Growth acceleration of Orlando; Tangelo (Citrus reticulata x Citrus paradisi) in Nurseries With a Commercial Extract of Kelp (Ascophyllum nodosum), a Commercial Amino Acid Mixture, and a Commercial N-Zn-B Fertilizer

Nursery experiments were carried out in Mayagüez, Puerto Rico, to determine the effect of increasing rates of a kelp extract (StimplexTM), a commercial formulation of amino acids (Macro-Sorb RadicularTM) and a fertilizer (PhotogroTM = 2% N, 0.9% Zn and 0.9% B) on the in-nursery growth of ‘Orlando’ tangelo budded on ‘Cleopatra’ rootstock. Every two weeks, Stimplex and Macro-Sorb were applied to the soil and PhotogroTM was sprayed on the tangelo canopy. Untreated plants reached the adequate transplanting stage significantly later than biostimulant-treated plants. Tangelo responded in a similar fashion to StimplexTM and Macro-Sorb, and the time to reach adequate transplanting size was reduced as the biostimulant rates increased. Applications of StimplexTM and PhotogroTM or of Macro-Sorb and PhotogroTM accelerated the growth of tangelo more than the separate application of either StimplexTM or Macro-Sorb.