Katsumi Ishikawa

Growth and fruit quality responses of hydroponically cultivated eggplants to mineral controlled deep sea water.

A suitable application of the deep seawater for high quality eggplant (Solanum melongena L.) production was examined on vegetative growth and fruit yield with special reference to qualities of fruits. Mineral controlled deep sea water was prepared by electrodialyzing deep sea water with a selective membrane cartridge for the exchange of monovalent ions. Eggplant plants variety ‘Ryoma’ were grown in the NFT system with the applications of 2% mineral controlled deep sea water to the standard nutrient solution (mineral controlled deep sea water treatment-MDST) under greenhouse condition with four replications. With the treatment eggplant had larger vegetative growth rate than with the control. Furthermore, MDST showed that total fruit yield and marketable fruit yield was 14% and 23% higher than the control. In this study, a new methodology to produce high quality eggplants enriched in sugar, minerals, and dry matter was demonstrated by applying the natural resource.

Control of Viscosity in Different Concentrations and Temperatures of Nutrient Solution for Hydroponic System

Abstract This paper was intended for the investigation of control of viscosity in different concentrations and temperatures of nutrient solution for hydroponic system. In this study, we focused on the water structure of the nutrient solution. Viscosity is one parameter in aqueous solutions. The viscosities measured by digital rotary viscometer in different concentrations and in different temperature of nutrient solutions. As a result, the viscosities increased with increasing electric conductivity (EC) of nutrient solution. The viscosity of EC5 (EC 16.31 dS/m) was 1.239 mPa·s at 25 °C. In different temperature, the viscosity of nutrient solution at 5.5 °C (1.540 mPa·s) was significantly higher than the viscosity at 35 °C (1.136 mPa·s). In conclusion, the result indicate that the liner increase in viscosity with increasing concentration of ions for nutrient solution. Moreover, the viscosities of nutrient solution were correlated with water temperature. These results suggest that the viscosity can be used for control of nutrient solution to cultivate in hydroponic system.

QUARTZ PORPHYRY TREATMENT ALTERS IRRIGATION WATER CHEMISTRY, AFFECTING HYDROPONIC VEGETABLE PRODUCTION

This study focused on using quartz porphyry (QP) as a water treatment to improve hydroponic production of komatsuna (Brassica rapa L. nothovar; Japanese mustard spinach). We compared the chemistries of the control and QP-treated nutrient solutions and found that magnesium (Mg2+) and calcium (Ca2+) concentrations increased linearly up to day 21 following sowing in both conditions, then declined slightly. The QP treatment reduced sodium (Na+) and chloride (Cl−) concentrations for the whole cultivation period. In both the control and QP-treated solutions, nitrate (NO− 3) and sulfate (SO2− 4) showed the same trend to a daily increase. In spite of these similarities, however, komatsuna production was better with the QP-treated nutrient solution compared to control. Treatment with QP during cultivation in August–September reduced the harmful effects of Na+, chloride (Cl−), nitrite (NO− 2), and SO2− 4 by reducing concentrations of these ions, possibly leading to decreased salinity and toxicity effects in the plants. Mineral concentrations during October–November differed from those of August/September, resulting in variation among the different growth parameters for komatsuna.