Increasing plant density suppresses lateral branch growth and pod set on low-order branches so the number of pods per plant is reduced, but not usually enough to reduce grain yield per unit area. The relationship between grain yield and plant density is usually asymptotic, often well described by a hyperbola.
Full Answer
What is plant density?
Plant density is a simple yet critically important variable that links the individuals to crops. Plant density is simply the number of individuals per unit ground area. In many circumstances, the identification of the individual is obvious. The unit of the population can clearly be identified as the individual plant in a crop of, for example, ...
How to study the plant population density by the quadrant method?
To study the plant population density by the quadrant method. Nail. Select a site for the study and hammer the nails on the site without harming the vegetation. Fix four nails in the form of a square. Each end of the nail is tied with the help of a thread making a 1m*1m quadrant.
Which species has the highest population density?
The population density is the highest for species A and the lowest for species C. The density value is expressed as the number of individuals per unit area. Learn more in detail about the plant population density, other related topics and experiments at BYJU’S Biology.
What is the maximum density of a herbaceous plant?
Experiments with herbaceous plants have been carried out with extremely high densities (up to 80,000 plants per square meter). At such high densities, these plants will start to compete soon after germination, and eventually a large number of those individuals (up to 95%) will die.
What is population density in plants?
Plant density is simply the number of individuals per unit ground area. In many circumstances, the identification of the individual is obvious. The unit of the population can clearly be identified as the individual plant in a crop of, for example, sunflowers (Helianthus annuus) or carrots (Daucus carota).
How does population density affect plant growth?
The higher the planting density, the smaller the space between plants. This results in longer, thinner, smaller and yellowing of leaves of the sprouts. In addition, high planting density inhibits photosynthesis resulting in rotting of seedlings and lower yield.
How do you find the population density of a plant?
— Plant population density. How to calculate plant population or the number of plants per acre?...FAQDetermine the area of the field in acres.Multiply the area of the field by the number of plants grown per stand.Divide the result by the product of space between plants in acres and space between rows in acres.
How can we maintain plant population?
Proper method of sowing, using good quality seed and right seed rate, optimum sowing depth, sowing seed in good quality soil, plant size and architecture, proper fertilization and irrigation, gap filling and reseeding, over-seeding and thinning, double transplanting and use of tolerance variety can be used to obtain ...
How can plant growth be controlled in high density planting?
The horticultural methods most commonly known to control tree growth are training and pruning. The training begins when the tree is first planted and continues throughout its productive life. Proper tree forms, branch angle and limb spacing in themselves aid in growth control.
What factors influence the plant density?
Optimum plant density depends on size of the plant, elasticity, foraging area, nature of the plant, capacity to reach optimum leaf area at an early date and seed rate used. The factors affecting plant density are grouped into two as (a) genetic and (b) environment factors.
What is the importance of plant population?
High plant population enhances the interplant competition for nutrients water and light which affect the yield due to the stimulation of apical dominance and induces barrenness which ultimately decreases ear production per plant in maize. The population of plants should always keep optimum.
How does plant density affect photosynthesis?
Abstract. Plant density has been recognized as a major factor determining the grain yield. The photosynthetic performance changes as the density increases.
What is meant by plant population?
Adult plants population: The number of adult plants (A) is a function of the number of seedlings:[2]At=sStwhere s is the seedling survival rate. From: Reference Module in Earth Systems and Environmental Sciences, 2013.
What is seed treatment?
Seed treatments are the biological, physical and chemical agents and techniques applied to seed to provide protection and improve the establishment of healthy crops. Optimizing production begins with elite genetics and protecting plants from pests and disease.
What happens when plant population increases?
Larger populations of plants are likely to be more attractive to pollinators resulting in higher visitation rates and therefore pollination success (Sih & Baltus 1987; Ågren 1996), whereas small populations may suffer from insufficient pollen transfer and consequently lower seed set (e.g. Jennersten 1988a; Lamont et al ...
How plant population affect crop yield?
Plant density affects crop yield indirectly, through the increase in the level of competition. Competition, i.e., the plant-to-plant interference with the equal sharing of growth resources increases almost linearly with the increase of plant density.
What is population density?
Population density is a measure of the number of organisms that make up a population in a defined area. Population density applies to all organisms on Earth, including the plants that make up vast crops, trees of the jungle, animals on the farm, fish in the ocean, and humans on the planet. No matter where a population of organisms lives, those ...
Why do populations change over time?
Populations change over time due to births, deaths, and the dispersal of individuals. Populations often increase greatly when conditions are favorable and resources are plentiful. The maximum rate that a population can increase during optimal conditions is called biotic potential. We know that in most instances conditions are not ideal.
What is the measure of the number of organisms that make up a population in a defined area?
Population density is a measure of the number of organisms that make up a population in a defined area. The correct number of organisms making up a population to utilize the resources available is called a carrying capacity. The maximum rate that a population can increase during optimal conditions is called biotic potential.
What happens if a population gets too large?
If a population gets too large for the area, the ecosystem will be strained and eventually part of the population will die. The population density of organisms determines how successful they will be and what effects they will have on their environment. In biology, populations are a group of individuals belonging to the same species ...
What are the factors that keep populations in check?
Things such as climate, food, water availability, and other factors keep populations in check. Competition and predation also work as biological means of regulating populations. If you have ever lived on or visited a farm, you have seen population density at work.
How are plant populations regulated?
Plant Population. Plant populations are regulated by herbivores, natural enemies regulate herbivore populations, and natural enemies of herbivores are regulated by their own natural enemies. From: Encyclopedia of Agriculture and Food Systems, 2014. Download as PDF. About this page.
What is population ecology?
Plant population ecology and plant demography are consolidated research fields providing insights into how plant populations perform in their environments. In a context of conservation biology, understanding the functioning of plant populations is important since this knowledge has to do with our potential to develop comprehensive and effective conservation plans of endangered plant species. On the other hand, given that evolutionary change begins at the population level, population ecology studies shed light on the forces that affect the life and death and the fecundity of individual plants, determining therefore the fitness of all different variants of a population.
How does seed dispersal affect the ecosystem?
Seed dispersal may drive plant gene flow, plant population dynamics and functional connectivity along landscapes and affect to key ecosystem functions related to (a) revegetation, recolonization and population dynamics of vegetation, and (b) the connectance and connectivity of information (species and genetic diversity), and it intimately depends on the scale of landscape structure of habitat. Due to these roles, seed dispersal is now considered a key ecosystem function as it has major implication for the colonization and recovery of fragmented and altered landscapes and the conservation and resilience of native ecosystems. Seed dispersal outcome may even be quantified in economic terms, when linking the process of vegetation recovery to recreation or carbon-sink uses as seed dispersal enhances the ecological succession. As suggested for other provisioning ecosystem services, at least three relevant components may be distinguished in seed dispersal function: the magnitude of seed delivery (abundance of seeds), the composition of seed input (richness of species dispersed), and the spatial pattern of seed rain which cascades into those processes structuring species communities.
Do plant species depend on mutualists?
Many plant species have become dependent on animal mutualists for seed dispersal. Seed and seedling survival for some species depends on distance from parent plants, under which seed predation may be concentrated ( O’Dowd and Hay 1980, Schupp 1988 ).
How does the resource concentration hypothesis explain the phenomenon that habitat patches with large amounts of resources have higher densities of insects
Therefore, the resource concentration hypothesis conjectures that population density should be positively correlated with patch area. Root (1973) conjectured that the higher density of animals in larger patches might be solely a consequence of movement behavior; herbivores are more likely to find, and remain in, large, monospecific stands of their host plant than in small or heterogeneous patches. If many species have higher population densities in large patches because of the resource concentration hypothesis, then extinction probabilities should be even lower than expected from the area per se hypothesis, and hence resource concentration could contribute to observed species–area relationships. Connor et al. (2000) reviewed the existing literature on the relationships between animal population density and patch area and found that positive area–density relationships are common for insects and birds, but not for mammals.
What is the resource concentration hypothesis?
The resource concentration hypothesis attempts to explain the phenomenon that habitat patches with large amounts of resources (e.g., monocultures, areas of high plant density, or large patches) have higher densities of insects. Therefore, the resource concentration hypothesis conjectures that population density should be positively correlated with patch area. In 1973, R.B. Root conjectured that the higher density of animals in larger patches might be solely a consequence of movement behavior (the movement hypothesis); herbivores are more likely to find, and remain in, large, monospecific stands of their host plant than in small or heterogeneous patches. If many species have higher population densities in large patches because of the resource concentration hypothesis, then extinction probabilities should be even lower than expected from the area per se hypothesis, and hence resource concentration could contribute to observed species–area relationships. E.F. Connor and co-workers have recently reviewed the existing literature on the relationships between animal population density and patch area and found that for insects and birds positive area–density relationships are common, but not so for mammals.
How does ENSO affect biodiversity?
ENSO-induced increases in precipitation act as resource pulses for primary producers in water-limited ecosystems. The expected effect of such pulses is an immediate increase in ephemeral plant density, with a delayed increase in perennial plant abundance, and herbivore and predator abundance. Over the short term, local biodiversity can change dramatically, as in the Flowering Desert of Copiapó, Chile. For example, normally arid islands in the Gulf of California experience an increase in plant cover from 0–4% in non-El Niño years to 54–89% during El Niño events (Polis et al., 1997 ). While annual plants account for the majority of ground cover increase, perennial plants also respond to increased water availability by increasing growth, and flower and fruit set production. Seed banks in arid and semiarid regions have been observed to experience a 5–10 fold increase during ENSO-induced wet periods. The species composition of these plant communities also changes during wet years, with normally uncommon or absent species becoming dominant. Thus, the species richness apparent during the common, dry years is not representative of the overall diversity contained in the seed bank ( Gutierrez et al., 2000 ).
How does the resource concentration hypothesis explain the phenomenon that habitat patches with large amounts of resources have higher densities of insects
Therefore, the resource concentration hypothesis conjectures that population density should be positively correlated with patch area. Root (1973) conjectured that the higher density of animals in larger patches might be solely a consequence of movement behavior; herbivores are more likely to find, and remain in, large, monospecific stands of their host plant than in small or heterogeneous patches. If many species have higher population densities in large patches because of the resource concentration hypothesis, then extinction probabilities should be even lower than expected from the area per se hypothesis, and hence resource concentration could contribute to observed species–area relationships. Connor et al. (2000) reviewed the existing literature on the relationships between animal population density and patch area and found that positive area–density relationships are common for insects and birds, but not for mammals.
What is the resource concentration hypothesis?
The resource concentration hypothesis attempts to explain the phenomenon that habitat patches with large amounts of resources (e.g., monocultures, areas of high plant density, or large patches) have higher densities of insects. Therefore, the resource concentration hypothesis conjectures that population density should be positively correlated with patch area. In 1973, R.B. Root conjectured that the higher density of animals in larger patches might be solely a consequence of movement behavior (the movement hypothesis); herbivores are more likely to find, and remain in, large, monospecific stands of their host plant than in small or heterogeneous patches. If many species have higher population densities in large patches because of the resource concentration hypothesis, then extinction probabilities should be even lower than expected from the area per se hypothesis, and hence resource concentration could contribute to observed species–area relationships. E.F. Connor and co-workers have recently reviewed the existing literature on the relationships between animal population density and patch area and found that for insects and birds positive area–density relationships are common, but not so for mammals.
How does ENSO affect biodiversity?
ENSO-induced increases in precipitation act as resource pulses for primary producers in water-limited ecosystems. The expected effect of such pulses is an immediate increase in ephemeral plant density, with a delayed increase in perennial plant abundance, and herbivore and predator abundance. Over the short term, local biodiversity can change dramatically, as in the Flowering Desert of Copiapó, Chile. For example, normally arid islands in the Gulf of California experience an increase in plant cover from 0–4% in non-El Niño years to 54–89% during El Niño events (Polis et al., 1997 ). While annual plants account for the majority of ground cover increase, perennial plants also respond to increased water availability by increasing growth, and flower and fruit set production. Seed banks in arid and semiarid regions have been observed to experience a 5–10 fold increase during ENSO-induced wet periods. The species composition of these plant communities also changes during wet years, with normally uncommon or absent species becoming dominant. Thus, the species richness apparent during the common, dry years is not representative of the overall diversity contained in the seed bank ( Gutierrez et al., 2000 ).
What is plant density?
Plant density is defined as the number of plants present per unit area of ground. In nature, plant densities can be especially high when seeds present in a seed bank germinate after winter, or in a forest understory after a tree fall opens a gap in the canopy. Due to competition for light, nutrients and water, individual plants will not be able ...
How does density affect a plant?
As plant density increases it will affect the structure of the plant as well as the developmental patterns of the plant. This is called 'asymmetric competition' and will cause some subordinate plants to die off, in a process that has been named 'self-thinning'. The remaining plants perform better as fewer plants will now compete for resources..
What is the density of a plant in forestry?
In forestry, normal densities are less than 0.1 plants per square meter. Not only the biomass per square meter increases with density, but also the Leaf Area Index (LAI, leaf area per ground area). The higher the Leaf Area Index, the higher the fraction of intercepted sunlight will be, but the gain in light interception ...
How many plants per square meter of rice?
Normal densities in modern agriculture depend on final plant size and vary between 5-10 plants per square meter for Maize till 200-300 plants per square meter for Rice or Barley.
Why do densely grown plants produce fewer seeds per individual?
Because densely-grown plants are smaller , they will also produce fewer seeds per individual. But also the seed production as a fraction of total plant biomass ( harvest index) is lower, and so is the seed weight of an individual seed .
What is the gradient of light in dense stands?
In dense stands, there is a strong gradient of light from top to bottom. Lower leaves in high-density stands will therefore have a lower photosynthetic rate and a lower transpiration rate than similar leaves of plants in open stands.
What is the difference between a high density plant and a high density plant?
Average plant height or vegetation height often remains remarkably similar, but a very consistent difference is that the stems of high-density plants have a much smaller diameter. They also have fewer side shoots ( tillers) in the case of grasses, or branches in the case of herbs and trees.
