Phenotypic plasticity of shoot-root relation under stress conditions and crop growth

点击翻译按钮获取中文摘要

Under excess and deficient soil water environments, crop grow with adaptive modification between shoot-root relation. This study was focused to clarify the dynamismus of adaptive responses of shoot and root organs in the aspect of plant as a whole. The main results obtained were as follows; Seminal root axes of large drought tolerant cultivars of rice were superior in elongation rate (cm/day) and their penetrating depth than those of drought susceptible ones. Broad sense heritabilities of rice root characters which related with drought tolerance, such as diameter of xylem vessel which affected hydrogic resistance, seminal root axis length, and number of L-type laterals, and so on were estimated around 60 to 85 %. Patterns of acropetal development of lignification in hypodermis, cortical sclerenchyma and endodermis of nodal roots in drought-tolerant and waterlogging- tolerant cereals grown under susceptible soil moisture conditions to each cereals, indicated that these tissues had a rol … More e as protective ones to adverse environments to each cereals. Bound-form cytokinin which was produced in roots and was translocated to shoot played as an important role to delay the senescence of leaves in rice plants. Application of triacontanol, a kind of growth regulators, promoted in root growth in the early developmental stage of rice, but in the ripening stage, it played as an retardant of scenescence of leaves, by controlling nitrogen translocation to panicle . Adaptive development of peripheral reticulum of chloroplast was superior in C_4-plants than in C_3- plants, when grown under increasing drought stress. Depressing water supply to leaf blade by means of lowering respiratory activity of rice roots treated with various stresses, net photosynthesis was also depressed because of excess moisture status of leaf derived from the close of stomata. Q_<10> of exudating rate of rice roots was estimated 2.1, and there was found highly positive correlation between its rate and the density ( no./axile root length ) of the first order laterals. Less