Leaf index. Leaf surface index, leaf index. See the meaning of Leaf Surface Index, Leaf Index in other dictionaries
Under natural conditions, environmental factors act together. Therefore, plant gas exchange reflects the interaction of all internal and external factors. According to the concept of limiting factors G. Blackman (196_). The IF is limited by the factor or process that proceeds at the lowest rate under given conditions, but other factors also have some influence. For example, with increasing illumination, the optimal and maximum temperature visible photosynthesis increase by several degrees. For plants, this is beneficial, since strong lighting is always associated with leaf heating. If it finally leads to overheating (or to difficulty in water supply), then light ceases to be a factor determining photosynthesis, and the FI decreases. Therefore, under natural conditions, in the daytime course of photosynthesis, not light saturation curves are obtained, as in laboratory experiments, but curves with optimum.
Light and CO 2 interact in a similar way. With an increase in the concentration of the latter, the radiation at which the efficiency of photosynthesis reaches a maximum should also increase, which should be borne in mind when enriching the air with CO 2 in greenhouses in winter. Although the concept of limiting factors is useful as a first approximation to the solution of the problem, in nature there is usually an interaction of environmental factors that is not taken into account by this concept. For example, stress factors (drought, heat, or cold) in combination with varying concentrations of CO 2 and O 2 can affect the rate of photosynthesis at light intensities that strongly limit photosynthesis. This clearly contradicts the theory of limiting factors, since in this case photosynthesis is already strongly limited by light. This type of interaction can be understood by taking into account. that the FI under limiting illumination is determined not only by the throughput of the slowest stage, but also by its efficiency.
Crops and plantations as photosynthetic systems
Leaf area index (ilp)
Distinguish critical (minimum) and optimal (at which it is absorbed the maximum possible amount (90-95%) of incident radiation under these conditions and the highest rate of biomass accumulation is achieved) ILP values. After reaching the critical value of the ILP further increase in leaf area does not lead to a significant increase in the growth rate of crops(SRP), and in crops characterized by the formation of optimal ILP, it even decreases. Thus, the dependence of the rate of accumulation of the crop biomass on the ILP in the first case characterized by a parabola with a plateau at the critical value of the ILI, and in the second bell-shaped curve with a maximum at the optimal value of the ILI.
critical ILP value equal to 4-7 , typical for crops cereals, leguminous crops, sugar beets and others, with higher values noted for crops with erectoid arrangement of upper leaves in favorable conditions cultivation. Optimal ILP achieved in crops fodder cabbage, some herbs.
The main reason for the different dependence of the rate of accumulation of biomass in the crop on the ILP in these cases are the features changes in crop respiration as the leaf area increases. In the first case, it increases only up to a certain ILP value equal to the critical value, and then, like the visible photosynthesis of the crop, it reaches a plateau. In the second case, respiration increases as the leaf index increases linearly.
Under good growing conditions the value of the optimal ILI one or another varieties is determined by its adaptability to the PAR regime of a given territory. If the formation of the optimal ILI value coincides in time with the maximum values of PAR coming for sowing, the highest photosynthetic productivity and efficiency of PAR use are achieved. Otherwise, a significant amount of solar energy is spent inefficiently (Fig.). Since, in this case, the formation of the crop is limited by some factor, the question of the optimal ILP should be decided. empirically.
Thus, for the selection of spring wheat in the steppe part of the Volga region, V. A. Kumakov (1975) substantiated the conclusion that there is no prospect of increasing the ILP in comparison with released varieties.
For each set of conditions, the same variety and species of plants may have its own optimal schedule for the formation of leaf area. Yield is most closely correlated with leaf area in a number of crops.. However, cases of non-correlation between the specified parameters, especially with strong thickening of crops and excessive doses of nitrogen fertilizers. This is explained by the fact that the yield does not always grow on a par with the increase in leaf area and biomass, but only with an increase in their up to certain values after which its growth stops. However, high intensity grade Bezostaya 1 does not reduce the yield of grain during the accumulation of biomass 16-18 t/ta, and in less productive varieties, the grain yield decreases already with the accumulation of biomass of about 10 t/ha.
The leaf index is not directly related to rainfall and is not necessarily in strict accordance with the production of plants in ecosystems. The average leaf index in general for continental ecosystems is assumed to be about 4.[ ...]
LEAF SURFACE INDEX, leaf index - indicator of photosynthetic biomass, equal to the area illuminated leaves per unit of soil surface. The maximum net production corresponds to an I.l.p. close to 4 (i.e., when the area of illuminated leaves is 4 times more area occupied by plants), while the maximum gross production is achieved at I.l.p. equal to 8-10 (this level is typical for forests).[ ...]
The leaf index is the ratio of the total plant leaf area to the planted area. Depending on the culture and growing conditions, its indicator usually varies from one to seven or more; it can be used to judge the degree of provision of sowing with water and mineral nutrients. It has been established that in most agricultural plants the optimal leaf index is 4.. .5 m2-m2 of sowing.[ ...]
Due to a significant increase in the leaf index (the ratio of the total surface area of the leaves; vegetation to the soil surface) in loss up to 10, and on land on average up to 5, transpiration of vegetation can significantly exceed evaporation from areas devoid of vegetation, and even from open areas. water surfaces. According to observations, in virgin forests up to 90% solar energy absorbed by the leaves is used for transpiration.[ ...]
An important varietal trait is the "leaf index", that is, the ratio of the width of the leaf to its length (Fig. 118). The leaf index is typical for a number of varieties only in its extreme manifestations, i.e. if the length is 1.5-2 times greater than the width.[ ...]
The real amount of chlorophyll is equal to the leaf index multiplied by the content of chlorophyll per unit area of the leaf, and is 0.1-4.6 g/m2 for most communities; the average value is estimated at 1.6 g/m2.[ ...]
The function of photosynthesis to a large extent depends on the area of the leaf surface (leaf index). Visual Methods estimates of the area of leaves and the percentage of damage to leaf tissue have very low accuracy, although in general they reflect the overall picture of damage.[ ...]
Introductory explanations. When studying the intensity of photosynthesis, respiration, transpiration, the values obtained are most often calculated per unit leaf area, so it becomes necessary to measure it. Determining the leaf area is also of independent importance in determining the leaf index, photosynthetic potential, etc.[ ...]
AT present work adopted the second way. The velocity profiles and the coefficient of turbulent viscosity in the sowing are given by an exponential dependence on the integral leaf index. The corresponding coefficients are approximated according to the quadratic regression dependence on the density of phytoelements and the height of sowing.[ ...]
The value equal to the ratio of the projection area of a heterotropic organism to the effective territory of biomass consumption (food territory) per one organism can be called the projection index of heterotropes. This value is equivalent to the leaf index for plants.[ ...]
It can be seen that the maximum yield of the edible parts does not coincide with the maximum of the total production of the whole plant. A. Ratio between gross primary production (/) and net primary production (II) with increasing leaf index (expressed in square centimeters, the area of illuminated leaves per square centimeter of soil surface). See the text for an explanation of the comparison with mature forest (from Moiteate, 1965, after Vlak, 1963). B. The influence of the length of the growing season on the yield of grain II) and the total dry matter of the ground parts - grain and straw (I) of rice (Best, 1962).[ ...]
Some other characteristics of the biosphere are reflected in Table. 5-3. Majority plant communities in sufficiently favorable conditions, the land is located to intercept sunlight with a surface of leaves from 3 to 8 m2 per 1 m2 of soil surface (“leaf surface index” 3-8). Higher estimates of this indicator are found in a number of communities, especially in evergreen and coniferous plants. The total leaf area estimated for all terrestrial communities is 644 X X 106 km2 with an average leaf index of 4.4. The average efficiency of formation of net dry matter production and energy absorption per unit area of leaf area is 178 g/m2 of leaf area per year (760 kcal/m2 of leaf area per year). For terrestrial communities in favorable conditions of existence, the efficiency of dry matter production ranges in general from 150 to 300 g/m2 of leaf area per year with the most low values in evergreen communities; for many communities in arid and cold climates, this figure ranges from 50 to 150 g/m2 of leaf area per year. In table. 5-3 shows the calculated data on the leaf surface and chlorophyll, which do not include the green surfaces of trunks and branches and chlorophyll contained in living tissues of all organs other than leaves, and in dead organic matter.[ ...]
Further, it is obvious that the greatest grain production falls on an earlier stage of plant development than the maximum total net production (dry matter accumulation) (Fig. 15, 2>). AT last years grain yields have increased significantly due to the fact that attention has been paid to the structure of the crop. Varieties have been bred with a high ratio of grain weight to straw weight, which also quickly produce leaves, so that the leaf index reaches 4 and remains at this level until harvest, which is carried out at the time of greatest accumulation. nutrients(see Loomis et al. 1967; Armey and Greer 1967). Such artificial selection does not necessarily increase the total dry matter production of the whole plant; it leads to a redistribution of this production, as a result of which more production falls on grain and less on leaves, stems and roots (see Table 36).[ ...]
On the graph, show the growth of populations of two types of clover in pure (i.e., without admixture of another aida) and mixed herbage. Pay attention to that. that the growth of these species in pure herbage has different character and nx maturation occurs in different time. Due to these and other differences, both species, although there are interactions between them, can coexist in mixed herbage, but their density in this case decreases. The leaf index (the ratio of leaf surface area to soil surface area, cm/cm2) was used as an indicator of biomass density. /-T. frahlferum, pure herbage; // - G. repens, pure herbage; ///- T, repens, mixed herbage; IV-T. frahlferum, mixed herbage.[ ...]
This is a general flowchart for grassland biome models typical of a number of western US states. The purpose of constructing the model was to study the intraseasonal dynamics of both the meadow biome as a whole and its parts - vegetation cover, animals, and soil, taking into account the influence of climate and anthropogenic impacts. To characterize the behavior of the system, the constants and variables of the model are singled out. The latter are divided into external and internal variables. External control variables affect the performance within the system. The most important external control variables include precipitation, solar radiation, temperature and wind speed over vegetation. Next, we consider a set of internal state variables (levels). These variables change from step to step in response to changes in external controls or other internal variables. Examples of such variables are the moisture content in the soil layers, green mass, and the number of animals. Rates (speeds of processes), i.e. flows from one 'capacity' to another may be influenced by either physical or physiological processes. So, for example, for the state variable 'terrestrial plant biomass', the input flow rate is determined by the intensity of photosynthesis and the movement of water and mineral elements from the roots. The rate of outflow from this “capacity” is associated with the eating of grass by animals, dying off, the outflow of metabolites into the roots, and trampling the grass cover by animals. Each tempo variable is affected by several variable equations and control actions. The rate of photosynthesis, for example, depends on the leaf index of available soil moisture, solar radiation, and air temperature. The person is also considered as a control variable or external force, which affects flows into or out of the system.
indicator of photosynthetic biomass, equal to the area of illuminated leaves per unit of soil surface. The maximum net production corresponds to an I.l.p. close to 4 (i.e., when the area of illuminated leaves is 4 times the area occupied by plants), while the maximum gross production is achieved with an I.l.p. equal to 8 - 10 (this level is typical for forests).
Watch value Leaf Area Index, Leaf Index in other dictionaries
Index- (de), index, m. (Latin index - index) (book). 1. List, index, list of things. banned books. 2. Numerical indicator expressing consecutive ........
Explanatory Dictionary of Ushakov
Sheet- sheet, sheet. having the shape or size of a leaf. tobacco (in sheets, not crushed). Sheet iron (in sheets, roofing). format of a book or notebook (in a whole, unfolded ........
Explanatory Dictionary of Ushakov
Index M.- 1. List, list, index of names, titles, etc. 2. Symbol(alphabetic, numeric or combined in some system. classification). 3. Digital indicator, ........
Explanatory Dictionary of Efremova
Index- -a; m. [lat. index - list].
1. Index, list, a list of things. I. outgoing books. I. goods.
2. Economy A numerical indicator expressing as a percentage of changes in quantitative ........
Explanatory Dictionary of Kuznetsov
Index- 1) List, index, list of something. 2) A numerical indicator of successive changes in the development of any economic phenomenon, eg. production volume....
Political vocabulary
Sheet— oh, oh.
1. to List (1 character). L system. L-th crown of a tree. L. tobacco (unground tobacco leaves). L vegetables (= leafy vegetables).
2. Made in the form of sheets (2 characters). L-th iron. L glass.
Explanatory Dictionary of Kuznetsov
Aggregate Index — -
consolidated form
index used to characterize the relative change in the indexed value in the current
period compared to the base period.
Economic dictionary
Value-weighted Market Index— an exchange index, in which the contribution of a particular security to the formation of the index is a function of the market capitalization of the security.
Economic dictionary
Waste index- parameter economic efficiency system, its usefulness and environmental safety, including the resources used in production. In and. represents........
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Capitalization Weighted Index— (capitalization-weighted index) – an index calculated as the weighted average price of financial instruments of a certain group, where the weights are the shares of market capitalization........
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Price-weighted Market Index is a market index that specific gravity stocks is a function of their current market prices.
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Price-Weighted Index— Index in which
Components-
shares are weighted by their price. More
expensive stocks will thus be more significant (in percentage terms) when formed........
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Hedonic Index — -
index calculated taking into account changes in product quality.
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Annoying Index- price index for small groups of goods, which are sharp, to a greater extent than others
commodities respond by raising prices to changes in the state of the economy. Concerning........
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Dow Jones Index— See Dow Jones Index
Economic dictionary
Index— - statistical
indicator characterizing
change of certain phenomena, including economic ones. I. as certain
value (previous
........
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Index +/-- Basic
an index that gives investors a basis for benchmarking performance
fund. For all such comparisons, Morningstar uses
S&P 500 index as primary........
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Index 20 Bonds— An index that takes into account the return on 20 municipal bonds backed by a general guarantee from the state or municipal authorities with a 20-year maturity and an average........
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Index All Ordinaries- presenter
index on the Sydney Stock Exchange in Australia.
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Apics Index- Definition:
Research Based Index industrial enterprises, and signaling
growth in economic activity, if its value exceeds ........
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Bond Buyer Index- Price index of first-class municipal bonds, published daily in the newspaper "Buyer shares" (Bond Buyer). the index is the main criterion for evaluating ........
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Index Dax-30- Leading German
the blue chip index on the Frankfurt Stock Exchange.
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Eafe Index (eadv)- The index of shares of European, Australian and Far Eastern companies, calculated by Morgan Stanley (Morgan Stanley).
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Leaf area index
LEAF AREA INDEX expressed in square centimeters (cm2) is the area of illuminated leaves per square centimeter of soil surface; leaf indices can be considered as a measure of photosynthetic biomass. The maximum net production corresponds to a leaf index close to 4 (i.e., when the area of illuminated leaves is 4 times the area occupied by plants), while the maximum gross production is achieved at a leaf index of 8 - 10. This level is typical for mature forests.
Ecological encyclopedic Dictionary. - Chisinau: Main edition of the Moldavian Soviet encyclopedia . I.I. Grandpa. 1989
Leaf surface index - the ratio of the area of leaves (one of their sides) and needles to the area of \u200b\u200bthe soil of the biocenosis. In coniferous forests, it can reach 28, in meadows - up to 30, in the steppes it drops to 2.5 (Greyger, 1964). To calculate the productivity of photosynthesis, the indices of each day of vegetation are summed up, and this sum is called the photosynthetic potential (in m 2 / ha).
Ecological dictionary. - Alma-Ata: "Science". B.A. Bykov. 1983
Leaf area index Leaf index
indicator of photosynthetic biomass, equal to the area of illuminated leaves per unit of soil surface. The maximum net production corresponds to an I.l.p. close to 4 (i.e., when the area of illuminated leaves is 4 times the area occupied by plants), while the maximum gross production is achieved with an I.l.p. equal to 8 - 10 (this level is typical for forests).
Edwart. Glossary of environmental terms and definitions, 2010
See what the "Leaf Surface Index" is in other dictionaries:
Indicator of photosynthetic biomass, equal to the area of illuminated leaves per unit of soil surface. The maximum net production corresponds to an I.l.p. close to 4 (i.e. when the area of illuminated leaves is 4 times the area, ... ... Ecological dictionary
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This article does not have an introduction. Please complete an introductory section briefly describing the topic of the article. Depending on the accuracy of the results that need to be obtained when monitoring for a particular component, phenomenon, etc ... Wikipedia
See Leaf Area Index. Ecological encyclopedic dictionary. Chisinau: Main edition of the Moldavian Soviet Encyclopedia. I.I. Grandpa. 1989... Ecological dictionary
GOST R 53636-2009: Pulp, paper, cardboard. Terms and Definitions- Terminology GOST R 53636 2009: Pulp, paper, cardboard. Terms and definitions original document: 3.4.49 absolutely dry mass: The mass of paper, cardboard or pulp after drying at a temperature of (105 ± 2) ° C to constant weight under conditions ... ... Dictionary-reference book of terms of normative and technical documentation
Leaf area index is an indicator that allows you to calculate the optimal density of planting plants on the site.
It turns out that the leaf index for good growth must be in the corridor neither below nor above a certain value.
Let's see how it works. The leaf index is the ratio of the total “leaf” area of a plant to the area of land occupied by the plant. For example, a plant bush grows on an area of 1 square meter total area of all the leaves of which, when counted, will be 4 square meters. Thus the leaf index will be equal to 4. Everything is very simple.
What are the leaf indices of different plant communities? In coniferous forests, it can reach 28, in meadows - up to 30, in the steppes it drops to 2.5 (Greyger, 1964).
Why consider it at all, why is this indicator important? The point is that he is measure of photosynthetic biomass. The higher the index, the more fully used sunlight in this territory. coniferous forests from spruce - dark, gloomy, all the sunlight is intercepted by spruce needles. But in the litter of even such a forest one can find plants of the type , which live well with a minimum flow of sunlight.
For industrial Agriculture calculated that the maximum net production corresponds to a leaf index close to 4 (i.e., when the area of illuminated leaves is 4 times the area occupied by plants).
Although the maximum gross production is achieved with a leaf index of 8 - 10. The difference between net and gross production is that for agriculture only the increased biomass is considered a benefit, while in forestry and park business, for example, production is also oxygen produced by the forest. And this total productivity (plant respiration + biomass growth) works best with an index of 10 units.
If the leaf index is below 4, thenhiccup unpleasant consequences for plant growth. The point is that in summer period leaf index shows whether the ground under the plants will overheat. If the index is 4-5, then all the sunlight is intercepted by the green mass and the frying rays do not reach the ground.
If the leaf index is low 1-2, then Sun rays through such rare leaves penetrate to the earth, heat it. There are several unfortunate consequences. Firstly, moisture evaporates strongly, and the earth dries out, i.e. the lower the leaf index, the more often the plot will have to be watered. Secondly, the overheated earth to a certain depth is “sterilized” under the influence of ultraviolet radiation and simple overheating. Microorganisms for which the thermal corridor is superior, the “animals” are larger, the living ones go deeper. And as a result, the nutrition of the soil is disturbed, due to the activity of beneficial microorganisms. And thirdly, the light and heat reflected from the ground rises and strongly heats the lower part of the plant leaves, which ultimately leads to a suspension of the biomass growth processes. And it turns out that there is a lot of light, and the plant cannot use it, as it “freezes”.
Let's sum up some results:
1. If we want to get the maximum yield, we need to achieve a leaf index of at least 4.
2. Pretty much garden plants do not give such a leaf index. And it can only be achieved if mixed landings . (A well-known, but rarely used scheme: Corn, curly beans along it and a pumpkin below, covering the whole earth with leaves)
4. Weeds growing on the site are not always a disaster or a competitor to the plants we grow. Often they together create the desired leaf index and, to the surprise of the owner, in the rough thickets of “weeds” the harvest is often better than on weeded hot clean land.
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