Abstract

It has been reported that the process of nitrate reduction is coupled with a photochemical reaction and CO2 assimilation taking place in the aerial portion of plants (4,10,14,15). It has also been reported that those enzymes, i. e. nitrate reductase, nitrate reductase, and dehydrogenases, needed for nitrate reduction are localizied within the chloroplast (3, 20). Thus nitate reduction is closely associated with photosynthesis, at least in some tissues. In contrast to this, some investigators (8,9,23) have concluded that plant roots, lacking chloroplasts and devoid of illumination, and so unable to carry out photo-chemical reactions and CO2 assimilation, still have nitrate reductase activity. Therefore, photosynthesis does not seem to be a necessary requirement for nitrate reduction. The odject of our present studies, in addition to looking into the above two contradictory theories, is to further study; (1). Distribution of nitrate reductase in plants, (2). Change of nitrate reductase activity in plant life, (3). The effect of malnutrition on nitrate reductase activity, and (4). The effect of the N-source on the nitrate reductase activity.