Dried Nostoc commune exhibits nitrogen-fixing activity using glucose under dark conditions after rehydration

Nostoc commune is an edible cyanobacterium that produces a massive gelatinous polysaccharide matrix around the filamentous cells. The polysaccharides, more than 70% of which comprise glucose, are essential for resistance to environmental stresses. In the present study, we collected naturally growing N. commune colonies, dried them for preservation, rehydrated them, and then examined their nitrogen-fixing activity using the acetylene reduction method. As expected, the rehydrated N. commune performed nitrogen fixation after illumination with white light. Notably, under dark, aerobic conditions, the rehydrated N. commune exhibited nitrogen fixation in the presence of glucose. In contrast, under dark, anaerobic conditions, nitrogen fixation was low. Because the natural habitats of N. commune are aerobic but lack carbohydrates, N. commune cells may exhibit glucose utilization activity constitutively

Effects of waterweed compost derived from Lake Biwa on Komatsuna (Brassica rapa var. perviridis) growth

ABSTRACTIn Lake Biwa, located in Shiga Prefecture, Japan, the overgrowth of waterweeds has become a significant environmental and human-life problem. Therefore, the waterweeds are systematically harvested and composted. In order to consider the effective use of waterweed compost for carbon neutrality and resource recycling, we clarified the characteristics of the waterweed compost by cultivation experiments with Komatsuna (Brassica rapa var. perviridis). When the waterweed compost (20%) was applied alone, the growth of plants was promoted about 1.7 times compared to a control containing the same amount of fertilizer components. However, the plant showed yellowing of leaves and a high C/N ratio, indicating obvious symptoms of nitrogen deficiency. The application of the waterweed compost (20%) with chemical fertilizer remarkably enhanced plant growth up to about 3.5 times without nitrogen deficiency compared to a control containing only chemical fertilizer. Interestingly, the coexistence of the waterweed compost and chemical fertilizer activated nitrification and diversified soil bacteria (Chao1 index, 213.0; Shannon index, 6.50) rather than the waterweed compost alone (Chao1 index, 41.3; Shannon index, 4.34). Our results indicate that the waterweed compost functions effectively as an organic fertilizer and a soil amendment, contributing to sustainable agriculture

Nitrogen Balance in Forage Rice (Oryza sativa L. cv. Tachisuzuka) Cultivation in Pots with Animal Manure Application

Experiments were conducted to evaluate the nitrogen (N) balance in forage rice cultivation using animal manure in 1/2,000a Wagner pots in a greenhouse. The cattle manure and poultry manure were applied at 3 levels of N (0, 14, 28 g available N m–2) without additional chemical fertilizer application. The pots were designed to simulate the fluid percolation in the paddy field. The results indicated increasing levels of N input improved plant height, tiller number, SPAD value and biomass (straw, grain and root) production, however, N leaching from soil (Andosols) due to percolating water also increased. The planting of rice plants proved to reduce 30% of the N leaching loss. N use efficiency, the ratio of N uptake by plant per unit N application, decreased in higher N application. The N uptake by the above-ground parts occupied about 66% of the whole plants

Nitrogen Balance in Forage Rice (Oryza sativa L. cv. Tachisuzuka) Cultivation in Pots with Animal Manure Application

Abstract: Experiments were conducted to evaluate the nitrogen (N) balance in forage rice cultivation using animal manure in 1/2,000a Wagner pots in a greenhouse. The cattle manure and poultry manure were applied at 3 levels of N (0, 14, 28 g available N m–2) without additional chemical fertilizer application. The pots were designed to simulate the fluid percolation in the paddy field. The results indicated increasing levels of N input improved plant height, tiller number, SPAD value and biomass (straw, grain and root) production, however, N leaching from soil (Andosols) due to percolating water also increased. The planting of rice plants proved to reduce 30% of the N leaching loss. N use efficiency, the ratio of N uptake by plant per unit N application, decreased in higher N application. The N uptake by the above-ground parts occupied about 66% of the whole plants. Key words: Animal manure, Biomass production, Forage rice, N balance, N leaching