Plant Science Research, Vol. 37, 2015

Biodiversity of soil algae in a tropical endoaquept planted to rice under flooded condition under long-term application of chemical and organic-N sources

Organic N resources are being increasingly used to meet the N demand of the growing rice crop under organic cultivation which could be a win-win option for restoring soil health as well as reducing leakage of reactive N to the environment apart from impact on microbial diversity of rice soils. We studied the diversity of algae and cyanobacterial strains in a field experiment with 9 treatments involving chemical, organic and a combination of chemical and organic-N sources being used for growing rice crop for the last 15 years. A total of 66 species belonging to 33 genera under 4 classes of cyanobacteria, green algae, diatoms and euglenoids were recorded. Highest diversity of species was found for the cyanobacteria (30 species) followed by diatoms (22 species). Among the different treatments, the community structure of soil algae varied with highest diversity being recorded in field plots amended with chemical fertilizer (Shannon diversity index 3.22) and the lowest in the unamended field plots where no N source was added. Results indicate that anthropogenic activities in rice fields including application of organic residues can influence the diversity of soil algae