Winter production of white asparagus from one-year-old rootstocks by forcing culture.

摘要

Recently, the demand for fresh white asparagus spear has the tendency to increase gradually since its specific taste and texture are appreciated. Although this trend would be continued, the amount of fresh white spears in Japanese domestic market is much less compared with that of green ones. Thus, in this study, we determined the feasibility to produce white asparagus spears in winter by combination of plastic film covering method to blanch asparagus spears and Japanese specific forcing cultivation system by using one-year-old rootstocks. A strong correlation was observed between the fresh weight of one-year-old rootstocks and their marketable yield in three cultivars in both 2005 and 2006. Blanching conditions during the harvesting time influenced anthocyanin pigmentation in the spear. When asparagus spears were harvested under darkness maintained by a 2.0 m-high walk-in tunnel covered with a shading film, anthocyanin pigments in the spears did not appear. There were differences among cultivar yields, and 'UC-157' and 'Grande', showed higher yield than 'Gijnlim', suggesting that these cultivars possess shallower dormancy in winter than 'Gijnlim'. From 'UC-157' one-year-old rootstocks, marketable yield of 4,553-5,138 kg ha-1 was obtained in this study. These results demonstrated that white asparagus spears can be produced with no anthocyanin pigment in forcing culture by using one-year-old rootstocks of cultivars with a slight dormancy like 'UC-157', if spears are harvested under completely dark conditions maintained by a large shaded tunnel.