have gone for graph paper calculation of leaf area but can anyone help me out with tricky and easy method/formula to know total leaf area of a plant without measuring every leaf?
Why dont you measure canopy volume of trees. Secondly, you can measure the number of leaves per meter of shoot length and number of growing fruits per meter shoot length to give you fair idea about leaves-to-fruit ratio ...This is what , we follow as standard practice....
The best is to take same number of the leaves from the top, the middle and the bottom parts of the tree and then I agree with Mr Pegman you could multiply your mean by the total number of the leaves
it depending on the crops or trees, take a possible number of leaf samples may be 30/50/------ depending on the volume of trees, here after measure the leaf area and make it average and multiply the whole numbers.