‘Improved Meyer’ lemon response to selected bioregulators in a tropical location

The effects of selected bioregulators on ‘Improved Meyer’ lemon were studied in an experiment conducted under tropical conditions in Puerto Rico. Lemon trees of fruit production age were sprayed with a biostimulant based on acetylthiazolidine-4-carboxylic acid (ATCA) (0, 50, 100, 150 mg a.i. L^‑1), and an extract of the Ascophyllum nodosum marine alga (EAN) (1, 2, and 3 mL L^‑1). The treatments were applied 4 times at 14-day intervals. The number of marketable fruits was not significantly influenced by the treatments, however, fruit weight, amount of juice, and titratable acidity in the juice were significantly improved in trees sprayed with ATCA (50-100 mg L^‑1) and with EAN (2 mL L^‑1) as compared to the other treatments. ATCA and EAN may be useful to increase the yield of ‘Improved Meyer’ lemon in tropical locations.