2019 ASHS Annual Conference

Many biostimulants (humic substances, protein hydrolysates, chitosan, beneficial fungi, and bacteria) are being manufactured and sold with claims such as increased growth, yield and quality, and increased tolerance to stress. Although many of the products that make up biostimulants are sought after by sustainable and organic growers, research on commercial biostimulants is minimal and results are often varied depending on the type of biostimulant, time of application, and even species and cultivar under study. Even less is known about the use of biostimulants categorized under beneficial fungi and beneficial bacteria.

The objectives of this study were to assess the growth and quality of bell pepper (Capsicum annum ‘Ace’) and lettuce (Lactuca sativa ‘Magenta’), grown in soil-less medium under greenhouse conditions, using six commercial biostimulants (beneficial fungi and bacteria) in combination with two rates of fertilizer (200 and 100 ppm N for pepper and 150 and 75 ppm N for lettuce). Biostimulant products included Bioyield^®, Environoc 401^®, Mycoapply^®, Rootshield^®, Select^®, and Spectrum + Myco^®). The experimental design was a split plot design with fertilizer as the main plot factor and biostimulant the sub plot factor. Plants were grown until horticultural maturity and data was collected, both, at the end of the transplant production phase and at horticultural maturity. Pepper plants receiving the 200 ppm N had significantly higher biomass, height, and stem diameter than those receiving the 100 ppm N at the end of the study. Treatments Bioyield^®, Spectrum + Myco^®, and Rootshield^® resulted in significantly taller pepper plants than the control at the end of the study. Select^® had significantly higher average yield/plant than the control treatment. Lettuce receiving the Spectrum treatment had significantly longer roots at transplant stage than the control. The 75 ppm N resulted in significantly longer roots of lettuce transplants and more marketable lettuce heads at the conclusion of the study as compared to the 150 ppm N.

Bioyield^®, Rootshield^®, and Spectrum + Myco^® have the potential to enhance transplant health and crop growth in pepper and lettuce production but continued research is needed on the use of biostimulants in open-field conditions and in combination with different crops and cultivars to determine best uses for vegetable growers.