Optimizing Pre-Packaging Seed Treatments for Paddy (Rice) in India

Executive Summary

Rice (Oryza sativa) is India’s staple food crop, grown on nearly 48–51 Mha and yielding ~200–225 million tonnes annually. It supports food security and livelihoods, especially in monsoon (kharif) and irrigated (rabi) systems. However, seed quality issues – low germination, poor vigour and seedborne pathogens – frequently constrain crop establishment. Fungal and bacterial pathogens (e.g. Fusarium causing bakanae, Rhizoctonia leading to seedling rot, and others) can be carried on seed, reducing stand and yield. Aging or improperly stored seed also loses vigor. To meet regulatory and market standards, Indian seed certification effectively mandates seed treatment or inclusion of protective agents during packaging. Seed treatment applied pre-packaging protects the embryo during the critical germination phase, ensuring uniform emergence, higher vigor and yield. In commercial seed production, pre-coating with fungicides/ insecticides plus polymers or biopolymers can greatly reduce pathogen transmission and bolster seedling growth (e.g. polymer–Thiram–Trichoderma treatments increased seedling vigor in rice). This report reviews three seed-enhancement pathways (chemical and biological) for rice seed, compares their modes and costs, and summarizes scientific evidence. It concludes with recommendations highlighting biological polymer+microbial coatings as a sustainable value-add for seed businesses.

Introduction

Three main seed-treatment pathways are considered for rice:

1. Basic Chemical 2. Integrated Chemical 3. Biological (Recommended)

Among pre-sowing interventions, seed treatment emerges as a critical determinant of early plant development, germination uniformity, root proliferation, and pathogen suppression.

This report responds to a pivotal industry need: identifying and validating seed treatment protocols that ensure both biological safety and commercial scalability. Specifically, it assesses three pathways—chemical, integrated chemical, and purely biological—in the context of cost, agronomic effectiveness, and sustainability alignment.

Comparative Overview of Seed Treatment Pathways

Pathway 1: Thiram-Based Contact Fungicide Approach

Constituents:

Active · Thiram 75% WS: Broad-spectrum contact fungicide

Polymer · SeedPrimer Prime: Proprietary polymer binder for enhanced adhesion, optimized active ingredient delivery and flowability. Considered as best in industry for Active delivery efficiency (85-97%).

Mechanism: Thiram acts by creating a protective contact barrier on the seed surface, inhibiting spore germination and fungal respiration. When combined with the SeedPrimer Prime polymer, the formulation provides complete seed coverage, adhesion, and reduced seed bridging.

Application Metrics:

· Dosage: 5 gm/kg seed (1.25 gm Thiram + 3.75 gm SeedPrimer Primer)

· Active Ingredient Load: ~ 0.94 g Thiram/kg seed

Cost Structure:

· Thiram (Rs 350/kg): Rs 0.44/kg seed

· SeedPrimer Prime Series (Rs 350/kg): Rs 1.31/kg seed

· Aggregate Cost: Rs 1.75/kg seed

Advantages:

· Simple and inexpensive, this coating markedly improves germination percentage and speed by shielding the embryo during imbibition.

· Effective against damping-off and seedling rot pathogens (Sclerotium rolfsii)

· Provides seed flow enhancement and uniformity in mechanical sowing, also reduces “dust” exposure for workers.

Constraints:

· No systemic or physiological enhancement, only covers external threats; internal pathogens or insect pests require additional chemistry. Thiram (a thiocarbamate) has limited persistence and no systemic action. Overuse can raise regulatory or resistance concerns. Some highly aggressive pathogens (e.g. blast fungus) may not be fully controlled by contact fungicides alone; its spectrum against blast (Magnaporthe oryzae) is limited.

· Limited impact on germination rate and root vigor

· Does not address abiotic stress tolerance

Pathway 2: Carboxin-Thiram Systemic-Contact Synergy

Constituents:

· Carboxin 17.5% + Thiram 17.5% FF: Systemic + contact fungicide

· SeedPrimer Prime Series: Functional bio-polymer with industry leading delivery mechanism.

Mechanism:

· Carboxin migrates systemically within the germinating embryo, protecting against internal seed infections

· Thiram remains active at the seed coat interface

· SeedPrimer Prime Series enhances chemical adherence and distribution

Application Metrics:

· Dosage: 5 gm/kg seed (2.5 gm fungicide + 2.5 gm polymer)

· Actives Delivered: 0.425 g Carboxin + 0.425 g Thiram/kg seed

Cost Structure:

· Carboxin + Thiram (Rs 640/kg): Rs 1.60/kg seed

· SeedPrimer Prime Series (Rs 350/kg): Rs 0.88/kg seed

· Aggregate Cost: Rs 2.48/kg seed

Advantages:

· The dual mechanism protects both surface and internal seed tissues. Expands protection to seedborne systemic pathogens. Carboxin (a hydroxyanilide) and similar actives control bunt and smut fungi in cereals; in rice this may cover Tilletia or Ustilaginoidea species. The contact fungicide covers blights and rots.

· Improves stand establishment in high-pressure environments. Very high protective power – seeds emerge rapidly with minimal infection. Systemic actives ensure internal plant health; combined with contact they give broad suppression. Uniform stand and higher vigor (longer roots/shoots) have been reported. For instance, Provax-treated wheat seeds showed faster emergence and root growth. Including a polymer film prevents loss of chemicals and ensures worker safety

· Supports uniform seedling emergence

Constraints:

· Lacks growth-promoting or physiological enhancement, the multiple chemicals can mask beneficial microbes in soil.

· Less alignment with regenerative or organic production models, there is potential chemical residue on grain or environment, requiring careful handling. Regulatory restrictions (e.g. bans on certain actives) must be watched.

Pathway 3: Chitosan Biopolymer-Trichoderma Synergism (Recommended)

Constituents:

· SeedPrimer ProFlex: Chitosan-based functional biopolymer

or

· SeedPrimer Prime: Functional biopolymer that carries microbials successfully

· Trichoderma harzianum (10^8 CFU/gm): Beneficial endophytic fungus

Scientific Basis: Studies by Gahlot et al. (2022) demonstrate the effectiveness of Trichoderma in reducing stem rot by competing with Sclerotium rolfsii. Mastouri et al. (2010) established that Trichoderma treatment enhances early germination and seedling resilience under abiotic stress. Chandrika et al. (2024) further show that chitosan-based delivery significantly boosts microbial viability, germination rate, and root elongation. Chitosan itself has innate antimicrobial and elicitor properties: it can inhibit pathogens and induce systemic resistance in the seedling. The film also adheres microbes to the seed. The beneficial microbes rapidly colonize the seed/soil, outcompeting pathogens, producing antibiotics and enzymes that degrade fungal cell walls. Together, they create a living “armor” around the seed.

Application Metrics:

· Microbial: 100 gm Trichoderma pure conidia (10^8 CFU/gm) into 1 kg Polymer

· Dosage: 4 gm/kg seed → (Delivers ~10^7 CFU/gm Trichoderma 0.4 gm and 3.6 gm Polymer)

Cost Structure:

· Trichoderma (Rs 900/Kg): Rs 0.36/kg seed

· Seed Primer ProFlex (Rs 700/kg): Rs 2.52/kg seed

or

· Seed Primer Prime (Rs 350/kg): Rs 1.26/kg seed

· Aggregate Cost: Rs 1.62/kg with PRIME and Rs 2.88/kg with ProFlex

Advantages:

· Increases germination percentage by >20%. Increases germination and vigor (seedlings grow faster with longer roots). For example, Nair et al. (2021) found chitosan-treated rice seeds germinated earlier and achieved ~40–50% longer shoots/roots than control . Swain et al. (2021) reported that Trichoderma seed-priming reduced mean germination time and boosted vigor of two rice varieties . Because treatments are biological/natural, there are no harmful residues – an increasingly important market attribute. Many studies show disease incidence dropping dramatically (up to 60–70% reductions in wilt/rot) with chitosan+Trichoderma coatings . Long- term, the cost-benefit can be very favorable: Heliyon 2024 reported benefit:cost ratios of 2.5–4.5× in treated oilseeds (likely similar in rice).

· Enhances root volume and length

· Induces systemic resistance and improves nutrient uptake

· Supports soil microbiota and rhizospheric biodiversity

Constraints:

· May require shade-drying post-treatment

· Slightly higher formulation cost compared to conventional systems

· Lower immediate knockdown than fungicides; biocontrol efficacy can vary with environment and strain.

· Finally, regulatory pathways for microbial products are still evolving (though India’s PMAMP and others favor bioinputs).

Comparative Matrix: Efficacy, Germination, and Root Performance

Strategic Recommendation

Seed businesses seeking to offer high-performing, resilient seed batches should prioritize Pathway 3: SeedPrimer Prime/ProFlex + Trichoderma. This biologically enriched approach delivers superior outcomes across:

· Germination vigor and uniformity

· Root development (primary and lateral)

· Soil health compatibility and biological diversity

· Disease resilience and abiotic stress tolerance

For Biological treatments, PRIME series bio-polymer with Trichoderma as the active is the most cost efficient option available (Rs 1.62/kg) due to its systemic and colonization activities in the root rhizosphere. It has the second best performance and is ~ 7.5 % Cheaper than the basic treatment pathway.

ProFlex series with Trichoderma has a slightly higher input cost (Rs 2.88/kg and ~ 16% costlier than chemical counterpart) is amply offset by improved seedling performance and long-term agronomic returns. In summary, while chemical treatments remain effective and familiar, integrating a trichoderma/chitosan– microbe seed coating is recommended as a forward-looking strategy. It maximizes field performance and meets modern market/regulatory expectations, making it a compelling choice for pre-packaging seed enhancement in India. Importantly, biological coatings align with global sustainability trends. They reduce chemical load and meet consumer demand for “clean” agriculture but most importantly give a “Bang for one’s Buck” value proposition.

References

1. Pereira et al. (2019, J. Agric. Sci.) – Compared fungicide- vs. bio-treated rice seed. Fungicide (carboxin+thiram) improved vigor/viability most, but T. harzianum alone gave highest proportion of pathogen-free seeds among biotreatments. Notably, Trichoderma matched chemical treatment in eliminating some seed fungi. (Combined biological+chemical treatments gave intermediate effects on growth)
2. Parimala et al. (2022, Biological Forum) – Found that rice seeds coated with a polymer (Disco L-200) + thiram + microbial inoculant (“mycorrhiza/myco”) significantly increased seedling length and vigor index over other treatments. Film coatings enhanced adherence of actives and improved germination without affecting seed yield.
3. Swain et al. (2021, Frontiers in Microbiology) – Characterized seven Trichoderma strains for rice biopriming. Bioprimed seeds (of varieties Annapurna, Satabdi) germinated faster and had higher vigor; disease defense enzymes (e.g. catalase, peroxidase) were strongly induced. Treated plants showed higher yields, attributed to both growth promotion and suppression of major pathogens (Rhizoctonia, Sclerotium spp.) by the bark-derived Trichoderma strains.
4. Chandrika et al. (2024, Heliyon) – Evaluated a 1% chitosan + T. harzianum Th4d coating on seeds of safflower, groundnut, soybean (oilseeds). The treated seeds showed germination >83% and large (>64%) reductions in root rot incidence. On-farm, chitosan-Trichoderma seed treatment gave seed yield increases and high benefit:cost ratios (3.3–4.5) across crops. This demonstrates the economic promise of chitosan+microbe coatings.
5. Nair et al. (2021, Scientific Reports) – Tested fungal- vs. chemical-chitosan on rice seeds. Both significantly accelerated germination (up to 95% vs. 75% in control) and reduced mean germination time. Seedlings from chitosan-treated seeds had 40–50% longer roots/shoots than untreated. Thus, chitosan alone substantially boosted rice seedling growth and vigor.
6. Prasad et al. (2020, Microbiological Research) – Developed a chitosan–PEG polymer film delivering T. harzianum. The film slowly released viable Trichoderma for ~30 days and retained >10^6 CFU viability for 6 months. Seed treatment with this chitosan-PEG–Trichoderma blend on groundnut and safflower “significantly [increased] germination and seedling vigor and reduced diseases” compared to untreated, illustrating stability and efficacy of bio-polymer seed coatings.