Approaches for increasing photosynthetic efficiency.

Abstract

This paper is one of several to discuss an important yet obvious point that photosynthesis is the ultimate source of energy for nitrogen fixation and nitrate reduction, and if net photosynthetic efficiency could be increased net nitrogen utilization should also be increased and/or prolonged. This will be true for nitrogen utilization directly linked to photosynthetic electron transport or more spatially separated as in the case of higher plants with photosynthesis in the chloroplasts and N2 fixation in the root nodules. In the latter case with the complex processes of sucrose biosynthesis, vein loading of sucrose, and directed sucrose transport to the sinks, the many intervening steps after the initial photosynthesis results in even greater reliance of net nitrogen fixation on the multiple steps for the efficiency of sucrose synthesis and its utilization. These facts have been repeatedly and conclusively demonstrated, most recently by Hardy’s program which demonstrated greatly increased nitrogen fixation and growth of soybeans grown in CO2 enriched atmospheres to stimulate photosynthesis (1). That will be described in the next paper. The problem now is no longer a need to demonstrate this fact, but how to increase net photosynthetic efficiency in a practical manner, particularly for those higher plants which support N2 fixation. Whether there are practical ways to increase the photosynthetic efficiency of higher plants is uncertain, but the problem is so important for increasing overall biomass production that collectively we must research it.KeywordsPhotosynthetic EfficiencyBundle Sheath CellOxygenase ActivityEnrich AtmosphereRibulose DiphosphateThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.