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The presence of NaCl in the nutrient solution promoted nitrate uptake in parent Anabaena sp. PCC 7120, mutants SP7 (defective in nitrate reductase activity) and SP17 (partially defective in nitrate reductase activity), but not in the mutant SP9 (defective in nitrate transport and reduction). Nitrate reductase activity of the parent and mutant SP17 increased with increasing concentration of nitrate in saline medium, while mutants SP7 and SP9 did not respond to the altered salinity. Although Na+ was not required for nitrate reductase activity, its presence in the nutrient solution enhanced nitrate reduction. Complete removal of Na+ from the nutrient solution markedly reduced nitrogenase activity in all the strains, while raising the concentration of NaCl to 50 mmol l−1 or above, was equally toxic to nitrogenase activity. External NaCl at 200 mmol l−1 brought down the nitrogenase activity to the same residual level as observed without Na+.

Field trials were conducted to determine the effect of algal biofertilizers (Aulosira fertilissima and Anabaena doliolum), alone or in combination with different doses of N-fertilizer (0–120 kg N/ha) supplied as urea, on biomass yield and nutritive value of rice. All doses of N-fertilizer, together with A. fertilissima or A. doliolum, significantly increased plant height, number of tillers/hill, root length, leaf length, chlorophyll content, number of panicles/hill, number of seeds/ear, seed weight, grain yield, protein, and N content of grain. However, lower doses of N-fertilizer resulted in more efficient and rapid responses. Maximal qualitative improvement in rice production was found with 90 kg N/ha together with 12.5 kg/ha algal biofertilizer. The responses to these biofertilizers appear to be strain-specific since application of A. fertilissima yielded better results than application of A. doliolum. Application of the former saved about 25% of the chemical N-demand of the crop.

The genus Trechispora accommodate species with corticioid, clavarioid, and polyporoid basidiomata, smooth to verrucose, angular basidiospores, monomitic or dimitic hyphal systems with clamp-connections, and ampullaceous septa. During a study of clavarioid fungi of Kerala, seven Trechispora species with clavarioid basidiomata were collected and studied. Morphological and molecular analyses revealed one species, T. cystidiata, characterized by cystidia, to be new to science. In addition, a new combination (T. angulispora) and a nomen novum (T. corneri) are also proposed. Descriptions of all the species collected and studied from Kerala, along with their phylogenetic placement in the order Trechisporales is presented. A taxonomic key to the clavarioid species of Trechisporales from India is also provided.

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