ASHS 2025 Conference

Sweet peppers are a warm-season vegetable prized for their vibrant colors, rich flavor, and high nutritional value. Biostimulants are a new class of agricultural products consisting of microorganisms or bioactive substances, used as a sustainable approach to enhance plant growth and productivity. This experiment aimed to evaluate the effects of biostimulant applications on plant growth, yield, and quality of sweet pepper cultivars grown in a container production system. Three biostimulants were tested including a seaweed extract (Kelpak Maxx, 1% solution), a plant growth-promoting rhizobacteria (Continuum V2, at a rate of 2 ml per gallon), and stabilized monosilicic acid (Dune, at a rate of 2 ml per gallon). Six sweet pepper cultivars were selected for the study: Cornito Giallo, Escamillo, Green Machine, Carmen, SVPB8500, and Cornito Rosso, all purchased from Johnny’s Selected Seeds. Biostimulant treatments were applied biweekly through manual fertigation with 120 ml of solution. Plants in the control group were fertigated with 120 ml of water. Plant vegetative growth including plant height, widths, and leaf SPAD were measured three times during the growing season. Once fruit ripening began, pepper fruits were harvested every two weeks from July to September. At each harvest, marketable and unmarketable yield and fruit number were recorded. Fruit quality variables including fruit length, diameters, and color were also measured. Results showed that the sweet pepper cultivars varied in vegetative growth, fruit yield, and quality. The two cultivars Green Machine and SVPB8500 had higher leaf SPAD of 64.2 and 63.9, respectively, than Carmen, Escamillo, Cornito Giallo, or Cornito Ross. The cultivars Carmen, Cornito Giallo, Cornito Rosso, and Escamillo had similar plant heights ranging from 36.4 cm to 38.4 cm, higher than Green Machine or SVPB8500. Biostimulant treatment did not affect leaf SPAD or plant height early in the season.