Cultivation of Satsuma Mandarin in Vinyl-Greenhouses in Japan
A main objective of growing satsuma mandarin (Citrus unshiu Marc.) in a vinyl-greenhouse is to secure competitiveness of the products in the markets by early shipping of high quality fruits. For early shipping of the products from the vinyl-greenhouses, heating starts in early December and fruits art harvested before the end of July. Although this type of cultivation is profitable under adequate managements, it has a problem caused by unreliability of flowering, which is related to completion of dormancy. To estimate the degree of dormancy completion, a simple method has been employed by the growers to determine contests tion, of carbohydrate. In addition, a benzylamine purine treatment has been developed to promote growth of sprouts and stimulate flower-bud emergence. Further improvements art required to ensure profitability of the cultivation in a vinyl-greenhouse, including reduction of production costs and quality improvement. It costs 70 to 100 million to build a one-hectare vinyl-greenhouse, including heating, ventilation and irrigation systems. The fuel required for one season operation is 250 kl, or 7.5 million equivalent per ha for the early shipping type. Cost reduction is vital for the future development of this cultivation system.