2018 ASHS Annual Conference

The use of biostimulants has been proposed as an innovative and promising approach to improve crop quality and yield. Among all biostimulant groups, plant-derived protein hydrolysate are gaining interest globally due to their remarkable agronomic value compared to other groups. In general, greenhouse production system is known as a high input system where high levels of fertilizers were consumed for intensive plants growth. In this study, a type of biostimulant, legume-derived protein hydrolysate, was used to improve crop quality and yield, while reducing fertilizer inputs for crop production. A series of experiments were conducted in the greenhouse to identify the effects of biostimulant on romaine lettuce ‘Sarah’ and dwarf tomato ‘Micro-tom’ on plant performance, which includes leaf/stem/root length, leaf number/area, root diameter, photosynthetic gas exchange, chlorophyll content, and crop yield. Treatments consisted of two levels of biostimulant (0 and 3 g/L biostimulant), which were combined with either nitrogen (N) treatments (low, medium, and high) or electrical conductivity (EC) treatments (low, medium, and high) with commercial fertilizer (4.5N-14P-34K). A solution of 50 mL containing biostimulant was applied to romaine lettuce and micro-tom as soil drenching once every week during production period. The results showed that leaf area and head fresh weight of romaine lettuce were increased by 11 % and 15 %, respectively, when 3 g/L biostimulant was applied with low nitrogen or low EC treatment. Even though the micro-tom experiment is currently ongoing, we observed similar results as romaine lettuce and the tomato plants applied with biostimulants have already shown better performance, particularly under low nitrogen and low EC treatments. Based on our findings, it is concluded that biostimulant improves productivity and quality of both romaine lettuce and tomato under low nutrition conditions. This suggests that the plant-derived protein hydrolysate application may contribute to the reduction of fertilizer inputs in greenhouse production systems.