Leaf scale photosynthesis measurements in maize field under different fertilization addition

Abstract

Carbon dioxide (CO2) fluxes between the surface and the atmosphere have large biological contribution. Photosynthesis is one of the largest of these fluxes. Components of the carbon balance are in close relationship with plant production, and eventually yield in agricultural vegetation. We examined photosynthesis of maize in the 2019 vegetation period in this study. The study site is a sowing time−fertilizer−maize variety field experiment near Martonvásár. This is a small plot experiment, where a treatment replicate consists only of two rows of maize i.e. a total of about 60-70 individual plants. Ecosystem scale micrometeorological measurements are not applicable in this type of setup and the only destructive examinations can be done upon harvest to avoid disturbance of the experiment in the vegetation season. We used non-destructive leaf scale photosynthesis measurement method (CIRAS-3, PPSystems, and Amesbury, MA, USA) regularly to explore temporal variations of assimilated CO2 during the vegetation period. The sampling was designed to include several plants and leaves to optimize number of replicates. We selected five plants per row in five replicates (leaves). The methodology was applicable for determination of maize photosynthesis in the experiment. Light response and temperature response of photosynthesis agreed with our knowledge. We found that net photosynthesis rate of maize leaves have a well-defined profile in the vertical canopy as light and leaf age changes, which highlights the importance of repeated measurements in the canopy when planning regular observations.