Diurnal fluctuations in photochemical activities of chloroplasts in field grown Cyamopsis tetragonoloba seedlings

In field-grown Cyamopsis seedlings, distinct changes were found in the rate s of photosystems (PS) 2 and 1 activities at different time of the day. Max imum PS2 activity was at around 11:00 h and decreased thereafter. On the co ntrary, PS1 activity continued to increase up to 14:00 h and declined in ev ening hours. Significant energy transfer from PS2 to PS1 was evident during the morning and evening hours of the day whereas a slow excitation of PS2 and energy transfer was favoured during noon hours.