods. Two experiments were carried out in ‘Tommy Atkins’ mango orchards in the first production cycle between September and December 2018 (first experiment) and between September and December 2019 (second experiment) in Petrolina, PE, Brazil. The experimental design adopted was randomized blocks in split plots in time, 4 × 4 + 1, with four replicates. The plots corresponded to the concentrations of fenpropimorph: 0, 0.7, 1.0, and 1.3 g per linear meter of plant canopy diameter plus the additional paclobutrazol treatment (1 g per linear meter of plant canopy diameter), and the subplots corresponded to the evaluation dates (0, 30, 60, and 90 days after the first application of treatments). The following traits were evaluated: CO2 assimilation rate, stomatal conductance, internal CO2 concentration, transpiration, water use efficiency, chlorophyll a, chlorophyll b, total chlorophyll, and carotenoids. The fenpropimorph dose of 1.3 g per linear meter of plant canopy promotes a higher rate of CO2 assimilation; however, paclobutrazol was more effective in the accumulation of chlorophyll a and total chlorophyll, and the use of fenpropimorph did not interfere in the concentration of photosynthetic pigments. RESUMO O objetivo do presente estudo foi avaliar a influência da aplicação de fenpropimorfe e paclobutrazol nas trocas gasosas e pigmentos fotossintéticos de mangueira ‘Tommy Atkins’ cultivada no semiárido em diferentes períodos de avaliação. Foram realizados dois experimentos em pomares de mangueira ‘Tommy Atkins’ no primeiro ciclo produtivo entre setembro e dezembro de 2018 (primeiro experimento) e entre setembro e dezembro de 2019 (segundo experimento) em Petrolina, PE, Brasil. O delineamento experimental adotado foi o de blocos casualizados em parcelas subdivididas no tempo, 4 × 4 + 1, com quatro repetições. As parcelas corresponderam às concentrações de fenpropimorfe: 0; 0,7; 1,0 e 1,3 g por metro linear de diâmetro da copa mais o tratamento adicional paclobutrazol (1 g por metro linear de diâmetro da copa), e as subparcelas corresponderam às datas de avaliação (0, 30, 60 e 90 dias após a primeira aplicação dos tratamentos). As seguintes características foram avaliadas: taxa de assimilação de CO2, condutância