2017 Volume 86 Issue 1 Pages 24-34
To increase the demand for “Toramame”, we investigated techniques for early harvesting by a combination of early planting, covering with sheets (CS) and cutting at the base of the stem (CB) in Hokkaido Kitami district. Seeding 9 to 18 days earlier than the conventional date (June 1), hastened germination by 5 to 10 days and 30% maturation by 5 to 11 days. CS from the day of seeding day hastened sprouting and 30% maturation by 4 days. Early seeding with CS also increased the seed yield by 6 to 7%, and hastened 30% maturation. The longer the duration of CS, the earlier the maturation. However, a longer duration of CS beyond the third leaf stage caused breaking of the stem at the cotyledonary node due to vigorous growth. Therefore, CS should be finished before the first to second leaf stage. CB is usually conducted at the 50 to 60% maturation stage. The seed yield and grain size were not affected by advancing CB to the 30% maturation stage. The effective minimum temperature and the effective accumulated temperature for sprouting were 7.1ºC and 107.3ºC, respectively. The earliest seeding date to avoid frost damage in Kitami district was estimated based on the daily average temperature and the fact that sprouting is advanced by 4 days by CS. Thus, the seeding date could be advanced 13 days from the conventional date (May 31). Combination of these techniques makes it possible to advance the date of CB by 18 to 19 days compared with the conventional date (Sept. 19), and after drying for one month, the products can be shipped at the beginning or middle of October, as demanded by the traders.
