Enironmental and physiological studies for optimization of transport systems in plants.

植物生产取决于植物及其环境中运输系统的动态，其中有助于植物生产的物质（例如水、光合同化物、二氧化碳、氧气和养分）在植物器官及其环境中交换和分配。本研究分析了环境对叶菜类蔬菜（莴苣）、果菜类蔬菜（番茄和黄瓜）和根菜类作物（甘薯）的根系生理功能、植物器官（叶、果和块茎）的膨胀生长、光合产物的运转和库源关系等运输系统的影响。为精确控制甘薯的溶氧浓度和进行甘薯气液栽培，开发了一套新的水培系统。此外，通过新开发的方法测量植物响应，即，1)用于在线和非接触测量果实、茎和块茎中生长速率的激光传感器系统，2）用于在线测量完整番茄果实中的水平衡、呼吸和汁液通量的室系统，和3）用于评估通过番茄花梗的光合同化物的移位通量的方法。根据有关运输系统的动力学，揭示了根系环境（溶解氧浓度和水分状况）和地上部环境（光、温、湿）的作用机理。这些方法和信息建立完整的整个工厂可以被认为是有助于逻辑的环境控制优化动态的运输系统在植物和它们的环境。

Plant production depends on dynamics of transport systems in plants and their environments, where substances contributing plant production (e.g. water, photoassimilates, carbon dioxide, oxygen and nutrients) are exchanged and distributed among plant organs and their environments. This study deals with analyses of environmental effects on the transport systems concerned with root physiological functions, expansive growth of plant organs (i.e. leaf, fruit and tuber), translocation of photoassimilates and sink-source relationship in the whole plant of a leaf vegetable (lettuce), fruit vegetables (tomato and cucumber) and a root crop (sweetpotato). Hydroponic systems were newly developed for accurate control of dissolved 0_2 concentration and for solution-air culture of sweetpotato. Furthermore, plant responses were measured by the newly developed methods, i.e., 1) laser sensor systems for on-line and non-contact measurements of growth rates in fruit, stem and tuber, 2) a chamber system for on-line measurements of water balance, respiration and sap flux in an intact tomato fruit and 3) a method for evaluating translocational flux of photoassimilates through a tomato pedicel. Mechanisms of effects of root environment (i.e. dissolved 0_2 concentration and water condition) and shoot environment (i.e. light, temperature and humidity) were revealed on the basis of dynamics of the transport systems concerned. These methods and information-established for the intact whole plant can be considered to contribute to logic of environment control for optimizing dynamics of the transport systems in plants and their environment.