We evaluated the nutrient solutions to establish high-yielding hydroponics of paddy rice. Takatsuji-type and Otsuka-type nutrient solutions which contained NH4-N, were more effective for vigorous growth with satisfactory plant length and tillers in early growth stages. In the case of Hyponica-Si- and Hyponica-type nutrient solutions, early growth was delayed slightly but it restored in the latter growth stages. From July when the NH4-N concentration in the nutrient solution rose, plants grown in Takatsuji-type, Otsuka-type and Kimura-A-type nutrient solutions exhibited yellow-brownish leaf streak symptom with long leaf blades and wide spreading of tillers. The onset of the symptom was related to the low CaO concentration in these nutrient solutions.
