Influence of light and pH on growth and nitrogenase activity on temperate-grown Azolla |
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| Authors: | A Moretti G Siniscalco Gigliano |
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| Institution: | (1) Dipartimento di Biologia vegetale, Facolté di Scienze, Universitá di Napoli, Via Foria 223, I-80139 Napoli, Italy |
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| Abstract: | Summary We investigated the influence of light intensity and pH on growth and acetylene reduction in three strains of Azolla filiculoides and one strain of A. pinnata cultivated under ambient conditions in Naples, Italy. A. pinnata showed maximum growth and acetylene reduction activity at 65% of natural light intensity (82 Klux) and at pH 5–7. In contrast, three A. filiculoides strains showed maximum values in a wider range of light intensity (50–100%) and pH (5–9). All optimal growth conditions of light intensity and pH were obtained from the determination of doubling time for dry and fresh weight increases. The lowest doubling time for all strains was in the range 2.7–3.3 days. Under these optimal conditions, the acetylene reduction activity rates were 46 nmol ethylene h–1 mg–1 dry weight for two strains of A. filiculoides from California, and 90 nmol for A. filiculoides from Naples and A. pinnata from Tancheng, Peoples Republic of China. These values correspond to those reported for strains of A. filiculoides and A. pinnata cultivated in areas outside Italy where the use of Azolla as biofertilizer has resulted in increased crop production. Therefore, the strains studied here may have a similar potential in Southern Italy as a source of biomass, dry matter and nitrogenous compounds.Research work supported by CNR, Italy. Special grant I. P. R. A. Sub-project 1. Paper No. 814 |
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| Keywords: | Azolla N2-fixation Biofertilizer A filiculoides A pinnata Light effect pH effect Acetylene reduction assay |
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