|Budget Amount *help
¥2,500,000 (Direct Cost : ¥2,500,000)
Fiscal Year 1998 : ¥900,000 (Direct Cost : ¥900,000)
Fiscal Year 1997 : ¥1,600,000 (Direct Cost : ¥1,600,000)
Root confinement culture of satsuma mandarin is a more reliable way of dwarfing tree vigor and producing high quality fruits. The mechanisms of dwarfing and improvement of quality with this culture system were not yet defined. The objectives in this studies were to 1) identify distribution of dry weight and mineral elements in the root confinement frees, 2) histological and physiological changes of confined roots, and 3) clarify the relationship existed between top and root growth by plant growth regulators.
In trifoliate orange grown in 3 soil volumes, vegetative growth was more retarded as soil volume were smaller. In the root confinement trees, ratio of shoot to root, and fine root to total root were increased but the content of mineral elements were decreased. In okitsu-wase frees, water potential of leaf was decreased rapidly in root confinement frees. In the confinement trees, hydraulic conductivity transpiration rate and TTC reducing activity were decreased, and the ratio of cortex of fine root was high. These results indicate that the dwarfing and improvement of fruit quality by root confinement may be due to histological and physiological changes of root. Eighteen months after grafting, the dry matter of top was the greatest on vigorous rootstock. Endogenous IAA and ABA were measured in the new shoots and fibrous roots. The IAA level in shoots was highest in vigorous rootstock, and ABA level was highest in dwarf rootstock. The levels in roots ware not clear. The vigorous rootstok had the highest Th and IAA/ABA ratios in the new shoot.