Suitable Conditions for Deep-water Hydroponic Kiwifruit Culture with Wet-tolerant Rootstock

Abstract

To clarify the suitable conditions of nutrient solution in deep-water hydroponic kiwifruit culture grafted on wet-tolerant rootstock, the effects of concentration, pH adjustment, and cooling of nutrient solution on vegetative growth of young trees were investigated. In experiment 1, nutrient concentration effects in culture solution on tree growth were surveyed. Water supply, shoot growth, and photosynthetic rates were higher in OAT’s standard solutions of 1/2 and 1/4 strength compared with that of 1. In experiment 2, the effect of pH adjustment on tree growth was investigated. No marked differences were observed in water supply, shoot growth, or leaf photosynthesis between pH-adjusted and non-adjusted samples. In experiment 3, the effects of solution cooling on shoot growth and leaf photosynthesis in summer were surveyed. Cooling increased water supply and shoot growth only when the summer temperature was high. These results suggest that in deep-water hydroponic kiwifruit culture with wet-tolerant rootstock, suitable concentrations of the solution are 1/4 and 1/2 of the standard, pH adjustment dose not affect tree growth, and solution cooling during hot summers can accelerate plant growth.