Dry Matter Accumulation in Sunflower and Maize Leaves as Measured by an Improved Half-Leaf Method

Abstract

An improvement of the half-leaf method was made by the application of steaming to conducting cells to stop translocative outflow of assimilates. The improved method was used for obtaining the diurnal change of the photosynthetic accumulation, translocative outflow and respiratory loss of matter in fully exposed leaves of sunflower and maize plants. The maximum rates of photosynthesis obtained, 28mg dry matter/dm²/hr for sunflower and 40mg for maize were comparable to those reported recently by the improved gasometric leaf-chamber methods. The photosynthetic activity proceeded roughly in parallel with the change of light intensity, and the variation of photosynthetic CO₂-fixation was closely followed by that of translocation; hence moat of the translocative outflow of assimilates occurred in daylight hours.