Among leguminous
crops, French bean has immense value as a fresh vegetable as well as a pulse
crop. Among the beans, it is one of the most popular and widely grown crops
worldwide due to its short growth cycle, high yield potential, and nutritional
richness. Globally, common bean is grown on approximately 35–37 million hectares with an annual
production exceeding 28 million tonnes,
making it a major source of dietary protein and calories for millions of people
(FAO, 2023). In India, French bean is cultivated both as a vegetable (for green
pods) and as a pulse crop (for dry seeds), particularly in the states of Himachal Pradesh, Jammu & Kashmir, Uttarakhand, West
Bengal, Karnataka, and Maharashtra, where it forms an important
component of hill and peri-urban farming systems (ICAR, 2022). The average
productivity of green pods ranges from 8 to
12 t ha⁻¹, while dry grain yields vary from 1.0 to 1.5 t ha⁻¹, depending on cultivar
and management practices (FAO, 2023).
Nutritionally,
French beans are valued for their high content of plant protein (18–25%),
complex carbohydrates, and dietary fibre, making them an important crop for
combating protein malnutrition (Gepts et al., 1986). The green pods are
rich in vitamin C, β-carotene,
folates, and minerals such as iron, calcium, magnesium, and potassium,
which contribute to immune function and metabolic health (USDA, 2022).
Furthermore, French beans contain significant levels of phenolic compounds,
flavonoids, and antioxidants, which are associated with a reduced risk of
chronic diseases such as diabetes and cardiovascular disorders (Nzaramba et
al., 2021).
Despite its
agronomic and nutritional importance, French bean productivity is often limited
by low soil organic matter, nutrient imbalances,
and excessive dependence on chemical fertilizers, which can
deteriorate soil health and reduce crop quality in the long term (Rouphael
& Colla, 2020). Therefore, there is a growing need for sustainable nutrient
management strategies that enhance both yield and nutritional quality without
causing environmental degradation.
Biostimulants
are defined as substances or microorganisms that, when applied to plants or
soil, stimulate natural processes to enhance nutrient
uptake, nutrient efficiency, stress tolerance, and crop quality,
independent of their nutrient content (Du Jardin, 2015). These biostimulants
(HA, SEW and E) are of natural origin, so they are eco-friendly and play a very
critical role in soil improvement and soil fertility, ultimately enhancing total plant growth.
Humic acid, a major fraction of soil organic matter,
plays a significant role in improving soil
physical properties, cation exchange capacity, and nutrient availability,
particularly for nitrogen, phosphorus, and micronutrients
(Canellas et al., 2015). It has been reported to stimulate root elongation, membrane permeability, chlorophyll
synthesis, and enzymatic activity, thereby improving
photosynthetic efficiency and biomass accumulation (Calvo et al., 2014).
In legumes, humic acid application has been shown to enhance nodulation,
nutrient uptake, and yield attributes by promoting better root–soil
interactions (Nardi et al., 2021).
Seaweed extract, derived from marine algae
such as Ascophyllum nodosum, Sargassum,
and Kappaphycus, contains bioactive compounds including auxins, cytokinins, gibberellins, amino acids, vitamins,
polysaccharides, and micronutrients (Stirk et al.,
2014). Foliar application of seaweed extract enhances seed germination, vegetative growth, flowering, and pod
formation by modulating hormonal balance and metabolic activity
(Rouphael et al., 2018). It also improves plant tolerance to abiotic
stresses such as drought and salinity by regulating osmotic adjustment and
antioxidant defence systems (Khan et al., 2009).
Effective Microorganisms (EM) comprise a
consortium of beneficial microbes, mainly lactic acid bacteria, photosynthetic
bacteria, yeasts, and actinomycetes, that improve soil microbial diversity and
nutrient cycling (Ezeagu et al., 2023). EM enhances the decomposition of
organic matter, the solubilization of nutrients, and the suppression of
soil-borne pathogens, resulting in improved root growth and nutrient-use
efficiency (Javaid & Shah, 2011). Application of EM has also been linked
with increased synthesis of secondary metabolites and improved crop quality
parameters such as protein and vitamin content (Nardi et al., 2021).
The combined application of
humic acid, seaweed extract, and Effective Microorganisms often produces synergistic effects, improving plant vigor,
pod yield, and phytochemical composition more effectively than individual
treatments (Rouphael & Colla, 2020). These biostimulants offer a
sustainable alternative to conventional fertilizers and contribute
significantly to eco-friendly French
bean production systems by improving soil fertility, enhancing
nutrient efficiency, and increasing the nutritional quality of produce.
