Leaf area index depending on intensity. Leaf index. Pain along the inner surface of the leg, radiating to the groin, and sometimes along the front of the thigh to the inner ankle

Body mass index (BMI) - Quetelet index Body mass index makes it possible to determine how much weight is deviated from the norm. This knowledge helps to prevent the development of a number of diseases that are associated with overweight. Determine the body mass index: divide your weight in kilograms

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 eventually 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 daily cycles 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.

1. Crops and plantations as photosynthetic systems

   1. 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.

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

index- 01 GENERAL PROVISIONS. TERMINOLOGY. STANDARDIZATION. DOCUMENTATION 01.020 Terminology (principles and coordination) 01.040 Dictionaries 01.040.01 General provisions. Terminology. Standardization. Documentation (Dictionaries) 01.040.03 Services. Organization of companies... Index of National Standards 2013

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

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 - an 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 at an I.l.p. equal to 8- 10 (this level is typical for forests).[ ...]

The leaf index is the ratio total area leaves of plants to the area of ​​crops. 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 entire 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. Most plant communities in fairly favorable land conditions have from 3 to 8 m2 of leaf surface for intercepting sunlight 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.