CLIMATIC FACTORS AFFECTING GROWTH
The climatic factors include water, light, temperature, relative humidity, air and wind.
It is the falling of water in droplets on the Earth from clouds. Other forms of precipitation are freezing rain, sleet or ice pellets, snowfall, and hail (Eagleman 1988, Miller 2001). The amount and regularity of rainfall vary with location and climate types and affect the dominance of certain types of vegetation as well as crop growth and yield.
In crop agriculture, water is an important climatic factor. It affects or determines plant growth and development. Its availability, or scarcity, can mean a successful harvest, or diminution in yield is increased from 1 to 2 but plant responses differ depending on plant species. Most plant are mesophytes, that is, they are adapted to conditions with moderate supply of water.
But some, called hydrophytes, require watery or water – logged habitats while others, called xerophytes, are more tolerant to dry conditions.
The resurrection plants are in fact capable of surviving near complete desiccation. They are capable of losing 90% or more of cellular water in their vegetative tissues and still remain alive. They can remain dried and appear some dead for several years but when rehydrated, suddenly spring back to life.
Is a substance with the unique property of being able to exist in three states:
As a Liquid it is clear, colorless and odorless. In state of matter it has been described as a fluid, a substance which flows freely without fixed shape. It melts and freezes at Oo c (32o F) and boils at 100o c (212o F) under normal atmospheric pressure. Through precipitation mainly rainfall, liquid water is made available to plants as surface water, soil moisture, ore groundwater. It comprises about 70 – 90% of the body or even more on fresh weight basis, although only a small fraction of the water absorbed is utilized. Most of the absorbed water in plants is lost through transpiration and only about I percent or less is used in the various biochemical processes.
However, the importance of water in plants can be negated in some cases. Water can possibly cause unfavourable effects on plant growth and development. Excess water in the soil can insure flood prone plants, like corn (maize), due to lack of oxygen. In this case water stress due to flooding means oxygen stress by deficiency (hypoxia) or total absence (anoxia) on the other hand, the injury caused by acid rain indicates that purity and quantity relate to the importance of water. With dissolved sulfuric acid and nitric acid that are formed in the air from sulfur dioxide and nitric oxide generated by power plant, smelters, other industrial plants, factories cars acid rain can seriously injure plant.
Light is a climatic factor that essential in the production of chlorophyll and in photosynthesis the process by which plants manufacture food in the form of sugar (carbohydrate). Other plants processed that are enhanced or inhibited by this climatic factor include stomata movement, phototropism, photo morphogenesis, translocation, mineral absorption, and abscission.
Light is visible portion of the solar radiation or electromagnetic spectrum. It is a form of kinetic energy that comes from the sun in tiny particles called quanta or photons, travelling in waves.
There are three properties of light climatic factor that affect plant growth and development are
(i) Light intensity
(ii) Light intensity
(iii) Day length or photoperiod
This refers to the specific wavelengths of light
Is the degree of brightness of a plant receives
Is the duration of the day which respect to the night period
Is the degree of hotness or coldness of a substance. It is commonly expressed in degree Celsius or centigrade (c) and degree Fahrenheit (F). This climatic factor influences all plant growth processes such as photosynthesis, respiration, transpiration, breaking of seed dormancy seed germination, protein synthesis and translocation. At high temperatures the translocation of photosynthetic is faster so that plants tend to mature earlier.
In general, plant survive within a temperature range is 0 to 50oc enzyme activity and the rate of most chemical reactions generally increase with the rise in temperature. Up to a certain point, there is doubling of enzymatic reaction of 10oc temperature increase.
But at excessively high temperatures, denaturation of enzymes and other proteins occur.
Excessively low temperatures can also cause limiting affects on plant growth and development. For example, water absorption is inhibited when the soil temperature is low because water is more viscous at low temperature and less permeable. At temperature, the freezing point of water, there is change in the form of water from liquid to solid. The expansion of water at it solidifies in living cells causes the rupture of the cells walls.
The favourable or optimal day and night temperature range for plant growth and the maximum yields varies among crop species.
According to McKinley (2005), orchid plants are generally grouped into the following three temperatures and warm. Orchids nee a day – night temperature difference of 10 – 15 F or about 5.55 – 8.34 c to flower. The exact temperature range are associated with these terms vary, the flowing ranges being more common.
Cool 60 – 70 F or 15.55 – 21.11c (day), 50 – 55 F or 10 -12.77C (night) intermediate 70 – 80 F or 21.11 – 26.66 (day), 55 – 65 F or 26.66 – 32.22 C (day, 56.70 F or 18.33 – 21.11 C night.
Is a mixture of gases in the atmosphere. According to Miller (2001), about 75% of this air is found in the troposphere the innermost layer of the atmosphere which extends about 17km above sea level at the equator and about 8km over the poles.
About 99% of the cleanly dry air in the troposphere consists of 78% nitrogen and 21% oxygen. The remainder consists of argon (slightly less than 1%), carbon dioxide (0.036%) and traces of other gases.
The oxygen and carbon dioxide in the air are of particular importance to the physiology of plants. Oxygen is essential in respiration for the production of energy that is utilized in various growth and development processes. Carbon dioxide is a raw material in photosynthesis.
The air also consists of suspended particles of dust and chemical air pollutants such as carbon monoxide (Co), carbon dioxide (Co2), sulfur oxides, methane (CH4) propane, chlorofluorocarbons (Cfcs), solid particles of dust, soot, asbestos and lead Ozone and many more.
However, the composition of this climatic factor is susceptible of variation. Recently there has been a lighten and alarm about the increase of carbon dioxide in the atmosphere.
Is the amount of water vapor that the air can hold depends on its temperature; warm air has the capacity to hold more water vapor than cold air. According to Eagleman, there is almost one – half reduction in the amount of water vapor that the air can hold for every 100 drop in temperature.
Relative Humidity (RH) is the amount of water vapor is the air expressed as the proportion (in percent) of the maximum amount of water vapor it can hold at certain temperature for example, an air having a relative humidity of 60% at 27c temperature means that every kilogram of the air contains 60% of the maximum amount of water that it can hold at the temperature.
The amount of water vapor in the air ranges from 0.01% by volume at the frigid poles to 5% in the humid tropics. In relation to each other, high RH means that the air is moist while air with minimal content of moisture is described as dry air. Compared to dry air, moist air has a higher relative humidity with relatively large amounts of water vapor per unit volume of air.
The relative humidity affects the opening and closing of the stomata which regulates loss of water from the plant through transpiration as well as photosynthesis. A substantial understanding of this climatic factor is likewise important in plant propagation. Newly collected plant cutting and bareroot seedlings are protected against desiccation by enclosing them in a sealed plastic bag. The propagation chamber and plastic tent and also commonly used in propagating stem and leaf cuttings to ensure a condition with high relative humidity.
Is the existence of pressure gradient on a global or local scale caused by differences in heating. On a global scale it consists of the jet stream flow and movement of large air masses. On the local scale only a smaller quantity of air moves. Surface winds are lower and less turbulent at night due to the absence of solar heating.
When air that close to the ground cools, it contracts and the pressure rises, when it warms, it expands and loses pressure. When both cold and warm air occur in proximinity, as over a lake and its adjacent shore, the cold flows to the direction of the warm correct the pressure imbalance. This also happens n tropical Asia but in a larger and more complex way, as the monsoon winds.
This climatic factor serves as vestor of pollen from one flower to another thus aiding in the process of pollination. It is therefore essential in the development of fruit and seed from wind – pollinated flowers as n many grasses.
Moderate winds favor gas exchanges, but strong winds can cause excessive water loss through transpiration as well as lodging or toppling of plant. when transpiration rate excesses of water absorption, partial or complete closure of the stomata may ensure which will restrict the diffusion of carbon dioxide into the leaves. As a result, there will be a decrease in the rate of photosynthesis growth and yield.
Each of the above discussed climatic factors has been shown to produce limiting effects on various growth processes. However, the various climatic factor always operate together and interact with each other under natural conditions.
ADAPHIC FACTOR AFFECT GROWTH
Adaphic factor include topography and soil
Topography is a nonliving factor that refers to the “lay of the land” it includes the physical features of the earth such as the land elevation slope, terrain (flat, rolling, hilly etc) mountain ranges and bodies of water.
The slope of inclination of a land inclination of a land n the percentage change in its elevation over a certain distance. It is measured by dividing the vertical distance from the foot to the top of the land by the horizontal distance between those points, multiplied by 100. A 45 degree angle of elevation is equivalent to 100% slope.
The steepness of a slope affects plant growth through differential incidence of solar radiation, wind velocity and soil type. A steep slope is susceptible of rapid surface runoff and soil erosion which cause soil degradation. It is know that where a landscape serves as a barrier against the movement of pollen or seed between two plant populations, the populations will begin to differ either through mutation or genetic drift. However depending on the plant species and their modes of dispersal, habitat fragmentation and their separation by distance may not always become effective barriers.
Researcher recently found that hummingbirds seem to be more effective than bees in transferring pollen of penstemon from one mountain range to another across large distance. The altitude or elevation of the sea surface influences plant growth temperature effect.
The word soil is derived from the Latin word Solum meaning earthy material in which plant grow. The science which deals with the study of soil is called soil science, pedology (pedos = earth) or edaphology (edaphos = soil).
The process of formation of soil is called pedogenesis. A soil complex is formed of 5 categories of components namely mineral matter, organic matter or humus, soil water, soil air, and living organisms. This quality of soil is due to its fertility, texture, structure, organic content and air – water relationship.
The vertical layered structure of soil is called the soil profile. There are four main horizons in a soil profile.
O – Horizon is the organic layer composed of deed organic residues.
A – Horizon is the top soil, the upper most layer which contains roots.
B – Horizon is the sub soil.
C – Horizon is the less weathered parent.
The organic matter in the soil is of two type:
1. Freshly dead and partially decomposed plant and animal material called litter or detritus.
2. Colloidal, amorphous and dark coloured humus.
SOIL HELPS IN:
· Providing water and mineral to the land plants.
· It act as a substratum for a variety of organisms like bacteria, fungi, many kinds of animals and plants.
· It is the site for decomposition of plants and animals.
· It provides water, minerals and fossil fuels to man.
TYPES OF SOIL
(Clayed Sand and Loamy) and it water retention aeration and mineral contents determine the nature of plant and animals on the basis of these characters of soil, the plants are divided into 5 ecological categories
· Halophytes – plants found on saline soil.
· Psammophytes – plants found on sandy soil.
· Lithophytes – plants found on rock surface
· Chasmophtyes - plants found in rock crevices
· Oxylophytes – plants found on acid soil.
The ground dwelling animals which may be censorial (running) such as ostrich, rhea, ungulates, wolves, cats, bears, hyaenas etc. salutatory (jumping) such as rodents, rabbits, wallabies, kangaroos or gravipon – tal (heavy) such as turtles armadillos, elephants etc, different kinds of soil for example, if the soil is firm and hard, the large animals inhabiting the ecosystem tem tend to have small hooves or paw. If the soil is wet and spongy, they tend to have broad hooves or paws.
Minerals are also called as biogenic materials and are essential for the proper growth of plant and animals are determined by specific distribution of minerals. Deficiency or absence or excess of minerals results in abnormal growth or even death or organisms are adapted differently.
A). Plants found in nitrogen – deficient bog soil have either nitrogen fixing bacteria or become in sectivorous.
B). Snails occur in soils rich in calcium content to form their shell.
C). Halophytes and many marine animals have salt secreting glands.
D). Leguminous plants like pea, gram meth show symbiosis with nitrogen fixing bacterial in their root nodules.
High concentration of minerals generally limits the distribution of animals.
Fire has important effects on the environment. Fire removes plant cover, burns litter on the soil surface and causes loss of nutrients. Due to forest fires a variety of animals groups die.
Range of tolerance
Plants and animals show a range of tolerance to environmental factors. The factor, which is present in least amount may become limiting. For example water availability limits plants growth in deserts.
But, on only “to little” of something is a limiting factor, even “too much” may be the limiting factor. The organisms and abundant in the central optimum range in the zone of stress, only a few organism survive and in the zone of intolerance, organisms are absent. If is organism has wide range of tolerance range is narrow it is restricts.
Weeds are foreign plants i.e. they are plants net intend to be where they are.
Weeds are a problem because they compete for the same soil and nutrients within it, sunlight and water that are intended for those plants specifically placed in an area within the garden. Some cause little harm but other more aggressive weeds can destroy areas of a garden rapidly especially in the spring and early summer months.
The most common perennial garden weeds are.
- Creeping butter cup
- Ground elder
The most common annual garden weeds are
- Bitter cress
As with diseases weeds are difficult to eliminate and regulate maintenance is best form of defense. The removal of weeds little or often will help prevent establishment and spread and it is paramount not to let the weed develop to the sede producing stage.
The application of anti weed material can also help. By laying weed control fabric before planning a beed will provide a defense wall a prohibit weeds and the use of mulches and /or chipped barks on beds around plants will also provide a deterrent to weeds
Garden pest can take many forms with insects, birds and animals all providing a threat to health plant successful plant growth. Health plant tend to be resilient to some pest damage but action should be out of control.
The list of insect pests in the garden is extensive and includes wasps on fruits aphids and whitefly on a whole range of plant. vine weevil are also a pest. Removal of these insect is most effective when using nature reduce them. For instance wasps can be lured to traps filled with sugary bait and the attraction of birds into your garden will keep caterpillar numbers down, the introduction of lady bird, lace wing and lover flies will all reduces the aphid population as will nematodes particularly in war locations.
A whole variety of animal can be regarded as garden pests from the over exuberant to the neighbors stray cats, each individual garden will have its own hit list of animal problems. Cats can be deterred by using cat repellant using strong scents where they tend to use the garden as a toilet. Citrus peel or moth ball are recommend here. Wild animal such as deer or bulgers can also present a problem. Badgers are protected and therefore be encouraged to explore other areas and not your garden. Badgers have been known to destroy fences and barriers to gain access to their usual foreign grounds so simply re fence the area will not solve the problem.
When dealing with all living things disease can always be present disease are caused by either bacteria, virus or fungus and can have a devastating effect, even killing plants in extreme cases when left untreated. Diseases can affect all growing stages of plants and all areas of it from the roots to the flowers, sometimes affecting the whole plant and sometimes just part of it.
INTERNAL FACTORS - GENETIC FACTORS
The basis of the genetic control of plant expression is the gene a carrier of information that determines a biological characteristic of an organism and is transmitted from parents to progeny upon reproduction.
The gene is composed of the deoxyribonucleic acid (DNA) the chemical basis of heredity or transmission of traits from parents to progeny. The DNA directs the synthesis of proteins, particularly enzymes, by the plant. Each enzyme in turn catalyzes specific biochemical reaction which leads to the formation of certain products. In order for a biochemical reaction to proceed, a specific enzyme must be available.
The genetic control of plant growth and development also has reference to the chromosome. The genes are located at specific loci in the chromosome, those cellular bodies within the uncleus which, under the microscope, appear as coiled contracted threads or rod – like bodies at certain stage of mitosis. The number as well as the size and shape of chromosomes, called karyotype, varies from species to species.
The chromosomes are considered the physical basis of heredity. They occur single in haploid (1N) spores and gametes, in pairs (2N) in the diploid body (somatic) cells, mother cells and the fertilized egg, in triplicates (3N) in the triploid endosperm cells; and in multiple sets in the polyploidy cells.
The diploid (2N) number of chromosomes in the body cells in humans is 46, 24 in rice and tomato, 20 in corn, and 14 in garden pea. In 2005, Genome refers to all the genes present in one complete haploid set of chromosomes or an organism.
In diploid organisms such as garden pea, the gene exist n two alternative forms called alleles that are always found at the same point or locus on homologous chromosomes (pair chromosomes). These alternative genes are always denoted by letter symbols. For example, the experiment conducted by Gregor Mendel on garden pea is illustrated by assigning the capital letter “s” for the smooth character of seeds and the small letter ‘S’ for the wrinkled character.
The credit for the formulation of the basis of genetic control goes to Gregor Mendel he discovered that the genes are transmitted between generations in uniform predictable fashion. He crossed strains true – breeding pea that offer in seven of the alternative characters. It is now know that in pea the inheritance of these observable characters, or phenotype is controlled by a genetic constitution, organenotype consisting of a single gene pair.
The entire genetic make – up determines whether an organism should be a plant, an animal a fungus, a protest, or a mineral. This factor also determines whether a plant should be a tree, a shrub, a herb, a vine, a liama, either a vascular or a non vascular plant, a gymnosperm or an angiosperm, and down to the smallest classification of a species, a variety alone or a strain.
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Goetz . H.1969. composition and yield of native grassland sites fertilized at different rates of nitrogen: Range manage. 27:384 – 390
Deltilis, J.k M.I. Dyer and D.T winn 1979. Net photosynthesis root respiration and regrowth of bouteloua gracile following stimulated grazing. Oecology 41;127 – 137
Davidson, J.L and F.C mithorope. 19660 leaf growth in daclylis glumerate following defliation annuals of botany 30;173 – 184.
Mastaler 2, J.W. 1977. The Green House Environment. John Wiley and Sons. Pp.629
RESEARCH INSTITUTE IN NIGERIA
1. Arable Crops Research Institutes
2. National Agricultural Extension Research & Liaison Services (AERLS)
3. Institute of Agricultural Research (IAR)
4. Institute of Agricultural Research and Training (IART)
5. National Cereal Research Institute (NCRI)
6. Lake Chad Research Institute (LCRI)
7. National Root Crops Research Institute (NRCRI)
8. National Stored Products Research Institute (NSPRI).
9. Forestry, Horticulture and Tree Crop Research Institute
10. Forestry Research Institute of Nigeria
11. National Horticulture Research Institute (NIHORT)
12. Cocoa Research Institute of Nigeria (CRIN)
13. Nigeria Institute for oil palm Research (NIFOR)
14. Rubber Research Institute of Nigeria (RRIN)
15. Animal Production, Fisheries and Oceanography Research Institute
16. National Animal Production Research Institute (NAPRI)
17. National Institute for Freshwater Fisheries Research (NIFFR)
18. Nigeria Institute for Oceanography and Marine Research
19. Animal Health Research Institute
20. Nigeria Veterinary Research Institute (NVRI)
21. Nigerian Institute for Trypansomiasis Research (NITR)
22. International Institute for Tropical Agriculture (IITA)
RESEARCH AGAENCIES IN NIGERIA
1. Agricultural Marketing Service (AMS)
2. Agricultural Research Service (ARS)
3. Animal and Plant Health Inspection Services (APHIS)
4. Centro for Nutrient Policy and Promotion (CNPP)
5. Economics Research Service (ERS)
6. Farm Services Agency
7. Food and Nutrition services (FNS)
8. Food Safety and Inspection Service (FSIS)
9. Foreign Agriculture Service (FAS)
10. Forest Services (FS)
11. Gain Inspection Packers and Stockyards Administration (GIPSA)
12. National Agriculture Library (NAL)
13 National Agricultural Statistics Service (NASS)
14. National Resources Conservation Service (NRCS)
15. National Institute of Food and Agriculture (NIFA)
16. Risk Management Agency (RMA)
17. Rural Development (RD)