The role of blue-green algae in nitrogen fixation in rice-fields

De, P. K.

doi:10.1098/rspb.1939.0014

Cited by 189 publications

(29 citation statements)

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“…In culture media, the optimal pH for the growth of cyanobacteria ranges from 7.5 -10, with a lower limit of 6.5 -7.0. However, in soilculture experiments, soils having slightly alkaline reaction were more favourable, while in natural environments cyanobacteria prefer neutral to alkaline pH [3,20]. The development of soil acidity is generally believed to be associated with the base unsaturation caused by leaching out of bases and genesis from base-poor acidic rocks.…”

Section: Resultsmentioning

confidence: 99%

Soil Ph and Its Role in Cyanobacterial Abundance and Diversity in Rice Field Soils

Prasanna¹

2007

Appl Ecol Env Res

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Nayak -Prasanna: Soil pH and its role in cyanobacterial abundance and diversity in rice field soils - Abstract. The influence of soil pH was evaluated on the abundance and generic diversity of cyanobacteria in soil samples collected from diverse rice soil ecologies of India. Qualitative and quantitative studies of the 52 soil samples collected from nine agroecologies was carried out using enrichment, MPN (Most Probable Number) techniques and diversity indices were measured. A total of 166 forms, including 130 heterocystous and 36 non-heterocystous isolates were isolated and the highest percentage of abundance of heterocystous forms was observed at pH of 8.1. Highest Shannon's diversity index was recorded at a pH of 6.9, followed by pH of 7.4, while indices of richness and evenness (J and E) were highest in soil samples of pH of 9.3. This study highlighted the successful colonization of cyanobacteria in rice field soils of diverse pH and the need for enrichment of the native flora as a means of exploiting the full potential of cyanobacterial biofertilizers in agriculture

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Section: Resultsmentioning

confidence: 99%

Soil Ph and Its Role in Cyanobacterial Abundance and Diversity in Rice Field Soils

Prasanna¹

2007

Appl Ecol Env Res

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“…Phosphatase activity has been found in all major groups and numerous species of algae and is found widespread among Plimited cyanobacteria though not universally [9,12,17,18]. Rice fields constitute a very interesting habitat for the study of phosphatase activity as they are dominated by cyanobacteria and contribute significantly to maintain soil fertility [1,5,15]. There is evidence that cyanobacteria belonging to Rivulariaceae occur in environments where organic phosphate is an important source of phosphate [10].…”

Section: Introductionmentioning

confidence: 99%

Phosphatase Activity of Non-Hair Forming Cyanobacterium Rivularia and Its Role in Phosphorus Dynamics in Deepwater Rice-Fields

Banerjee¹,

John²

2005

Appl Ecol Env Res

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Abstract. Phosphatase activity of Rivularia strains II and I isolated from a deepwater rice field was studied. When grown under conditions of P-limitation the strains did not form hair and showed great variations in induction time and pattern of enzyme activity in relation to growth. Phosphomonoesterase activity (PMEase) was induced earlier in the Rivularia strain I which was maintained in high phosphate concentration in the medium before the study. Rivularia strain II on the other hand showed induction of PMEase activity after 3-4 days and this strain was maintained in low phosphorus concentrations in the medium before the study. The comparison of K m and V max values early in the growth phase showed that affinity of both PMEase (phosphomonester) and PDEase (phosphodiester) for the substrate was higher in early growth phase rather than in later stages suggesting that there is presence of more than one phosphatase enzymes in these organisms. The observations from the above study have important implications in rice fields where constant fluctuations in nutrients can be observed -especially by phosphorus in its most available form phosphate. Equal enzyme activity in both light and dark for the two strains (non hair-forming) implies that phosphatase activity may not be affected by changes in light regimes in rice fields which do occur due to the plant growth. This can in turn contribute significantly to maintain the growth of cyanobacteria for prolonged periods even under unfavorable conditions of phosphorus depletions. These strains of Rivularia can therefore biotechnologically exploited as biofertilizers (phosphatic fertilizer) when there is phosphorus deficiency. During the unfavorable conditions of phosphorus deficiency, phosphatase activity may play a significant role in providing phosphate for its own growth and for the rice plants.

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“…Together with certain Proteobacteria and Archaea they are common inhabitants of extreme environments that are generally inhospitable to most June 2016 Journal of the National Science Foundation of Sri Lanka 44 (2) During the 19 th century cyanobacteria (considered as blue-green algae at that time) were first suspected to fix atmospheric nitrogen due to their ability to grow well under nitrogen deficient conditions (Frank, 1889;Schloesing & Laurent, 1892), but the observations were not based upon axenic cultures. Conclusive proof was provided by Drewes (1928) and this work was supported by De (1939), who showed that nitrogen fixing cyanobacteria were abundant in paddy fields of India. This showed the economic importance of these organisms as contributors for sustaining the natural fertility of rice soils (Singh, 1961).…”

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Nitrogen fixing cyanobacteria: their diversity, ecology and utilisation with special reference to rice cultivation

Kulasooriya¹,

Magana-Arachchi²

2016

J. Natn. Sci. Foundation Sri Lanka

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organisms. The role of N 2 fixing cyanobacteria are exemplified by the significant contribution they make to the nitrogen budget of the oceans, which occupy more than 80 % of the Earth's surface. Cyanobacteria are also found in freshwater and terrestrial habitats spanning across all latitudes and longitudes of the world and contribute significantly to the carbon and nitrogen cycles of wetlands, freshwater and brackish ecosystems as free-living, symbiotic, epiphytic, benthic and periphyton organisms. Certain N 2 fixing cyanobacteria form blooms in lentic water bodies and some of them produce cyanotoxins. N 2 fixing cyanobacteria therefore play both positive and negative roles in nature.Cyanobacteria form symbiotic associations with all other major groups of organisms and contribute to the nutrition of their hosts. Certain cyanobacteria and their symbiotic systems like Azolla are used as biofertilizers, particularly in rice production. This paper is a review of literature on N 2 fixing cyanobacteria, their diversity, their roles in nature and their utilisation.

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The role of blue-green algae in nitrogen fixation in rice-fields

Cited by 189 publications

References 1 publication

Soil Ph and Its Role in Cyanobacterial Abundance and Diversity in Rice Field Soils

Soil Ph and Its Role in Cyanobacterial Abundance and Diversity in Rice Field Soils

Phosphatase Activity of Non-Hair Forming Cyanobacterium Rivularia and Its Role in Phosphorus Dynamics in Deepwater Rice-Fields

Nitrogen fixing cyanobacteria: their diversity, ecology and utilisation with special reference to rice cultivation

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