ISSN:
1432-0789
Keywords:
Blue-green algae
;
Chemical composition
;
N2
;
fixation
;
Rice fields
;
Cyanobacteria
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
,
Geosciences
,
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Summary Laboratory cultures, soil cultures, and natural samples of N2-fixing blue-green algae (BGA) from rice fields were analyzed for dry matter, ash, N, C, P, and a few other constituents. Results show a very large variability of the composition. Dry matter contents ranged from 0.28% to 13.6% (average 3.3%). Ash contents ranged from 15.6% to 71.3%. Nitrogen contents ranged from 1.9% to 11.8% on an ash-free basis (average 6%). Carbon content was less variable, ranging from 37% to 72% and averaging 43.7%. A decrease in N and pigment contents, and an increase in reducing sugars, was observed in aging laboratory cultures. Large differences in composition were observed between field samples and material grown in artificial medium. Soil-grown BGA and field samples were characterized by very high ash contents, N contents lower than those in laboratory cultures, and P deficiency. Extrapolation from (1) average dry matter, ash, and N contents and (2) records of BGA biomass in rice fields indicates that an algal bloom has a potentiality of about 15–25 kg N per hectare and that a BGA biomass of agronomic significance is visible to the naked eye.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00257592
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