Paper presented at the 52nd CFCS Annual Meeting, Guadeloupe, July 10-16, 2016
EFFECTS OF A PHYTOSTIMULANT AMINO ACID FORMULATION ON BREADFRUIT PLANTS IN THE NURSERY J. Pablo Morales-Payan Department of Agro-Environmental Sciences, University of Puerto Rico, Mayaguez Campus Keywords : Artocarpus altilis; biostimulant; plant growth. Abstract The breadfruit (Artocarpus altilis) is generally propagated by root cuttings an emerging crop in Puerto Rico. Producing transplants from root cuttings is generally slow, and there is little information regarding the effects of practices that may help hasten their growth, such as fertilizers and phytostimulants. The objective of this research was to determine the effects of rates of a commercially available agricultural formulation of amino acids on the performance of breadfruit plants in the nursery. Rates of a phytostimulant with 6% free L-amino acids formulated for soil application (from BioIberica, Barcelona, Spain) was evaluated. Root cuttings of 15 cm in length and 2.5 cm in diameter, taken from a selected tree (‘Ballester’) were planted in plastic containers 20-cm in diameter and 30-cm tall, filled with a commercial peat moss substrate. When breadfruit shoots were 10 cm tall, the phytostimulant was applied as a substrate drench, using 200 ml of aqueous phytostimulant solution per plant. The aqueous phytostimulant solutions (treatments) were prepared at the rates of 0 (check), 1, 2, 3, or 4 ml of commercial formulation/L of water. The treatments were arranged in a completely randomized design with 7 replicates (plants). The phytostimulant solutions were applied 11 times at 14-day intervals. Stem diameter was not affected by phytostimulant rates. Leaf number, leaf area, shoot biomass, and root biomass had quadratic responses to phytostimulant rates. These results indicate that using agricultural amino acid formulations may help in hastening the growth of breadfruit plants in the nursery. Materials and methods Root cuttings 15-cm in length and 2.5-cm in diameter, were taken from a selected breadfruit tree in a farm located in the municipality of Las Marias, Puerto Rico. The root cuttings were planted were in plastic containers 20-cm in diameter and 30-cm tall, filled with a commercially-available peat moss substrate. The containers were kept in a greenhouse and the substrate was irrigated daily. The treatments were rates of a phytostimulant based on 6% free L-amino acids, commercially available and formulated for soil application, manufactured by BioIberica, Barcelona, Spain. The phytostimulant was applied as a substrate-drench, applying to each plant 200 ml of an aqueous solution of the phytostimulant. The aqueous solutions contained 0 (check), 1, 2, 3, or 4 ml of the commercial formulation per L of water. The treatments were first applied when breadfruit plants reached 10 cm in height and were repeated at 14-day intervals for a total of 11 applications. The treatments were arranged in a completely randomized design with 7 replicates, where one plant was a replicate. Stem diameter and height, as well as number of leaves and leaf area were evaluated every 2 weeks. Root and shoot biomass were determined destructively 22 weeks after first application of the treatments. Results were submitted to statistical analyses. Main results The treatments did not affect stem diameter. In contrast, stem height, leaf number, leaf area, shoot biomass, and root biomass by 22 weeks after first treatment application followed the same pattern of quadratic responses to phytostimulant rates, increasing until phytostimulant rate was 2 ml/L, and declining at higher phytostimulant rates (Figure 1). This kind of response has been reported for other plants in nursery, greenhouse and field conditions (Flores Torres, 2013; Maini, 2006; Mancilla, 2000), showing that there is a limit to how much amino acid formulation may be applied and still obtain a favorable response from the crop, while at higher rates amino acids may have adverse effects on plants. The extent of such effects may be somewhat different depending on the target plant species, amino acid concentration in the formulation, and frequency and mode of application of the formulation, and among other factors.
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