know leaf area index (LAI) for crop production

Leaf Area Index (LAI) is a term used to measure forests, crops, climate, and the environment and is calculated as half the area of all leaves per unit area of ground.

It is usually measured as the leaf area (m2) per ground area (m–2) and is unitless. 

A key variable often used in horticultural studies involves crop growth and yield. This variable is so important to check the performance of the crop.

We can make predictions about how much production based on these variables.

Know Leaf Area Index

In what is LAI, you better know that it represents the structural attributes of the leaf components estimated by the leaf area per unit of ground surface area.

This variable can easily represent the space for photon interception, affecting yield. The leaf index can indicate canopy health or development because it can affect how light moves through the canopy.

Also, know that LAI affects the canopy and the surrounding microclimate. Therefore, growers must check the relation between the canopy, leaf area, and surface for better yields.

They can identify how different variables can affect or promote plant growth with that information.

 determination of leaf area index

In simple terms, leaf area index is-

  • A key variable used in horticultural studies involving the relation between crop growth and yield
  • A helpful tool when looking to evaluate the performance of the crop
  • An indicator of canopy health or development
  • The most important parameters to measure leaves and their activity
  • A vegetation structural variable and essential in the feedback of vegetation to the climate system

How To Measure LAI

Now, as you know, what is the leaf area index? It is high time to measure it to make the most.

In calculating the leaf area index, it is said that LAI measurement can sometimes be time-consuming, but it solely depends on the method used.

To measure LAI, we have many direct and indirect ways. Direct methods can be in situ or destructive. For example, it involves removing leaves from the plant to make direct measurements or scans to calculate leaf area using different software.

leaf area index formula

For the direct calculation of the LAI leaf area index, one must use the following LAI formula:

Leaf area (m2)/ Ground area (m2) = m2/m2

LAI measurements methods

Direct methods involve direct measurements of the leaf, and to simplify the process, one needs to assume a specific geometric figure.

When it comes to indirect methods, we can use a variety of sensors working within the software to infer LAI using measurements. These measurements involve - light transmission to absorption and reflection of light through the canopy.

Here are the various sensors and software used to estimate the range of leaf area index value:

  1. Licor LAI-2000 Plant Canopy Analyzer
  2. PAR (active radiation) interception mapping method
  3. Digital images
  4. WinSCANOPY analysis system

You must know that a plant with an LAI of 2 has several leaves that can cover a given area 2 times. 

Thus, LAI is calculated for a plant or provided readings for a whole crop or region.

One of the most important parameters to measure leaves and their activity. One can use any of the mentioned methods for better information on calculating the leaf area index of maize.

importance of Leaf Area Index

LAI is known from leaves to the plants, which are many and varied. As leaves are the major eco-physiological parts of a plant, the leaves interact with the atmosphere and do many things, including

  • Absorbing carbon dioxide
  • Intercepting light necessary for photosynthesis
  • Releasing the oxygen formed as a byproduct of photosynthesis

What's more,

LAI is an essential parameter in plant ecology. It tells how much foliage can be measured by the active photosynthetic area and the area subjected to transpiration.

The LAI also provides complete knowledge of how much light comes through the canopy. In the case of a multi-layer ceiling, the LAI of an upper layer is important for the light received by a lower layer.

The LAI also indicates radiation, precipitation interception, energy conversion, and water balance indicator.

Overall, this is called a reliable parameter for plant growth. That is why most studies in agronomy and horticulture measure the results of fertilizers and irrigation LAI and yield.

How To Use Leaf Area Index

LAI provides plant response to environmental variables, net photosynthetic rate, transpiration, and more.

In addition, one can use the data and look for interaction between LAI and the variable measured, which will provide information on how different variables can affect or promote plant growth and yield.

LAI Measurement In A Greenhouse

LAI is the best at finding new applications in agriculture. For example, it calculates the correct amounts of foliar sprays of pesticides or fungicides needed to protect a crop.

With the help of the LAI, growers can easily diagnose the nitrogen status of cereals through satellite imagery, leading to timely applications of fertilizers to boost yield.

Apart from this, greenhouses can get many benefits via LAI. It provides clear information about the crop needs and helps evaluate new methods or management to improve production.

It can also tell growers about microclimate and system management necessities.


Learn about plant transpiration, water use, and humidity and directly relate its information to the yield. Then, with all the measured parameters, it is established in experimental greenhouses and tested in commercial greenhouses to get healthy plants and soil.

Therefore, estimating LAI is very promising and can play a role in the decision support systems used in modern greenhouse management for better crops.