The environment has a significant impact on plant growth and regional spread. In the absence of ideal conditions, a plant cannot develop and/or disperse. In deserts, for example, only plants that can survive on very little water are able to thrive.
Environmental stress is a factor in the majority of plant issues, whether it’s a direct or indirect one.
Environmental stress is a factor in the majority of plant issues, whether it’s a direct or indirect one. When a plant is exposed to adverse environmental circumstances (such as a lack of water), it might suffer immediate damage. When a plant is under stress, it is more vulnerable to disease or insect assault.
Light, temperature, water, humidity, and nutrition are all environmental elements that influence plant growth. It’s critical to know how these elements influence plant development and growth. It is possible to modify plants based on these factors, whether you want to boost leaf, flower, or fruit output. You’ll also be better equipped to diagnose plant problems caused by environmental stress if you recognize the functions these factors play.
The quality, quantity, and duration of light all have an impact on plant growth.
By “light amount,” we mean how intense or concentrated sunshine is. As the seasons change, so does this. In summer, there is the most light, and in winter, there is the least. A plant’s ability to produce food via photosynthesis increases with the amount of sunshine it gets.
Plants can grow in a variety of ways depending on the amount of light they receive.
Plants can grow in a variety of ways depending on the amount of light they receive. Enhance the light in your garden by using reflective materials, a white background, or additional lighting to enhance the visibility of your plants. Reduce it by draping cheesecloth or woven shade cloths over plants to exclude direct sunlight.
The color (wavelength) of light is referred to as light quality. Red, orange, yellow, green, blue, indigo, and violet are all colors that may be separated by a prism from the spectrum of the sun’s light.
Plant growth is most influenced by the wavelengths of blue and red light that they absorb. During vegetative (leaf) growth, blue light is most important. The combination of red and blue light stimulates flowering in a plant. Because plants reflect rather than absorb green light, they appear green to us.
Plant growth can be manipulated by using the correct light source. Fluorescent (cool white) light, for example, has a high concentration of blue wavelengths. It promotes healthy, green growth and is a good seed starter. Incandescent light, which emits a lot of heat, tends to be too red or orange in color to be a useful source of light for plants. To mimic sunlight, fluorescent grow lights use red and blue wavelengths, although they are expensive and typically ineffective.
The length of time a plant is exposed to light is referred to as its duration, or photoperiod, in the scientific community. Many plants’ flowering is regulated by their photoperiod (Figure 1). The length of the light period was once thought to be a trigger for blooming and other plant responses by scientists. Consequently, plants are categorized as short-day or long-day depending on the conditions in which they bloom. Flower development is influenced by the length of uninterrupted darkness, rather than light duration, as previously thought.
Short-day (long-night) plants, long-day (short-night) plants, and day-neutral plants all have different responses to light and darkness. Only when the length of the day is less than or equal to 12 hours do short-day plants produce flowers. Among the many spring and fall blooming plants in this group are chrysanthemums and poinsettias, as well as the Christmas cactus itself.
Long-day plants, on the other hand, do not produce flowers until the length of the day reaches 12 hours. Plants and vegetables that bloom in the summer, such as the rudbeckia and the California poppy (as well as radishes, lettuce and spinach), fall into this category.
Regardless of the duration of the day, day-neutral plants produce flowers. Tomatoes, corn, cucumbers, and some strawberry cultivars are some examples of this. A variety of day lengths may have an effect on plants that may not fit neatly into any one category. With long days, the flowering of Petunias, for example, occurs earlier and with more frequency.
Light, temperature, water, humidity, and nutrition are all environmental elements that influence plant growth.
Flowering can be induced by manipulating the photoperiod. With a cloth that screens out light for 12 hours a day, chrysanthemums can blossom in the middle of the summer, despite the fact that they generally bloom in the spring or fall. Plants will bloom as if it were spring or fall after a few weeks of this treatment, eliminating the requirement for an artificial dark period. Poinsettias can also be made to bloom in time for Christmas using this method.
Supplemental light can be used to put long-day plants into flower if the day length is less than 12 hours. Flower buds will begin to form in a few weeks.
Germination and blooming are all affected by temperature, which affects nearly every aspect of photosynthesis, transpiration, and respiration in plants. Photosynthesis, transpiration, and respiration all increase with rising temperature. It’s not just day length that has an impact on the transition from vegetative to reproductive growth, but also the temperature. Temperature can either speed up or slow down this transition, depending on the situation and the unique plant.
The temperature at which seeds germinate varies depending on the type of seed. Temperatures between 55 and 65 degrees Fahrenheit are ideal for germinating cool-season crops like spinach, radish, and lettuce, while temperatures between 65 and 75 degrees Fahrenheit are ideal for germinating warm-season crops like tomatoes, petunias, and lobelia.
Temperature and day duration can be used to regulate flowering in some cases. Christmas cactus blooms because of the short days and cold temperatures, for example (Figure 1). It’s best to keep the Christmas Cacti in a room with at least 12 hours of darkness each day and a temperature between 50 and 55 degrees Fahrenheit to encourage it to bloom.
Warm-season crops like spinach will bloom if the weather is hot and long enough (bolt). If the temperature is too low, the fruit of warm-season crops like tomatoes won’t ripen.
Low temperatures have the dual effect of reducing energy consumption while also increasing the body’s ability to store sugar. In order to enhance their flavor, you should leave crops such as ripe winter squash on the vine during fall evenings when temperatures are cool.
Temperatures that are too high or too low can hinder the growth of plants and provide poor-quality produce. High temperatures, for example, result in bitter lettuce.
Photosynthesis and respiration
Thermoperiod is a term used to describe the daily fluctuations in temperature. A temperature difference of 10 to 15 degrees between day and night is ideal for plant growth. During optimal daytime temperatures, plants build up and break down during photosynthesis and respiration, and then limit their activity at night. However, not all plants thrive in the same temperature range at night and during the day. Nighttime temperatures between 55 and 62 degrees Fahrenheit are ideal for snapdragons and poinsettias, respectively.
Breathing is sped up when temperatures are greater than they should be. Photosynthesis is therefore outpacing the rate at which it is being created. Photosynthesis must outpace respiration in order for a plant to grow.
Photosynthesis is slowed down when the daytime temperature is too low. As a result, the yield is diminished (i.e., fruit or grain production).
Some plants that thrive in colder climates require a particular number of days of low temperatures in order to flourish (dormancy). If a plant requires a period of low temperature, it is critical to know how long that period should be.
A good example is peaches, which require 700 to 1,000 hours of 32° to 45°F rest before resuming growth. Temperatures below 33°F are required for six weeks before lilies begin to bloom.
Bulbs of daffodils can be coaxed to bloom in October by keeping them between 35° and 40°F. The chilly weather aids in the growth of the bulbs. Flowers can be harvested in three to four weeks after being moved to a greenhouse in the middle of winter.
A plant’s hardiness is determined by how well it can survive freezing conditions. Plants that are hardy are those that are able to survive in cold climates.
Temperature sensing is a complex process for woody plants in the temperate zone. Hormonal changes caused by shorter days and cooler temperatures force leaves to suspend photosynthesis and instead send nutrients to the twigs, buds, stems, and roots of the tree. When a petiole is attached to a stem, a layer of abscission occurs. In a relatively short length of time, changes in the trunk and stem tissues “freeze-proof” the plant.
When temperatures decrease too quickly in the fall before a plant has entered full dormancy, it can result in winter damage to hardy plants. In some circumstances, if the weather is unusually warm in the middle or late winter, a plant may emerge from dormancy. Hardy plants can be severely harmed by an abrupt cold snap that follows a warm season.
The crowns of tough plants are far more tolerant of freezing temperatures than the roots. Plants that are ordinarily hardy to 10°F may die if their roots are exposed to temperatures above 20°F while they are in containers.
Even in the dead of winter, many people forget to water their plants.
Winter damage can also be caused by plant tissue drying out. Even in the dead of winter, many people forget to water their plants. Water circulation into a plant is significantly impeded when the soil is frozen. It just takes a few minutes for the leaves or needles of broadleaf evergreens to turn brown on a windy winter day. Make sure your plants are well-watered before the winter to reduce the possibility of this type of damage.
Water and humidity
Approximately 90% of the water in a plant that is growing is water. Plants use water in a variety of ways. It’s as simple as that:
- In photosynthesis and respiration, chloroplasts play an important role.
- In cells, responsible for maintaining turgor pressure. It is water that gives plants their fullness and solidity, much as air does in inflated balloons.). Maintaining cell form and ensuring cell development necessitates turgor.)
- In the plant, it serves as a carrier for nutrients and carbohydrates.
- As it evaporates from the leaf tissue during transpiration, it cools the leaves.
- Controls stomatal opening and shutting, which in turn affects transpiration and photosynthesis to a certain extent.
- what causes the dirt to be pushed about by roots?
- Most biological reactions take place in this medium.
It is the amount of water vapor in the air divided by the amount of water that can be held in the air at the current temperature and pressure. More water vapor can be held by warm air than by cold air. The following equation can be used to express RH:
Humidity = amount of water in the air minus the maximum amount of water the atmosphere can contain (at constant temperature and pressure)
Percentage values are provided for relative humidity. Relative humidity (RH) can be calculated by comparing the amount of water in the air to the amount of water vapor that can be held by a given volume of air at a given temperature.
0.75 Equals 0.75 percent of 3 x 4
When the relative humidity is high, water vapor travels from the high area to the low area. The faster water moves, the greater the variation in humidity. The transpiration rate of a plant is directly influenced by the pace of water transport, hence this is an important consideration.
In the air gaps between leaf cells, the relative humidity approaches 100%. Stomas release water vapor into the atmosphere when they open, causing a high-humidity bubble to form around them. The bubble minimizes the relative humidity difference between the air spaces within the leaf and the air close to the leaf by soaking this little patch of air. Consequently, the rate of transpiration decreases.
Transpiration increases if the humidity bubble is blown away by wind. Transpiration is therefore most active on days with high temperatures and little humidity, as well as when the wind is blowing. Conversely, when temperatures are low, humidity is high, and there is no wind, sweat loss is slow.
Summers are often hot and dry, which contributes to the rapid wilting of plants. Turgor pressure is lost when there is not enough water for the roots to absorb and distribute to the leaves.
Fertilization and plant nourishment are frequently conflated terms. Chemical components such as sulfur and nitrogen are essential for plants to thrive. Adding these materials to a plant’s surroundings is known as fertilization. It takes a long time for a plant to take advantage of a fertilizer’s chemical elements.
For regular growth, plants require 17 components. Carbon, hydrogen, and oxygen are all present in air and water, respectively. Other from that, they’re present in the soil.
Macronutrients are soil elements that are used in high quantities by plants, and there are six of them. You’re looking at elements such as nitrate (nitrogen), phosphate (phosphorus), and sulfur (sulfur).
Micronutrients or trace elements refer to the eight additional soil elements that are needed in considerably smaller proportions. Iron, zinc, molybdenum, manganese, boron, copper, cobalt, and chlorine are the metals that make up the iron-making process.
Many nutrients that plants need are found in water, which is subsequently absorbed through the roots. There are only approximately two percent of the nutrients taken from the soil that are actually absorbed from the soil-water combination.
Adding fertilizer to the soil around a plant provides it with the nutrition it needs to thrive. Some can be sprayed directly on the leaves, but most are mixed with water or soil. Foliar fertilization is the name given to this technique. A high fertilizer concentration can harm leaf cells, so use a diluted solution and proceed with caution. A thin layer of wax (cutin) is necessary for the nutrient to penetrate through the leaf surface.
Fertilizers are not a plant’s primary source of nutrition! Photosynthesis is the process by which plants synthesize their own sustenance from water, carbon dioxide, and sunlight. These sugars and carbohydrates are mixed with plant nutrients to generate proteins, enzymes, vitamins, and other nutrients required for growth..
Inhibiting sugar synthesis in leaves has the potential to limit food uptake. Plants may become deficient in nutrients when they are exposed to poor light or high temperatures.
It is also possible that the rate of growth of a plant has an impact on the amount of nutrients that are absorbed by it. Many plants go into dormancy for a period of time each year. There are minimal nutrients taken during this period. During periods of rapid vegetative growth, plants may also use different nutrients than they do during the development of flower buds.
Differences between air temperature and plant temperature
At greater temperatures, most biological processes will speed up, which can have both positive and harmful consequences. In most circumstances, one of the advantages is faster growth or fruit output. Excessive respiration, on the other hand, is harmful since it reduces the amount of energy available for fruit development, resulting in smaller fruits. Short-term and long-term consequences can be seen in some cases. Temperature, for example, has a direct impact on a plant’s assimilation balance. In contrast, flower induction is influenced by the climate over a much longer time frame.
Traffic on a highway is a good analogy for this. The stomata are the highway’s exit pathways, allowing traffic to depart. Cars exiting have to slow down and traffic builds up if there are a lot of cars at the beginning of exit roads. Traffic speeds up when there are less vehicles on the road. Air molecules and water vapor molecules in the air behave similarly. A higher concentration of them around the stomata (the escape pathways) means that they can exit the stomata slower and become clogged. When VPD is high, this is what occurs. As a result, the plant’s cooling capacity is lowered, and stress is induced. In addition, a thin film of water will form on the leaf’s surface, creating an ideal habitat for infections.
Evaporation and irradiance allow plants to cool off and heat up, respectively, although air temperature and plant temperature are not identical. In order for plants to thrive, they must have the right balance of air temperature, humidity, and light. There will be a discrepancy between the ambient temperature and the temperature at which the plant is heating up if light levels are high. Transpiration must be increased in order for the plant to cool down. The transpiration rate is affected not just by temperature but also by other factors such as light, CO2 concentration, and relative humidity.
Temperature affects each portion of a plant in a unique way. A rise in air temperature corresponds to a rise in fruit temperature and the opposite is true when the temperature of the fruit falls. In contrast to air temperature fluctuations, fruit temperature is more stable and takes longer (up to several hours longer) to increase or fall. Petal transpiration is substantially slower than leaf transpiration because flowers have a higher temperature than air or leaves. The temperature of the plants at the top of the canopy will fluctuate more than the temperature of the plants at the bottom. When light levels are high, the top will heat up more quickly than the air, resulting in higher temperatures.
Plant temperature and Vapour Pressure Deficit
Temperature and wind speed affect the amount of humidity in the air. As the temperature rises, so does the rate of evaporation. Warm air is able to hold more water vapour because the molecules move more quickly. As a result, evaporation will be slowed down since the air around the leaves is saturated with water vapour. Viruses and pathogens thrive in moist environments, such as those seen in stagnant pools of water on the leaves of waterlogged plants.
When it comes to the Vapour Pressure Deficit (VPD), it might be likened to a car’s rev counter. The needle on the rev-counter spins and enters the red zone as the engine speed increases. There will be no immediate harm done to the engine, but it will over time if you keep driving the automobile like that. A similar phenomenon occurs when the VPD is excessively high for an extended length of time: the plant is unable to recuperate the following night and can suffer irreparable plant damage (burned leaves or petals).
The vapour pressure deficit is the difference in water vapour content between the air and the saturation point (VPD). Through transpiration, larger VPDs allow plants to expel more water. This might lead to stress for the plant because it is unable to restore all of the water it is losing through transpiration. For brief periods of time, this is not a concern because the plant will absorb enough water the following night to recuperate. Plant damage such as burned leaves or petals might become irreparable when the VPD is high for an extended length of time.
Leaf thickness measures give a visual impression of a plant’s ability to recover after a traumatic event. Because they lose water through transpiration, leaves get thinner throughout the day. However, leaves that are thinner at night indicate that a plant has failed to recuperate. As a result, it may be tempting to keep VPD levels low in order to avoid any harm, but this can have detrimental consequences when the plant is confronted with stressful situations.
Overall, it is possible to compare it to a car’s rpm counter. Increasing engine speed causes the rev counter needle to rise and enter the “red” zone. The engine won’t be damaged right away, but if the needle continues in the red zone for an extended period of time, it will. The ideal VPD for most plants is around 0.85 kPa, with a range of 0.45 to 1.25 kPa (the unit of pressure). To a large extent it mirrors that of the ambient irradiance levels: The VPD rises with sunrise and then begins to decline as the sun sets. The ambient temperature, plant temperature, and relative humidity must be known in order to calculate the VPD.
Water vapour accounts for the majority of the water in the atmosphere. We can tell if water vapour is present in the air by how comfortable we feel (higher humidity makes us feel sticky and less comfortable). Additionally, the amount of moisture present in the air might have an impact on visibility. Water vapour in clouds has cooled to the point where the molecules of water begin to condense and form microscopic droplets or even ice crystals in the atmosphere, making them visible. These appear to be clouds in the sky.
What are stomata?
Stomata, specialized plant organs, allow plants to regulate the transpiration and cooling processes they go through. Leaves have unique cells called stomata, which open and close to regulate how much water vapour can escape. When the stomata are open, the evaporation rate increases as the temperature rises. The VPD can be used to estimate the stomata’s aperture because it is difficult to assess this directly. The more open the stomata, the more gases can enter and exit the leaves.
For example, higher relative humidity promotes faster conductance, but higher CO2 levels slow down conductance. Both of these environmental conditions affect stomatal conductance. Other than external influences, conductivity is also controlled by plant hormones and the wavelength of the light that the plant receives. You’ll see that the plant’s hormone abcisic acid will swiftly open its stomata because it will control and maintain an ideal concentration of the plant hormone abscisic acid (AHA). When the light is blue, the stomata open wider than when the light is red, which has longer wavelengths (about 700 nm), which leads the stomata to close. The lower leaf surface of a Garden Rose Rosa sp. shows an open stoma in this coloured SEM image. Two kidney-shaped guard cells surround a tiny pore called a stoma. Photosynthesis necessitates the entry and escape of gases through the pore. During the night or in dry weather, their pores seal to avoid water loss.
Optimum day and night temperatures for plants
The ideal temperature for a plant varies depending on the time of day and night it is operating. Transport of sugars takes place primarily at night and in the warmer regions of the plant. The plant’s leaves cool more quickly than its fruits and flowers, therefore the plant’s available energy is concentrated in these areas.
The world’s first air-conditioned greenhouse, a phytotron, was built at the California Institute of Technology in 1949 to study optimal day and night temperature combinations. Tomato plants grew higher when exposed to a temperature gradient that alternated between a high temperature during the day and a low temperature at night, according to the research. The term “thermoperiodism” refers to plants’ ability to “distinguish” between day and nighttime temperature fluctuations, and it has an impact on flowering, fruiting, and growth.
Sugar transfer to growing tissue can be inhibited when nighttime temperatures are greater, and hence growth can be limited as a result of this restriction. The combination of high daytime temperatures and low nighttime temperatures has also been reported to result in stem elongation. Stem lengthening occurs mostly as a result of the plant’s water balance being improved by a lower nocturnal temperature. In this way, low nocturnal temperatures can conserve energy while also helping to regulate plant height through the use of temperature. Temperature fluctuations’ impact on plant shape is referred to as thermomorphogenesis.
In addition to light intensity and carbon dioxide concentration, air temperature is also influenced by the temperature of the surrounding environment. As with cold-blooded organisms, plants’ metabolism and photosynthesis speed up as the temperature rises in the surrounding air. When temperatures are extremely low (the exact low temperature depending on the type of plant), very little photosynthesis occurs, regardless of the amount of light available. As the temperature rises, photosynthesis speeds up. The amount of CO2 in the air becomes a limiting factor when light and temperature are both optimal. The rate of photosynthesis will increase as the temperature rises if there is adequate CO2 available, however other factors, such as the enzyme RuBisCo, also play a role.
Photosynthesis necessitates the presence of RuBisCo. As a result of photorespiration, the RuBisCo will connect with oxygen rather than carbon dioxide, as is the case during regular photosynthesis. This is called photorespiration. At low light levels, CO2 levels and optimal temperature are both lower, and enzyme activity is likewise higher at higher temperatures.
What is drop and temperature integration (DIF)
DIF refers to the relationship between the temperature during the day and the temperature at night. To better understand the impacts of diurnal temperature alternation on the growth of plant stems, we need to look at the DIF (day-night temperature difference) rather than the separate and independent responses to day and night temperatures. To put it another way, the difference in temperature matters, as does the question of which is higher: the temperature at night or the temperature during the day.
Effects of DIF on plant growth
DIF has little effect on the growth of foliage, but it has a significant impact on the growth of the internode stem portions. When the DIF is positive, plants grow taller than when the DIF is zero, and when the DIF is zero, plants grow taller and have longer internode sections. Shorter petioles, flower stalks, flower peduncles, and leaves are other major morphogenetic responses to negative DIF (in which the daytime temperature is lower than the nighttime temperature).
Because of variations in cell elongation and cell division, internode elongation and leaf expansion are different. As a result of decreased gibberellin activity in the subapical meristem, both processes are impeded (a plant tissue responsible for growth). Gibberellin is a hormone produced by plants that promotes their growth. DIF has the largest impact on stem lengthening during the time of rapid growth, hence seedlings are more susceptible to temperature variations between day and night than adult plants are. In order to limit the height of a plant, negative DIF must be applied early in stem elongation.
In addition, a two-hour reduction in temperature throughout the 24-hour development cycle might result in elongation of the stem, which occurs at or just before the onset of daylight. When it comes to temperature variations, long-day plants, short-day plants, and day-neutral plants appear to be most responsive in the first hours of the light period. As a result, a temperature dip in the final two hours of the night will have an impact on plant height. In greenhouses in cool climate zones, this is usually a simple task due to the low nighttime temperatures.
Temperature-dependent stem elongation may be regulated by an endogenous growth rhythm that changes during the day and night. Chrysanthemum was discovered to have a 24-hour growth cycle in 1994. During a 24-hour light and dark cycle, plant stem elongation is not consistent. When grown in flower-inducing conditions, plants of both short and long day lengthen more rapidly at night than during the day. Orchids need a period of low night temperature to flower.
An endogenous growth rhythm may be in charge of the day/night cycle of stem elongation sensitivity to temperature. Chrysanthemum has a 24-hour growth cycle that was discovered in 1994. Stem length is not constant during the 24-hour cycle of light and darkness in a plant. Flower-inducing conditions cause both short-day and long-day plants to lengthen more rapidly at night than during the day. In order for orchids to bloom, they require a period of cool nighttime temperatures.
Conclusion air temperature and plant growth
The temperature of the air is the most important environmental factor affecting plant growth and development. Air temperature, on the other hand, is seldom a solitary problem. The aim is to uncover any weak links in the network of factors that affect plant development. Other aspects, such as water balance and hence indirectly transpiration, have not been discussed in this article but are just at crucial. The air temperature is the first control point in the plant, and getting it correct is the first step on the long path to effective crop production.