Effects of early shading of roots of asparagus (Asparagus officinalis L.) on harvesting time, spring yield and farm income in Republic of Korea

Recently, asparagus (Asparagus officinalis L.) has become a popular vegetable in republic of Korea. So the greenhouse cultivated area of asparagus is increasing by more than 100 ha, but annual production is concentrated in the spring (April-May) and price problems occur. The influence of early shading of roots of asparagus on harvesting time, spring yield and farm income was investigated in this study. The cultivated region of asparagus (cultivar is grande F₁) is Gangwon-do (highland region) in the Republic of Korea. The artificial shading (covered 99% shading net) was applied in greenhouse on January 20. When the artificial shading was applied, the first harvesting time was delayed about 2 weeks, ratio of freezing and frost injury was decreased. So spring yield of asparagus was increased by 792 kg ha^-1 and farm income has increased by 4,018 $ ha^-1. As a result, early artificial shading was judged as a way to delay of first harvest time and to avoid freezing and frost damage.