Development of New Irrigation System based on Water Relations Research for Citrus Fruit Production

A new cultivation system using drip irrigation and liquid fertilization methods combined with year-round plastic mulching system (DLYM system) was developed, expecting high quality and stable fruit production based on the research results on water relations of Satsuma mandarin (Citrus unshiu M.), where sugar accumulation in fruit was caused by an increase in translocation of photosynthates into fruit under drought stress. 　Water and/or nutrient solution is automatically supplied through the drip tubes laid under mulching sheets to give adequate water stress. Fruit quality was well controlled through the DLYM system. Sugar content of fruit increased by 2 Brix %, and functional components such as β‒cryptoxantin and β‒caroten increased by about 50% compared to juice from fruit grown on control trees. In addition, new technologies were developed, such as hydraulic design support system and water stress indicator sheet.

研究紹介 (Research Report)