Manganese Requirement with Respect to Growth, Hill Reaction and Photosynthesis.

The necessity of manganese for the growth of both autotrophic and heterotrophic plants was reported first by Bertrand (5, 6) more than 50 years ago, and the essentiality of manganese for the growth of Chlorella was shown originally by Hopkins (20) of Cornell University in 1930. The relation of manganese to photosynthesis was suspected by McHargue (24) and Bishop (7). However, it was not until 1937 when Pirson (25) showed that the photosynthesis of manganese-deficient Chlorella cells was partially inhibited and that the inhibition could be relieved instantaneously by the addition of manganese to the medium. Emerson and Lewis (12, 13) observed that the absence of micronutrient elements in the culture medium caused a decrease in the quantum yield of photosynthesis, and that the efficiency of photosynthesis was improved more with the addition of manganese than with the addition of any other micronutrient element. The literature on this subject has been reviewed by Pirson (26). AMore recently, there has been the work of Kessler (21), Habermann (18), Pirson and Bergmann (27) and Reisner and Thompson (31, 32, 33). This paper reports a study of the growth, Hill reaction, and photosynthesis of Chlorella pyrenoidosa cultured autotrophically and heterotrophically at various levels of managanese, and similar studies with autotrophically cultured Nostoc muscorum, Scenedesmus quadricauda, Porphyridium cruentum and Lemna minor. Measurements pertaining to the chlorophyllmanganese ratio and the relation of manganese both to the chlorophyll content and to the destruction of chlorophyll by light are also included. Preliminary results have already been published (14), and some of the present results were reported at the 1956 meeting of the American Institute of Biological Sciences (15).