Abstract
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.
Highlights
T, RH (%) and Radiation (MJ m-2 day-1)The mango (Mangifera indica L.) crop has high biosynthesis of gibberellins that favor vegetative growth and inhibit flowering (Sandip et al, 2015)
This study aimed 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
The evaluation dates (ED) affected all variables studied and there was an individual effect of the doses of fenpropimorph on water-use efficiency (WUE), while in the second experiment all variables were significantly improved and there was an individual effect of the doses of fenpropimorph on stomatal conductance, transpiration, and water-use efficiency (Table 2)
Summary
T (oC), RH (%) and Radiation (MJ m-2 day-1)The mango (Mangifera indica L.) crop has high biosynthesis of gibberellins that favor vegetative growth and inhibit flowering (Sandip et al, 2015). The use of gibberellin biosynthesis inhibitors, especially triazoles such as paclobutrazol (PBZ) and uniconazole (UCZ), has been adopted for flowering management (Cavalcante et al, 2020). The application of these plant regulators promotes a series of chain reactions to favor floral bud differentiation, including the increase of total soluble sugars in the apical bud (Upreti et al, 2014), of cytokinin levels, and the C:N ratio (Upreti et al, 2013). The effects of gibberellin biosynthesis inhibitors on gas exchange and photosynthetic pigments are little studied. The use of paclobutrazol (PBZ) has tended to reduce net CO2 assimilation rate and transpiration by increasing stomatal resistance in ‘Palmer’ mango grown in the semi-arid region (Souza et al, 2016), and the chlorophyll concentrations in ‘Banganpalli’ mango grown in India (Subbaiah et al, 2018)
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