asacomm

Many thanks for your comment, Rj,

You are right in saying that so many variable factors should be examined
and verified before deciding any conclusion.

But on the other hand, the biggest reason of my guess is that the same
thing had happened with my avocado trees.

The leaves of the same species and the same year showed exactly the
opposite result against the temperature difference between the lowest
and the highest depending on their standing locations.

The leaves of the tree planted under full sunshine died, while the other one
under limited sunshines were alive and kept green.