FOLIAR BIOSTIMULANT, N AND K RATE, AND CULTIVAR EFFECTS ON FRESH-MARKET TOMATO

The effect of two foliar-applied biostimulants, KeyPlex 350 and 'Tri-A g', at two N plus K rates, 1x and 1.5x (1x = 195 N plus 324 K kg ha(-1 )), was evaluated with regard to growth and yield of two tomato, Lycop ersicon esculentum Mill., cultivars (cvs.) 'Equinox' and 'Sunbeam'. Th e study was conducted during the spring (Feb-June) 1995 on an EauGalli c fine sand (sandy, siliceous, hyperthermic Alfic Haplaquods). Product ion system was the full-bed polyethylene mulch with seepage (modified furrow) irrigation. Experimental design was a split-split plot arrange d in a randomized complete block with four replications. Main plots we re the two biostimulants and a water control, subplots were the N plus K rates, and sub-sub plots were the tomato cultivars. In the main plo ts the foliar sprays were applied at 6, 32, and 48 days after planting (DAP). Plant heights were affected by cultivars only. 'Equinox' plant s were taller (P less than or equal to 0.01). The 'Tri-Ag' biostimulan t increased the yield of medium (57.2 - 64.3 mm diameter) fruits in th e early harvest (P less than or equal to 0.01), but the seasonal yield s of all fruit sizes were similar with either biostimulant or water tr eatments. The higher (1.5x) N plus K rate resulted in an increased yie ld of medium-size fruits (P less than or equal to 0.01). Early yields of 'Equinox' were higher than 'Sunbeam' yields (P less than or equal t o 0.01); however, for the season, 'Equinox' yields were higher only in the large (63.5-70.6 mm diameter) fruit size (P less than or equal to 0.05). Macro- and microelement concentrations in tomato shoots and in fruits were similar with biostimulant or water treatments.