Olivera Olivera, Virgilio

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    Evaluación de bioestimulantes y prácticas orgánicas de manejo de malezas en la productividad y calidad de la fruta de pulasán [Nephelium ramboutan-ake (Labillardiére) Leenhouts]
    (2015) Olivera Olivera, Virgilio; Morales Payán, José P.; College of Agricultural Sciences; Goenaga, Ricardo; Robles, Wilfredo; Róman Paoli, Elvin; Department of Crops and Agro-Environmental Sciences; Plaza, María L.
    In 2012 and 2013 experiments were conducted in the mountains of Mayaguez, Puerto Rico to establish the effects of biostimulants and weed control in pulasán (Nephelium ramboutan-ake). The biostimulants used were seaweed extract (EAN) at 2 L/ha, a mixture of free aminoacids (MAA) at 2 L/ha and a plant extract from the Caryophyllaceae and Fabaceae (ECF) family. Also, natural brassinosteroids at a rate of 100 g/ha, and a control treatment. We applied 500 ml of the biostimulant solution on each tree every 14 days in the EAN and MAA treatments, and every 28 days in the ECF treatment, once fruits reached a diameter of approximately 25 mm. In the 2012 biostimulant experiment, number of marketable and non-marketable fruits, fruit weight, diameter, pericarp weight, pulp weight, seed weight, and total soluble solids determined. In the 2013 biostimulant experiment, the same treatments used in 2012 were used, but application of biostimulants started at bloom. Treatments and parameter studied were the same as in 2012, but fruit retention and fruit diameter in randomly-selected branches during fruit development until harvest process were determined. In the 2013 weed control experiment we evaluated weed damage by the herbicide, weed biomass thru time, weight and diameter of fruit at harvest, and number of marketable and non-marketable fruits. The predominant weeds were jungle rice (Echinochloa colona), green killinga (Kyllinga brevifolia), Johnsongrass (Sorghum halepense), nutgrass (Cyperus rotundus), crabgrass (Digitaria sanguinalis) and bitter lettuce (Launaea intybacea). The weed control treatments were: 1) soil coverage using jute sacks (Corchorus olitorius); 2) limonene 3) acetic acid; 4) weed trimming; 5) glyphosate as the reference treatment (control). In 2012, there was no significant response of biostimulants, on any of the variables measured, except for diameter of marketable fruit which was significantly larger in those treated with ECF than in the control group. In 2013, the results showed that trees treated with MAA had more fruit harvested than the ones in the control group, meanwhile the trees treated with ECF had less commercial fruit harvested than the ones treated with MAA. There were no other significant differences for the rest of parameters. In the 2013 weed control experiment, trees treated with jute sack produced fruit with significantly larger diameter and weight than in trees were weeds were controlled with glyphosate. Trees treated with glyphosate produced more commercial fruits than trees treated with jute sacks. There were no other significant differences for the rest of parameters. Weed biomass produced in the jute sack treatment was lower than the biomass produced in the glyphosate treatments, although the biomass produced at 48 days was significantly equal. The organic herbicides acted quickly and had their greatest effect 2 days after application, but weeds recovered shortly afterwards. In contrast, glyphosate effects were seen 14 days after application, and weeds did not recover and died.