Dr. Usha, You may be right here...
the fall started, the plant was capable enough to convert most of its flowers into fruits, successfully...during its life...
now the season nearing end...
no more photosynthesis required...
when chlorophyll diminishes, hues of other pigments dominate...
abscission might have already started, or might be in the process, to curtail the food and water supply...from and to the leaves....
now its ready for hibernation...
with the satisfaction of producing numerous offspring for the generations to come...
Vijayasankar Raman
National Center for Natural Products Research
University of Mississippi