Nitrogenase activity in the papyrus swamps of Lake Naivasha, Kenya

✍ Scribed by F. B. Mwaura; D. Widdowson

• Publisher: Springer
• Year: 1992
• Tongue: English
• Weight: 492 KB
• Volume: 232
• Category: Article
• ISSN: 1573-5141
• DOI: 10.1007/bf00014608

✦ Synopsis

Nitrogenase activity (acetylene reduction activity) was found to occur universally in the Cyperus papyrus swamp in Lake Naivasha. Low rates of acetylene reduction activity (0 .9-104 .9 nmol C 2H 4 g d.wt . roots -' h -1 ) were associated with excised roots of C . papyrus but higher rates of activity (89 .0-280 .4 nmol C 2H4 g d .wt . roots -1 h -') were associated with intact root systems of the plant . It was estimated that nitrogen fixation associated with young roots alone could supply about 26% of the nitrogen requirements of growing papyrus plants . Acetylene reduction activity in the lake bottom sediments was generally low and associated with adjacent papyrus stands . Plate counts of putative aerobic and facultatively anaerobic N 2-fixing bacteria associated with papyrus roots showed the presence of high numbers of diazotrophs (5 .4 x 106 CFU g d .wt . roots -') . Fewer numbers of N 2-fixing bacteria were detected in the sediments (1 .9 x 103-3.2 x 10 4 CFU g d .wt . sediment -1 ).