With the help of growth regulators plant can easily respond to environmental pressures. For instance, during the draught conditions, growth of a plant is suppressed because of less water. And, during the year where there is enough rain, the growth of a plant is triggered as the tree takes full advantage of different weather conditions. It’s very important to give plants special attention while providing them water, growth regulators or fertilizers, as it damage plants.
When people trick plants with applications of water, fertilizers, or growth regulators, sometimes they become unhealthy unless they are closely monitored. With the help of artificial growth regulators, can accomplish different goals, such as productions of healthy roots, encourage faster fruiting, reduce the number of suckers etc. Growth regulators are very helpful to grow ornamentals because they can efficiently prolong the flowering phase to give bigger and colorful flowers, they are also used for faster growth of vines, new leaves and fruits etc.
ARTIFICIAL GROWTH REGULATORS
Biochemists studied the structural properties and applications of IAA and Kinetin and prepared similar compounds in their laboratories. They are the synthetic growth regulators. They are also called artificial growth regulators. Some examples of synthetic growth regulators are IAA (Indole Acetic Acid), IBA (Indole Butyric acid), NAA (Naphthalene Acetic Acid), 2-4 D, (2-4-Dichlorophenoxy Acetic Acid), BAP (Benzyl Amino Purine) and Ethephon (2-chloroethyl phosphoric acid). Among these IAA, IBA, NAA and 2-4-D are the synthetic auxins. BAP is the synthetic cytokinin and Ethephon is a synthetic ethylene - releasing compound.
APPLICATION OF SYNTHETIC GROWTH REGULATORS
Synthetic growth regulators are commonly used in agriculture and horticulture for crop improvement. They are also used in tissue culture laboratories. Important applications are,
· Induction of rooting
Gardeners in nurseries dip the cut ends of branches and leaves in a dilute solution of NAA or IBA to induce adventitious roots. In practice, these synthetic growth regulators are more efficient than IAA.
Gardeners in nurseries dip the cut ends of branches and leaves in a dilute solution of NAA or IBA to induce adventitious roots. In practice, these synthetic growth regulators are more efficient than IAA.
· Prevention of Abscission layer
The premature fall of leaves, flowers and fruits is common in plants like apple, pear, mangoes etc. It is due to the development of abscission layer in the petiole and pedicel. The abscission layer development is due to the deficiency of natural auxins in the plants and that can be prevented by spraying synthetic growth regulators. This action of synthetic growth regulators has been used in agriculture and horticulture to prevent premature fall of leaves and fruits. Premature fall of fruits in apple and pear can be prevented by spraying proper concentrated solution of IBA or NAA. A spray of 2-4-D in dilute concentration over cabbage heads prevents defoliation.
The premature fall of leaves, flowers and fruits is common in plants like apple, pear, mangoes etc. It is due to the development of abscission layer in the petiole and pedicel. The abscission layer development is due to the deficiency of natural auxins in the plants and that can be prevented by spraying synthetic growth regulators. This action of synthetic growth regulators has been used in agriculture and horticulture to prevent premature fall of leaves and fruits. Premature fall of fruits in apple and pear can be prevented by spraying proper concentrated solution of IBA or NAA. A spray of 2-4-D in dilute concentration over cabbage heads prevents defoliation.
· Production of parthenocarpic fruits
Synthetic auxins are used to produce seedless or parthenocarpic fruits. A spray of NAA or IBA induced parthenocarpic fruits in tomato, brinjal, watermelon, certain varieties of grapes and oranges.
· Eradication of weeds
2-4-D is a selective weed killer. By spraying concentrated solutions of 2-4-D weeds can be eradicated from the crop fields, forests and along the railway lines. 2-4-D shows greater toxicity to dicotyledonous (broad leaved) plants than monocotyledonous (narrow leaved) plants. A spray of 2-4-D to corn field irradicated broad leaved weeds in the field leaving the corn plant intact.
2-4-D is a selective weed killer. By spraying concentrated solutions of 2-4-D weeds can be eradicated from the crop fields, forests and along the railway lines. 2-4-D shows greater toxicity to dicotyledonous (broad leaved) plants than monocotyledonous (narrow leaved) plants. A spray of 2-4-D to corn field irradicated broad leaved weeds in the field leaving the corn plant intact.
· Flower initiation
Auxins generally inhibit the flowering but in pineapple spraying of low concentration of NAA initiate uniform flowering in the whole crop, so that harvesting becomes easy. Lettuce is a leafy vegetable grown for its vegetative parts, but when the plant develops flower it looses the market value. But a spray of NAA is proper concentration over the plant lettuce delayed the flowering and induced the plant to grow vegetatively.
Auxins generally inhibit the flowering but in pineapple spraying of low concentration of NAA initiate uniform flowering in the whole crop, so that harvesting becomes easy. Lettuce is a leafy vegetable grown for its vegetative parts, but when the plant develops flower it looses the market value. But a spray of NAA is proper concentration over the plant lettuce delayed the flowering and induced the plant to grow vegetatively.
· Apical dominance and dormancy
Potato tubers can be stored maximum for one year and later the axillary buds in the "eyes" develop into small thick branches. But that can be prevented by spraying proper concentrated solution of NAA over the surface of tubers.
Potato tubers can be stored maximum for one year and later the axillary buds in the "eyes" develop into small thick branches. But that can be prevented by spraying proper concentrated solution of NAA over the surface of tubers.
· Induction of callus and regeneration of microshoots
Synthetic auxins like IAA, IBA, NAA and 2-4-D are used to induce callus formation. When the non meristematic tissues in the stem, root vegetative buds etc are cultured on a nutrient medium with the synthetic auxins they develop callus at the injured regions. Subculture of callus on a nutrient medium with cytokinin like BAP promote the development of stem buds and later the microshoots. BAP is a strong and effective cytokinin used extensively for the regeneration of microshoots in a variety of medicinal, ornamental, forest and crop plants.
Synthetic auxins like IAA, IBA, NAA and 2-4-D are used to induce callus formation. When the non meristematic tissues in the stem, root vegetative buds etc are cultured on a nutrient medium with the synthetic auxins they develop callus at the injured regions. Subculture of callus on a nutrient medium with cytokinin like BAP promote the development of stem buds and later the microshoots. BAP is a strong and effective cytokinin used extensively for the regeneration of microshoots in a variety of medicinal, ornamental, forest and crop plants.
· Ethephon is a commercial fruit ripener
Ethephon is known by its trade name, Ethrel. It has several valuable commercial applications. Ethephon is used to ripen bananas, pineapple, melons and tomatoes, and when applied as a pre-harvest spray it promotes uniform ripening of apples, cherries and pineapple. It is used to increase the production of female flowers in cucumbers, which develop fruits and increase yields.
RIPENING AGENTS
Ripening agents speed up the ripening process.
They allow many fruits to be picked prior to full ripening, which is useful, since ripened fruits do not ship well. For example, bananas are picked when green and artificially ripened after shipment by being gassed with ethylene. A similar method used in parts of Asia is to put a plastic cover over a bed of slightly green-harvested mangos and a few small open containers of clumps of calcium carbide. The moisture in the air reacts with the calcium carbide to release the gas acetylene, which has the same effect as ethylene. Ethylene is not emitted by the plant naturally, and cannot activate the ripening of nearby fruits, rather, it is used as a hormone within the plant.
Calcium carbide is used for ripening fruit artificially in some countries. Since industrial-grade calcium carbide may contain traces of arsenic and phosphorus, the use of this chemical for this purpose is illegal in most countries. Calcium carbide, once dissolved in water, produces acetylene, which acts as an artificial ripening agent. Acetylene is believed to affect the nervous system by reducing the oxygen supply to the brain; however, it has been shown that, in practice, acetylene is not sufficiently reactive to affect consumers.
Catalytic generators are used to produce ethylene gas simply and safely. Ethylene sensors can be used to precisely control the amount of gas.
Covered fruit ripening bowls are commercially available. The manufacturers claim the bowls increase the amount of ethylene and carbon dioxide gasses around the fruit, which promotes ripening.
Climacteric fruits are able to continue ripening after being picked, a process accelerated by ethylene gas. Non-climacteric fruits can ripen only on the plant and thus have a short shelf life if harvested when they are ripe.
Health consultants highly recommend fruits and salads in their prescriptions and we take the best advantage of the availability of the range of variety in the markets. But how close we are to nature, when we are consuming these fruits is a very big question mark. Fruits and vegetables are known to be possessing antioxidant and anti-aging factors. If they are a source of harmful chemicals as well, then are we heading towards fitness or otherwise some harmful effects.....
In recent times, there is much concern about artificial ripening of fruits. Though fruits like mango naturally ripen in trees, some chemicals are used to ripen them artificially which hasten the ripening process. Ripe fruits are not suitable to carry and distribute as they get rotten. So traders pick unripe fruits and use certain methods to increase their shelf life.
For many years, ethylene had been used as a fruit ripening agent, but nowadays ethane, calcium carbide and ethephon are commonly used for faster ripening. But inappropriate use of these chemicals to ripen fruits is associated with many health hazards.
Ripening is a process in fruits that causes them to become edible. Globally, the ripening is done through gas emission systems or ethylene generator systems, depending on quality and shelf life desired.
Effects of Artificial Ripening
· Ethylene is known to cause damage to the neurological system, affects the eyes, skin, lungs, memory and leads to prolonged hypoxia (lack of oxygen supply).
· Ethephon is a plant growth regulator. It promotes pre-harvest ripening in apples, currants, blackberries, blueberries, cranberries, morello cherries, citrus fruit, figs, tomatoes, sugar beet and fodder beet seed crops, coffee, capsicum. Ethephon is easily converted into ethylene and has the same harmful effects.
· State Food and Drugs Control Administration (FDCA) has banned the use of ethephon , but fruit traders have now resorted to bethylene.
· Bethylene is not known to have any harmful effects but it alters the taste and the nutritional value of fruits and also reduces the shelf life of the fruits, if used beyond the recommended limits. And most of the traders do use quantities of bethylene which are much higher than the prescribed limits.
· Besides ripening agents, farmers also use many pesticides to grow fruits and vegetables which are detrimental to our health.
· Calcium carbide is used for ripening the fruit artificially in some countries. Industrial-grade calcium carbide may contain traces of arsenic and phosphorus, and, thus, use of this chemical for this purpose is illegal in most countries. Calcium carbide, once dissolved in water, produces acetylene, which acts as an artificial ripening agent. Acetylene is believed to affect the nervous system by reducing oxygen supply to brain, however, it has been shown that, in practice, acetylene is not sufficiently reactive to affect consumers.
Ethylene and calcium carbide
Ethylene is a natural plant hormone.It affects the growth, development, ripening, and senescence (aging) of all plants. It is normally produced in small quantities by most fruits and vegetables. Many fruits produce larger quantities of ethylene and respond with uniform ripening when exposed to an external source of ethylene.
Ethylene is Generally Recognized as Safe (GRAS) by the United States Food and Drug Administration (FDA). Given the numerous amounts of food substances, the FDA does not categorize every one. Salt, pepper and vinegar are examples. These, along with ethylene, all are within the category of food substances that, when used for the purposes indicated, in accordance with good manufacturing practice, are regarded by the FDA as generally recognized as safe (GRAS) for such uses.
Ethylene has been found not harmful or toxic to humans in the concentrations found in ripening rooms. In fact, ethylene was used medically as a anesthetic in concentrations significantly greater than that found in a ripening room. However, ethylene is often targeted as the reason for difficulty in breathing in ripening rooms; what can affect some people is usually either:
a) Carbon Dioxide (CO2,) levels: CO2, is produced by the ripening fruit in the room and levels increase over time, or
b) Oxygen levels: The oxygen in the room when loaded is taken in by the ripening fruit. This sometimes will make breathing in a ripening room difficult. The increased CO2, and decreased oxygen levels are the main reasons for venting the ripening room.
Calcium Carbide is NOT safe for ripening. Calcium Carbide is used in some countries as source of acetylene gas, which is an artificial ripening agent. However, acetylene is not nearly as effective for ripening as is ethylene, and acetylene is not a natural plant hormone like ethylene. Also, calcium carbide may contain traces of arsenic and phosphorus, both highly toxic to humans, and the use of this chemical for ripening is illegal in most countries.
References :
www.tutornext.com
books.google.lk
www.catalyticgenerators.com
Ethephon is known by its trade name, Ethrel. It has several valuable commercial applications. Ethephon is used to ripen bananas, pineapple, melons and tomatoes, and when applied as a pre-harvest spray it promotes uniform ripening of apples, cherries and pineapple. It is used to increase the production of female flowers in cucumbers, which develop fruits and increase yields.
RIPENING AGENTS
Ripening agents speed up the ripening process.
They allow many fruits to be picked prior to full ripening, which is useful, since ripened fruits do not ship well. For example, bananas are picked when green and artificially ripened after shipment by being gassed with ethylene. A similar method used in parts of Asia is to put a plastic cover over a bed of slightly green-harvested mangos and a few small open containers of clumps of calcium carbide. The moisture in the air reacts with the calcium carbide to release the gas acetylene, which has the same effect as ethylene. Ethylene is not emitted by the plant naturally, and cannot activate the ripening of nearby fruits, rather, it is used as a hormone within the plant.
Calcium carbide is used for ripening fruit artificially in some countries. Since industrial-grade calcium carbide may contain traces of arsenic and phosphorus, the use of this chemical for this purpose is illegal in most countries. Calcium carbide, once dissolved in water, produces acetylene, which acts as an artificial ripening agent. Acetylene is believed to affect the nervous system by reducing the oxygen supply to the brain; however, it has been shown that, in practice, acetylene is not sufficiently reactive to affect consumers.
Catalytic generators are used to produce ethylene gas simply and safely. Ethylene sensors can be used to precisely control the amount of gas.
Covered fruit ripening bowls are commercially available. The manufacturers claim the bowls increase the amount of ethylene and carbon dioxide gasses around the fruit, which promotes ripening.
Climacteric fruits are able to continue ripening after being picked, a process accelerated by ethylene gas. Non-climacteric fruits can ripen only on the plant and thus have a short shelf life if harvested when they are ripe.
Health consultants highly recommend fruits and salads in their prescriptions and we take the best advantage of the availability of the range of variety in the markets. But how close we are to nature, when we are consuming these fruits is a very big question mark. Fruits and vegetables are known to be possessing antioxidant and anti-aging factors. If they are a source of harmful chemicals as well, then are we heading towards fitness or otherwise some harmful effects.....
In recent times, there is much concern about artificial ripening of fruits. Though fruits like mango naturally ripen in trees, some chemicals are used to ripen them artificially which hasten the ripening process. Ripe fruits are not suitable to carry and distribute as they get rotten. So traders pick unripe fruits and use certain methods to increase their shelf life.
For many years, ethylene had been used as a fruit ripening agent, but nowadays ethane, calcium carbide and ethephon are commonly used for faster ripening. But inappropriate use of these chemicals to ripen fruits is associated with many health hazards.
Ripening is a process in fruits that causes them to become edible. Globally, the ripening is done through gas emission systems or ethylene generator systems, depending on quality and shelf life desired.
Effects of Artificial Ripening
· Ethylene is known to cause damage to the neurological system, affects the eyes, skin, lungs, memory and leads to prolonged hypoxia (lack of oxygen supply).
· Ethephon is a plant growth regulator. It promotes pre-harvest ripening in apples, currants, blackberries, blueberries, cranberries, morello cherries, citrus fruit, figs, tomatoes, sugar beet and fodder beet seed crops, coffee, capsicum. Ethephon is easily converted into ethylene and has the same harmful effects.
· State Food and Drugs Control Administration (FDCA) has banned the use of ethephon , but fruit traders have now resorted to bethylene.
· Bethylene is not known to have any harmful effects but it alters the taste and the nutritional value of fruits and also reduces the shelf life of the fruits, if used beyond the recommended limits. And most of the traders do use quantities of bethylene which are much higher than the prescribed limits.
· Besides ripening agents, farmers also use many pesticides to grow fruits and vegetables which are detrimental to our health.
· Calcium carbide is used for ripening the fruit artificially in some countries. Industrial-grade calcium carbide may contain traces of arsenic and phosphorus, and, thus, use of this chemical for this purpose is illegal in most countries. Calcium carbide, once dissolved in water, produces acetylene, which acts as an artificial ripening agent. Acetylene is believed to affect the nervous system by reducing oxygen supply to brain, however, it has been shown that, in practice, acetylene is not sufficiently reactive to affect consumers.
Ethylene and calcium carbide
Ethylene is a natural plant hormone.It affects the growth, development, ripening, and senescence (aging) of all plants. It is normally produced in small quantities by most fruits and vegetables. Many fruits produce larger quantities of ethylene and respond with uniform ripening when exposed to an external source of ethylene.
Ethylene is Generally Recognized as Safe (GRAS) by the United States Food and Drug Administration (FDA). Given the numerous amounts of food substances, the FDA does not categorize every one. Salt, pepper and vinegar are examples. These, along with ethylene, all are within the category of food substances that, when used for the purposes indicated, in accordance with good manufacturing practice, are regarded by the FDA as generally recognized as safe (GRAS) for such uses.
Ethylene has been found not harmful or toxic to humans in the concentrations found in ripening rooms. In fact, ethylene was used medically as a anesthetic in concentrations significantly greater than that found in a ripening room. However, ethylene is often targeted as the reason for difficulty in breathing in ripening rooms; what can affect some people is usually either:
a) Carbon Dioxide (CO2,) levels: CO2, is produced by the ripening fruit in the room and levels increase over time, or
b) Oxygen levels: The oxygen in the room when loaded is taken in by the ripening fruit. This sometimes will make breathing in a ripening room difficult. The increased CO2, and decreased oxygen levels are the main reasons for venting the ripening room.
Calcium Carbide is NOT safe for ripening. Calcium Carbide is used in some countries as source of acetylene gas, which is an artificial ripening agent. However, acetylene is not nearly as effective for ripening as is ethylene, and acetylene is not a natural plant hormone like ethylene. Also, calcium carbide may contain traces of arsenic and phosphorus, both highly toxic to humans, and the use of this chemical for ripening is illegal in most countries.
References :
www.tutornext.com
books.google.lk
www.catalyticgenerators.com
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