Manganese in relation to photosynthesis

Summary It has been proved that manganese deficiency results in a reduced carbon dioxide assimilation. Different symptoms of manganese deficiency of oats could be traced back to shortage of assimilates in the leaves. This is particularly true for reduced growth, the bending over with a kink of the leaves, the necrotic leaf spots, the withering of the diseased leaves with phenolred, the accumulation of nitrates in the leaves and the reduced resistance of the roots towards bacterial infection.Investigations on the influence of manganese on photosynthetic processes were carried out by the author just before and during the beginning of the war. Owing to changing circumstances this work could not be continued and consequently remained fragmentary in some aspects. Those results, which still seem to be of sufficient importance will be published in a series of papers, of which this is the first.