HOME

TheInfoList



OR:

Physiological Physiology (; ) is the science, scientific study of function (biology), functions and mechanism (biology), mechanisms in a life, living system. As a branches of science, subdiscipline of biology, physiology focuses on how organisms, organ syst ...
plant disorders are caused by non- pathological conditions such as poor light, adverse weather, water-logging, phytotoxic compounds or a lack of nutrients, and affect the functioning of the
plant Plants are the eukaryotes that form the Kingdom (biology), kingdom Plantae; they are predominantly Photosynthesis, photosynthetic. This means that they obtain their energy from sunlight, using chloroplasts derived from endosymbiosis with c ...
system. Physiological disorders are distinguished from
plant disease Plant diseases are diseases in plants caused by pathogens (infectious organisms) and environmental conditions (physiological factors). Organisms that cause infectious disease include fungi, oomycetes, bacteria, viruses, viroids, virus-like or ...
s caused by
pathogen In biology, a pathogen (, "suffering", "passion" and , "producer of"), in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a Germ theory of d ...
s, such as a
virus A virus is a submicroscopic infectious agent that replicates only inside the living Cell (biology), cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea. Viruses are ...
or
fungus A fungus (: fungi , , , or ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified as one ...
. While the symptoms of physiological disorders may appear disease-like, they can usually be prevented by altering environmental conditions. However, once a plant shows symptoms of a physiological disorder, it is likely that that season's growth or yield will be reduced.


Diagnosis of disorders

Diagnosis of the cause of a physiological disorder (or disease) can be difficult, but there are many web-based guides that may assist with this. Examples are: ''Abiotic plant disorders: Symptoms, signs and solutions''; ''Georgia Corn Diagnostic Guide''; ''Diagnosing Plant Problems'' (Kentucky); and ''Diagnosing Plant Problems'' (Virginia). Some general tips to diagnosing plant disorders: *Examine where symptoms first appear on a plant—on new
leaves A leaf (: leaves) is a principal appendage of the stem of a vascular plant, usually borne laterally above ground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, stem, ...
, old leaves or all over? *Note the pattern of any discolouration or yellowing—is it all over, between the
vein Veins () are blood vessels in the circulatory system of humans and most other animals that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are those of the pulmonary and feta ...
s or around the edges? If only the veins are yellow, deficiency is probably not involved. *Note general patterns rather than looking at individual plants—are the symptoms distributed throughout a group of plants of the same type growing together? In the case of a deficiency all of the plants should be similarly effected, although distribution will depend on past treatments applied to the soil. *Soil analysis, such as determining pH, can help to confirm the presence of physiological disorders. *Considering recent conditions, such as heavy rains, dry spells, frosts, etc., may also help to determine the cause of plant disorders.


Weather damage

Frost Frost is a thin layer of ice on a solid surface, which forms from water vapor that deposits onto a freezing surface. Frost forms when the air contains more water vapor than it can normally hold at a specific temperature. The process is simila ...
and cold are major causes of
crop A crop is a plant that can be grown and harvested extensively for profit or subsistence. In other words, a crop is a plant or plant product that is grown for a specific purpose such as food, Fiber, fibre, or fuel. When plants of the same spe ...
damage to tender plants, although hardy plants can also suffer if new growth is exposed to a hard frost following a period of warm weather. Symptoms will often appear overnight, affecting many types of plants. Leaves and stems may turn black, and buds and flowers may be discoloured, and frosted blooms may not produce
fruit In botany, a fruit is the seed-bearing structure in flowering plants (angiosperms) that is formed from the ovary after flowering. Fruits are the means by which angiosperms disseminate their seeds. Edible fruits in particular have long propaga ...
. Many annual plants, or plants grown in frost free areas, can suffer from damage when the air temperature drops below 40 degrees
Fahrenheit The Fahrenheit scale () is a scale of temperature, temperature scale based on one proposed in 1724 by the German-Polish physicist Daniel Gabriel Fahrenheit (1686–1736). It uses the degree Fahrenheit (symbol: °F) as the unit. Several accou ...
(4 degrees
Celsius The degree Celsius is the unit of temperature on the Celsius temperature scale "Celsius temperature scale, also called centigrade temperature scale, scale based on 0 ° for the melting point of water and 100 ° for the boiling point ...
). Tropical plants may begin to experience cold damage when the temperature is , symptoms include wilting of the top of the stems and/or leaves, and blackening or softening of the plant tissue. Frost or cold damage can be avoided by ensuring that tender plants are properly hardened before planting, and that they are not planted too early in the season, before the risk of frost has passed. Avoid planting susceptible plants in frost pockets, or where they will receive early morning sun. Protect young buds and bloom with horticultural fleece if frost is forecast. Cold, drying easterly winds can also severely inhibit spring growth even without an actual frost, thus adequate shelter or the use of windbreaks is important. Drought can cause plants to suffer from water stress and wilt. Adequate
irrigation Irrigation (also referred to as watering of plants) is the practice of applying controlled amounts of water to land to help grow crops, landscape plants, and lawns. Irrigation has been a key aspect of agriculture for over 5,000 years and has bee ...
is required during prolonged hot, dry periods. Rather than shallow daily watering, during a drought water should be directed towards the roots, ensuring that the soil is thoroughly soaked two or three times a week.
Mulch A mulch is a layer of material applied to the surface of soil. Reasons for applying mulch include conservation of soil moisture, improving soil fertility, fertility and health of the soil, reducing Weed control, weed growth, and enhancing the v ...
es also help preserve soil moisture and keep roots cool. Heavy rains, particularly after prolonged dry periods, can also cause roots to split,
onion An onion (''Allium cepa'' , from Latin ), also known as the bulb onion or common onion, is a vegetable that is the most widely cultivated species of the genus '' Allium''. The shallot is a botanical variety of the onion which was classifie ...
saddleback (splitting at the base),
tomato The tomato (, ), ''Solanum lycopersicum'', is a plant whose fruit is an edible Berry (botany), berry that is eaten as a vegetable. The tomato is a member of the nightshade family that includes tobacco, potato, and chili peppers. It originate ...
es split and
potato The potato () is a starchy tuberous vegetable native to the Americas that is consumed as a staple food in many parts of the world. Potatoes are underground stem tubers of the plant ''Solanum tuberosum'', a perennial in the nightshade famil ...
es to become deformed or hollow. Using mulches or adding organic matter such as leaf mold,
compost Compost is a mixture of ingredients used as plant fertilizer and to improve soil's physical, chemical, and biological properties. It is commonly prepared by Decomposition, decomposing plant and food waste, recycling organic materials, and man ...
or well rotted
manure Manure is organic matter that is used as organic fertilizer in agriculture. Most manure consists of animal feces; other sources include compost and green manure. Manures contribute to the fertility of soil by adding organic matter and nut ...
to the
soil Soil, also commonly referred to as earth, is a mixture of organic matter, minerals, gases, water, and organisms that together support the life of plants and soil organisms. Some scientific definitions distinguish dirt from ''soil'' by re ...
will help to act as a 'buffer' between sudden changes in conditions. Water-logging can occur on poorly drained soils, particularly following heavy rains. Plants can become yellow and stunted, and will tend to be more prone to drought and diseases. Improving drainage will help to alleviate this problem. Hail can cause damage to soft skinned fruits, and may also allow brown rot or other
fungi A fungus (: fungi , , , or ; or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and mold (fungus), molds, as well as the more familiar mushrooms. These organisms are classified as one ...
to penetrate the plant. Brown spot markings or lines on one side of a mature
apple An apple is a round, edible fruit produced by an apple tree (''Malus'' spp.). Fruit trees of the orchard or domestic apple (''Malus domestica''), the most widely grown in the genus, are agriculture, cultivated worldwide. The tree originated ...
are indicative of a spring hailstorm. Plants affected by
salt In common usage, salt is a mineral composed primarily of sodium chloride (NaCl). When used in food, especially in granulated form, it is more formally called table salt. In the form of a natural crystalline mineral, salt is also known as r ...
stress are able to take water from soil, due to an osmotic imbalance between soil and plant.


Nutrient deficiencies

Poor growth and a variety of disorders such as leaf discolouration (
chlorosis In botany, chlorosis is a condition in which leaves produce insufficient chlorophyll. As chlorophyll is responsible for the green color of leaves, chlorotic leaves are pale, yellow, or yellow-white. The affected plant has little or no ability to ...
) can be caused by a shortage of one or more plant nutrients. Poor plant uptake of a nutrient from the soil (or other growing medium) may be due to an absolute shortage of that element in the growing medium, or because that element is present in a form that is not available to the plant. The latter can be caused by incorrect pH, shortage of water, poor root growth or an excess of another nutrient. Plant nutrient deficiencies can be avoided or corrected using a variety of approaches including the consultation of experts on-site, the use of
soil Soil, also commonly referred to as earth, is a mixture of organic matter, minerals, gases, water, and organisms that together support the life of plants and soil organisms. Some scientific definitions distinguish dirt from ''soil'' by re ...
and plant-tissue testing services, the application of prescription-blend
fertilizer A fertilizer or fertiliser is any material of natural or synthetic origin that is applied to soil or to plant tissues to supply plant nutrients. Fertilizers may be distinct from liming materials or other non-nutrient soil amendments. Man ...
s, the application of fresh or well-decomposed
organic matter Organic matter, organic material or natural organic matter is the large source of carbon-based compounds found within natural and engineered, terrestrial, and aquatic environments. It is matter composed of organic compounds that have come fro ...
, and the use of biological systems such as cover crops,
intercropping Intercropping is a multiple cropping practice that involves the cultivation of two or more crops simultaneously on the same field, a form of polyculture. The most common goal of intercropping is to produce a greater yield on a given piece of land ...
, improved fallows, ley cropping,
permaculture Permaculture is an approach to land management and settlement design that adopts arrangements observed in flourishing natural ecosystems. It includes a set of design principles derived using Systems theory, whole-systems thinking. It applies t ...
, or
crop rotation Crop rotation is the practice of growing a series of different types of crops in the same area across a sequence of growing seasons. This practice reduces the reliance of crops on one set of nutrients, pest and weed pressure, along with the pro ...
. Nutrient (or mineral) deficiencies include: * Boron deficiency * Calcium deficiency *
Iron deficiency Iron deficiency, or sideropenia, is the state in which a body lacks enough iron to supply its needs. Iron is present in all cells in the human body and has several vital functions, such as carrying oxygen to the tissues from the lungs as a key ...
* Magnesium deficiency * Manganese deficiency * Molybdenum deficiency * Nitrogen deficiency * Phosphorus deficiency * Potassium deficiency *
Zinc deficiency Zinc deficiency is defined either as insufficient body levels of zinc to meet the needs of the body, or as a zinc blood level below the normal range. However, since a decrease in blood concentration is only detectable after long-term or severe ...


References

{{physiology types 01 Horticulture