Yield of Organically Grown Mango As Affected by Soil Applications of a Biostimulant Alga Extract

Research was conducted in Lajas, Puerto Rico, to determine the effects of an extract of the marine alga Ascophyllum nodosum on the fruit yield of organically-grown 'Curva' mango. The orchard was managed following US organic production regulations. The commercially-available alga extract formulation was labeled as having active ingredients equivalent to 0.01% kinetin. The alga extract was drench-applied in aqueous solution at the rates of 0 (control), 10, 20, 40, and 60 ml of extract per tree, starting at flowering and applying the same rates three more times at 14-day intervals. Fruit retention was determined every two weeks after the first extract application, while fruit number and size were determined at harvest. Alga extract rates did not significantly affect fruit retention and marketable fruit number. The alga extract rates of 40 and 60 ml per tree per application did not significantly affect fruit size. However, on average marketable fruits from plants treated with the rate of 20 ml of extract per tree per application were 13% larger than fruits from control trees.