High Density-Low Truss NFT Tomato Production System with Quantitative Nutrient Management

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We developed the quantitative nutrient management (QNM) at low nutrient concentration technique using light dependent control and modified NFT system for high-density low-truss year-round tomato production system. In high-density tomato production system, the growth control to get compact and thick leaf system is very important technique for high productivity. The beneficial effects of our developed system were easy to control the growth of tomato plants (resulted in more stable and high yield), to support easy crop management (from short plant height), to uniform load of working (from multi-crop culture) and to reduce the emission of nutrients through the solution renewing process (resulted in environmentally friendly cultivation).Tomato seedlings with limited volume of growing media (RW granule) were planted in a closed NFT system in which channels were modified through the addition of a steep sloped section along the short axis of channel besides conventional slope along long axis. This modification accommodated low nutrient concentrations to uniform cultivation by reducing upstream-downstream gradients of nutrient concentrations.With QNM technique using light dependent control, the preset amount of nutrient (0.2 to 0.4me・plant^<-1>・MJ^<-1>・m^2) was supplied when the cumulative solar radiation (CSR) reached to given MJ・m^<-2> value. The preset amount was increased gradually (for instance 0.2-0.4me・plant^<-1>・MJ^<-1>-m^2) with the process of growth stage.Tomato was topped two leaves above the third truss. After the harvest of third truss, next crop started immediately and 3 to 3.5crops per year were realized. The estimated yield was near to 300t・-ha^<-1> with QNM using light dependent control.