Net Photosynthesis and Transpiration of Sun- and Shade-grown Ficus benjamina Leaves1

Suitable conditions for determining net photosynthesis (Pn) of individual sun- and shade-grown leaves of weeping fig ( Ficus benjamina L.) were 21°C dew point and an air flow rate between 1 and 3 liters/min. A diurnal trend in Pn occurred for sun leaves, with maximum rates between 0800 and 1200 hr ; shade leaves did not decline in Pn until mid-afternoon. Leaves which originated from nodes 4 through 10 (from the shoot apex) did not differ in Pn, transpiration (Tr), specific leaf weight (SLW), or leaf water content. Shade-grown leaves had a photosynthetic advantage over sun-grown leaves at levels of photosynthetically active radiation (PAR) below 77 μE m −2 s −1 , whereas at PAR levels above 100 μE m −2 s −1 the reverse was true. Sun-grown leaves had higher Tr rates than shade grown leaves at all PAR levels used.