Please see:

https://www.witpress.com/Secure/elibrary/papers/ECO09/ECO09010FU1.pdf

http://www.pjlss.edu.pk/pdf_files/2015_2/117-125.pdf

I suggest to read the following articles, they include a fairy useful information  about the best technique for leaf area measurements

Good luck

Thank you Gonzalo for your response, But I am still looking for more answers.

Thanks again

Jalal

Peace, Mercy and Blessings of God

Dr. Jawad; thanks for your kind response.

Actually, I am looking for a specific answer concerning the equation that I mentioned in my question above. We have been using this formula since the 1990s, but I have not found the reference that adopts this equation. Anyone who referred before to this equation has attributed it to a reference, which I am not sure of its accuracy yet. So, I'm trying to discover the matter.

Thanks again for your interest

Best regards

Jalal

Please find attached the full text of the first reference you mentioned (Thomas 1975). On page 335, para 1, line 2: the reference confirms your equation (for area of leaves)

Dear Dr. Tarafdar

Thank you so much for sending the full text of Thomas (1975) and I do really appreciate your attention.

The article shows that Thomas used the equation but he didn't mention, why this equation? The equation wasn't the subject of his study! It was just a tool! And he didn't refer to the reference that adopted the equation!. Thomas' article doesn’t confirm if the equation is right or not. In addition to all of that it's not about wheat.

Thanks a lot again. Your help really add more information, but I'll keep collecte any related information. I hope I'm not driving in wrong road! Thanks again.

Best regards

Jalal

Dr. Hamza, please see the attached publication, hope you will get your answer.

Dear Dr. Tarafdar

Thanks for your attention.

I think you sent me a wrong article lately. I think its just a mistake when you chose an article to upload!

Thanks again for being in touch.

Best regards

Jalal