Satoru Tsukagoshi

Effects of trampling on morphology and ethylene production in asiatic plantain

Abstract The effects of simulated trampling on shoot morphology and ethylene production of a trampling-tolerant perennial forb asiatic plantain were investigated. Trampling increased the number of leaves or inflorescences per plant, the petiole diameter, and the leaf blade length to width ratio but decreased the leaf blade width to petiole diameter ratio and the inflorescence length. Ramets subjected to trampling produced more ethylene than did nontrampled ramets originating from the same root crown. Moreover, an ethylene releaser ethephon decreased the leaf blade width to petiole diameter ratio and increased the leaf blade length to width ratio, in a manner similar to the changes induced by trampling. These results suggested that trampling-induced ethylene might be closely related to some of the adaptive morphological changes in asiatic plantain in response to trampling. Nomenclature: Ethephon, 2-chloroethylphosphonic acid; asiatic plantain, Plantago asiatica L.

Hydroponic Production of Low-Potassium Tomato Fruit for Dialysis Patients

ABSTRACT Chronic kidney failure is becoming a global problem. Patients with kidney failure cannot excrete excess K, and their intake of K is often restricted. If low-potassium (K) tomato fruit can be produced, it can improve the dietary options of dialysis patients and their quality of life. A method of producing low-potassium (K) content tomato (Solanum lycopersicum L.) fruit was investigated. Several medium-sized tomato cultivars were tested, and the K supply was restricted using hydroponic production. Some plants were maintained through setting of a single fruit truss, and fruit fresh weight was not affected by K restriction. Total K uptake per plant decreased by 92% with lower K compared to conventional cultivation in which K content in fruit decreased by only 25%. Other plants were maintained until three trusses per plant were set, and fruit K content decreased 40% to 60% depending on cultivar because of K restriction. The cv. Aichan was the most sensitive and cv. Frutica was the least sensitive to K restriction. Total soluble solids content decreased slightly. Titratable acid content was affected by K restriction and decreased 20% to 40% depending on cultivar. In either case, K withdrawn in hydroponic culture following anthesis of the third truss was effective in producing low-K tomato fruit and could decrease fruit K content to at least 50% of expected tomato fruit K content.

Three-dimensional video distance education system between indoor and outdoor environments

We have developed a prototype system for 3D video distance education using satellite communications and IP multicasting. Our system is based on personal computers and software codecs. The system is inexpensive and flexible for various configurations because it utilizes software modules. Our system can be easily installed outdoors since it does not use special hardware to encode, decode, or transmit multimedia data. Testing of our system implemented between a horticulture farm and an indoor studio, approximately 140 km apart, showed that it effectively supports distance education between indoor and outdoor environments and that it provides an enhanced 3D educational environment.

Nutrition and Nutrient Uptake in Soilless Culture Systems

Abstract In soilless culture, all nutrients are supplied to the plants by nutrient solution sufficient to meet the plants’ demands. The composition of the solution means the concentration of each nutrient ion in the solution. Many kinds of composition have been designed; the composition should be chosen depending on the kind of plant, growth stage, target quality of the product, etc. Nevertheless, the only difference is the proportion of each ion and the concentration. In soilless culture, a slight change of nutrient management can greatly influence plant growth and the quality of the product. Therefore, a proper understanding of the nutrient solution is essential for successful plant cultivation even in artificial environments. In addition, a new concept of nutrient management, namely quantitative management, is described.

A Quantitative Analysis of Nutrient Requirements for Hydroponic Spinach (Spinacia oleracea L.) Production Under Artificial Light in a Plant Factory

Surplus absorption of elements that contribute little to crop productivity and quality can be avoided, and fertilizer consumption costs minimized, by applying elements quantitatively to the nutrient solution fed to the plants. The aim of this study was to determine the minimum macronutrient requirements of spinach (Spinacia oleracea L.) with a desired plant size, so that fertilizer management in plant factories can be maximized. Spinach plants were grown in a plant factory (20°C/17°C day/night temperature, photosynthetic photon flux (PPF) of 350 μmol·m-2·s-1 for 12 hours per day using cool-white fluorescent lamps, 1,000 μmol·mol-1 CO2). Spinach grew and developed rapidly, and reached its desired marketable size in only 12–15 days after being transplanted to the study conditions. At day 15 of cultivation under the treatment conditions, the required quantities of macronutrients per plant (90 grams in fresh weight) were determined as follows: 191 mg N, 31 mg P, 345 mg K, 34 mg Ca, 38 mg Mg, and 13 mg S. In conclusion, a quantitative nutrient managing method with low nutrient concentrations is feasible and resource-saving for hydroponic vegetable production in plant factories.