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