Photosynthetic Efficiency in Green Bean Plants through the Application of Omeprazole and Melatonin at Low Doses

Climate change has prompted agri-food systems to explore new strategies for improving the production of crops in a sustainable manner. This includes green bean, the most important legume in the world for its nutritional value. The use of omeprazole (OMP) and melatonin (MEL) has been proposed as innovative strategy for crop improvement when they are applied as biostimulants. However, although their role in the growth of several species has been studied, the results in photosynthetic efficiency parameters are still scarce. Therefore, the objective of the present study was to evaluate the effect of foliar application of OMP and MEL on biomass, yield, SPAD values, leaf chlorophyll fluorescence (Fv/Fm), photochemical quenching (qP), non-photochemical quenching (NPQ), quantum yield of photosystem II (PhiPSII), and electron transport rate (ETR) in bean plants. Treatments were applied separately at doses of 1, 10, and 100 µM, plus a control without application. The results obtained indicate that OMP and MEL were able to increase biomass; yield; SPAD values; and qP, Fv/Fm, and PhiPSII coefficients. Finally, it is concluded that foliar application of OMP and MEL at a dose of 1 and 10 µM can increase photosynthetic efficiency and decrease photoinhibition, which is reflected in higher biomass accumulation and yield in green bean plants cv. Strike.