Abstract
New cultivation system using drip irrigation and liquid fertilization methods combined with year-round plastic mulching was developed, expecting high quality and stable fruit production of satsuma mandarin. Water and/or nutrient solution is automatically supplied through the drip tubes that are laid under the mulching sheets to give adequate water stress. Extensive studies regarding to effect of the system on fruit quality, seasonal change in soil temperature, salt accumulation in soil and labor saving for the grower were conducted. Fruit quality was well controlled through the system, e.g. it raised sugar content by about 2 (Brix%). Functional components such as β-cryptoxanthin and β-carotene increased about 50% compared to juice from fruit grown by non-mulched cultivation. In addition, the system saved about 17.5 hr/10 a/year of labor time in orchard management. Salt in the surface soil had not significantly accumulated 3 years after this system introduced. Year-round mulching diminished the range of soil temperature, particularly in the summer season.
