Guttation is the exudation of drops of xylem sap on the tips or edges of leaves of some vascular plants, such as grasses, and a number of fungi, which are not plants but were previously categorized as such and studied as part of botany. Guttation (from Latin gutta 'drop') is not to be confused with dew, which condenses from humid air and onto the plant or fungus surface and does not originate from within them. Guttation generally happens at night.
At night, transpiration usually does not occur, because most plants have their stomata closed. When there is a high soil moisture level, water will enter plant roots, because the water potential of the roots is lower than in the soil solution. The water will accumulate in the plant, creating a slight root pressure. The root pressure forces some water to exude through special leaf tip or edge structures, hydathodes or water glands, forming drops. Root pressure provides the impetus for this flow, rather than transpirational pull. Guttation is most noticeable when transpiration is suppressed and the relative humidity is high, such as during the night.
Guttation formation in fungi is important for visual identification, but the process causing it is unknown. However, due to its association with stages of rapid growth in the life cycle of fungi, it has been hypothesised that during rapid metabolism excess water produced by respiration is exuded. [1]
Guttation fluid may contain a variety of organic and inorganic compounds, mainly sugars, and potassium. [2] On drying, a white crust remains on the leaf surface.
Girolami et al. (2005) found that guttation drops from corn plants germinated from neonicotinoid-coated seeds could contain amounts of insecticide consistently higher than 10 mg/L, and up to 200 mg/L for the neonicotinoid imidacloprid. Concentrations this high are near those of active ingredients applied in field sprays for pest control and sometimes even higher. It was found that when bees consume guttation drops collected from plants grown from neonicotinoid-coated seeds, they die within a few minutes. [3] This phenomenon may be a factor in bee deaths and, consequently, colony collapse disorder.
If high levels of nitrogen appear in the fluid, it is a sign of fertilizer burn [ citation needed ].
Xylem is one of the two types of transport tissue in vascular plants, the other being phloem. The basic function of xylem is to transport water from roots to stems and leaves, but it also transports nutrients. The word xylem is derived from the Ancient Greek word ξύλον (xylon), meaning "wood"; the best-known xylem tissue is wood, though it is found throughout a plant. The term was introduced by Carl Nägeli in 1858.
Root pressure is the transverse osmotic pressure within the cells of a root system that causes sap to rise through a plant stem to the leaves.
Germination is the process by which an organism grows from a seed or spore. The term is applied to the sprouting of a seedling from a seed of an angiosperm or gymnosperm, the growth of a sporeling from a spore, such as the spores of fungi, ferns, bacteria, and the growth of the pollen tube from the pollen grain of a seed plant.
poopski whoopskis (also known as upsie dasies) is a process in which metabolic waste is eliminated from an organism. In vertebrates this is primarily carried out by the lungs, kidneys, and skin. This is in contrast with secretion, where the substance may have specific tasks after leaving the cell. Excretion is an essential process in all forms of life. For example, in mammals, urine is expelled through the urethra, which is part of the excretory system. In unicellular organisms, waste products are discharged directly through the surface of the cell.
Imidacloprid is a systemic insecticide belonging to a class of chemicals called the neonicotinoids which act on the central nervous system of insects. The chemical works by interfering with the transmission of stimuli in the insect nervous system. Specifically, it causes a blockage of the nicotinergic neuronal pathway. By blocking nicotinic acetylcholine receptors, imidacloprid prevents acetylcholine from transmitting impulses between nerves, resulting in the insect's paralysis and eventual death. It is effective on contact and via stomach action. Because imidacloprid binds much more strongly to insect neuron receptors than to mammal neuron receptors, this insecticide is more toxic to insects than to mammals.
A seedling is a young sporophyte developing out of a plant embryo from a seed. Seedling development starts with germination of the seed. A typical young seedling consists of three main parts: the radicle, the hypocotyl, and the cotyledons. The two classes of flowering plants (angiosperms) are distinguished by their numbers of seed leaves: monocotyledons (monocots) have one blade-shaped cotyledon, whereas dicotyledons (dicots) possess two round cotyledons. Gymnosperms are more varied. For example, pine seedlings have up to eight cotyledons. The seedlings of some flowering plants have no cotyledons at all. These are said to be acotyledons.
A hydathode is a type of pore, commonly found in angiosperms, that secretes water through pores in the epidermis or leaf margin, typically at the tip of a marginal tooth or serration. Hydathodes occur in the leaves of submerged aquatic plants such as Ranunculus fluitans as well as herbaceous plants of drier habitats such as Campanula rotundifolia. They are connected to the plant vascular system by a vascular bundle. Hydathodes are commonly seen in water lettuce, water hyacinth, rose, balsam, and many other species.
Moisture stress is a form of abiotic stress that occurs when the moisture of plant tissues is reduced to suboptimal levels. Water stress occurs in response to atmospheric and soil water availability when the transpiration rate exceeds the rate of water uptake by the roots and cells lose turgor pressure. Moisture stress is described by two main metrics, water potential and water content.
In plants, the transpiration stream is the uninterrupted stream of water and solutes which is taken up by the roots and transported via the xylem to the leaves where it evaporates into the air/apoplast-interface of the substomatal cavity. It is driven by capillary action and in some plants by root pressure. The main driving factor is the difference in water potential between the soil and the substomatal cavity caused by transpiration.
Turgor pressure is the force within the cell that pushes the plasma membrane against the cell wall.
Damping off is a horticultural disease or condition, caused by several different pathogens that kill or weaken seeds or seedlings before or after they germinate. It is most prevalent in wet and cool conditions.
Neonicotinoids are a class of neuro-active insecticides chemically similar to nicotine, developed by scientists at Shell and Bayer in the 1980s.
Nitenpyram is a chemical frequently used as an insecticide in agriculture and veterinary medicine. The compound is an insect neurotoxin belonging to the class of neonicotinoids which works by blocking neural signaling of the central nervous system. It does so by binding irreversibly to the nicotinic acetylcholine receptor (nACHr) causing a stop of the flow of ions in the postsynaptic membrane of neurons leading to paralysis and death. Nitenpyram is highly selective towards the variation of the nACHr which insects possess, and has seen extensive use in targeted, insecticide applications.
Clothianidin is an insecticide developed by Takeda Chemical Industries and Bayer AG. Similar to thiamethoxam and imidacloprid, it is a neonicotinoid. Neonicotinoids are a class of insecticides that are chemically similar to nicotine, which has been used as a pesticide since the late 1700s. Clothianidin and other neonicotinoids act on the central nervous system of insects as an agonist of nAChR, the same receptor as acetylcholine, the neurotransmitter that stimulates and activating post-synaptic acetylcholine receptors but not inhibiting AChE. Clothianidin and other neonicotinoids were developed to last longer than nicotine, which is more toxic and which breaks down too quickly in the environment. However, studies published in 2012 show that neonicotinoid dust released at planting time may persist in nearby fields for several years and be taken up into non-target plants, which are then foraged by bees, caterpillars, and other insects.
A xerophyte is a species of plant that has adaptations to survive in an environment with little liquid water. Examples are typically desert regions like the Sahara, and places in the Alps or the Arctic. Popular examples of xerophytes are cacti, pineapple and some Gymnosperm plants.
Transpiration is the process of water movement through a plant and its evaporation from aerial parts, such as leaves, stems and flowers. Water is necessary for plants but only a small amount of water taken up by the roots is used for growth and metabolism. The remaining 97–99.5% is lost by transpiration and guttation. Leaf surfaces are dotted with pores called stomata, and in most plants they are more numerous on the undersides of the foliage. The stomata are bordered by guard cells and their stomatal accessory cells that open and close the pore. Transpiration occurs through the stomatal apertures, and can be thought of as a necessary "cost" associated with the opening of the stomata to allow the diffusion of carbon dioxide gas from the air for photosynthesis. Transpiration also cools plants, changes osmotic pressure of cells, and enables mass flow of mineral nutrients and water from roots to shoots. Two major factors influence the rate of water flow from the soil to the roots: the hydraulic conductivity of the soil and the magnitude of the pressure gradient through the soil. Both of these factors influence the rate of bulk flow of water moving from the roots to the stomatal pores in the leaves via the xylem.
Hydraulic redistribution is a passive mechanism where water is transported from moist to dry soils via subterranean networks. It occurs in vascular plants that commonly have roots in both wet and dry soils, especially plants with both taproots that grow vertically down to the water table, and lateral roots that sit close to the surface. In the late 1980s, there was a movement to understand the full extent of these subterranean networks. Since then it was found that vascular plants are assisted by fungal networks which grow on the root system to promote water redistribution.
Thiamethoxam is the ISO common name for a mixture of cis-trans isomers used as a systemic insecticide of the neonicotinoid class. It has a broad spectrum of activity against many types of insects and can be used as a seed dressing.
In higher plants water and minerals are absorbed through root hairs which are in contact with soil water and from the root hairs zone a little the root tips.
Plant root exudates are fluids emitted through the roots of plants. These secretions influence the rhizosphere around the roots to inhibit harmful microbes and promote the growth of self and kin plants.
