Promotion of root growth by the application of inosine

The aim of the present study was to verify the effect of inosine on plant growth. Rice (Oryza sativa L.), tomato (Solanum lycopersicum L.), onion (Allium cepa L.), sunflower (Helianthus annuus L.) and soybean (Glycine max (L.) Merr.) seedlings were grown in a hydroponic system with different added concentrations of inosine (0, 7.2, 72 and 373 mu mol L-1) in a greenhouse. The application of inosine improved the growth of all plant parts, particularly roots, except for soybean. The optimum inosine concentration for plant growth was 72 mu mol L-1. Furthermore, in rice, tomato and sunflower, treatment with inosine increased root length. To confirm the effect of inosine, an aseptic experiment was carried out using rice plants in a hydroponic system and using tomato in a rhizobox system with sterile soil. The positive effect of inosine was also confirmed under aseptic conditions in rice and tomato, indicating that inosine directly enhances plant growth without microbial decomposition.