I am studying faba bean and all the analysis I found are done on the third leaf (RNA extraction, SPAD, ...). I want to know why this leaf and if we start to count for the third leaf from the top or the bottom?
Ihsein Rokia Amine-Khodja, It is recognized that the first fully expanded leaf (the third leaf from the top of faba bean plant) expresses for the nutritional status of the plant.
Hi, usually the measurements are taken on the third leaf from the top beacuse by the time of having the other two top leaves, that third one has reached fully expansion and full maturity. So it has nothing to do with the faba bean in particular, it is a general rule in measurments for most plants.