Modulation of rhizosphere activity of crop plants through organic seed coating technology Ref.No.SSTCRC2616
1. Introduction
Modern agricultural strategies have a crucial function in enhancing crop yield, resilience, and growth in response to biotic and abiotic stress conditions by employing advanced seed treatment technologies. Among these, seed coating have emerged as effective methods, delivering nutrients, beneficial microbes, and bioactive agents directly to the seed to support improved crop performance. Seed coating improves seed handling by providing a thin film layer on seeds.
Traditionally, synthetic polymers like polyethylene glycol, polyvinyl alcohol, and polystyrene have been regarded as binding and film-forming agents. However, active investigations suggest significant environmental concerns regarding the settling of microplastics in agricultural soils, triggered by these materials. These microplastics can penetrate the plant roots and redistributed to stems and leaves acting as possible locations for accumulation. Consequently, the accumulation of microplastics in field-grown crops, particularly leafy vegetables, presents a food safety risk, along with impairing plant physiology, reducing yields, and disrupting rhizosphere microbial communities. The rise in awareness among farmers of seed treatment technology has initiated the demand for the development of eco-friendly and biodegradable seed treatment techniques. In addition to agronomic benefits, these organic, bio-compatible formulations intended for seed treatment also afford economic benefits. This adoption of a new approach towards sustainable agricultural inputs has influenced the global market for biostimulant based seed treatment methods from USD 112 million in 2015 to a projected USD 338 million by 2025.
While inorganic seed treatments may provide nutrient delivery and mechanical stability, their inadequacy in biological compatibility and their tendency to disrupt rhizosphere balance paved the way for the development of organic based formulations for seed treatment. To overcome these limitations, the present work aims to develop a microbe-assisted organic seed coating formulation (OSCF) composed of humic acid, bone meal, fish scale biochar, bone meal biochar, rock phosphate, and glycerol.
2. Objectives
a. To assess the seed invigoration potential of different organic ingredients
b. To analyze the physico-chemical characteristics of the organic ingredients that could support the maize and blackgram seed quality enhancement.
c. Development of organic seed coating formulation to modulate the rhizosphere activity and enhancing crop productivity in agriculture and horticulture crops
3. Research Progress
By combining the biochars (prepared from the fish scale and bone meal), humic acid and rock phosphate with 1.0% chitosan, a semi-solid Organic seed coating formulation (OSF) was prepared. Prepared material was used for coating (OSCF). Likewise, except chitosan remaining materials were mixed and subjected to ball milling. Ball milled material mix was used for pelleting using 1.0% chitosan solution as an adhesive. Material formulated for coating is mentioned as OSCF and pelleting is mentioned as OSPF in the figures given below. Both Coated (OSCF) and pelleted (OSPF) maize seeds were subjected to field emergence test under field condition. The coating and pelleting treatment significantly improved root and shoot elongation and biomass accumulation. Within ten days of sowing, the seedlings emerged from the pelleted seeds exhibited an enhanced root architecture, characterized by increased surface area (28.34 cm2), volume (0.627 cm3), and diameter (0.985 mm). This was supported by microscopy, which revealed an enlarged cortex. Initial field emergence study demonstrated that the developed crude formulation outperformed other treatments followed in this experiment. Further, enhanced root and soil dehydrogenase activity were also recorded in the seedlings emerged from the seeds offered with coating and pelleting treatment with developed crude formulation under field condition.
4. Cooperation Required
In the research program soil metagenomics and metabolic profiling of root exudates need to be done to find out how far the seed coating formulation is effective in establishing communication with soil microbes. Further, in comparison with synthetic polymer based seed coating material field trials need to be conducted to analyse the micro plastic content of the field cultivated with synthetic polymer coated seeds. This study need the following support viz.,
a. cryo term facility to visualize the entry of micro plastic into the plant in synthetic polymer coated seeds
b. GC MS and NMR aided metabolomics profiling of the root exudates
c. Soil metagenomic analysis
5. Benefits
As an outcome, valuable organic seed coating formulation will be developed from the waste material. This process paves the way for safer utilization of fish scale, bone meal and crab shell. At the end of the project, field level data will be generated with reference to impact of OSF based seed coating on maize and blackgram productivity and soil health. That will help us to promote this product among the farming community to use for seed coating instead of synthetic polymer based. This also helps to eliminate microplastic pollution in agriculture soils through usage of synthetic polymer in seed quality enhancement. Further, the OSCF intended to develop in the project expected to provide food for seed, seedling and above all for the native microbial population. This will help the farmers to revitalize the soil health and nutrient cycling. Large scale usage of this formulation will reduce the chemical input dependency and better establishment of synergy between the microbes and plants, thus leads to enhanced rhizosphere activity and resulted in efficient nutrient utilization of the crop and enhanced productivity. Indirectly this will promote the agro-ecological balance in the agriculture field and resulted in crops resilience to climate stress. The above all, introduction of this OSCF pave the way for use of organic volatile compounds aided microbial recruitment in the rhizosphere region of the coated seeds during early stage.
6. Outputs
Both research papers and product patent are possible.