IMPROVING THE GREEN ASPARAGUS PRODUCTION SYSTEM IN JAPAN

Forced or protected asparagus (Asparagus officinalis L.) cultivation has been developed in Japan for the purpose of whole season cropping and disease-control. Air temperature in forced or protected cultivation can rise too high in the summer season. It was clarified that open roof, side ventilation and spread treatment with shading material are effective methods for preventing inside air temperature from rising too high. Ventilation through insect-repellent net and covering with UV cut-off film decreased damage by moth and number of thrips, respectively. Application of 4 kg N/a inorganic fertilizer was the most effective for economical production, and using of controlled release fertilizer gave positive results in comparison with normal inorganic fertilizer.