LEAF SOLAR TRACKING RESPONSE EXHIBITS DIURNAL CONSTANCY IN PHOTOSYSTEM-II EFFICIENCY

A unique behaviour was observed in solar tracking plant (diaheliotropi c) species with a characteristic ability to maintain constancy in phot ochemical efficiency and photosynthetic rates throughout the day while the static leaved plants exhibited typical midday depressions in F-v/ F-m and photosynthetic oxygen evolution. The higher photosynthetic eff iciency of diaheliotropic plants is proposed to be due to greater quan tum efficiency of photosystem II at superoptimal irradiances, which wa s found detrimental to static leaved and paraheliotropic plants. This is the first demonstration of the lack of photoinhibition in field con ditions in plants that maximise solar interception through solar track ing.