Introduction

Researchers who work with plants performance repeatedly face difficulties to measure leaf surface area. The most difficult task for most of the crop scientists is to define leaf area of complex leaves. The hidden problem of this challenge is related to the curved contour of these leaves.

Hence, the question is about why do we need to struggle so much and measure leaf surface area? What value does leaf area bring about the plant growth?

What Is The Problem With Leaf Surface Area Measurement?

Leaf is a mirror of the plant’s health and leaf area is one of the key parameters of tracking the plant’s growth. As a result, the more data is available to get about the leaf – the better quality of decision making is expected.

On one hand, the problem of leaf area measurement is not a problem at all. There are plenty of methods how to measure this key performance indicator for plants in ecophysiological studies.

On the other hand, the most popular methods are not effective but time consuming, not accurate or not convenient.

For example, millimetre graph paper method is widely used for leaf area estimation. Based on this method, the leaf area is estimated by tracing the shape of every leaf on a graph paper. It is accurate but laborious when there are large numbers of leaves for area estimation [1].

Weight paper method is one of the widely used as well and has significant linear relationships with the estimates obtained by using sophisticated leaf area meter [2].

The leaf dimension method of determining leaf area requires only a millimeter rule, but it is also time-consuming [3].

In these circumstances, to illustrate the correctness of measurements and to reduce the value of the error, it is necessary to increase the number of repetitions of measurements, which in turn requires extra time.

That’s why in accordance with fast pace of plant phenotyping there is a need to find a method of effective and accurate leaf area measurement to leverage the cutting edge technologies for plant science.

Indirect and direct methods for leaf surface area measurement

Indirect leaf area measurement includes non-destructive methods but direct leaf area measurement can be divided on destructive and non-destructive as well. Direct methods are simple to perform and accurate, but they require time and efforts. Additionally, some of them become unviable for endangered species. Also there are issues to use this methods on plants smaller in size, and for plants at their growth stage, when it is not possible to cut out leaves due to possible severe damage to the plant.

In contrast, indirect methods are quicker in their performance. They are also precise for plants growing in different environmental conditions, and allow multiple evaluations of the same individual plant without destroying the sample [4].

How to find the leaf surface area of a leaf?

Leaf surface area can be estimated through different methods:

1. Using visual and manual approach, for example, graph paper methods, weight paper method.
2. By leverage of equipment - ruler, mechanical planimeter or photo-planimeter, handheld leaf area scanner or office scanner.
3. With PC software, for example, ImageJ, WinFolia, Adobe Photoshop).
4. With smartphone mobile application such as Petiole Pro, Petiole App, Easy Leaf Area, etc.

Does the leaf surface area and specific leaf mean the same?

No, it is not the same. It is not correct to use definition of leaf surface area as specific leaf area and vice versa. Some crop researchers incorrectly use “specific leaf area” with the same meaning as “leaf surface area” to determine how much new leaf area to deploy for each unit of biomass produced. However, the definition of these terms are different. Leaf surface area is an area of a leaf surface. At the same time, specific leaf area is the ratio of leaf area to leaf weight [3] and it explains more complex relationship between plant traits [5, 6, 7]

Is the leaf surface area and leaf area index the same?

Not exactly. The leaf surface area and leaf area index (LAI) are related but not the same. Leaf surface area refers to the total area of all the leaves on a plant.

Leaf area index, on the other hand, is a measure of how much leaf area there is in a given area of ground. It is calculated by dividing the total leaf area of a plant by the ground area that the plant is growing in.

Leaf Area Index is a common measure used in plant ecology, forestry, and agriculture to assess the canopy density and leaf area of a plant. It is an important factor in determining the efficiency of photosynthesis, water use, and the overall health of a plant.

Does leaf surface area and leaf size mean the same?

No, leaf surface area and leaf size are not the same. While leaf surface area refers specifically to the amount of surface area that a leaf occupies, leaf size is a more comprehensive term that encompasses multiple parameters such as leaf surface area, leaf dry mass, leaf length, and leaf width. Leaf surface area is an important metric in plant physiology and physiology studies, but it is not the only measure that can be used to understand the size of a leaf.

Additionally, leaf size can also be described by its shape, texture, color and other features. Therefore, leaf size is a more comprehensive term that describes the overall characteristics of a leaf, while leaf surface area is a specific metric that is used to measure one aspect of leaf size. [8].

What is leaf area, leaf surface area and leaf area index?

Leaf area and Leaf surface area in most cases mean the same. However, they differ from leaf area index. All three terms (words) are associated with the photosynthetic capacity of plants, but the meaning of “leaf area index” is wider. It means the proportion of leaf area per unit of land area and to get leaf area index you must know the leaf area. The basic LAI formula is LAI = [Leaf area (m2)/Ground cover (m2)], but there are more complicated versions. For example, the formula to calculate leaf area index based on leaf surface area and weight is: —image— This Leaf Area Index formula includes the following numbers:

• Dry weight sampling area in grams;
• Sampling area, which is leaf area or leaf surface area in square centimetres;
• Leaf dry weight in grams;
• Leaf area in square centimetres [9].

Why Is Leaf Surface Area Important?

Determining leaf surface area is a valuable tool for professionals working in the field of agronomy, plant breeding, biology, and ecology. By measuring leaf surface area, these experts can gain important insights into the growth and development of plants, and how they interact with the environment.

For agronomists, measuring leaf surface area can help to understand the impact of different varietal characteristics on crop development. This information can be used to improve crop productivity and develop sustainable agricultural practices. For example, agronomists can use leaf surface area measurements to determine the effects of varietal characteristics on crop growth and resistance to diseases and pests. They can also use this information to set irrigation standards, understand the performance of vegetative mass of plants, and calculate the economic damage threshold force.

For plant breeders, leaf surface area measurement can provide important information about the genetic makeup of plants. By understanding how different varietal characteristics affect leaf surface area, plant breeders can develop new crop varieties that are more productive and resistant to disease and pests.

For biologists, leaf surface area measurement can provide insights into the functioning of plants and how they interact with the environment. By measuring leaf surface area, biologists can understand how different plant species differ in their photosynthetic capacity, susceptibility to disease and pests, and growth and survival rates. This information can be used to understand how different plant species compete for resources and how these interactions impact the functioning of ecosystems. Additionally, leaf surface area measurement can be used to understand how different plant species respond to environmental changes such as changes in temperature, light, and water availability.

For ecologists, leaf surface area measurement can provide a deeper understanding of how plants interact with the environment and how this interaction affects the functioning of ecosystems. For example, by measuring leaf surface area, ecologists can understand how different plant species differ in their photosynthetic capacity and how this capacity is affected by environmental factors such as light intensity and temperature. They can also use this information to understand how different plant species adapt to different environmental conditions and how these adaptations impact the functioning of ecosystems.

In summary, determining leaf surface area provides a wealth of information for professionals working in the field of agronomy, plant breeding, biology, and ecology. By measuring leaf surface area, these experts can gain important insights into the growth and development of plants, and how they interact with the environment. This information can be used to improve crop productivity, develop sustainable agricultural practices, and understand the functioning of ecosystems.

Leaf area in Agronomy

An understanding of the leaf apparatus is crucial for a wide range of calculations in agronomy, as it plays a critical role in crop production. The leaf apparatus is involved in light interception, crop growth, weed control, crop-weed competition, crop water use, and soil erosion.

Measuring leaf area is an important task for agronomists as it is necessary for determining different characteristics such as transpiration of crops, photosynthetic pigments in cells of crop leaves, calculate area of leaves impacted by plant diseases and pests, estimate economic damage threshold force and assess performance of vegetative mass of plants

Transpiration of crops

Transpiration is the process by which water is lost from plants through the stomata of the leaves. By measuring leaf area, agronomists can determine the amount of water that is lost through transpiration and set irrigation standards accordingly.

Photosynthetic pigments in cells of crop leaves

Photosynthesis, as the process by which plants convert light energy into chemical energy, depends on leaves. Photosynthetic pigments, such as chlorophyll, are responsible for absorbing light energy.

Hence, leaf area measurement helps to determine the amount of photosynthetic pigments in the cells of crop leaves. This information also helps to suggest how different crop varieties differ in their photosynthetic capacity.

Area of leaves impacted by plant diseases and pests

Plant diseases and pests can have a significant impact on the growth and productivity of crops.

When measuring leaf area agronomists can determine the area of leaves that are impacted by diseases and pests. Also this information contributes to general understanding of how different crop varieties differ in their susceptibility to disease and pests.

Calculation of economic damage threshold force

Agronomists need to understand the economic impact of diseases and pests on crops. This is the core of farming business. Hence, measuring leaf area helps to calculate the economic damage threshold force.

This data is crucial to make decisions about the use of pesticides and other control measures.

Performance of vegetative mass of plants

Finally, agronomists need to understand the performance of vegetative mass of plants in order to make decisions about crop management and breeding. Leaf area measurement gives insights on how different crop varieties differ in their vegetative mass.

This data also contributes to overall understanding of how different crop varieties differ in their growth and productivity.

Leaf Surface Area Measurement for Plant Breeders

In plant breeding, measuring leaf surface area is an important tool for understanding the impact of different varietal characteristics on crop development. Specifically, leaf surface area measurement is used to determine the effects of varietal characteristics on two key aspects of crop growth and development:

Forming leaf apparatus

Leaf surface area is a critical indicator of the formation of the leaf apparatus, which is responsible for photosynthesis, transpiration, and the absorption of nutrients and water.

Plant breeders can understand how different varietal characteristics affect the formation of the leaf apparatus. It also can show how this affects the overall growth and productivity of the crop.

Resistance to diseases and pests lesions

Leaf surface area is also a useful indicator of a crop’s resistance to diseases and pests. By measuring leaf surface area, researchers may see how different varietal characteristics affect the susceptibility of a crop to diseases and pests.

Leaf area data used with other informational resources about the plants shows how this affects the overall growth and productivity of the crop. It is possible to use this information to select plant varieties that are more resistant to diseases and pests. It also helps to improve crop productivity.

Prediction of the yield of the crop

Additionally, leaf surface area measurement can also be used to understand how leaf surface area affects the yield of the crop. Plant breeders can understand how different varietal characteristics affect the yield of the crop, and how this affects the overall growth and productivity of the crop. This information can be used to develop crop varieties with improved yield.

Impact on water use efficiency of the crop

Leaf surface area measurement can also be used to understand how leaf surface area affects the water use efficiency of the crop. By measuring leaf surface area, plant breeders can understand how different varietal characteristics affect the water use efficiency of the crop, and how this affects the overall growth and productivity of the crop. This information can be used to develop crop varieties that are more efficient in the use of water and to improve crop productivity.

Estimation of the nutrient uptake of the crop

Furthermore, leaf surface area measurement can also be used to understand how leaf surface area affects the nutrient uptake of the crop. By measuring leaf surface area, plant breeders can understand how different varietal characteristics affect the nutrient uptake of the crop, and how this affects the overall growth and productivity of the crop. This information can be used to develop crop varieties that are more efficient in the uptake of nutrients and to improve crop productivity.

Role of Leaf Surface Area in Ecology

Measuring leaf surface area plays an important role in ecology, as it helps to understand the functioning of plants and their interactions with the environment. The following are some of the key ways in which leaf area measurement can be useful in ecology:

Assessment of photosynthetic capacity of plants

Photosynthesis is the process by which plants convert light energy into chemical energy. Leaf surface area is an important indicator of a plant’s photosynthetic capacity, as it is directly related to the amount of light that a plant can capture.

Measuring leaf surface area can help ecologists to understand how different plant species differ in their photosynthetic capacity.

Additionally, they can assess how this capacity is affected by environmental factors such as light intensity and temperature.

Determining the impact of environmental conditions on the formation of plants

Environmental factors such as temperature, light, and water availability can have a significant impact on the growth and development of plants.

Measuring leaf surface area can help ecologists to understand how these factors affect the size and shape of leaves, as well as the overall growth and survival of plants.

These findings can be used to understand how different plant species adapt to different environmental conditions and how these adaptations impact the functioning of ecosystems.

Defining the populations of insects and microorganisms that affects plants

Plants interact with a wide range of insects and microorganisms in the environment. Mentioned interactions can have a significant impact on the growth and survival of plants.

Measuring leaf surface area can help ecologists to understand how various plant species differ in their susceptibility to insect and microorganism damage.

They can also think about how this susceptibility is affected by environmental factors. For example, the most important of them are temperature, light, and water availability.

Availability of this information is supporting overall understanding of how different plant species compete for resources.

Understanding the effects of leaf surface area on the growth and survival of plants

Leaf surface area, as an important factor, affects the growth and survival of plants. It relates to the amount of light that a plant can capture and the amount of water and nutrients it can absorb.

Measuring leaf surface area can help ecologists to understand how different plant species differ in their growth and survival rates. Also, as it was mentioned above - it supports their overall understanding of how these rates are affected by environmental factors.

Understanding the leaf surface area in relation to the biomass

Leaf surface area is also a good indicator of the total biomass of a plant. Measuring leaf surface area can help ecologists to understand how different plant species differ in their biomass. Additionally, it may help in understanding of how this biomass is affected by environmental factors.

Case Study of Leaf Surface Area Measurement

The case studies below can help you understand why measuring leaf surface area is important. They show how measuring leaf surface area can be helpful for plant science research. By reading these case studies, you will be able to see the benefits of measuring leaf surface area.

Leaf Surface Area of Maize after Application of Bio-based products

A team of Ukrainian scientists from the National University of Life and Environmental Sciences, in collaboration with researchers from the Institute of Energy Crops and Sugar Beet, conducted an experiment to study the effects of pre-sowing treatment on maize.

The scientists applied bio-based products Mycofriend, Mikovital, and Florobacillin (all produced in Ukraine) to the maize plants and then measured various performance indicators such as leaf surface area, water content and mass of leaves and root system, soil moisture holding capacity and its physical state, and yield.

The leaf surface area was measured at 30th, 60th, 90th and 120th days of vegetation. Petiole App was the tool they used for leaf area measurement.

The researchers randomly selected 100 leaves in each variant (25 leaves from each repetition) and used these measurements to analyze the results. The findings of this experiment were published in April 2021 as a part of E3S Web of Conferences. The research aims to contribute to the development of sustainable agricultural practices and improve crop productivity.

To watch how Petiole Pro helps to measure leaf area of corn leaves, watch one of our latest videos:

Non-destructive leaf area measurement of alfalfa in biotechnology

A team of Canadian plant breeders were conducting research to enhance the drought tolerance of forage crops, with a particular focus on alfalfa. As one of the most vital crops for animal feed, alfalfa is a crucial area of study for the group.

The breeders have been conducting experiments on alfalfa plants and measuring the leaf surface area. To obtain the leaf area data, they employed both destructive and non-destructive methods and both mobile applications Petiole App and Petiole Pro. Specifically, they destructively measured leaf surface area for 45 leaves and non-destructively for 16 leaves.

The findings of their research have been published in the journal Frontiers in Plant Science on January 13, 2022. This study aims to contribute to the development of more resilient and sustainable crop varieties, thus improving food security and reducing the environmental impact of farming.

Leaf Surface Area and Leaf Area Ratio in Beech Forest Research

Scientists from the Swiss Federal Institute for Forest, Snow and Landscape Research (WSL) were investigating the survival time and mortality rate of regeneration in the deep shade of a primeval beech forest.

They proposed that Leaf Area Ratio (LAR), as an alternative to radial stem growth, can be a crucial characteristic in understanding the mortality rate of juvenile trees in beech forests.

To test this theory, they measured the leaf surface area of 289 living seedlings and saplings and used these measurements to calculate LAR using the formula: LAR = LA/m(total), where LA represents leaf area and m(total) represents the total dry mass (aboveground and belowground) of the tree.

The results of this study were published in the European Journal of Forest Research on November 5, 2021.

The research aims to provide a better understanding of the growth and survival of beech forests, which play an important role in maintaining biodiversity and carbon sequestration. The use of LAR as a key characteristic can also aid in the management and restoration of these forests.

Conclusions

Measuring leaf surface area is a commonly used performance indicator for plants, as it provides insight into how plants adapt to environmental changes and monitor their development. This parameter is essential for fields such as agronomy, plant breeding, and ecology. Finally, there are various methods for measuring leaf surface area, but the choice of technique depends on the specific plant being studied.

References

[1] Jadon M. A Novel Method for Leaf Area Estimation based on Hough Transform. Journal of Multimedia Processing and Technologies, Volume 9, No. 2, June 2018, https://doi.org/10.6025/jmpt/2018/9/2/33-44

[2] Pandey S., Singh H. A simple cost-effective method for leaf area estimation. Journal of Botany, 2011, https://doi.org/10.1155/2011/658240

[3] Wolf D., Carson E., Brown R. Leaf Area Index and Specific Leaf Area Determinations, 1972, https://www.crops.org/files/publications/nse/pdfs/jnr001/001-01-0024.pdf

[4] Non-destructive method for estimating leaf area of Erythroxylum pauferrense (Erythroxylaceae) from linear dimensions of leaf blades. Acta botánica mexicana, no. 127, e1717, 2020, https://doi.org/10.21829/abm127.2020.1717

[5] Chelli, S., Ottaviani, G., Simonetti, E., Campetella, G., Wellstein, C., Bartha, S., Cervellini, M. and Canullo, R. Intraspecific variability of specific leaf area fosters the persistence of understorey specialists across a light availability gradient. Plant Biol J, 23: 212-216. https://doi.org/10.1111/plb.13199 .

[6] de Ávila Silva, L., Omena-Garcia, R.P., Condori-Apfata, J.A. et al. Specific leaf area is modulated by nitrogen via changes in primary metabolism and parenchymal thickness in pepper. Planta 253, 16 (2021). https://doi.org/10.1007/s00425-020-03519-7

[7] Firn, J., McGree, J.M., Harvey, E. et al. Leaf nutrients, not specific leaf area, are consistent indicators of elevated nutrient inputs. Nat Ecol Evol 3, 400–406 (2019). https://doi.org/10.1038/s41559-018-0790-1

[8] Wang C, He J, Zhao T-H, Cao Y, Wang G, Sun B, Yan X, Guo W and Li M-H (2019) The Smaller the Leaf Is, the Faster the Leaf Water Loses in a Temperate Forest. Front. Plant Sci. 10:58. https://doi.org/10.3389/fpls.2019.00058

[9] Campillo C., García M., Daza C., Prieto M. Study of a Non-destructive Method for Estimating the Leaf Area Index in Vegetable Crops Using Digital Images, HortScience, 45:10. https://journals.ashs.org/hortsci/view/journals/hortsci/45/10/article-p1459.xml?rskey=0ngapT