Here’s a detailed, structured overview of factors influencing resin yield and quality in Aquilaria spp.:
1. Genetic Factors
| Factor | Effect on Resin |
|---|
| Species / Genotype | Different Aquilaria species produce varying amounts and compositions of resin; some genotypes are naturally high-resin producers. |
| Tree age / maturity | Mature trees (typically >5–10 years) produce more resin; young trees may produce minimal or low-quality resin. |
| Clonal selection | Elite clones selected for high sesquiterpene/chromone content yield superior resin consistently. |
2. Environmental Factors
| Factor | Influence |
|---|
| Climate | Temperature, rainfall, and humidity affect tree metabolism and secondary metabolite synthesis. Optimal growth usually occurs in tropical climates. |
| Soil | Nutrient-rich, well-drained soils support vigorous growth and resin accumulation. Deficient soils can reduce resin yield and quality. |
| Light exposure | Sunlight influences photosynthesis and energy availability for defense and resin biosynthesis. |
| Altitude | Some studies suggest resin composition may vary with elevation. |
3. Tree Physiological Factors
| Factor | Influence |
|---|
| Tree vigor / health | Healthy trees respond better to induction methods. Stressed or diseased trees may produce less resin. |
| Wound response capacity | Trees with more active defense metabolism produce higher-quality resin. |
| Heartwood development | Well-developed heartwood correlates with higher resin deposition zones. |
4. Induction Methods
| Method | Effect on Yield & Quality |
|---|
| Physical wounding | Moderate yield; resin may be patchy; quality varies. |
| Chemical elicitors | Controlled induction; quality depends on elicitor type and concentration. |
| Biological induction (fungal inoculation) | Typically highest quality and quantity; induces natural defense responses rich in sesquiterpenes and chromones. |
| Dual-action formulations (e.g., MnO₂ + Fusarium) | Synergistic effect → higher yield, faster induction, and more uniform resin deposition. |
5. Biotic and Abiotic Stress
| Factor | Influence |
|---|
| Pathogen attack | Can trigger resin biosynthesis; controlled inoculation produces high-quality resin. |
| Mechanical injury | Promotes localized resin deposition. |
| Nutrient stress / fertilizer | Proper fertilization enhances resin formation; excessive nitrogen may favor vegetative growth over resin. |
| Water stress | Moderate stress may enhance secondary metabolite production; severe drought reduces yield. |
6. Harvesting and Post-Harvest Factors
- Time of harvest after induction: Resin content and chemical profile change over time; usually, 6–12 months after induction is optimal.
- Harvest technique: Improper cutting can damage heartwood or reduce resin yield.
- Storage and drying: Resin compounds can degrade if improperly stored; proper drying preserves quality.
7. Summary
Resin yield and quality are multifactorial, influenced by:
Genetics → Tree physiology → Environment → Induction method → Stress factors → Harvest and post-harvest handling
Key Takeaways for Maximizing Yield & Quality:
- Use high-resin genotypes or clones.
- Maintain healthy, mature trees.
- Optimize induction method (physical + chemical + biological).
- Apply controlled stressors to stimulate defense pathways.
- Harvest at the right time to capture maximal sesquiterpene and chromone content.
