Can plants absorb organic compounds?

Can plants absorb organic compounds?

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Plants are autotrophs, meaning that they grow by building organic matter out of inorganic compounds (and energy).

Is it then also true that plants are generally not capable of absorbing organic compounds? There are certainly some plants that can do it, e.g. carnivorous plants absorbing amino acids of their (dissolved) prey. But what about, say, the common sunflower on my balcony?

Yes plants can absorb organic compounds… For example plants can absorb citric acid

Due to citric acid's ability to chelate metals and be absorbed by plants, it is hypothe-sized that exposure to it will increase the ability of wheat-grass to absorb macro- and micro-nutrients, as well as heavy metals, from soil.

Citric acid chelates absorption

Also plants have the ability to absorb and release sugars.

Plant roots are able to absorb sugars from the rhizosphere but also release sugars and other metabolites that are critical for growth and environmental signaling. Reabsorption of released sugar molecules could help reduce the loss of photosynthetically fixed carbon through the roots

Monosacharid absorption activity

I'm sure there are other examples, feel free to edit the answer.

There are whole groups of plants that don't photosynthesize, but which derive their nutrients from other plants in various ways.

For instance, the common (hereabouts) Snow Plant gets nutrition from soil fungi (mycorhizzae) which in turn get it from conifers.

There are a great many other parasitic plants, which derive some or all of their nutrients from other plants, or from soil fungi. See e.g.

Then there's the whole subject of mutualistic relationships between plants and mycorrhizae fungi:

Plant physiology

Plant physiology is a subdiscipline of botany concerned with the functioning, or physiology, of plants. [1] Closely related fields include plant morphology (structure of plants), plant ecology (interactions with the environment), phytochemistry (biochemistry of plants), cell biology, genetics, biophysics and molecular biology.


As already explained, the nutrients obtained by most green plants are small inorganic molecules that can move with relative ease across cell membranes. Heterotrophic organisms such as bacteria and fungi, which require organic nutrients yet lack adaptations for ingesting bulk food, also rely on direct absorption of small nutrient molecules. Molecules of carbohydrates, proteins, or lipids, however, are too large and complex to move easily across cell membranes. Bacteria and fungi circumvent this by secreting digestive enzymes onto the food material these enzymes catalyze the splitting of the large molecules into smaller units that are then absorbed into the cells. In other words, the bacteria and fungi perform extracellular digestion—digestion outside cells—before ingesting the food. This is often referred to as osmotrophic nutrition.

Like bacteria, protozoans are unicellular organisms, but their method of feeding is quite different. They ingest relatively large particles of food and carry out intracellular digestion (digestion inside cells) through a method of feeding called phagotrophic nutrition. Many protozoans also are osmotrophic to a lesser degree. Some organisms, such as amoebas, have pseudopodia (“false feet”) that flow around the food particle until it is completely enclosed in a membrane-bounded chamber called a food vacuole this process is called phagocytosis. Other protozoans, such as paramecia, pinch off food vacuoles from the end of a prominent oral groove into which food particles are drawn by the beating of numerous small hairlike projections called cilia. In still other cases of phagotrophic nutrition, tiny particles of food adhere to the membranous surface of the cell, which then folds inward and is pinched off as a vacuole this process is called pinocytosis. The food particles contained in vacuoles formed through phagocytosis or pinocytosis have not entered the cell in the fullest sense until they have been digested into molecules able to cross the membrane of the vacuole and become incorporated into the cellular substance. This is accomplished by enzyme-containing organelles called lysosomes, which fuse with the vacuoles and convert food into simpler compounds (see figure ).

Most multicellular animals possess some sort of digestive cavity—a chamber opening to the exterior via a mouth—in which digestion takes place. The higher animals, including the vertebrates, have more elaborate digestive tracts, or alimentary canals, through which food passes. In all of these systems large particles of food are broken down to units of more manageable size within the cavity before being taken into cells and reassembled (or assimilated) as cellular substance.

Some indoor plants may be bad for your health

Houseplants are not only aesthetically pleasing giving a touch of color to otherwise drab offices or houses, they also combat indoor air pollution, particularly with their ability to remove volatile organic compounds (VOCs) from the air. These compounds are gases or vapors emitted by solids and liquids that may have adverse short- and long-term health effects on humans. But in addition to giving off oxygen and sucking out harmful VOCs, a new study has shown that some indoor plants actually release VOCs into the environment.

A research team at the University of Georgia’s Department of Horticulture conducted a study to identify and measure the amounts of VOCs emitted by four species of popular indoor potted plants and to note the source of VOCs and differences in emission rates between day and night. The four plants they chose were Peace Lily (Spathiphyllum wallisii Regel), Snake Plant (Sansevieria trifasciata Prain), Weeping Fig (Ficus benjamina L.), and Areca Palm (Chrysalidocarpus lutescens Wendl.).

Samples of each plant were placed in glass containers with inlet ports connected to charcoal filters to supply purified air and outlet ports connected to traps where volatile emissions were measured. The results were compared to empty containers to verify the absence of contaminants. A total of 23 volatile compounds were found in Peace Lily, 16 in Areca Palm, 13 in Weeping Fig, and 12 in Snake Plant. Some of the VOCs are ingredients in pesticides applied to several species during the production phase.

And it turns out the plants themselves aren’t the only ones responsible for the release of VOCs. Micro-organisms living in the soil were also to blame for releasing volatiles into the atmosphere along with the plastic pots containing the plants, which were the source of 11 of the VOCs – several of which are known to negatively affect humans.

The study also found that VOC emission rates were higher during the day than at night in all of the species, and all classes of emissions were higher in the day than in the night. This was expected as the rate of release is determined by the presence of light along with many other factors that affect synthesis.

The study concluded that, although ornamental plants are known to remove certain VOCs, they also emit a variety of VOCs, some of which are known to be harmful to humans and animals. However the researchers did go on to say that the longevity of these compounds hasn’t been adequately studied, so their impact on humans is unknown.

That plant sitting in the corner isn’t looking quite so attractive now, is it? But before you relegate any plants to the garbage consider this. If the plastic pots were found to be the source of 11 VOCs, you’ve got to thankful the plants at least remove some VOCs as well as emitting them – the same can’t be said for the mass of plastic that probably surrounds you right now. Maybe give that plant some water instead.

The study, Volatile Organic Compounds Emanating from Indoor Ornamental Plants, appears in the American Society for Horticultural Science journal HortScience.

165 Nutritional Requirements of Plants

By the end of this section, you will be able to do the following:

  • Describe how plants obtain nutrients
  • List the elements and compounds required for proper plant nutrition
  • Describe an essential nutrient

Plants are unique organisms that can absorb nutrients and water through their root system, as well as carbon dioxide from the atmosphere. Soil quality and climate are the major determinants of plant distribution and growth. The combination of soil nutrients, water, and carbon dioxide, along with sunlight, allows plants to grow.

The Chemical Composition of Plants

Since plants require nutrients in the form of elements such as carbon and potassium, it is important to understand the chemical composition of plants. The majority of volume in a plant cell is water it typically comprises 80 to 90 percent of the plant’s total weight. Soil is the water source for land plants, and can be an abundant source of water, even if it appears dry. Plant roots absorb water from the soil through root hairs and transport it up to the leaves through the xylem. As water vapor is lost from the leaves, the process of transpiration and the polarity of water molecules (which enables them to form hydrogen bonds) draws more water from the roots up through the plant to the leaves ((Figure)). Plants need water to support cell structure, for metabolic functions, to carry nutrients, and for photosynthesis.

Plant cells need essential substances, collectively called nutrients, to sustain life. Plant nutrients may be composed of either organic or inorganic compounds. An organic compound is a chemical compound that contains carbon, such as carbon dioxide obtained from the atmosphere. Carbon that was obtained from atmospheric CO2 composes the majority of the dry mass within most plants. An inorganic compound does not contain carbon and is not part of, or produced by, a living organism. Inorganic substances, which form the majority of the soil solution, are commonly called minerals: those required by plants include nitrogen (N) and potassium (K) for structure and regulation.

Essential Nutrients

Plants require only light, water, and about 20 elements to support all their biochemical needs: these 20 elements are called essential nutrients ((Figure)). For an element to be regarded as essential , three criteria are required: 1) a plant cannot complete its life cycle without the element 2) no other element can perform the function of the element and 3) the element is directly involved in plant nutrition.

Essential Elements for Plant Growth
Macronutrients Micronutrients
Carbon (C) Iron (Fe)
Hydrogen (H) Manganese (Mn)
Oxygen (O) Boron (B)
Nitrogen (N) Molybdenum (Mo)
Phosphorus (P) Copper (Cu)
Potassium (K) Zinc (Zn)
Calcium (Ca) Chlorine (Cl)
Magnesium (Mg) Nickel (Ni)
Sulfur (S) Cobalt (Co)
Sodium (Na)
Silicon (Si)

Macronutrients and Micronutrients

The essential elements can be divided into two groups: macronutrients and micronutrients. Nutrients that plants require in larger amounts are called macronutrients . About half of the essential elements are considered macronutrients: carbon, hydrogen, oxygen, nitrogen, phosphorus, potassium, calcium, magnesium and sulfur. The first of these macronutrients, carbon (C), is required to form carbohydrates, proteins, nucleic acids, and many other compounds it is therefore present in all macromolecules. On average, the dry weight (excluding water) of a cell is 50 percent carbon. As shown in (Figure), carbon is a key part of plant biomolecules.

The next most abundant element in plant cells is nitrogen (N) it is part of proteins and nucleic acids. Nitrogen is also used in the synthesis of some vitamins. Hydrogen and oxygen are macronutrients that are part of many organic compounds, and also form water. Oxygen is necessary for cellular respiration plants use oxygen to store energy in the form of ATP. Phosphorus (P), another macromolecule, is necessary to synthesize nucleic acids and phospholipids. As part of ATP, phosphorus enables food energy to be converted into chemical energy through oxidative phosphorylation. Likewise, light energy is converted into chemical energy during photophosphorylation in photosynthesis, and into chemical energy to be extracted during respiration. Sulfur is part of certain amino acids, such as cysteine and methionine, and is present in several coenzymes. Sulfur also plays a role in photosynthesis as part of the electron transport chain, where hydrogen gradients play a key role in the conversion of light energy into ATP. Potassium (K) is important because of its role in regulating stomatal opening and closing. As the openings for gas exchange, stomata help maintain a healthy water balance a potassium ion pump supports this process.

Magnesium (Mg) and calcium (Ca) are also important macronutrients. The role of calcium is twofold: to regulate nutrient transport, and to support many enzyme functions. Magnesium is important to the photosynthetic process. These minerals, along with the micronutrients, which are described below, also contribute to the plant’s ionic balance.

In addition to macronutrients, organisms require various elements in small amounts. These micronutrients , or trace elements, are present in very small quantities. They include boron (B), chlorine (Cl), manganese (Mn), iron (Fe), zinc (Zn), copper (Cu), molybdenum (Mo), nickel (Ni), silicon (Si), and sodium (Na).

Deficiencies in any of these nutrients—particularly the macronutrients—can adversely affect plant growth ((Figure)). Depending on the specific nutrient, a lack can cause stunted growth, slow growth, or chlorosis (yellowing of the leaves). Extreme deficiencies may result in leaves showing signs of cell death.

Visit this website to participate in an interactive experiment on plant nutrient deficiencies. You can adjust the amounts of N, P, K, Ca, Mg, and Fe that plants receive . . . and see what happens.

Hydroponics Hydroponics is a method of growing plants in a water-nutrient solution instead of soil. Since its advent, hydroponics has developed into a growing process that researchers often use. Scientists who are interested in studying plant nutrient deficiencies can use hydroponics to study the effects of different nutrient combinations under strictly controlled conditions. Hydroponics has also developed as a way to grow flowers, vegetables, and other crops in greenhouse environments. You might find hydroponically grown produce at your local grocery store. Today, many lettuces and tomatoes in your market have been hydroponically grown.

Section Summary

Plants can absorb inorganic nutrients and water through their root system, and carbon dioxide from the environment. The combination of organic compounds, along with water, carbon dioxide, and sunlight, produce the energy that allows plants to grow. Inorganic compounds form the majority of the soil solution. Plants access water though the soil. Water is absorbed by the plant root, transports nutrients throughout the plant, and maintains the structure of the plant. Essential elements are indispensable elements for plant growth. They are divided into macronutrients and micronutrients. The macronutrients plants require are carbon, nitrogen, hydrogen, oxygen, phosphorus, potassium, calcium, magnesium, and sulfur. Important micronutrients include iron, manganese, boron, molybdenum, copper, zinc, chlorine, nickel, cobalt, silicon, and sodium.

Review Questions

For an element to be regarded as essential, all of the following criteria must be met, except:

  1. No other element can perform the function.
  2. The element is directly involved in plant nutrition.
  3. The element is inorganic.
  4. The plant cannot complete its lifecycle without the element.

The nutrient that is part of carbohydrates, proteins, and nucleic acids, and that forms biomolecules, is ________.

Most ________ are necessary for enzyme function.

What is the main water source for land plants?

Critical Thinking Questions

What type of plant problems result from nitrogen and calcium deficiencies?

Deficiencies in these nutrients could result in stunted growth, slow growth, and chlorosis.

Research the life of Jan Babtista van Helmont. What did the van Helmont experiment show?

van Helmont showed that plants do not consume soil, which is correct. He also thought that plant growth and increased weight resulted from the intake of water, a conclusion that has since been disproven.

List two essential macronutrients and two essential micro nutrients.

Answers may vary. Essential macronutrients include carbon, hydrogen, oxygen, nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur. Essential micronutrients include iron, manganese, boron, molybdenum, copper, zinc, chlorine, nickel, cobalt, sodium, and silicon.


Synthetic Vs Organic

Plant nutrients are inorganic elements such as zinc or magnesium that are absorbed by plant roots in order to fuel growth and development. Most of the nutrients required for plant growth are already present in traditional soil, although not always in the required volume or form. In contrast, given the use of inert media, hydroponic farming requires that all nutrient application and management come from external sources. Regardless of cultivation media, most cultivators will apply some additional level of nutrition to ensure optimal plant outcomes. For the purpose of this paper, nutritional inputs will be classified as fertilizers. Finding the proper source for nutritional inputs, and whether they qualify as “organic” or “inorganic / synthetic”, is currently a subject hotly debated in the cannabis community. Our purpose here is to provide explanations and education to ensure this debate leads to informed decision making across cultivators and their end-consumers.


There are 17 essential minerals required by plants to grow three of those are supplied through air and water (carbon, hydrogen and oxygen). The other 14 must either be available in the soil or water or added as a supplement. There are also several nutrients that are considered nonessential, meaning plants will grow without deficiencies if these elements are not present, but they are considered beneficial to enhanced plant growth.

Table 1. Plant Nutrients

Chemical Nutrients From Air & Water
Primary Macronutrients Secondary Macronutrients Micronutrients Non-Essential Nutrients
Carbon (C) Nitrogen (N) Calcium (C) Boron (B) Aluminum (Al)
Chlorine (Cl)
Hydrogen (H) Potassium (K) Magnesium (Mg) Copper (Cu) Cobalt (Co)
Iron (Fe)
Manganese (Mn) Selenium (Se)
Oxygen (O) Phosphorus (P) Sulfur (S) Molybdenum (Mo) Silicon (Si)
Nickel (Ni)
Zinc (Zn) Sodium (Na)

NITROGEN: Nitrogen (N) is the most important nutrient in the plant growth cycle. It is an essential element in chlorophyll, the green molecule that plays a major role in photosynthesis. All N in fertilizers originates from atmospheric N gas, or N2 . This can be converted into ammonia in fertilizer factories, and is also converted to ammonium by microorganisms in the soil. Many animal-based nitrogen sources, such as guano, are not water soluble and require further microbial breakdown to provide available N to the plant. Plants use N in the form of nitrate or ammonium.

PHOSPHORUS: Phosphorus (P) is the fuel source for the plant’s metabolism and vital for photosynthesis. The phosphate in fertilizers is either fully water soluble or partly water soluble and partly citrate soluble, both of which are considered plant available. Citrate-soluble P dissolves slowly and is relatively more effective in acidic soils. The concentration of P (usually indicated as percent P2 O5 ) refers either to the available or the total portion of phosphate. Phosphate rock (PR) is a naturally occurring source of P, which can then be processed with acid to yield superphosphate, a highly available and soluble source of P commonly used in manufactured fertilizers. PR can be used directly as a fertilizer, but only provides about half the available P as the superphosphates. Diluted phosphoric acid is also a common P source for use in hydroponics.

POTASSIUM: Potassium (K) is essential for photosynthesis and enzyme reactions. Potash, a.k.a. potassium, fertilizers are predominantly water-soluble salts. Raw K salts can be found in seawater (or left behind as seawater evaporates) as a major component of rock salt formations in ocean basins. Raw potassium salts are combined with a variety of other salts by various methods of heating, cooling, and chemical reactions with acids to produce fertilizers.

CALCIUM: Calcium (Ca) is a major component of plant cell walls and assists with transporting other plant-essential minerals. There is no shortage of raw materials for Ca fertilizers as whole mountains consist of naturally occurring calcium carbonate (CaCO3 ). Ca is also found in gypsum either as a mineral or as a by-product of wet-process phosphoric acid production. Calcium nitrate is a synthetic compound that provides a good source of nitrate N and water-soluble Ca and is especially useful for fertilizing horticultural crops.

MAGNESIUM: Magnesium (Mg) is part of the chlorophyll molecule and is also important for key plant enzyme functions. Natural reserves of Mg are very large, both in salt deposits and in mountains consisting of dolomitic limestone. Mg fertilizers are grouped by water soluble and water insoluble classifications. Among the soluble fertilizers are magnesium sulfates and magnesium chelates. Among the insoluble or partially water-soluble sources are magnesium oxide, magnesium carbonate and magnesium silicate. The insoluble or partially soluble materials are frequently used as liming materials for soil pH correction rather than as fertilizers.

Table 2. Micronutrient Function in Plants

Element Function in Plant
B Important in sugar transport, cell division, and amino acid production
Cl Used in turgor regulation, resisting diseases and photosynthesis reactions
Cu Component of enzymes, involved in photosynthesis
Fe Component of enzymes, essential for chlorophyll synthesis, photosynthesis
Mo Involved in nitrogen metabolism, essential in nitrogen fixation by legumes
Mn Chloroplast production, cofactor in many plant reactions, activates enzymes
Zn Component of many enzymes, essential for plant hormone balance and auxin activity

SULFUR: Sulfur (S) is an important part of protein synthesis, enzyme development and compounds involved in cold tolerance. Most S-containing fertilizers are in fact sulfate salts of compounds that also contain other major nutrients or micronutrients, such as magnesium sulfate or copper sulfate. The only truly single-nutrient S fertilizers are elemental S products. Pure elemental S has to first be oxidized to sulfate in the soil by bacteria before it can be absorbed by plant roots.

TRACE ELEMENTS: Trace elements, or micronutrients, play vital roles in plant metabolism and photosynthesis. In hydroponic media, multiple micronutrient fertilizers are required. In traditional soil farming, slow-release micronutrient fertilizers that can provide a continuous supply without toxicities are required. Such fertilizers, with several or all micronutrients, are generally partly water soluble and have slow-acting components. Many of the naturally occurring and minimally refined micronutrient sources rely on oxidation by soil bacteria to convert into plant-available, ionic forms.


In order to understand the difference between organic and inorganic (“synthetic” in industry-terms) plant nutrition inputs, it is important to first understand that plants can only absorb nutrients in their ionic form. Ions are elements found on the periodic table that carry either a negative or positive charge depending on the total electrons hanging on to it. A negatively charged ion is called an anion, and a positively charged ion is called a cation. Due to the laws of attraction, anions and cations are attracted to each other when they are together, which leads them to form ionic compounds.


Ionic compounds made from mineral nutrients are commonly used in synthetic fertilizer blends as a readily available source of food for plants. These are often referred to as mineral salts, not to be confused with table salt, or sodium chloride. Salts, by their chemical definition, are “any chemical compound formed from the reaction of an acid with a base, with all or part of the hydrogen of the acid replaced by a metal or other cation.”

Mineral salts dissociate, or break apart, in water to reveal their ionic nutrients. Calcium nitrate and potassium phosphate are some of the ionic compounds you may recognize as plant nutrients. Plant roots then absorb the dissociated mineral salts as ions. Organic fertilizers can be broken down by soil organisms over time to reveal their ionic, plant-available elements. Plants do not know the difference between organic and inorganic inputs, as they only use nutrients that are available in their inorganic, ionic form. Plants use these inorganic nutrients to make necessary metabolites, such as amino acids, simple sugars and other organic compounds.


Organic fertilizers rely on the mineralization process to release their plant-available source of nutrients. Soil has a complex and elaborate ecology consisting of bacteria, fungi, protozoa and insects. These organisms use the larger organic compounds found naturally in soil and organic amendments as a source of food. When these organisms “eat” the organic material, the breakdown of the material releases ions that plants can use as food (hence “mineralization”). Plant roots will then take up these minerals as needed, or as they become available. The length of time required for full mineralization varies based on the soil environment, microbial species found in the soil and the specific mineral compounds contained in the fertilizer full nutrient availability may take years after application. Balancing soil amendment applications based on soil analysis test results, combined with sustainable farming practices such as low till and cover cropping, can provide longterm, adequate soil fertility.


In the world of indoor and greenhouse growing, the efficiency of soil organisms to feed plants cannot be relied upon. The time it takes for organic compounds to break down and provide plantavailable nutrition is not often available to soilless farmers.

Soilless substrates contain very little, if any, of the plant-essential nutrients. Therefore, these substrates require complete fertilizers that provide the full spectrum of macro and micronutrients, preferably in a water-soluble form. The correct balance of nutrients must be added in the early vegetative growth stage in order to prevent deficiencies from limiting growth and yields.


The simple definition of organic is “consisting of or derived from living matter.” According to the National Organic Program (NOP), “organic is a labeling term for food or other agricultural products that have been produced using cultural, biological, and mechanical practices that support the cycling of on-farm resources, promote ecological balance, and conserve biodiversity in accordance with the USDA organic regulations. This means that organic operations must maintain or enhance soil and water quality, while also conserving wetlands, woodlands, and wildlife.” Soil organic matter refers to all parts that are of biological origin including decomposing plant material and animal wastes, soil microorganisms and the substances synthesized by the soil microbiome. Organic matter contributes to pools of plant available nutrients through gradual breakdown of materials. If relying entirely on organic matter in soil for nutrients, plants may not receive enough nutrition to provide optimal yields and quality. This is where soil amendments, or fertilizers, play an important role.

Raw materials for organic fertilizers are generally sourced from animal manures, animal by-products, rural and urban human waste, compost and crop residues. Animal by-products include fresh or composted manure, worm castings, bat guano, bone meal, feather meal and fish meal. Plantderived amendments include kelp meal, alfalfa meal and soybean meal. Town/urban compost is made from industrial waste, city garbage, sewage sludge, etc. Rural compost is made from straw, leaves, livestock bedding and manure, animal rendering material, plant waste material, etc.

Table 3. Nutrient Content of Manure and Composts
Average nutrient content of bulky organic manures and composts

Type of manure N (%) P2 O5 (%) K2O (%)
Cattle dung 0.3 0.10 0.15
Sheep/goat dung 0.65 0.5 0.03
Human excreta 1.2-1.5 0.8 0.5
Hair and wool waste 12.3 0.1 0.3
Farmyard manure 0.5 0.15 0.5
Poultry manure 2.87 2.90 2.35
Town/urban compost 1.5 1.0 1.5
Rural compost 0.5 0.2 0.5

Livestock manures contain N, P and K, but only a fraction of the total nutrient content is plantavailable. A variety of synthetic substances including inorganic, mineral fertilizers are also approved for use in organic production when they are not available as a naturally-occurring substance. Mined minerals include gypsum, humates, rock phosphate and potassium sulfate. Acceptable synthetic, or manufactured, materials include vitamins and certain micronutrients.


The definition of inorganic is the opposite of organic: “not consisting of or derived from living matter.” Inorganic, synthetic or mineral are collective terms used to describe fertilizer that is not derived from living or biological matter. Minerals can still be considered a natural input, while synthetic fertilizers contain minerals that are modified during manufacturing to produce a finished, more effective product. These modifications are essential to create a product that has greater solubility, stability, and plant-uptake efficiency.

The use of inorganic fertilizers has advantages in the cannabis industry depending on the management and cultivation style used. Indoor and greenhouse space, when growing in containers, will benefit greatly from the use of mineral-based fertilizers due to the high level of nutrient availability from this type of fertilization. Fast-growing annuals require rapid nutrition, and the ionic form of elements provided by mineral nutrients delivers exactly that.

The source of raw materials can make a difference, especially when growing cannabis. We know that cannabis is an accumulator of heavy metals, which means that it can absorb and retain toxins from its growing environment at much higher levels than other plant species. Cheap, industrial grade minerals may be contaminated with high levels of toxic heavy metals, such as cadmium or mercury. Further processing to a higher-quality grade, such as pharmaceutical grade, will greatly reduce or eliminate (depending on the process) the levels of these contaminants, ensuring safe end-consumer use.


Traditional organic inputs, typically supplied as raw minerals, compost and manures, can be difficult to rely on and may not supply adequate plant nutrition. The nutrient availability of organic sources is widely varied, and only provides minimal availability in the first year of application. Compost and manures yield as little as 3% of the available N in the first yeari . That said, excessive inorganic fertilizer application may be harmful to the diversity of soil organisms and overall soil structure. Combining resource inputs can potentially produce optimal results, especially if growing outdoors in soil. The soil fertility enhancement offered by organic inputs, such as compost or manures, coupled with the precise nutrient delivery of inorganic components, can provide the best long-term results.

The Journal of Agronomy published research findings that soils treated with inorganic fertilizers vs. organic fertilizers still had higher levels of organic carbon, N, P, K, bacteria and fungi than soils that were untreatedii. In fact, the nutrient levels were higher than in the organic plots, and the biological organisms were higher than the untreated plots. This implies that, in contrast to popular belief, inorganic fertilizers do not kill organisms, and in fact offer an additional food source for soil biology and further contribute to soil fertility.

The addition of mineral fertilizers to compost and even to manures can increase the effect of these amendments on organic C and N content in soil and soil enzyme activityiii. Complete nutrient fertilizer applications may take care of existing nutrient deficiencies when applied at the correct time in the plant’s life cycle. In the absence of having the ability to test soil every week for nutrient status, applying inorganic fertilizers throughout the crop cycle is a reasonable alternative to assure optimal yield and quality.

Organic materials can greatly increase soil fertility and improve soil ecology, while inorganic amendments provide a readily available source of nutrition for plants. Combining nutrient sources can often provide optimal outcomes for both crop yields and soil ecologyiv.

Plants in a recirculating hydroponic, soilless or container garden will see the most benefit from using mineral nutrients, as it is difficult to maintain positive microbial life in these environments. If plants require only one or a few elements right away, a synthetic fertilizer will provide it quickly. If you are using a fertigation or automated irrigation system, water-soluble nutrients are mandatory.

Growing outdoors in field soil will see the most benefit from using organic nutrients. This is where the microbes are at their best, working with organic compounds from soil amendments and insoluble minerals naturally occurring in the soil. The nutrients can break down slowly and feed the plant as it needs it. Inorganic amendments can provide additional nutrition, and when applied conservatively, will not harm soil organisms and should correct any potential nutrient deficiencies.

Table 4. Comparison of Inputs
Chemical Fertilizer vs Organic Fertilizer Comparison Chart

Chemical Fertilizer Organic Fertilizer
Example Ammonium sulfate, super phosphates, ammonium nitrate, urea, ammonium chloride, etc. Cottonseed meal, blood meal, fish emulsion, manure and sewage sludge, etc.
Advantages Chemical fertilizers contain the three primary macronutrients that provide an immediate supply of nutrients may also contain secondary macronutrients and trace minerals. Adds natural nutrients to soil, increases soil organic matter, improves soil structure, improves water holding capacity, reduces soil crusting problems, provides slow release of nutrients
Disadvantages Several chemical fertilizers have high acid content. They have the ability to burn the skin. Changes soil fertility. Have slow release capability distribution of nutrients in organic fertilizers is not equal
Rate of Production Immediate supply or slow release. Slow release only
About Chemical fertilizers are manufactured from synthetic or inorganic material. Organic fertilizers are made from materials derived from living things or inorganic minerals.
Nutrients Have equal distribution of three essential nutrients: phosphorus, nitrogen, potassium. Have unequal distribution of essential nutrients.
Cost Chemical fertilizers turn out to be cheaper because they pack more nutrients per pound of weight. Organic fertilizer may be cheaper per pound but works out to be more expensive over all because more of it is needed for the same level of nutrients.


Roy, R. N. (2007). Plant nutrition for food security: A guide for integrated nutrient management. New Delhi: Discovery Publishing House.
Lowenfels, J., & Lewis, W. (2016). Teaming with microbes: The organic gardeners guide to the soil food web. Portland, Or.: Timber Press.

i Ozores-Hampton, M. (2012). Developing a Vegetable Fertility Program Using Organic Amendments and Inorganic Fertilizers. HortTechnology,22(6), 743-750.
ii Nakhro, N., & Dkhar, M. (2010). Impact of Organic and Inorganic Fertilizers on Microbial Populations and Biomass Carbon in Paddy Field Soil. Journal of Agronomy, 9(3), 102-110.
iii Šimon, T., & Czakó, A. (2018). Influence of long-term application of organic and inorganic fertilizers on soil properties. Plant, Soil and Environment, 60(No. 7), 314-319.
iv Ozores-Hampton, M. (2012). Developing a Vegetable Fertility Program Using Organic Amendments and Inorganic Fertilizers. HortTechnology,22(6), 743-750.


Chlorophyll’s name is derived from ancient Greek: chloros = green and phyllon = leaf. Chlorophyll is the pigment that gives plants their green color, and is an essential component of photosynthesis


Chlorophyll was first isolated and named by Joseph Bienaimé and Pierre Joseph Pelletier in 1817.In 1883 German physiologist Julius Van Sachs showed that chlorophyll is not scattered all around in plant cell but it is found in special structures called chloroplast. He proved that chlorophyll involved in photosynthesis. The presence of magnesium in chlorophyll was discovered in 1906.

The general structure of chlorophyll a was elucidated by Hans Fischer in 1940. In 1960, when most of the stereo-chemistry of chlorophyll a was known, Robert Burns Woodward published a total synthesis of the molecule. In 1967, the last remaining stereo chemical elucidation was completed by Ian Fleming, and in 1990 Woodward and co-authors published an updated synthesis.

Chlorophyll f (C55H70O6N4Mg) was announced to be present in cyanobacteria and other oxygenic microorganisms that form stromatolites in 2010.


There are five types of chlorophylls occur in plants other than bacteria— a, b, c, d and e. Out of these only two chlorophylls occur in the chloro­plasts of higher plants, a and b. The amount of chlorophyll b is roughly one fourth of total chloro­phyll content.

Chlorophyll a is found in all photo­synthetic plants except bacteria. Hence, it is termed as universal photosynthetic pigment.Bacteria possess two types of related pigments— bacteriochlorophyll (further of several sub types) and bacterioviridin (= chlorobium chlorophyll).

Properties of chlorophyll-

  • Chlorophylls are fat soluble green pigments.
  • These are chlorines which absorb blue region and reflect green light.
  • They are responsible for the green colour of algae and other higher plants.
  • chlorophyll is one of the best antioxidants.

Chemical Structure:

Chemists have identified more than 1,000 different, naturally occurring chlorophylls. All chlorophylls are classified as metallotetrapyrroles. a tetrapyrrole is simply four pyrroles joined together. Chlorophyll has a tadpole like configuration with a head called porphyrin and a tail made up of long chain alcohol called phytol (Fig.1).

Porphyrin head is made up of four pyrrole rings which are linked by methine bridges(—CH=). The skeleton of each pyrrole ring is made up of 5 atoms— 4 carbon and one nitrogen. The latter lies towards the centre.Chlorophyll has molecular formula (C55H72O5N4Mg) Molar mass 893.51g/mol,Density = 1.079g/cm 2 , Melting point =152.3 o C.

A non ionic magnesium atom is held in the centre of porphyrin head by nitrogen atoms of pyrrole rings (through two covalent and two coordinate bonds).

The external carbon atoms of the pyrrole rings have been given specific numbers, 1-8. Carbon atoms 1, 3, 5 and 8 have methyl groups ( __ CH3). Carbon atom 2 possesses a vinyl group (—CH = CH2) while carbon atom 4 has an ethyl group (— CH2 — CH3). Carbon atom 6 is attached to next methine group by a fifth isocyclic ring called cyclopentanone.

Fig.1 . Chlorophyll Structure

Carbon atom 7 is connected to phytol tail through a propionic acid residue. Phytol is an insoluble long chain of carbon and hydrogen atoms with a formula of C20H39OH. It anchors the chlorophyll molecule into the lipid part of thylakoid membrane. Chlorophyll without its Mg-core is colourless and called phaeophytin. It is the early electron acceptor.


Fig. The diversity of chlorophyll pigments
Chlorophyll a Chlorophyll b Chlorophyll c1 Chlorophyll c2 Chlorophyll d Chlorophyll f
M. Formula C55H72O5N4Mg C55H70O6N4Mg C35H30O5N4Mg C35H28O5N4Mg C54H70O6N4Mg C55H70O6N4Mg
C2 group CH3 CH3 CH3 CH3 CH3 CHO
C7 group CH3 CHO CH3 CH3 CH3 CH3
C8 group CH2CH3 CH2CH3 CH2CH3 CH=CH2 CH2CH3 CH2CH3
C17 group CH2CH2COO−Phyty l CH2CH2COO−Phytyl CH=CHCOOH CH=CHCOOH CH2CH2COO−Phytyl CH2CH2COO−Phytyl
C17−C18 bond Single
Occurrence Universal Mostly plants Various algae Various algae Cyanobacteria Cyanobacteria
Molar Mass 833.51g/mol 907.49g/mol 895.462g/mol 907.4525g/mol
Appearance bluish-green Olive/Yellow green blue greenish blue greenish
M. Point 152.3 o C 125 o C

Chlorophyll a-

  • Chlorophyll-a is the primary pigment for photosynthesis in plants and occurs in all photosynthetic organisms except photosynthetic bacteria.
  • It is a specific form of chlorophyll, used in oxygenic photosynthesis, where it occurs in both reaction centres (RC) and in all light-harvesting complexes (LHC) , Because of its role as a primary electron donor in electron transport chain .
  • It absorbs most energy wavelengths of violet blue and orange red light.
  • Soluble in a number of organic solvents but it is more soluble in petroleum ether.
  • Chlorophyll a is also transfer resonance energy in the antenna complex ,ending in the reaction centres where specific chlorophylls p680 and p700 are located.
  • Chlorophyll a is bluish-green in the pure state. It has an empirical formula of C55H72O5N4Mg and molecular weight of 893.
  • Bacte­riochlorophyll a has an empirical formula of C55H74O6N4Mg and molecular weight of 911.

Chlorophyll b-

  • Chlorophyll b is olive green in the pure state with an empirical formula of C55H70O6N4Mg and molecular weight of
  • Chlorophyll b (Chl b) is distinguished from Chi a by a 7-formyl instead of the 7-methyl substitutent. Its structure has been established by chemical correlation with Chl a the stereochemistry and esterifying alcohol of both pigments are identical.
  • It is more soluble then chlorophyll a in organic solvents because of carbonyl group, but is more soluble in 92% methyl alcohol.
  • It absorbs blue light.
  • In land plants, the light harvesting antenna complex around photosystem II contain the majority 50% of chlorophyll b.
  • Hence, in shade adopted chloroplast which have an increased ratio of chl b then chl a. This is adaptive as increase in chl b increase in range the wavelength absorbed by the shade chloroplast.

[email protected] Chlorophyll a and b.

Chlorophyll c-

  • This form of chlorophyll found in certain algae.
  • It has blue greenish colour and is an accessory pigment.
  • It absorb light of 447-452 nm.
  • It is soluble in organic solvents.
  • Like chl a and chl b it help in absorbing light and passing a quanta of excitation through light harvesting antenna to photosynthetic reaction center.
  • It is devided into C1 C2 C………………C8.

Chlorophyll d-

  • It is a form of chlorophyll identified by Harlod strain and winsten in 1943.
  • It is present in marine algae and cyanobacteria which is used them for the capturing of sunlight for photosynthesis.
  • Chl d differs from Chl a by the presence of a 3-formyl group
  • It absorbs far-red light at 710nm wavelength.
  • It is soluble in organic solvents.
  • Its molar mass is 895.462 g/mol.

Chlorophyll e-

  • Its Molecular formula is: C54H70O6N4Mg
  • It is present in algae (xanthophyceae).
  • It is rare type of chlorophyll found in few algae like Tribonema,Vaucheria.

Chlorophyll f-

  • It is the type of chlorophyll which absorb further red(infrared light )then the other chlorophyll.
  • Its Molecular formula is: C55H70O6N4Mg
  • Its molar mass is 907.4725 g/mol.
  • In 2010 it has been reported from Stromatolites


Several investigators have unfolded some of the suggested steps are as follow:

(a) Succinyl COA, an intermediate of Krebs cycle combines with glycine amino acid to form δ- amino β- Ketoadipic acid as unstable compound. This loses CO2 to yield aminolevulinic acid. The presence of cofactors pyridoxal phosphate and iron are essential. The enzyme δ- aminolevulinic acid synthetasecatalyses it. As mentioned earlier, iron deficiency causes chlorosis of young leaves. Light is shown to mediate the condensation of these two compounds.

(b) In the next step two molecules of δ-aminolevulinic acid condense, and the process is mediated by the enzyme δ-aminolevulinic acid dehydrase, to form porphobilinogen. In this reaction there is a fusion of two molecules.

(c) Then 4 molecules of porphobilinogen condense to form uroporphyrinogen III. Four ammonium ions are lost in this reaction and the process is mediated by the enzyme uroporphyrinogen-Isynthetase and uroporphyrinogen III cosynthetase.

(d) The four acetic acid substitutes of uroporphyrinogen-III yield coproporphyrinogen-III and the reaction is catalyzed by uroporphyrinogen decarboxylase.

(e) Under aerobic conditions, coproporphyrinogen-III, in the presence of coproporphyrinogen oxidative decarboxylase gives rise to protoporphyrinogen IX.

(f) Protoporphyrinogen IX undergoes oxidation and thus protoporphyrin IX is formed. It takes magnesium to form Mg protoporphyrin IX. Mg protoporphyrin methyl esterase catalyzes the addition of a methyl group of Mg protoporphyrin IX. It may be mentioned that the methyl group is donated by S-adenosyl methionine.

(g) In the next step, Mg protoporphyrin IX mono-methylester is converted to protochlorophyllide.

(h) A phytol group is added to protochlorophyllide to produce protochlorophyll. Once it was believed that protochlorophyll is the immediate precursor of chlorophyll a. However, recent evidences suggest that the immediate precursor of chlorophyll a is chlorophyllide a. When the etiolated seedlings are subjected to light, protochlorophyllide is reduced to form chlorophyllide a. The light is essentially required for this conversion.

(i) In the final step esterification of a phytol group to chlorophyllide a occurs and so chlorophyll a is produced. Enzyme chlorophyllase is involved in the process.

In gymnosperms, some ferns, and many algae, chlorophyll can be synthesized in die dark solely through enzymatic activity. On the other hand, it is believed that chlorophyll b is formed from chlorophyll a. Some of the minerals like manganse, potassium, zinc, copper, magnesium, iron, and nitrogen are essential for the synthesis of chlorophyll.

When absent or deficient they cause chlorosis. Chlorophyll formation is also dependent upon genetic factors as well. Absence of the gene(s) essential for its formation in the genetic constitution, produces seedlings from the germinating seeds which lack chlorophyll.

Can plants absorb organic compounds? - Biology

VOC catabolism can enhance growth rates and increase tolerance to oxidative stress.

Uptake of VOCs from the atmosphere has implications for air quality.

The degradation of VOC signals can hinder plant defense and reproduction.

VOC catabolism and degradation are important pathways influencing plant survival.

Plants emit a diverse array of phytogenic volatile organic compounds (VOCs). The production and emission of VOCs has been an important area of research for decades. However, recent research has revealed the importance of VOC catabolism by plants and VOC degradation in the atmosphere for plant growth and survival. Specifically, VOC catabolism and degradation have implications for plant C balance, tolerance to environmental stress, plant signaling, and plant–atmosphere interactions. Here we review recent advances in our understanding of VOC catabolism and degradation, propose experiments for investigating VOC catabolism, and suggest ways to incorporate catabolism into VOC emission models. Improving our knowledge of VOC catabolism and degradation is crucial for understanding plant metabolism and predicting plant survival in polluted environments.

Plants can be engineered to help fight the effects of climate change

Good news for those despairing at our rapidly warming planet: we can supercharge plants to help fight the effects of climate change. Scientists have found two ways to make plants better at turning carbon dioxide into energy — and these techniques could help plants help us create better biofuels and produce more food to save the world.

Two studies published today in Science show different ways that beefing up the process by which plants create energy — called carbon fixation, or photosynthesis — could lead to a better future. In one, scientists decided that the entire process of carbon fixation was too slow and created a new, and faster, cycle. In the other, researchers engineered plants so they could absorb more sunlight. These enhanced plants grew up to 20 percent bigger, which is a big deal for food supply.

Plants are some of our best allies in the climate change fight. Global warming happens because of too much carbon dioxide in the atmosphere, and we add CO2 through activities like burning fossil fuels for energy. Because plants absorb carbon dioxide, they suck up some of the extra CO2 in the air and can even buy us extra time on global warming. But photosynthesis isn’t as efficient as it could be, so scientists are teaching plants how to do their jobs better to make our own lives easier. There may be other benefits besides locking down carbon: better plant growth means more food for a booming human population.

To make carbon fixation happen, organisms use molecules called enzymes. But the main enzyme doesn’t work very fast, says Tobias Erb, a synthetic biologist at the Max Planck Institute for Terrestrial Microbiology who is a co-author of one of the Science papers.

His team decided that they could design a way to make the process happen more quickly. They spent years figuring out which combination of enzymes would work together to get the job done. In the end, a combination of 17 enzymes fit the bill. These enzymes come from nine organisms (including e. coli bacteria and the human liver). Three of the enzymes were designed using a computer that’s how delicate the balance is. When these enzymes are combined together, they can turn carbon dioxide into organic compounds better than plants and other organisms currently do.

This work is in very early stages — that is, inside a tube, because it hasn’t been tested in actual living organisms. In theory, it should work on all organisms that do photosynthesis because the cycle is the same for all of them. But in practice, things can get tricky. Think of the process like a heart transplant, says Erb. When you transplant a heart, you first have to suppress the immune system so that the body doesn’t reject the new organ. To transplant this new pathway into plants, Erb’s team also has to tinker with all the other plant processes — such as its metabolism — to make sure everything still works. “This paper is really pushing the technical boundaries,” says Christine Raines, a biologist at the University of Essex. “You’re designing a completely new pathway, and the big question is whether it’ll hold up in living organisms, but this is an interesting proof of concept.”

Plants are very complex, so Erb’s team will first focus on bacteria and algae, which also undergo carbon fixation. “The idea is first to create organisms that can make any compound from carbon dioxide — like making biofuels more efficient or making chemical building blocks for pharmaceuticals,” says Erb.

Instead of creating a new photosynthetic process entirely, you could take a shortcut by making plants’ existing energy processes more efficient, says Krishna Niyogi, a UC Berkeley biologist also affiliated with the Howard Hughes Medical Center and the Lawrence Livermore National Laboratory. He is the co-author of a separate study on photosynthesis.

Plants need sunlight, but the dosage they require varies — so when they detect too much light, they quench some of the chlorophyll, which absorbs light, so that they take in less of it. But when a plant does that, it can take a long time for it to recover to their usual level of light absorption, slowing their growth. And it doesn’t take much to trigger this coping mechanism, either, says Niyogi. So his team targeted this “recovery” process, in the hopes of helping plants use as much sunlight as possible to grow big.

All plants have three specific proteins that regulate how quickly they “recover” after shutting down the chlorophyll. Niyogi’s team added more of these proteins to certain tobacco plants. This way, the plants still absorb less light when there’s too much sun, but go back to their normal level of light absorption much more quickly.

Compared to the non-engineered plants, the new ones grew anywhere from 14 percent to 20 percent bigger. The United Nations already said that we’re going to need to produce 70 percent more food by 2050 to feed everyone, and climate change is likely to cause food shortages. If this method becomes widely adapted, it could help us produce a lot more food without needing more land.

The initial experiments are on tobacco because the plant is very easy to modify. Since no one eats tobacco, Niyogi’s team is now working on crops like rice, sorghum, and cassava. (The research is funded by the Bill and Melinda Gates Foundation, so they’re focusing on plants that are readily available in sub-Saharan Africa.) “They’ll still need to explore a wide range of different conditions to make sure this is really a generally useful tool, and that they don’t accidentally mess up one of the plant’s backup systems,” says Robert Blankenship, a biologist at Washington University in St. Louis. “But this is a really excellent study — it’s well-designed and well-carried-out and exciting.”

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I need to do an assignment on this subject. When I'm looking up stuff online about organic chemicals, I see different categories like bioorganical chemicals, physical organic chemicals, synthetic organic chemicals, organometallic chemicals and some others.

I had read about Friedrich Wöhler's discovery before. From what I remember, most scientists and chemists at the time ignored his findings. He wasn't really appreciated until much later.

I think it was because chemists thought of organic and inorganic chemicals to be completely different. The article also talked about this.

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Structural Differences Between Chlorophyll A and B

Both Chlorophyll A and B have very similar structures. Both are “tadpole” shaped due to a hydrophobic tail and hydrophilic head. The head consists of a porphyrin ring, with magnesium in the center. The porphyrin ring of chlorophyll is where light energy is absorbed.

Chlorophyll A and B differ in only one atom in a side-chain on the third carbon. In A, the third carbon is attached to a methyl group whereas, in B, the third carbon is attached to an aldehyde group.


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