ABSTRACT The aim of the present study was to evaluate the effect of biostimulant containing amino acids and yeast extract on the physiological and reproductive characteristics of mango cv. Tommy Atkins during the shoot maturation phase in tropical semi-arid region. The experimental design consisted of randomized blocks with five treatments, five replications and five plants per plot. Treatments consisted of: T1) two foliar sprays with [biostimulant + KCl] + two foliar sprays with K2SO4; T2) No biostimulant and four foliar sprays with K2SO4; T3) three individual foliar sprays with biostimulant and one foliar spray with K2SO4; T4) two foliar sprays with biostimulant and two foliar sprays with K2SO4; and T5) two foliar sprays with [biostimulant + K2SO4] + one foliar spray with K2SO4. There is a positive effect of the biostimulant containing amino acids and yeast extract on transpiration, internal CO2 concentration, water-use efficiency and number of reproductive and non-differentiated shoots of mango cv. Tommy Atkins cultivated under tropical semi-arid condition, with attenuating effect on plant abiotic stress. For shoot maturation of mango cv. Tommy Atkins, three foliar sprays with biostimulant containing amino acids and yeast extract (10 mL per plant) and one with K2SO4 (3%), starting at 45 days after paclobutrazol application (T3), can be recommended.

This study evaluated the impact of fulvic acid and free amino acids on paclobutrazol soil residue, their absorption and effects on ‘Keitt’ mango grown in tropical semi-arid environmental conditions. The experiment was carried out from 2017 to 2018 simultaneously in two orchards with the same plants and management characteristics, located in Cabrobó, Pernambuco, Brazil. The experimental design was randomized blocks with four treatments, five replications and four plants per replication. The treatments consisted of paclobutrazol combinations with acid fulvic and free amino acids, as follows: Treatment 1: paclobutrazol + water (control); Treatment 2: paclobutrazol + fulvic acids; Treatment 3: paclobutrazol + free amino acids; and Treatment 4: paclobutrazol + fulvic acids + free amino acids. According to the results, the use of fulvic acids, free amino acids or both affects the paclobutrazol absorption by 'Keitt' mango. The addition of fulvic acid to the paclobutrazol improves the absorption of this molecule by the plant, with greater inhibition of vegetative growth of 'Keitt' mango and lower soil residues.

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The objective of this study was to evaluate the effectiveness of fulvic acids and free amino acids on paclobutrazol in the flowering of mango ‘Keitt’ cultivated in the semi-arid region. The experiment was performed from 2017 to 2018 simultaneously in two orchards with the same plants and management characteristics, located in Cabrobó, State of Pernambuco, Brazil. The experimental design was randomized blocks with four treatments and five replications of four trees. The treatments were: T1: paclobutrazol + water (control); T2: paclobutrazol + fulvic acids; T3: paclobutrazol + amino acids; T4: paclobutrazol + fulvic acids + amino acids. Applying fulvic acids plus paclobutrazol increased gas exchange efficiency, favoring flowering and fruiting. In contrast, amino acids alone or with fulvic acids decreased the flowering efficiency.

Water stress should be adequately managed during shoot maturation to improve the floral induction of mango grown in semi-arid regions. In this scenario, proline association with algal extracts has a potential stress-mitigating effect. However, even though this practice has been reported separately for some crops, its effects on mango are still unknown. From this perspective, this study investigated the role of proline and algal extract in mitigation of water deficit effects during shoot maturation of the mango variety ‘Tommy Atkins’ grown in the tropical semi-arid region. The study consisted of five consecutive individual experiments (five foliar application treatments) in a randomized block design and a 4 x 2 factorial corresponding to i) four proline concentrations (Pro): 0.0% (without proline), 0.287, 0.575, and 1.150%, and ii) the presence of algal extract (AE) (presence and absence). The following parameters were evaluated: photosynthetic pigments, soluble carbohydrates, photochemical and non-photochemical efficiency, and flowering and production uniformity. Carotenoids were interactively affected by the factors evaluated. On the other hand, as additive effects, proline provided the highest values of gas exchange and total soluble carbohydrates, with a higher internal CO2 concentration and greater flowering uniformity. The application of proline and the algal extract of A. nodosum promoted different responses in mango physiology and can be used during shoot maturation.