Effects of Blanching and Its Method on Yield and Quality of Asparagus Spears by Whole Harvest Cultivation Method for One-year-old Plants

Abstract

The whole harvest cultivation method for one-year-old plants (new cultivation method) is a labor-saving open field asparagus cultivation method that allows growers to produce a high yield of high-quality asparagus at low-cost. Green and purple asparagus production by the new cultivation method is becoming popular in Japan. White asparagus production in Japan is usually based on blanching with soil (SOIL). On the other hand, the film-cover method (FILM) has also become popular in recent years. In this study, for the purpose of introducing the new cultivation method for white asparagus production, green and purple asparagus were examined regarding the effects of blanching and its methods on the yield and quality of spears. The test was conducted both in Nagano and Kanagawa (cold and warm areas, respectively). The yield and rate of thick spears (L or larger size) cultivated by SOIL and FILM in both cold and warm areas were equivalent to or higher than without blanching (WITHOUT BLANCHING). The amount of rutin in spears cultivated by WITHOUT BLANCHING was significantly higher than by SOIL and FILM. The amount of protodioscin in spears cultivated by SOIL was significantly higher than WITHOUT BLANCHING and FILM. From these results, on using green and purple asparagus blanched by SOIL and FILM to cultivate as white asparagus with the new cultivation method, the quality of spears was different from WITHOUT BLANCHING, and the yield and rate of thick spears were equal or higher.