Abstract
In order to recycle a higher concentration nutrient solution (HCNS) for high soluble solids tomato production,a new recirculating capillary culture system (RCC system) was developed and certain characteristics of the system were investigated. The RCC system used the irrigation method with a drip tube and two capillary mats (CM) connected to a fertigation gutter. The tomato root zone was restricted using a root protection bag (RPB;made of a root protection sheet) inserted between the upper and lower CM. The total amount of nutrient solution supply using CM was changed only 0.45-0.70 L RPB-1 (for 5 minutes), supplying 2-12L min-1 water for the fertigation gutter. By dividing the mineral components of HCNS in basic nutrient solution (BNS:NO3-N, P, K, minor elements, EC1.8 dS m-1) in order to supply nutrients in response to the plant growth stage, and stress nutrient solution (SNS:Mg, Ca, Na) to control water stress, these nutrient solutions were irrigated to the RPB by drip tube and CM, respectively. The surplus drainage solution from RPB was recycled as SNS with EC control. Tomatoes were grown under two EC levels (2.0, 6.0 dS m-1) in SNS in the RCC system and pot system irrigated with HCNS (EC 4.0 dS m-1). In triple-truss cultivation using the RCC system,high Brix fruits (higher than 9%) were successfully harvested with recycling of all drainage solutions. Thereafter, the top fresh weight, dry weight, leaf area and marketable yield of EC6 in SNS were lower than that of EC2; Brix of tomato fruit from EC6 treatment was higher than that from EC2. There was no difference in plant growth,marketable yield and Brix of tomato fruits between the pot system and RCC system (EC2).
