Agriculture today faces unprecedented challenges that demand innovative solutions. With the global population projected to reach 9.3 billion by 2050, farmers must produce more food and medicinal plants while using fewer resources.
Traditional farming methods struggle with multiple issues including water shortages, soil degradation, and unpredictable weather patterns caused by climate change.
Lemongrass (Cymbopogon citratus), a tropical plant highly valued for its medicinal properties and essential oils used in pharmaceuticals, cosmetics, and food industries, is particularly vulnerable to these challenges.
Wild harvesting has led to overexploitation of natural populations, while conventional soil-based cultivation requires substantial amounts of water and arable land.
These pressing concerns have led researchers to explore alternative cultivation methods – specifically hydroponics and aquaponics – which promise higher yields, superior water efficiency, and more consistent quality, especially in arid regions like Iran where water scarcity is a major constraint.
Examining the Research Methodology
The comprehensive study conducted at Yazd University employed rigorous scientific methods to compare different cultivation systems.
Over a period of six months (180 days), researchers divided lemongrass plants into three distinct experimental groups.Ttraditional soil cultivation, hydroponic system, and aquaponic setup.
The hydroponic system utilized the Nutrient Film Technique (NFT), an advanced method where plants grow in shallow, gently flowing streams of nutrient-enriched water solution that provides constant access to both nutrients and oxygen.
The aquaponic system created a symbiotic environment by integrating Nile tilapia (Oreochromis niloticus) fish tanks with hydroponic components, where fish waste served as organic fertilizer for the plants while the plants naturally filtered the water for the fish.
The control group used conventional loamy soil cultivation for baseline comparison.To ensure scientific validity, the research team implemented multiple measurement protocols.
They meticulously tracked daily water consumption, carefully monitored nutrient levels in each system, recorded plant growth metrics, and analyzed the chemical composition of lemongrass leaves.
The extraction and analysis of essential oils formed a crucial part of the study, as these contain the valuable medicinal compounds that give lemongrass its commercial and therapeutic value.
The experimental design included five replications (copies) of each cultivation system to account for variability and ensure statistically significant results, with all data undergoing rigorous validation processes.
Analyzing the Remarkable Results
The study yielded compelling evidence demonstrating the superiority of soilless cultivation systems across multiple parameters.
Most strikingly, the hydroponic system produced an extraordinary yield of 2.5 kilograms of lemongrass per square meter.
A remarkable 92% increase compared to traditional soil farming which yielded only 1.3 kilograms.The aquaponic system also showed significant improvement with a yield of 1.8 kilograms, representing a 40% boost over conventional methods.
These impressive yield increases came with substantial water savings, a critical advantage in water-scarce regions.The hydroponic system consumed just 1.29 liters of water per square meter daily – exactly half the amount required by soil cultivation (2.33 liters).
The aquaponic system used 1.79 liters, achieving a 23% reduction in water usage compared to traditional farming.Water Use Efficiency (WUE), a crucial metric that measures crop output relative to water input, further highlighted the advantages of soilless systems.
Hydroponics achieved an exceptional WUE of 11.2 grams of lemongrass per liter of water – three times higher than soil’s 3.7 grams. Aquaponics reached 5.7 grams, still 1.5 times more efficient than conventional farming.
These efficiency gains are particularly valuable in arid climates where water conservation is paramount for sustainable agriculture.
Understanding Nutrient Dynamics in Different Systems
The research provided fascinating insights into how different cultivation systems affect nutrient uptake in lemongrass. Hydroponic cultivation excelled in delivering nitrogen (N), a macronutrient essential for plant growth and protein synthesis.
Lemongrass grown hydroponically contained 42% more nitrogen than soil-grown plants, explaining its superior growth rates and higher protein content.
Aquaponics, meanwhile, provided optimal levels of phosphorus (P) and magnesium (Mg) – phosphorus being vital for energy transfer (ATP production) and genetic material (DNA/RNA), while magnesium serves as the central atom in chlorophyll molecules necessary for photosynthesis.
- The aquaponic system delivered 31 milligrams of phosphorus per liter, nearly four times the concentration found in soil (8.33 milligrams).
However, traditional soil cultivation still maintained advantages for certain micronutrients. Calcium (Ca), important for cell wall structure; iron (Fe), crucial for chlorophyll synthesis and electron transport; and zinc (Zn), essential for enzyme function.
Growth regulation, all occurred in higher concentrations in soil-grown lemongrass. Specifically, soil cultivation produced plants with 8.63 milligrams of iron per kilogram – significantly more than both hydroponic (1.09 mg) and aquaponic (0.17 mg) systems.
This nutrient profile difference suggests that soilless systems might benefit from targeted micronutrient supplementation to match the nutritional diversity provided by healthy soils.
Exploring Enhanced Medicinal Compound Production
The study’s analysis of essential oil composition revealed particularly exciting findings for pharmaceutical and cosmetic applications.
Lemongrass essential oils contain valuable bioactive compounds including terpenoids (such as β-Myrcene, geraniol, and limonene) and ketones, which contribute to its medicinal properties.
- The research identified 25 distinct chemical compounds, with soilless systems significantly enhancing the concentration of most therapeutic components.
- Hydroponic cultivation increased geraniol (an alcohol used in antiseptics and fragrances) by 42% and geranyl acetate (an ester with antifungal properties) by 79% compared to soil-grown plants.
The aquaponic system boosted β-Myrcene (a terpene with analgesic and anti-inflammatory effects) by 60% and juniper camphor (a compound with antiseptic qualities) by 61%.
These dramatic increases in bioactive compounds make soilless-grown lemongrass substantially more valuable for therapeutic applications, potentially commanding higher market prices for pharmaceutical and cosmetic uses.
Evaluating Physiological Advantages
Beyond yield and chemical composition, the study examined important physiological differences between cultivation methods. Chlorophyll content, a key indicator of photosynthetic efficiency and plant health, showed significant variation.
Hydroponically grown lemongrass contained 7.0 milligrams of chlorophyll-a per gram of fresh weight – 90% more than soil-grown plants. Aquaponic plants also outperformed conventional cultivation with 5.0 milligrams, representing a 48% increase.
These elevated chlorophyll levels directly contribute to enhanced growth rates and biomass production in soilless systems.Protein content, another important quality metric, reached 23.3% in hydroponic lemongrass – the highest among all cultivation methods.
Crude fat content in hydroponic plants measured 3.8%, 26% higher than in soil-grown specimens. These physiological advantages demonstrate that soilless systems not only produce more lemongrass but also generate plants with superior nutritional and biochemical profiles.
The Science Behind Hydroponic Success
Hydroponic systems achieve their remarkable results through precise control of plant nutrition and root environment.
The Nutrient Film Technique (NFT) used in this study maintains a thin film of nutrient solution flowing past bare roots, ensuring constant access to water, oxygen, and all essential minerals.
This method eliminates the variability of soil composition and prevents competition from weeds or soil-borne pathogens. The carefully balanced Hoagland’s solution provides all macro and micronutrients in optimal ratios, with pH maintained between 6.5-7.5 for maximum nutrient availability.
Root zone oxygenation is another critical factor in hydroponic success. Unlike soil where roots may experience oxygen deprivation, NFT systems expose roots directly to air, preventing anaerobic conditions that can stunt growth.
This oxygen-rich environment promotes vigorous root development and efficient nutrient uptake, explaining the faster growth rates and higher yields observed in the study.
The Symbiotic Magic of Aquaponics
Aquaponics creates a miniature ecosystem that mimics natural nutrient cycles. In the studied system, Nile tilapia fish produced waste rich in ammonia, which beneficial bacteria converted first to nitrites then to nitrates – the preferred nitrogen source for plants.
This biological filtration process simultaneously cleans the water for fish while providing natural fertilizer for lemongrass.The system’s biofilter, containing porous plastic media, provided surface area for bacterial colonization.
Mechanical clarifiers removed solid waste before water entered the hydroponic component, maintaining water quality.
This closed-loop design demonstrates remarkable efficiency – the same water continuously circulates between fish and plants, with minimal loss to evaporation or runoff.
The fish component also offers additional income potential through protein production, making aquaponics a doubly valuable system for farmers.
Recognizing the Strengths of Soil Cultivation
While the study highlighted advantages of soilless systems, it also confirmed benefits of traditional soil cultivation. Soil’s complex ecosystem of microorganisms and organic matter facilitates natural nutrient cycling and provides a buffer against rapid changes in growing conditions.
The higher iron and zinc content in soil-grown lemongrass likely results from microbial activity that makes these micronutrients more available to plants.Soil also contains countless beneficial microbes that form symbiotic relationships with plant roots.
Mycorrhizal fungi, for instance, extend root systems and enhance nutrient absorption in exchange for plant sugars.
These natural partnerships contribute to plant health and may influence the production of secondary metabolites like essential oils, though the study showed higher concentrations in soilless systems.
Addressing Challenges and Limitations
Despite their advantages, soilless systems present several practical challenges that must be acknowledged.
The initial investment required for hydroponic or aquaponic infrastructure can be substantial, including costs for grow beds, water pumps, aeration systems, and monitoring equipment.
Technical knowledge requirements also present a barrier – successful operation demands understanding of nutrient solution management, pH balancing, and (for aquaponics) fish health maintenance.
In the aquaponic system studied, maintaining proper ammonia-to-nitrate conversion required careful monitoring of fish stocking density, feeding rates, and biofilter performance.
Hydroponic systems need regular adjustment of nutrient solutions to prevent deficiencies or toxicities. These technical demands may limit adoption among small-scale farmers without access to training or support services.
Future Research Directions
The study identifies several promising avenues for future investigation. Economic analyses comparing setup and operational costs against yield gains and product quality improvements would help farmers evaluate return on investment.
Research into low-cost, locally adaptable soilless system designs could improve accessibility for resource-limited growers.Long-term studies tracking system performance over multiple growing seasons would provide valuable data on sustainability and maintenance requirements.
Investigations into micronutrient supplementation strategies could help soilless systems match soil’s nutritional diversity. Exploration of alternative fish species in aquaponics might reveal options better suited to different climates or market preferences.
Practical Applications in Arid Regions
The study’s findings have particularly important implications for arid and semi-arid regions like Iran’s Yazd province, where annual rainfall rarely exceeds 50 millimeters.
A one-hectare hydroponic lemongrass farm could produce double the yield of conventional farming while saving approximately 2.7 million liters of water annually – a game-changing advantage in drought-prone areas.
These systems can be implemented in controlled environments like greenhouses, protecting crops from extreme temperatures and sandstorms common in desert regions.
The water savings come from precise delivery to plant roots, elimination of soil evaporation, and (in recirculating systems) minimal wastewater. Such efficiency could allow agricultural expansion in areas previously considered unsuitable for cultivation.
Urban Agriculture Potential
Soilless systems offer exciting possibilities for urban agriculture, where space constraints and land costs often limit farming opportunities.
Rooftop aquaponic installations could simultaneously produce lemongrass and fish, maximizing output per square meter while enhancing urban food security.
Singapore’s Sky Greens vertical farm demonstrates this potential, producing one ton of vegetables daily from just 3.5 hectares of vertical growing space.
Urban soilless farms can reduce “food miles” by growing medicinal plants near population centers, ensuring fresher products while lowering transportation emissions.
These systems can utilize abandoned buildings or repurposed infrastructure, contributing to urban renewal while creating local jobs in agriculture and technology sectors.
Implications for Pharmaceutical and Cosmetic Industries
The enhanced concentrations of bioactive compounds in soilless-grown lemongrass present significant opportunities for therapeutic product development.
β-Myrcene, which showed 60% increases in aquaponics, possesses documented analgesic and anti-inflammatory properties valuable for pain management formulations.
Geraniol, increased by 42% in hydroponics, serves as both a fragrance component and antimicrobial agent in cosmetics and cleaning products.Pharmaceutical companies could benefit from more consistent, potent raw material supplies for essential oil extraction.
The ability to standardize compound concentrations through controlled environment agriculture may improve drug formulation reliability. Cosmetic manufacturers could market products containing “high-potency” lemongrass extracts with verified bioactive content.
Conclusion
The Yazd University study provides compelling evidence that soilless cultivation methods represent more than just an alternative approach – they offer a necessary evolution in agricultural practice to meet 21st century challenges. By demonstrating substantial improvements in yield, water efficiency, and medicinal compound production, the research makes a strong case for wider adoption of hydroponic and aquaponic systems, particularly for high-value crops like lemongrass.
For agricultural policymakers, the findings suggest prioritizing support programs that help farmers transition to soilless methods, including technical training and financing for infrastructure. Researchers should focus on developing affordable system designs and optimizing protocols for different medicinal plants. Consumers and industries can drive demand for sustainably grown, high-quality plant materials.
Power Terms
Hydroponics: A method of growing plants without soil, using nutrient-rich water solutions. Importance: Allows farming in water-scarce areas and increases yields by precisely controlling nutrients. Uses: Ideal for crops like leafy greens and medicinal plants (e.g., lemongrass). Example: The study used the Nutrient Film Technique (NFT) to grow lemongrass.
Aquaponics: A farming system combining hydroponics with fish farming (aquaculture). Importance: Creates a symbiotic loop where fish waste fertilizes plants, and plants clean water for fish. Uses: Produces both crops and fish protein. Example: Nile tilapia and lemongrass were paired in the study.
Nutrient Film Technique (NFT): A hydroponic method where a thin stream of nutrient-rich water flows over plant roots. Importance: Ensures roots receive oxygen and nutrients continuously. Uses: Commercial herb and vegetable production. Example: Lemongrass grown in NFT systems showed 92% higher yields than soil.
Traditional Soil Cultivation: Growing plants in natural soil. Importance: Supports ecosystems with microbes and organic matter. Uses: Common for crops like grains and vegetables. Example: Soil-grown lemongrass had higher iron and zinc levels.
Nile Tilapia (Oreochromis niloticus): A freshwater fish used in aquaponics. Importance: Provides natural fertilizer through waste. Uses: Integrated with hydroponic systems. Example: Fish tanks in the study supplied nutrients for lemongrass.
Water Use Efficiency (WUE): A measure of crop yield per unit of water used. Formula: WUE = Yield (grams) / Water Input (liters). Importance: Critical for farming in dry regions. Example: Hydroponics achieved a WUE of 11.2 g/L, triple that of soil.
Nitrogen (N): A macronutrient vital for plant growth. Importance: Key for protein synthesis and leaf development. Uses: Boosts biomass and green color. Example: Hydroponic lemongrass had 42% more nitrogen than soil-grown plants.
Phosphorus (P): A macronutrient essential for energy transfer and DNA. Importance: Supports root growth and flowering. Uses: Added to fertilizers. Example: Aquaponics delivered four times more phosphorus than soil.
Magnesium (Mg): A mineral central to chlorophyll molecules. Importance: Enables photosynthesis. Uses: Prevents yellowing leaves. Example: Aquaponic lemongrass had optimal magnesium levels.
Calcium (Ca): Strengthens plant cell walls. Importance: Prevents rot and disorders. Uses: Added to soil or hydroponic solutions. Example: Soil-grown plants had higher calcium content.
Iron (Fe): A micronutrient for chlorophyll and enzyme production. Importance: Prevents leaf yellowing (chlorosis). Uses: Vital for photosynthesis. Example: Soil cultivation provided 8.63 mg/kg of iron.
Zinc (Zn): A micronutrient for enzyme and hormone function. Importance: Regulates growth and development. Uses: Enhances stress resistance. Example: Soil-grown lemongrass had higher zinc levels.
Essential Oils: Concentrated plant extracts with aromatic compounds. Importance: Used in medicine, cosmetics, and food. Example: Lemongrass oil contains geraniol and β-Myrcene.
Terpenoids: A class of organic compounds in plants. Importance: Provide medicinal and aromatic properties. Example: β-Myrcene and limonene in lemongrass oil.
β-Myrcene: A terpene with pain-relieving and anti-inflammatory effects. Importance: Valued in pharmaceuticals. Example: Increased by 60% in aquaponic lemongrass.
Geraniol: An alcohol used in fragrances and antiseptics. Importance: Adds floral scent and antimicrobial properties. Example: Hydroponics boosted geraniol by 42%.
Geranyl Acetate: An ester with antifungal benefits. Importance: Used in natural cleaning products. Example: Increased by 79% in hydroponic systems.
Limonene: A citrus-scented terpene. Importance: Used as a solvent and fragrance. Example: Found in lemongrass essential oils.
Juniper Camphor: A compound with antiseptic properties. Importance: Treats skin infections. Example: Increased by 61% in aquaponics.
Chlorophyll: The green pigment in plants that captures sunlight. Importance: Drives photosynthesis. Example: Hydroponic plants had 90% more chlorophyll-a.
Hoagland’s Solution: A nutrient mix for hydroponics. Importance: Provides balanced minerals for plant growth. Example: Used in the study’s NFT system.
Biofilter: A device using bacteria to clean water. Importance: Converts fish waste into plant nutrients. Example: Porous media in aquaponics hosted beneficial bacteria.
Mycorrhizal Fungi: Soil fungi that partner with plant roots. Importance: Enhances nutrient and water absorption. Example: Supported iron uptake in soil-grown lemongrass.
Macronutrients: Nutrients plants need in large amounts (N, P, K). Importance: Fuel growth and reproduction. Example: Nitrogen and phosphorus in hydroponic solutions.
Micronutrients: Nutrients needed in trace amounts (Fe, Zn). Importance: Support enzyme and hormone functions. Example: Iron and zinc in soil cultivation.
Reference:
Alizadeh, P., Sodaeizadeh, H., Arani, A.M. et al. Soilless Systems Improved Nutrient Uptake, Water Use Efficiency, and Chemical Composition of Lemongrass (Cymbopogon citratus). J Soil Sci Plant Nutr (2025). https://doi.org/10.1007/s42729-025-02389-w
