Abstract
Tomato, cv.‘Fukuzyu No. 2’, eggplant, cv.‘Hayabusa’and sweet pepper, cv.‘Shinsakigakemidori’were grown in sand culture under glasshouse conditions in order to clarify the differences in the effects of various concentration ratios of NO3-N to NH4-N (10: 0, 7: 3, 5: 5, 3: 7, and 0: 10) on growth, fruit development and chemical constituent.
1. The highest dry weight of plants and fruit yield were found in each crop under the concentration ratio of 7 NO3-N: 3 NH4-N, but higher concentration ratio of NH4-N severely inhibited growth and fruit development. The decrease in dry weight and yield at higher concentration ratio of NH4-N was greatest in tomato followed by sweet pepper and then eggplant.
2. When the plants were supplied with higher concentration ratio of NH4-N, the incidence of fruits with blossom-end rot was observed in tomato and sweet pepper in contrast with very few incidence in eggplant.
3. The higher concentration ratio of NH4-N markedly enhanced NH4-N and soluble organic N in all plant tissues, and conversely reduced insoluble N and ratio of insoluble N to total N in the following descending order; tomato, sweet pepper, and eggplant.
4. The higher concentration ratio of NH4-N reduced not only starch content in all plant tissues, especially in the root, but also soluble sugar content in the stem and root. Eggplant showed higher soluble sugar and starch contents in the leaf, stem and root than those of other crops.
5. P content in all plant tissues was increased as the concentration ratio of NH4-N increased, whereas the cations such as K, Ca, Mg, Fe, Mn, Cu and Zn were decreased, particularly K, Ca and Mg. The mineral uptake of tomato was more remarkably impaired compared to that of eggplant and sweet pepper.
