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

在土壤水分过剩和不足的环境下，作物生长适应性地调整着冠根关系。本研究从植物整体的角度阐明了植物地上部和根系器官适应性反应的动态性。主要结果如下：水稻大耐旱品种的种子根轴在伸长速率（cm/d）和穿透深度上均上级耐旱品种。与水稻耐旱性有关的根系性状，如影响耐水性的木质部导管直径、种子根轴长度和L型分枝数等的广义遗传力估计在60 ~ 85%之间。耐旱和耐涝禾本科植物在对土壤水分敏感的条件下生长，其节根的下皮层、皮层厚壁组织和内皮层木质化的向顶发育模式表明，这些组织在干旱和耐涝条件下， ...更多信息 对每种谷物都有保护作用。结合型细胞分裂素是水稻根系产生并转运到地上部的物质，对延缓叶片衰老具有重要作用。三十烷醇是一种生长调节剂，在水稻生育前期能促进根系生长，但在成熟期，它通过控制氮素向穗部的转运，起到延缓叶片衰老的作用。在干旱胁迫下，C_4植物的叶绿体外围网的适应性发育比C_3植物的好，表现为上级。不同胁迫条件下，水稻根系呼吸活性降低，叶片水分供应受到抑制，气孔关闭导致叶片水分过剩，净光合作用也受到抑制。水稻<10>根系分泌速率的Q值为2.1，与密度（根数/根数）呈极显著正相关。轴根长）的第一级。少

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