Part 2: aspects of the relation between photosynthesis and crop productivity

Photosynthesis is amongst the basic physiological processes, affecting plants productivity. There can be different means to increase productivity, and most of them involve increase of photosynthetic activity. Photosynthesis can be influenced by many stressors, which exert different effects, but they have in common a negative impact on productivity. Moreover, the alleviation of stress by plants correspondingly decreases productivity. Thus, the summarised effects of stress were only generally mentioned in this article, and the process of photorespiration was underlined. Photorespiratory pathway relates photosynthesis and productivity, and can also protect plants from oxidative stress at the expense of carboxylation. In addition, alterations of the photorespiration can disrupt the balance between carbon and nitrogen in the biomass of plant. Being a common metabolic pathway between the photosynthesis and many assimilatory metabolic pathways, such as the biosynthesis of proteins and assimilaiton of nitrogen and sulphur, photorespiration binds the photosynthesis to productivity. One very important topic, especially under the global increase of CO2 content in the atmosphere is the relation between carbohydrates and protein biosynthesis. It affects differently the C-3 and C-4 species, thus photosynthetic specifics of these plants were reviewed as well. C-4 are often considered more competitive and productive, as compared with other plants and therefore are preferred as innovative crops under the future climatic conditions.