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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_5217_Библиотеки_им_академика_М_И_Перельмана.pdf
Chapter 3 Challenges encountered in growing medicinal and aromatic plants 133
sponse and can influence secondary metabolite production [115]. High temperatures
can damage the photosynthetic apparatus, particularly photosystem II, reducing photosynthetic efficiency and overall plant productivity. This not only affects growth but can
also influence secondary metabolite production, as many are derived from photosynthetic products. Heat stress can alter the activity of key enzymes involved in secondary
metabolite biosynthesis [116]. For example, it may enhance phenylalanine ammonialyase (PAL) activity, potentially increasing concentrations of certain beneficial phytochemicals. However, effects vary, depending on the specific compound and plant species [117]. These stress-induced changes in secondary metabolite composition can have
significant implications for medicinal properties and therapeutic applications. While
some changes might enhance certain medicinal properties, they can also lead to unpredictable variations in therapeutic effects. The plant’s response to heat stress is often
influenced by other environmental factors, such as water and nutrient availability
[118]. Drought stress, often accompanying heat stress, can exacerbate negative effects
on plant growth and metabolism. Understanding heat stress effects on medicinal plants
is crucial for cultivation and natural medicine production. Controlled environmental
stress techniques may enhance product quality without significantly compromising
yield. However, implementing such strategies requires a thorough understanding of
species-specific responses and optimal stress levels [119]. In conclusion, heat stress effects on medicinal plants involve a complex interplay of growth impacts and potential
increases in certain bioactive compounds (Figure 3.2). This presents both challenges
and opportunities for cultivation in a changing climate. Ongoing research is crucial for
developing sustainable practices that balance productivity with high-quality medicinal
products [120]. Understanding these mechanisms may provide insights into improving
plant-based medicine efficacy and production, contributing to the ongoing importance
of medicinal plants in healthcare and traditional medicine systems worldwide.
3.11 Soil pH
Soil pH significantly impacts the growth, development, and phytochemical composition
of medicinal plants. As a key factor affecting nutrient availability and microbial activity,
soil pH plays a crucial role in determining plant health and therapeutic potential [121].
Most medicinal plants thrive in soil pH between 6.0 and 7.5, though specific species may
have different preferences. Acidic soils (pH below 6.0) can lead to nutrient deficiencies,
particularly phosphorus, calcium, and magnesium. This can result in stunted growth,
reduced flower and seed production, and weakened root systems. Alkaline soils (pH
above 7.5) may reduce the availability of micronutrients like iron, manganese, zinc, and
copper, impacting various physiological processes, including photosynthesis and secondary metabolite biosynthesis [122]. Soil pH also influences rhizosphere microbial
communities, affecting nutrient cycling and plant health. Acidic soils may suppress ben-
Figure 3.2: Physiological and molecular aspects of heat stress in the medicinal plants.
134 Fatemeh Ahmadi, Maximilian Lackner, and August Starzinger
eficial microorganisms, while alkaline soils can favor certain microbes but also promote
some pathogens [123]. These microbial community changes can indirectly impact secondary metabolite production in medicinal plants. The effect of soil pH on phytochemical compounds is complex and species-specific. Mild pH stress may stimulate the production of certain secondary metabolites as a plant stress response. For instance,
slightly acidic conditions can enhance phenolic compound and flavonoid production in
some species [124]. However, severe pH stress can lead to an overall decline in phytochemical content. Alkaloid biosynthesis and accumulation are particularly sensitive to
soil pH changes. In some plants, like Catharanthus roseus, slightly acidic conditions enhance valuable alkaloid production. Essential oil composition and yield in medicinal
plants also vary with soil pH [125]. For example, some mint species show higher essential oil yields in slightly acidic soils. Long-term exposure to suboptimal pH can lead to
genetic and epigenetic changes in plant populations, potentially altering their adaptive
Chapter 3 Challenges encountered in growing medicinal and aromatic plants 135
strategies and phytochemical profiles over generations [126]. This highlights the importance of maintaining appropriate soil pH in natural habitats and cultivation areas to
preserve the genetic diversity and medicinal properties of these plants. Managing soil
pH is crucial for optimizing growth and phytochemical production in medicinal plants.
Various strategies can be employed to adjust soil pH to suit the specific requirements of
different medicinal plant species [127].
Soil pH management is crucial for optimizing medicinal plant cultivation. For
acidic soils, liming with materials like agricultural limestone or wood ash can gradually
raise pH. Careful application is necessary to avoid micronutrient deficiencies. Alkaline
soils can be acidified using elemental sulfur or organic materials like peat moss [128].
Container-grown plants may benefit from acidifying fertilizers or organic acids. Regular
soil testing is essential for maintaining optimal conditions. Soil pH significantly affects
nutrient availability, impacting plant growth and bioactive compound synthesis. Acidic
soils may reduce macronutrient availability, while increasing certain micronutrients to
potentially toxic levels. Alkaline soils often decrease phosphorus and micronutrient
availability [129]. Understanding these pH-dependent nutrient dynamics is vital for optimizing medicinal plant cultivation and phytochemical yield. Root architecture and rhizosphere interactions are also influenced by soil pH [130]. Acidic conditions can alter
root morphology, affecting nutrient and water uptake. Soil pH impacts root exudates,
shaping the rhizosphere microbiome, which in turn affects nutrient cycling and plant
defense mechanisms. Innovative cultivation techniques have emerged from research
on soil pH effects [131]. Controlled pH stress can stimulate the production of specific
secondary metabolites, potentially enhancing the therapeutic efficacy and commercial
value of certain medicinal plants. Aquatic and semiaquatic medicinal plants are also
affected by pH, with water pH playing a similar role to soil pH in terrestrial systems
[132]. This is crucial for cultivating and conserving aquatic medicinal species. Climate
change further complicates the relationship between soil pH and medicinal plant
growth. Changes in precipitation, temperature, and CO
ics, potentially affecting medicinal plant distribution and phytochemical profiles. In
conclusion, soil pH fundamentally shapes medicinal plant growth and phytochemical
composition [133] (Figure 3.3.). Ongoing research is essential for developing tailored pH
management strategies for different species, ensuring sustainable cultivation practices,
and preserving these valuable plant resources for future generations.
levels can alter soil pH dynam-
2
3.12 Light intensity
Light intensity significantly impacts the growth, development, and phytochemical
composition of medicinal plants. As photosynthetic organisms, plants depend on light
for energy, and variations in light quantity and quality can substantially affect their
morphology, physiology, and biochemistry [134]. Understanding these effects is crucial
Reduced Nutrient
Availability
Decreased
Medicinal Compounds
Increased
Toxicity
Maximum Nutrient
Availability
Reduced Enzyme
Activity
Imbalanced
Microbial Populations
Low pH
Soil pH
Optimal pH
High pH
Lowered Metabolite
Biosynthesis
Figure 3.3: Effect of soil pH on medicinal compounds.
136 Fatemeh Ahmadi, Maximilian Lackner, and August Starzinger
for optimizing medicinal plant cultivation and ensuring consistent production of
high-quality phytochemicals. Plants exhibit various responses to different light intensities at multiple organizational levels. Morphologically, high light intensity often results in thicker leaves with smaller surface areas, while low light conditions produce
larger, thinner leaves [135]. This adaptation optimizes light-capturing ability in different environments. For example, sage (Salvia officinalis) grown under partial shade developed larger leaf areas compared to those in full sunlight. Light intensity also affects
stem length and plant architecture [136].
Low light conditions often lead to elongated stems and internodes (shade avoidance
response), while high light intensities produce shorter, more compact growth habits
[137]. This compact growth can be advantageous in medicinal plant cultivation, potentially increasing yields and simplifying management practices. Physiologically, light intensity directly impacts the photosynthetic apparatus. Chlorophyll content, crucial for
photosynthesis, is particularly sensitive to light intensity changes [138]. Plants grown in
lower light conditions generally have higher chlorophyll content per unit leaf area, an
adaptive response to capture more light energy. However, the relationship between
light intensity and photosynthetic efficiency is not linear [139]. While moderate increases in light intensity can enhance photosynthetic rates, excessively high levels can
cause photoinhibition, damaging the photosynthetic apparatus and reducing growth
and productivity. Light intensity also influences secondary metabolite production,
which is often of primary interest in medicinal plants due to their therapeutic properties. Secondary metabolite biosynthesis is closely linked to photosynthetic activity and
overall metabolic state, both heavily influenced by light intensity [140]. Higher light in-
Chapter 3 Challenges encountered in growing medicinal and aromatic plants 137
tensities generally promote the production of certain secondary metabolites, particularly those involved in photoprotection and antioxidant defense [141].
Flavonoids, a diverse group of phenolic compounds known for their medicinal
benefits, are highly responsive to variations in light intensity. Numerous studies have
indicated that medicinal plants exhibit increased flavonoid production when grown
under bright light conditions [142]. For instance, research on Anoectochilus formosanus demonstrated that total flavonoid levels rose with light intensity, peaking at
60 μmol/m
2
/s. This boost in flavonoid synthesis is believed to serve as a protective
mechanism against excessive light and the oxidative stress it can cause [143]. Essential
oils, another critical category of secondary metabolites in medicinal plants, also react
to changes in light intensity. However, the specific response can differ among plant
species and the compounds involved [144]. For example, higher light levels have been
linked to increased essential oil content in plants like Thymus vulgaris (thyme) and
Matricaria chamomilla (chamomile). Conversely, species such as Anethum graveolens
(dill) and Salvia officinalis (sage) tend to produce more essential oils in shaded conditions. These variations underscore the complex and species-specific relationship between light intensity and secondary metabolite production [145]. The production of
alkaloids, which are nitrogen-containing compounds with significant pharmacological
effects, is also influenced by light intensity [146]. In some instances, increased light
exposure correlates with higher alkaloid levels. For example, Catharanthus roseus,
known for its anticancer alkaloids, shows enhanced production of vinblastine and
vincristine under high-light conditions. However, optimal alkaloid synthesis may
occur at intermediate light levels for certain species. While elevated light intensities
generally boost secondary metabolite production, this relationship is not uniform
across all plants and can have limitations [147]. Excessive light can induce oxidative
stress and photodamage, reducing overall plant productivity and the yield of secondary metabolites. Thus, identifying the ideal light intensity for each medicinal plant
species is essential for maximizing growth and phytochemical output [148].
Light intensity effects are further complicated by interactions with other environmental factors like temperature, water availability, and nutrient status. High light levels
often coincide with elevated temperatures that can independently influence plant metabolism and secondary metabolite production [149]. Additionally, plants exposed to intense light may require more water; insufficient hydration can adversely affect secondary metabolite synthesis. Understanding how light intensity impacts medicinal plants
has significant implications for their cultivation and natural medicine production [150].
In controlled agricultural settings such as greenhouses or indoor farms, growers can
manipulate light conditions to enhance plant growth and phytochemical yields. Various
lighting strategies have been developed, including artificial lighting to supplement natural sunlight [151]. LED systems are particularly popular due to their energy efficiency
and precise control over light spectrum and intensity. Adjusting light exposure during
different growth stages has shown potential for increasing both biomass production
and secondary metabolite accumulation in medicinal plants. Some studies suggest that
138 Fatemeh Ahmadi, Maximilian Lackner, and August Starzinger
providing higher light intensities during specific developmental phases can stimulate
phytochemical production without hindering overall growth [152]. This targeted approach allows growers to customize lighting conditions according to the needs of various medicinal plant species [153]. It is crucial to recognize that the optimal lighting for
growth may not align with conditions that maximize secondary metabolite production;
a balance must be struck between enhancing biomass yield and optimizing phytochemical content. The influence of light intensity on medicinal plants extends beyond immediate physiological responses; long-term exposure to varying light environments can induce genetic and epigenetic changes in plant populations [154]. These changes may
alter adaptive strategies and phytochemical profiles over generations, emphasizing the
importance of preserving diverse habitats to maintain the full range of medicinal properties in these species. As research progresses in this area, new technologies are being
developed to deepen our understanding of how light intensity affects medicinal plants
[155]. Techniques such as high-throughput phenotyping, combined with metabolomics,
provide valuable insights into the intricate relationships between lighting conditions,
plant physiology, and secondary metabolite production. In conclusion, light intensity
plays a fundamental role in shaping the growth and phytochemical composition of medicinal plants [156]. Its effects range from influencing basic morphological traits to modulating complex biochemical pathways involved in producing important compounds.
Optimizing lighting conditions requires a nuanced approach, tailored to each species’
specific needs, while considering interactions with other environmental factors [157].
By effectively managing light intensity throughout the growth cycle, it is possible to enhance both yield and quality in medicinal plant cultivation, supporting sustainable production of valuable natural medicines as global demand for plant-based therapies continues to rise [158].
Long-term exposure to varying light conditions can result in genetic and epigenetic modifications within plant populations, potentially altering their adaptive strategies and phytochemical profiles across generations [159]. This is particularly significant for conserving and sustainably utilizing medicinal plant species, emphasizing the
importance of safeguarding diverse habitats and genetic resources to preserve their
medicinal properties. As research progresses, new technologies are emerging that enhance our understanding of how light intensity influences medicinal plants [160].
Techniques such as high-throughput phenotyping, combined with metabolomics and
transcriptomics, are offering valuable insights into the intricate relationships between
light conditions, plant physiology, and secondary metabolite production [161]. These
advanced methods enable researchers to pinpoint key genes and metabolic pathways
involved in responses to light, which could lead to new strategies for improving the
medicinal qualities of plants through targeted genetic enhancements or optimized cultivation practices. In summary, light intensity is essential in shaping the growth, development, and phytochemical composition of medicinal plants. Its effects range from
influencing basic morphological traits to modulating complex biochemical pathways
linked to the production of important medicinal compounds [162, 163]. While general
Figure 3.4: Effect of light intensity on medicinal plant growth.
Chapter 3 Challenges encountered in growing medicinal and aromatic plants 139
trends exist – such as increased secondary metabolite production under higher light
levels – the specific responses can vary widely among different plant species and compounds. Therefore, optimizing light conditions for cultivating medicinal plants requires a detailed, species-specific approach that considers the interactions between
light intensity and other environmental factors. By effectively managing light exposure throughout the growth cycle, it is possible to improve both yield and quality in
medicinal plant cultivation, supporting the sustainable production of valuable natural
medicines [164] (Figure 3.4). As our understanding of these complex interactions
evolves, we can anticipate further innovations in cultivation practices that enhance
the efficient and targeted production of therapeutic compounds to meet the rising
global demand for plant-based medicines [165, 166].
3.13 Pest and disease management
Pest and disease management is a critical aspect of growing medicinal plants, as it directly impacts the quality and yield of the final product. Effective strategies must balance the need for plant protection with the requirement to maintain the purity and
safety of medicinal compounds. Integrated Pest Management (IPM) forms the cornerstone of modern pest control in medicinal plant cultivation. This approach combines
various techniques to minimize pest damage, while reducing reliance on chemical pesticides [167]. Cultural practices play a significant role in IPM for medicinal plants. Crop
rotation helps break pest life cycles and reduces the buildup of soil-borne pathogens.
Intercropping with companion plants can deter pests and attract beneficial insects. For
instance, planting marigolds alongside medicinal herbs can repel nematodes and some
insect pests [168]. Proper sanitation is crucial in preventing disease spread. This includes removing infected plant material, sterilizing tools, and maintaining clean growing areas. Pruning and thinning improve air circulation, reducing humidity levels that
140 Fatemeh Ahmadi, Maximilian Lackner, and August Starzinger
favor fungal growth. The timing of planting and harvesting can also be adjusted to
avoid periods of high pest pressure or disease susceptibility [169].
Biological control methods are increasingly important in medicinal plant production. Predatory insects, such as ladybugs and lacewings, can be introduced to control
aphids and other soft-bodied pests. Beneficial nematodes are effective against soildwelling insect larvae. Microbial pesticides, including Bacillus thuringiensis (Bt) preparations, offer targeted control of certain caterpillar species without leaving harmful residues. Physical barriers and traps provide nonchemical pest control options. Row covers
protect young plants from insect damage and can create microclimates that accelerate
growth. Sticky traps monitor pest populations and can help control flying insects. Pheromone traps disrupt the mating cycles of specific pests, reducing their populations over
time [170]. Water management is crucial in disease prevention. Drip irrigation or soaker
hoses deliver water directly to plant roots, keeping foliage dry and reducing the risk of
fungal infections. Proper drainage prevents waterlogging, which can lead to root rot
and other soil-borne diseases. Mulching helps retain soil moisture, suppress weeds, and
create a barrier against soil-splash pathogens [171]. Nutrient management plays a dual
role in pest and disease control. Well-nourished plants are more resistant to pests and
diseases. However, overfertilization, especially with nitrogen, can make plants more attractive to certain pests and more susceptible to fungal infections. Balanced fertilization
based on soil tests and plant requirements is essential [172].
When chemical interventions are necessary, selecting appropriate pesticides is crucial. For medicinal plants, products with short residual periods and low toxicity to nontarget organisms are preferred. Botanical pesticides derived from plants like neem or
pyrethrum offer effective control with reduced environmental impact [167]. Sulfur and
copper-based fungicides are often used in organic production systems to manage fungal
diseases. Timing and application methods of pesticides are critical to their effectiveness
and safety. Spot treatments targeting affected areas can minimize overall pesticide use
[168]. Applying pesticides during periods of low bee activity helps protect pollinators.
Rotating pesticides with different modes of action prevents the development of resistance in pest populations. Disease-resistant varieties offer a long-term solution to recurring pathogen problems. While breeding programs for medicinal plants are less extensive than for major crops, selecting cultivars adapted to local conditions can
significantly reduce disease pressure. Some medicinal plants have natural resistance to
specific pathogens, which can be enhanced through selective breeding. Monitoring and
early detection are crucial components of effective pest and disease management. Regular scouting allows growers to identify problems before they become severe [170]. This
includes inspecting plants for signs of pest damage or disease symptoms, as well as
using traps and other monitoring tools to track pest populations. Early intervention
often allows for the use of less intensive control measures. Climate control in a greenhouse or indoor cultivation can significantly impact pest and disease pressure. Maintaining optimal temperature and humidity levels reduces plant stress and creates an
environment less favorable to many pests and pathogens. UV sterilization of irrigation
Chapter 3 Challenges encountered in growing medicinal and aromatic plants 141
water and air filtration systems can further reduce the risk of disease introduction and
spread. Postharvest handling is an often overlooked aspect of pest and disease management in medicinal plants. Proper drying and storage conditions prevent the growth of
molds and other microorganisms that can contaminate the final product [172]. Implementing good manufacturing practices (GMPs) throughout the processing chain ensures
the quality and safety of medicinal plant products.
Research into plant-microbe interactions is opening new avenues for disease management in medicinal plants. Beneficial microorganisms, such as mycorrhizal fungi and
plant-growth-promoting rhizobacteria, can enhance plant resistance to pathogens and
improve overall plant health [173]. Inoculating growing media or applying these microorganisms as seed treatments shows promise in reducing disease incidence. The use of
plant extracts and essential oils for pest and disease control is an area of growing interest, particularly for medicinal plants where chemical residues are a concern. Many medicinal plants produce compounds with antimicrobial or insecticidal properties. Extracts from plants like garlic, cinnamon, or thyme have shown efficacy against various
pests and pathogens when applied as foliar sprays or soil drenches [174]. Precision agriculture techniques are increasingly being applied to medicinal plant cultivation. Dronebased imaging and sensors can detect early signs of pest infestation or disease outbreaks, allowing for targeted interventions. This technology can also optimize resource
use, reducing plant stress and improving overall crop health [175].
Environmental manipulation can create conditions unfavorable to pests and diseases. For example, some pathogens are sensitive to soil pH. Adjusting soil acidity
through liming or the application of organic amendments can suppress certain soilborne diseases. Similarly, altering light spectra in greenhouse environments can influence pest behavior and plant defense responses [176]. Quarantine measures are essential in preventing the introduction of new pests and diseases, especially when sourcing
plant material from different regions. Implementing strict protocols for incoming
plants, including isolation periods and thorough inspections, can safeguard existing
crops from exotic threats. Education and training of growers and workers are crucial
for the successful implementation of integrated pest and disease management strategies
[173]. This includes recognizing early symptoms of pest damage or disease, understanding pest life cycles, and proper application of control measures. Ongoing research and
extension services play a vital role in disseminating new knowledge and techniques to
medicinal plant growers. In conclusion, effective pest and disease management in medicinal plant cultivation requires a holistic approach that integrates various strategies
tailored to specific crops and local conditions. By combining cultural practices, biological control, judicious use of pesticides, and emerging technologies, growers can maintain plant health and product quality, while minimizing environmental impact [175].
Continuous monitoring, adaptation of strategies, and ongoing research are key to addressing the evolving challenges of pest and disease management in this important agricultural sector.
142 Fatemeh Ahmadi, Maximilian Lackner, and August Starzinger
3.14 Conclusion and future perspective
Growing MAPs presents a multitude of challenges that span various aspects of cultivation, processing, and market dynamics [114]. These challenges require careful consideration and innovative solutions to ensure sustainable production and high-quality yields
[172]. One of the primary challenges in cultivating MAPs is the maintenance of optimal
growing conditions. These plants often have specific requirements for soil composition,
pH levels, temperature, and humidity. Achieving and maintaining these conditions can
be particularly difficult in outdoor settings where environmental factors are less controllable [176]. Climate change further complicates this issue, as shifting weather patterns and extreme events can disrupt established growing practices and necessitate
adaptive strategies. Pest and disease management pose significant challenges in MAP
cultivation. Many of these plants are susceptible to a range of pathogens and insect infestations that can severely impact crop yield and quality [170].
The use of chemical pesticides is often restricted due to concerns about residues in
the final product, especially for plants intended for medicinal use [162]. This necessitates
the development and implementation of integrated pest management strategies that rely
on biological controls and cultural practices, which can be more labor-intensive and require specialized knowledge [168]. Water management is another critical challenge, particularly in regions facing water scarcity or unpredictable rainfall patterns. Many MAPs
require precise irrigation schedules to optimize growth and the production of active compounds. Overwatering can lead to root rot and fungal diseases, while underwatering can
stress plants and reduce yields [152]. Implementing efficient irrigation systems and water
conservation techniques are essential but can be costly and technically demanding. Soil
fertility management presents its own set of challenges. MAPs often have specific nutrient
requirements that influence the production of desired compounds. Balancing soil nutrients without overfertilization is crucial, as excessive use of chemical fertilizers can lead
to environmental pollution and may affect the quality of the plant material [171].
Organic and sustainable fertilization practices are increasingly important but require careful planning and execution [175]. Harvesting and postharvest handling are
critical stages that significantly impact the final quality of MAPs. Timing the harvest to
coincide with peak levels of active compounds requires precision and often specialized
equipment. Postharvest processing, including drying and storage, must be carried out
under controlled conditions to preserve the plant’s medicinal properties and prevent
contamination. Inadequate facilities or improper handling can lead to significant losses
in both the quantity and quality of the harvested material [172]. Genetic diversity and
varietal improvement pose ongoing challenges in the sector. Many MAPs have not undergone extensive breeding programs compared to major food crops. This limits the
availability of high-yielding, disease-resistant varieties adapted to different growing
conditions [174]. Developing new cultivars that maintain or enhance the desired medicinal properties, while improving agronomic traits, is a long-term process that requires
significant investment in research and development. Regulatory compliance and quality