Leaf area determination in fruit crops

 Leaf area determination in fruit crops

Aim of the experiment: To determine the leaf area of fruit crops by adopting different methods.

Important information:

The plant parameters such as leaf area (LA) or leaf area index (LAI) play an important role in understanding photosynthesis, light interception, water and nutrient use and crop growth. A better understanding of the relationships between crop development and environment is thus important. Both LA and LAI can be measured directly by using digital meters (destructive methods) and graphical methods or indirectly using developed regression techniques (non-destructive methods).

Determination of leaf area by leaf area meter:

In direct method (destructive methods), leaves are removed from the plant and measurements are done using digital leaf area meter or hand leaf area meter. Leaf area meter provides leaf area measurement through electronic rectangular approximation this instrument can also be used to measure the area of non-transparent flat surface material like cloth/paper/plastic/leather etc. A leaf area meter provides a non-destructive means for environmental scientists and farmers alike to ascertain plant health, quality and local ecological trends as reflected in the leaf’s area, length, average width and maximum width.

In principle the leaf is placed between a light source and a photocell, the reduction in photocell output due to the presence of the leaf then gives a measure of leaf area. The transmission of light through the leaves is a source of error, and an attempt to minimize this is usually made by fitting a magenta filter between the leaf and the photocell to absorb any green light passing through the leaf.

Leaf area measurement of plants are useful for many scientific disciplines. Monitoring the distribution and changes of leaf area is important for assessing growth and vigour of vegetation on the planet. It is fundamentally important as a parameter in land-surface processes and climate models.

This variable represents the amount of leaf material in ecosystems and controls the links between biosphere and atmosphere through various processes such as photosynthesis, respiration, transpiration and rain interception. A measurement that is seemingly so simple and fundamental is really the backbone that provides the framework for further research in areas like ecology, agronomy, entomology, carbon cycle research and plant pathology. These and many other disciplines rely on the measurement of leaf area in much of their work.

The steps for the digital leaf area meter are as follows;

1.      On your digital leaf area meter 30 min for warmup prior-to taking observations.

2.      Calibration of the digital leaf area meter.

3.      Then select the appropriate glass plate and place it on the dark plate.

4.      Place the leaf upside down on the dark plate then place the glass plate on the leaf so as to press it.

5.      Then pull the shutter of the digital leaf area meter out, the leaf area will be displayed on the screen.

Determination of leaf area by graph paper method:

Leaf area can be calculated by grid or graph paper technique. In this method the leaves are removed and the leaf outer lamina was drawn in the graph paper then the leaf area is counted manually. The bigger square represents the area of 1cm2, while the smaller one represents the area of 1mm2. The total leaf area can be calculated by adding all the squares.

While calculating leaf area, a box occupying area more than half the area of a complete square box was taken equal to area of a complete square box. The area of a half square box was taken exactly half the area of a complete square box, while the box occupying area less than half area of a complete square box was discarded.

Determination of leaf area by empirical formulae method:

The developed equations were used to estimate the leaf area and LAI separately. The equations are already being developed for many crops. By using graphical and leaf area meter 1st the equations constant is determined then verified and recommended.

The formulae for a few fruit crops are mentioned below;

Fruit crop

Cultivar

Formulae

R2

Remarks

Banana

Basrai

0.0266 + 0.7629 Leaf width

0.980

Potdar M.V., Pawar K.R., Non-destructive leaf area estimation in banana, Sci. Hortic.45 (1991) 251–254

Strawberry

General

1.89 + 2.145 × (upper lobe length) × (left lobe width)

0.993

Demirsoy H., Demirsoy L., Ozturk A., Improved model for the non-destructive estimation of strawberry leaf area, Fruits 60(2005) 69–73.

Guava

General

16.44 – 3.11 L + 0.58 L2

L= length of the leaf midvein

0.961

Kobayashi K.D., Estimating leaf area of ‘Beaumont’ guava, Trop. Agric. 65 (1988).173–175

 

Assignment:

1.      Determine the leaf area of 5 fruit crops by adopting the different methods and compare the accuracy.

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