Abstract
EM (effective microorganisms) is a biofertilizer consisting of a mixed culture of potentially beneficial microorganisms. In this study, we investigated the effects of EM treatment on leaf in vivo chlorophyll a fluorescence of photosystem II (PSII), yield, and macronutrient content of bean plants grown on different substrates (nutrient rich substrate vs. nutrient poor sandy soil) in controlled environmental conditions (pot experiment in greenhouse). EM-treated plants maintained optimum leaf photosynthetic efficiency two weeks longer than the control plants, and increased yield independent of substrate. The levels of seed nutritionally-relevant molecules (proteins, lipids, and starch) were only slightly modified, apart from the protein content, which increased in plants grown in sandy soil. Although EM can be considered a promising and environmentally friendly technology for sustainable agriculture, more studies are needed to elucidate the mechanism(s) of action of EM, as well as its efficacy under open field conditions.
Highlights
The global food security challenge is straightforward: by 2050, the world must feed around 9 billion people, and, the demand for food will increase by 60%
EM application was found to significantly increase yield in bean plants even when grown on poor, sandy soil, showing promising potential as a biostimulant
The first finding, that yield increased with EM treatment, is in agreement with previous studies on bean plants grown under saline conditions
Summary
The global food security challenge is straightforward: by 2050, the world must feed around 9 billion people, and, the demand for food will increase by 60%. Biostimulants, including plant-growth promoting microorganisms, have been shown to increase plant nutrient uptake, growth, and yield via different underlying mechanisms such as changes in soil structure, nutrient solubility, root growth and morphology, plant physiology, and symbiotic relationships. They can improve the plant tolerance to abiotic stresses, as well as the resistance to pathogens [2,3]. All seed macronutrients, apart from the protein content, which was strongly increased in plants grown in sandy soil. Increase with EM treatment on sandy soil, but EM treatment was associated with significantly lower zinc contents on greenhouse substrate (Table 2). 594.40 ± 9.85 b 4.67 ± 0.11 b 1984.14 ± 22.67 b 5875.30 ± 58.35 b 14.28 ± 0.13 b 8.96 ± 0.35 b
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