Germination Process of seeds

Germination is a process by which an organism puts its buds forth from a seed. There is a sequence of events in germination process. The germination process of seeds is a series of events which are given as follows:

  • Imbibition (absorption of water)
  • Hydration of protoplasm(see streaming of protoplasmic theory)
  • Activation and synthesis of enzymes
  • Increase in respiration
  • Increased synthesis of nucleic acids and proteins
  • Synthesis and release of hormones from embryo
  • Increased cell enlargement and cell division
  • Hydrolysis of deserved food substances in endosperm and cotyledon
  • Utilization of soluble organic substances by developing embryo
  • Growth of radicle into root and plumule into shoot

Difference between growth and development

Growth

Germination process of seeds start with imbibition followed by its growth. Growth is the increase in the size of plant or other words quantitative increase in plant body. An irreversible increase in the size of the plant body is growth. Imbibition of water and an increase in the size of wood is not considered to be growth.

Similarly, an increase in the size of seed after absorption of water is not a growing phenomenon. In both cases, size becomes reverted upon drying. Growth is limited to living organisms only. Growth is not taking place in the entire seed or tuber, but it takes place only in specific regions. 

Development

It refers to the qualitative changes taking place in the plant body, for example, germination of seed, falling of leaves, and others. Things improve in the development process. Growth and development are not two different phenomenons occurring at different times.

On the other hand, one follows the other in quick succession. When meristem changes from vegetative to reproductive stage, this change is development. So the life of the plant is divided into two phases:

Vegetative phase that occurs from the emergence of seedling till flowering.

Reproductive phase occurs from the initiation of flowering till the completion of seed formation.

Phases of growth

Cell division

It is an important phase of plant growth. It starts from unicellular zygote to a multicellular embryo and then develops into a plant. The size of the plant depends upon the number of cells and the size of cells. 

Cell expansion

The expansion is predominantly in the longitudinal direction. It may have the same meaning as cell elongation.

Cell differentiation

With the division of and enlargement of cells, these newly formed cells undergo mutation or specialization. During this, cells change their shape. Cell walls undergo thickening. Often lignin and suberin deposit on the walls. This process of specialization of cells to perform different functions is differentiation. 

Introduction to Plant Physiology

Introduction to Plant Physiology

Plant physiology is the study of the internal processes that take place inside the plant body, for example, photosynthesis and respiration. Two Greek words combine to make this word ‘physis’ meaning nature and ‘logos’ meaning discourse. So, plant physiology is a discourse about the plant. 

The following key can better make us understand the origin of physiology.

Introduction to Plant Physiology

Why study plant physiology?

  • Understanding the basic physiological functions for processes, for example, photosynthesis.
  • Studying the integration(relationship) of these processes concerning productivity.
  • To study the influence of different environmental factors, for example, soil environment, pH, temperature, texture, etc. 
  • To test the effect of various processes on plant activities, for example, growth, development, and yield.
  • Learning the sequence of events, for example, cell division, elongation, etc.

Water Potential 

Movement of water from one place to another because of energy i.e. from one soil zone to another soil zone. It relates the tendency to move or change state to energy level differences. 

There are different energies.

  • Kinetic energy
  • Potential energy
  • Gravitational energy

Gibbs Free Energy is the sum of kinetic, potential and gravitational energy.

Because of this free energy, the molecules are in constant motion and move from a region of higher concentration to a region of lower concentration by diffusion. Water potential depends upon the number of water molecules. The water potential of pure water is zero. This serves as a reference position. Water potential is positive if it is over zero and negative if it is less than zero. Water potential is a measure of the free energy content of water molecules. A Greek letter ᴪ expresses water potential and its measuring unit bars. 

1 bars= 0.987atm

1 atm=14.7lbf/in2

 Some forces affect this energy

  • Matric force
  • Osmotic force
  • Gravitational force

Matric force

The force of attraction between soil colloids and water molecules. It decreases the water potential.

Osmotic force

Osmotic force results from attraction between water and ions and some other solutes present in the soil. It also reduces water potential.

Gravitational force

Gravitation force is the downward pull of water. 

Components of water potential

Matric potential

ψm is the symbol that represents matric potential. It decreases water potential because of the affinity of water molecules to colloidal substances such as protoplasm and cell wall as colloidal particles tightly attach water molecules. The movement of water molecules becomes more difficult hence, water potential decreases. 

So, it is necessary to give attention to water potential while calculating the water potential of water in seeds or soils. 

Solute potential

ψs is the symbol that represents solutes potential which is the force of attraction between ions and water molecules. The free energy of water molecules decreases if some solutes are present in it. This is because of the collision of water molecules and solute molecules or ions. 

Pressure/turgor potential

ψp refers to the turgor pressure exerted by vacuoles. ψp is always positive. It means pressure potential increases the water potential of the cell. The pressure potential varies from +4 to +5bars during the day and +10 to +15bars during the night. ψp is zero in young non-vacuolated cells and plasmolyzed cells. Therefore water potential of the cell is a sum of component potential, 

 ψ=ψm + ψp + ψs

 In the cell, matric potential is negligible. So,

 ψ=ψp + ψs

This is was a brief introduction to plant physiology we shall be posting the full course of plant physiology soon.

Translocation in plants

All parts of the plant require a continuous supply of food for their nutrition and development,this is referred to as translocation. Plants differ in their cell arrangement. In simple plants like spirogyra, all cells are green, and each cell can make enough food for its requirement. The higher plants have a great differentiation of structure and division of labor. In higher plants, green cells mainly stick to the leaves, which make up the chief center where synthesis of carbohydrates takes place. The non-green parts of the plant like stem and root get their food supply from leaves. Before food can reach the non-green parts, there must be a proper infrastructure for transferring food. It must travel from leaves through intervening cells and tissues. The food material travels within the plant in the form of a solution in water.

This cell-to-cell movement of food material from one part of the plant to another or through a tissue is the translocation or conductance of solutes. Source is the point where plant synthesis food and sink is the part where plants use food. 

Longitudinal translocation in plants

Translocation of food material takes place in plant in different directions. Mainly, food material travels in a downward and upward direction. The path of food flow is not constant throughout the life of the plant. At one time, the flow of the food is upwards, and at other times its direction is downward. The plant manufactures food material in leaves and that material travels downward to the stem and root. The synthesized food nourishes old cells and builds new ones. Plant stores some food in storage organs. In these cases, food is rapidly migrating from the seeds or the vegetative storage organs to the growing tips where they use it rapidly. 

This upward movement continues till the seedling or the new shoot develops photosynthetic activity. After that plant reverses the direction of translocation. Upward movement takes place during the development of cereal grains where the ear head is terminal. Another instance of upward movement of food is in the stems of woody plants. The food stored in older parts move upward to the sprouting buds. So we can understand that the direction of transport of food is from the region of higher concentration towards lower concentration. 

Lateral translocation in plants

Lateral translocation involves the movement of nutrients both outward to the cortex and inward to the center. 

Path of translocation in plants

In simple plants, like thallophyta and Bryophyta, the problem of translocation is simple as the substances move from only small distances. On other hand in high plant, long distances intervene between source and sink, and food material has to travel a long distance even up to several feet in tall trees. In such cases, there must exist adequate channels that carry food. Upward and downward movement of food takes place in the phloem. 

Anatomy of phloem

Phloem is a composite tissue comprising five different cells.

  • Sieve tubes
  • Phloem parenchyma
  • Companion cells
  • Phloem fibers
  • Phloem ray cells

The phloem fibers are dead cells, therefore they are unfit for translocation. They constitute the mechanical tissue of the phloem. 

The ray cells assist in lateral translocation, and it is a very slow process. Longitudinal translocation in both directions, occurs mostly in sieve tubes.

Sieve tubes are the most dominant part of the phloem, and are the only living element that are present in vascular plants. 

The companion cells are absent in gymnosperms, and phloem parenchyma are absent in monocots. In conifers, the albuminous cells perform the function of companion cells. 

Mechanism of phloem conductance

There are three hypotheses or explanations for longitudinal conductance of food substances in sieve tubes, but none is entirely satisfactory. 

Diffusion hypothesis

We know that the direction of the flow of food substance is from the region of higher concentration of solutes to lower concentration. Translocation continues as long as there is positive concentration gradient from supply end to consumption end. Moreover, the rate of translocation increases with the increase in steepness of gradient. 

Streaming of protoplasmic theory

According to DeVries (1985), the rapid translocation is due to the streaming movement of protoplasm in sieve tubes. The rapid streaming movement of the protoplasm carry the enclosed solutes from one end to another end. 

Munch theory

This hypothesis assumes that the solutes translocate in the sap of sieve tubes, which flow from supply end to consumption end under a turgor pressure gradient. 

Reproduction of horticultural crops

Plant species extend themselves in two ways, sexually or asexually. Reproduction through seed is sexual, except some parthenogenetic species which do not involve sex. Seeds of some species, including mango, give rise to more than one seedling per seed.

Reproduction of horticultural crops through seed

Reproducing horticultural plants from seed has various drawbacks. Ordinarily, when cross-pollinated plants produce seeds, the seedlings do not bear the characters of their parents. It takes so long for fruit trees to come into bearing and have the potential to grow tall, which may increase maintenance and harvesting costs. 

However, reproduction through seed also has some goodness. Seedlings are generally hardy, bear heavy crops, and are long-lived. Moreover, it is vital in the breeding of hybrids and new varieties. It can also raise seedlings that we can use as rootstock in vegetative propagation. 

Preparation for sowing

We should consider several factors before actually sowing the seed. 

Collection of seed: 

Collecting seeds from authentic sources can reduce the chances of seedling variation. We should select those fruits for seed extraction which possess good fruit and high-quality characteristics. In most cases, they should be healthy and fully mature and have a high degree of disease resistance. 

Storage of seed:

Seeds of most of the evergreen fruit species lose viability soon after extraction. Growers should sow them before any prolonged storage period. If it is necessary to store seeds, carefully wash them, surface dry, mix with an equal part of charcoal, and pack in suitable containers and store them in a dry and cool place. 

Pre-germination seed treatment:

In some deciduous fruit species, like apple, pear, peach, plum, and cherry, the seeds need a certain period of rest after extraction before they will germinate. To store such seeds, place them with alternate layers of moist sand, at a controlled cold temperature and suitable moisture conditions before sowing. This process is called stratification. It allows the embryos in the seeds to complete their development. 

Plants with hard shells like ber and guava need to have the seed coat cracked or softened by soaking in water for several hours or days. 

Sowing:

The seed is either crop up in pots, trays, or plastic bags; or in beds in nursery rows. When we need a small number of seedlings, we sow seeds in earthen pots, wooden trays, plastic bags. The container consists of a potting mixture of equal parts of topsoil, sand, and well-rotted leaf mold or FYM. 

Methods of asexual propagation

Asexual or vegetative reproduction uses a part of the plant for multiplication. Growers use stems, leaves, buds, roots, bulbs, corms, rhizomes, suckers, and tubers as plant parts. Plants resulting from asexual reproduction are identical to parent plants in all aspects. These traits result in saving in cultural operations and make harvesting of the crop and its marketing easier. 

In budding and grafting, use only the most compatible scion and rootstock combinations. Incompatible combinations result in poor bud take, weak graft or bud union, overgrowth of stock as compared to scion or vice versa, low disease resistance, excessive leaf drop, earl decline, low yields of poor quality fruit, and short life span.

Budding

Budding is relatively easy to do. Experts use it in the vegetative propagation of vast numbers of species of fruit and flowering trees, particularly evergreens. Generally, there are four different methods of budding.

Shield budding or T-budding

This type of budding is the most common method of vegetative propagation of citrus, jujube, apple, loquat, roses, and many other ornamental trees and shrubs.

Pre-condition the rootstock seedling and bud wood and prepare when the sap is moving freely. For convenience in handling, before removing the buds, the leaf blades are cut off, leaving the petioles intact. Remove a narrow shield of bark 3-4cm in length, with a single bud. The shield will have a thin layer of wood. On the rootstock, make a vertical cut 3-4cm in length just through the bark. At the top end of this cut, make a horizontal cut about 1.25-1.5cm long, so that the cut resembles the letter T. Use the plastic or bone spur of the knife, insert the bud in the bark after loosening it from the wood. To hold the bud firmly in position and to exclude air and moisture, wrap the bud union carefully using stable plastic strips and keep the bud exposed. 

Ring budding

In this method, loosen a ring of bark 1.5-2cm in length, containing a well-developed bud on the scion shoot and gently pull out from the thinner end of the shoot. Use handkerchief in pulling off the ring, to avoid injury to the bud. Remove the top of the stock seedling and peel off the bark downward where the ring of the bark bearing the bud fits tightly. No tying is necessary in ring budding. 

Chip budding

Place a single bud with a large piece of wood on a corresponding cut on the stock and tie it firmly. Growers use this method rarely. 

Flapped-patch budding

Loosen a rectangular or square flap of bark on the stock on three sides. Insert the corresponding bud shield underneath the loosened flap of bark. Then place the flap over the bud shield and wrap it. It takes about two months for the bud to sprout. Remove the wrapping material after this. 

Grafting methods

Inarching or approach grafting

Unlike other grafting operations, in inarching, attach the scion to the stock while it is still attached to the parent plant. In Pakistan, this method extensively produces mango. The method involves potting healthy one-year-old seedlings in earthen pots, which are usually 12 inches deep and 8 inches wide at the top. Kepp the earth ball intact along with the root system and place it in the pot. Fill the unfilled space in the pot with a mixture of well-rotted manure and canal silt. Press the soil firmly around the earth ball and water the transplanted seedlings. 

Bring the potted seedlings near the parent plant for inarching. The size of the rootstock and scion shoot should be the same. Make a slanting cut of about 5 cm long and 2cm  deep on the stock seedling at the height of 15-20cm. Make a similar cut on scion shoot and bring together the corresponding cuts and tie them with plastic film.

Factors limiting the growth of horticulture

There are several factors and constraints which are limiting the growth of the horticultural industry. Practitioners and researchers should consider these factors both on a long term and short term basis to improve yields and induce more farmers to grow fruits and vegetables. Some of these factors are:

How seeds affect the growth of horticulture

In the total cost of production, the cost of seed is of little account, except for potatoes, ginger and a few other crops. The chance of agricultural investments involves the quantity and quality of seed. Unfortunately, farmers do not pay enough attention to the processing, storage, and distribution of seed. Most of the vegetables and flower seeds in our country either come from poor quality or expired produce. 

The most considerable downside is the failure to reproduce our varieties. It takes a lot of expense in importing seed from abroad. This situation is alarming for crops like potatoes that rely on foreign introductions. 

We must overcome this issue of seed by developing a native technology of breeding, production, processing, and marketing of seeds. There is a need for enough research input to build up the seed business. 

Role of Nurseries in the growth of Horticulture

Private sector nurseries supply most of the plants to the fruit growing industries and for ornamental purposes. There are no regulations to start a nursery business in Pakistan. Any business-minded person can go ahead with a commercial nursery. Most big cities have a large number of such industries. 

For fruit trees, there is no system for the production and supply of rootstock seed. As a result, many orchards contain inferior quality plants. The life span of such plants is short and, yields are low. The poor gains consequently result in the uprooting of orchards or intercropping with other crops. This problem allows the grower to consider fruit trees as a bonus or side business only. The need of the hour is to approve laws to ensure the supply of quality plant material. 

How Capital affects the growth of horticulture

The horticultural industry requires a large amount of investments. These investments can be in the form of land preparation, purchase of plant materials, fertilizers, implements, and management costs. High risks make farmers unwilling to proceed into horticultural business. In a small farming community like ours, growers are subsistence-oriented, and food for their families and fodder for their livestock is the first consideration. 

Horticulture, on the other hand, is a profit-oriented industry. Grower should invest before he expects a profit. Small farmers in the rural areas can also benefit if the necessary investment is available to them in the form of credit, roads and marketing facilities, etc.

Role of Marketing system in the growth of horticulture

The marketing of horticultural produce has unique characters. Most fruits and vegetables are more likely to decay, with a short post-harvest life. So, the producer has to sell the harvest as early as possible. Seasonal variations in supply are common, with alternating shortage and surplus. 

There is a need to develop the processing industry to consume the excess during surplus periods. We should encourage farmers to approach direct marketing if facilities like roads and other capital incentives are available. 

Role Management problems

As with any business, management has an important responsibility to build profitable farming. One can make wise decisions by selecting the right kind of crops according to the soil and climate suitability. Similarly, the right time and method of sowing can make significant differences in the profitability of farming. 

The biggest drawback is the lack of research-based information on technology available to the farmers. There is a need for new crops to expand the production base. 

Role of Export production

Export of fruits and vegetables can bring much-needed foreign exchange. Growers get back the benefit of higher prices. For an export-oriented production of horticultural crops, we must design a long-term strategy for export production. To be an active part of the market, we will have to ensure a constant supply and quality of the produce. 

We should encourage our farmers to specialize in the export production of specific high-quality products and varieties of fruits, vegetables, and cut flowers by offering them premium prices on a contract basis. 

Role of Public awareness

Most of the people are not sufficiently aware of the importance of horticultural food and appreciative of its aesthetics. The human diet is incomplete without the essential vitamins and minerals which come from fruits and vegetables. The general public is not aware of the aspect of vitamin loss during the cooking of vegetables. Increasing awareness and concern about the environment plays an important role in human health. 

Significance of Horticulture

The horticulture industry plays an significant role in many important components of our daily diet and meets one’s need for pleasure. It can be a profession for researchers and teachers and an occupation or position for others working in the production phases. It is a business for merchants and a means of exercise and a small income for beginners. Horticulture enhances the physical and mental health and improves the economic success of individuals and nations. 

Dietary significance of Horticulture

A complete food must have carbohydrates, proteins, fats, fiber and other important nutrients in it. Roundabout 30% of the food consumed in the world comes from the horticulture sector. All fruits and vegetables have some amount of edible carbohydrates and other food parts in different proportions. Potatoes and sweet potatoes are especially in starch. On a per-acre basis, potatoes and bananas produce more calories as compared to wheat. Potato is the fourth-ranking food crop in the world. Increased potato production can reduce the compulsion on grain products. 

A Variety of colors, textures, and flavors make eating more interesting. Some fruits and vegetables contain high fiber contents. Leafy vegetables like celery, cabbage, lettuce, and other with high cellulose value add volume to food. Lack of vitamins and minerals cause chronic diseases. The red pigment in ‘red-blood’ oranges is a source of anthocyanin, while grapefruit contains carotene in its red pigment. Deficiency of ascorbic acid or vitamin C causes hemorrhaging and swollen gums and lower body resistance against infection. Citrus, ber, guavas, tomatoes, and melons are rich in ascorbic acid. The insufficient amount of vitamin E results in sterility. Onions, lettuce, oranges, bananas, and avocados are a great source of vitamin E.

Deficiencies of vitamin B causes beriberi, numbness and heart enlargement. Thiamine, riboflavin and nicotinic acid are important B-vitamins present in considerable amount in many fruits and vegetables. Vitamin D helps the body to utilize calcium. Children who are deficient in vitamin D develop rickets, a softening and curvature of the bones. 

Minerals have a vital role in building up the human body as main parts of tissue. Important minerals that come from vegetables and fruits are Ca, Na, P, Co, Mg, Mn, Fe, and I. 

The nutritional value of fruits and vegetables 

The nutritional value depends on culture, conditions, consumption, and treatment in the field and after harvesting. A high level of nitrogen in the soil lowers the Ca content of vegetables and affects the consumption of proteins. Boron deficiency lowers the carotene and riboflavin content of tomatoes. The amounts of rainfall and sunlight that a crop receives also influence its ascorbic acid content. 

Storage of crates and bags at high temperature, high respiration levels, and loss of water leads to loss of vitamins. Water loss resulting from ruptures takes away the water-soluble vitamins. 

Cooking methods also play a role in the vitamin content of food eaten. Loss of vitamins occur due to heat and leaching. The best way to eat vegetables is fresh, or preferably raw. 

Economic position

In Pakistan, there is greater demand for fruits and vegetables that the existing products can meet. Generally, our supply of all horticultural products fall short of the amount to meet the requirements. Need of the hour is to make cooperative efforts to increase the production of horticultural products in our country. Higher fruit and vegetable production would improve the nutritional status of the people of Pakistan. 

Higher investment in different phases of production, handling, processing, and marketing of these crops involves a higher flow of capital. Thus production of horticultural crops involves a faster economic activity in the agriculture sector. The growth of the horticultural industry will create more job opportunities and better returns to farmers. 

Aesthetic value

The beauty and satisfaction from plants are not visible qualities and no one can measure them. People of different cultures and values will have different opinions about what is beautiful and what is ugly. In horticulture, the elements of plant beauty relates to enhance their utility for human use. Whether horticultural products are food or desserts, their aesthetic value always take superiority over economics. The aesthetic value of horticulture promotes mental health and is a way of relaxation. Horticultural therapy is now a well-known field of medical science. 

Role of horticulture in the Environment

Plants act as lungs in cleaning our environment by regulating CO₂ content of the air. Proper plant materials can control air pollution and general destruction of the environment due to industrialization. Plants prevent soil erosion. Hardy trees like ber, guava, date palm, and pomegranate can also reclaim waterlogged soils. Trees play a role as a barrier to reduce wind velocity. The presence of vegetation results in mild climates at both the micro and macro levels. 

Medicinal plants

Many plants with medicinal value are produced in the horticulture sector. Pharmacology, the science of drugs and medicines, depends on these plants. The cultivation and maintenance of these plants have their own aesthetic and economic value. Falsa, sweet lime, and Jamun have cooling effects. Bitter gourd and Jamun also help to cure diabetes. 

Forage induced animal disorders

Naturally occurring plant toxins are not unfamiliar or scarce and it may sometimes give a negative impact on animals as these compounds are frequently present in forages they consume. Herbivores are unable to consistently avoid harmful plants. So, the controller must be aware of forage related factors that cause serious injury to animal health. One of the major causes of animal health demolition is the imbalance of nutrients. Interaction between plant species, environmental conditions, and management practices may cause the occurrence of health problems. Different anti-quality compounds affect different biochemical pathways of animals. This may lead to different symptoms and severity of impact. One should understand the biochemistry involved to get more approximate and preventive measures.

Why do plants contain harmful compounds?

One suggestion is that such compounds developed over time as a mechanism for prevention of herbivore feeding and thus produce anti-herbivore agents. This characteristic could be beneficial if reducing defoliation is required for plant survival and reproduction. One of its best examples is the availability of high levels of HCN (hydrogen cyanide) in seeds of certain sorghum genotypes that greatly reduce feeding by birds. Forage related animal disorders can be categorized in three main groups:

  • Poisonous animal disorders
  • Seasonal or conditional disorders
  • Species related disorders

Poisonous plant disorders

These are unpleasant and may be present in pasture and rough land conditions. These kinds of disorders resulting from poisonous plants are not unfamiliar especially under conditions of overgrazing when forage availability is limited. These toxic effects in plants may cause short term damage to animal health or even sometimes may cause rapid death. 

Following are some forage plant families and species that contains toxic compounds:   

Forage species Common name Anti-quality compounds
Poaceae / Grassy
Forage sorghum

Tall fescue

Tropical grasses
HCN, cyanogen

Ergovaline, ergot alkaloids

Oxalates, Saponins
Fabaceae / Leguminosae Alfalfa

White cloves

Red clover


Crown wedge
Phytoestrogen

Phytoestrogen

Blotting agents

Glycoside
BrassicaceaeTurnips


Rape
Brassica anemia(goitrogens)

Glycosynolates

It seems natural that animals should avoid consuming toxic plants. Herbivores tend to select nutritionally superior diets especially concerning energy and proteins. They naturally have some ability to avoid toxins in their diet. Young animals in herd learn from their dams which plant to consume and which to avoid. Animal disorders usually occur when animals are hungry and unable to avoid harmful plants. These disorders may be reduced if these poisonous plants are eliminated from the pasture and fields.

Seasonal and conditional disorders

These kinds of disorders occur only under certain environmental conditions at specific plant growth stages or certain vulnerable stages for animals. Mineral uptake pattern of forage plants is disturbed by environmental temperature and may cause grass tetany. Animals are more sensitive to this disorder at some age or reproductive stage as compared to other disorders. Tolerance towards forage toxins is sometimes lower during gestation, lactation, and weaning than during other life stages.

Grass Tetany

Grass tetany also called hypomagnesemic tetany is a metabolic disorder due to low blood magnesium level. It occurs usually during transition from winter to spring when temperature rises to the range of 40-60°F encouraging a rapid flush of grass growth. It is most common in grass pastures but may also occur in pasture containing legumes or non-grassy hays. 

Symptoms

Cattle with early symptoms may exhibit nervous behavior or graze away from the herd. In extreme conditions, animals collapse and go into convulsions. Affected animals may arch their head back and trash the legs may be called paddling. Older cows nursing calves under 2 months of age are more prone because recombination of magnesium from their tissue is less effective.

How to avoid Grass tetany?

Strategies to avoid grass tetany include direct supplementation of animals with Mg. Supplementation is usually accomplished by adding 75-150 pounds MgO per ton of salt per mineral mixture. For dairy cows, an intake of 30g Mg per day is recommended for lactating ewes an intake of 3g of Mg per day is recommended. Animals showing early symptoms of grass tetany (before coma) can be given intravenous injections of Ca Mg gluconate solution. Subcutaneous injections of a saturated solution of MgSO₄ may also be given. 

Bloat

Legume bloat occurs when stable foam forms at the surface of the floating raft actively digesting forage in the rumen and blocks the access to the esophagus carrying gases to accumulate. Death losses calculated due to bloat are 0.5% of the cattle population annually. 

The large amount of gases released during fermentation in the rumen are CO₂ and CH₄. Bloat occurs in animals consuming hay.

Symptoms

Bloating animals exhibit distension of the rumen on the left side. Other symptoms of bloat include cessation of grazing, frequent urination, labored breathing and restless movements. In extreme conditions distension may also occur on the right side. Onset of acute bloat may cause death within minutes. Sub-acute bloat may cause distension of the left side with no negative effect on the animal. 

How bloat can be treated?

Bloat can be cured by adding vegetable oil or any other anti-foaming agent directly to the rumen. Bloat can normally be controlled by feeding anti-foaming agents like poloxalene. Supplementation of cattle diet with monensin, an ionophore reduce the bloat incidents. Another way to reduce bloat is providing animals with the dry forage before grazing. 

Nitrate toxicity

Negative effects including death can occur when ruminants ingest more than the ability of rumen microbes to convert into nitrate to ammonium form. When nitrate is produced faster, the rumen microbes can utilize it, some nitrate is absorbed through the walls of rumen and enters the bloodstream. Once it enters the bloodstream, nitrate transforms hemoglobin into the form methemoglobin, thereby restricting its ability to transport oxygen to body tissues.

Symptoms

Rapid breathing, muscle incoordination, diarrhea, and frequent urination are symptoms of nitrate poisoning. Blood from affected animals changes its color from normal bright red to chocolate brown. 

How nitrate toxicity can be treated?

Treatment involves intravenous injections of methylene blue solution. Feeding an energy supplement such as corn can hasten microbial utilization of nitrate thus reducing nitrate accumulation in the rumen. Nitrate test can be done on forages such as corn and sorghum by cutting a shoot near the soil surface, splitting the stem lengthwise and dropping a solution of diphenylamine in H₂SO₄. Onto the exposed pith. 

Development of dark blue color indicates the presence of nitrate. If this Qualitative field test is positive, a sample should be collected for lab analysis and sent to the lab for nitrate testing.