Application of Bio-Stimulants in Comparison with Organic and Mineral N Fertilizers for Growth Promotion of Spinach and Common Bean Grown on Sandy Soil

Abstract

Spinach and common bean plants as representatives of leafy and legume vegetables were subjected to some biostimulants to evaluate its effects, against organic and mineral fertilizers, on plant growth, nutrient uptake and nitrate accumulation under field conditions. Individual treatments of humic acid (HS) and seaweed extract (SW) as bio-stimulants were tested in comparison with organic compost and ammonium nitrate as mineral fertilizer. Fresh and dry weight of spinach and common bean plants were significantly positively affected by application of seaweed extract and humic acid, respectively. Incorporation of organic compost resulted in fresh and dry biomass yields of spinach leaves, common bean green vegetative part and pods nearly closed or slightly lower than those recorded with ammonium nitrate fertilizer. In most cases, seaweed extract was superior over other treatments. Both of humic acid and seaweed extract relatively increased fresh or dry weights of both crops by about 50% in average over the plants fertilized with ammonium nitrate or treated with organic compost. Application of seaweed extract and humic acid had reduced the nitrate content in spinach leaves as compared to plants treated with ammonium nitrate but nearly closed to those of organic compost. Either organic compost or biostimulants (SW and HS) produced edible leaves of spinach with lower nitrate content that makes it marketable according to permissible level organized by European Commission Regulation (3500 mg kg-1 FW). Nitrogen, phosphorus and potassium uptake by leaves of spinach and pods of common bean were positively significantly increased with application of all tested treatments in comparison to the untreated control, but seaweed extracts and to somewhat extent the humic acid resulted in NPK values more or nearly closed to those recorded with either mineral fertilizer or organic compost additive. These results gave the chance to accept the biostimulants in addition to organic additive as alternative and sustainable tools complementing a high yield with premium quality.

Bio-stimulants in vermicomposting: a closer look

“…These versatile creatures can be adapted everywhere on the planet except for desert, sea and area which is devoid of vegetation. Using these small creatures which was entitled the intestine of the soil by the great Aristotle, there came an idea to use them to our advantage by providing the suitable environment for them to produce enriched compost as an alternative for the first leap towards sustainability (Soliman and Hamed 2019).…”

“…The entire plant underground root system could be viewed as a 'receiver' or 'reservoir' of the multitudes of biochemical signals which plants use to 'sense' the soil rhizosphere for the availability of water, mineral nutrient, phytohormone and other metabolites. Specific biochemical signals are 'received' at the root tips before being 'assimilated' and sent to the other plant parts where strong responses are induced at actively growing regions (Soliman et al, 2019).…”

Potencialidades de dos bioestimulantes en la germinación y el crecimiento de las plántulas de tomate

“…Por otra parte, las sustancias húmicas (SH), que resultan de transformaciones químicas y biológicas de residuos de plantas y animales, así como del metabolismo microbiano, comprenden pequeñas moléculas orgánicas de estructura definida que están unidas a través de enlaces débiles y forman una asociación supramolecular (Soliman & Hamed, 2019). Una revisión sobre las SH como bioestimulantes en la horticultura evidencia que tienen efectos en el crecimiento y desarrollo de las plantas, la absorción de nutrientes y el metabolismo primario y secundario, este último relacionado con la tolerancia al estrés abiótico (Khan et al, 2019).…”