2005 Volume 74 Issue 3 Pages 276-284
We modified the development model established for early warning of cool-weather damage to estimate the percentage of productive panicles and glumous flowers at a specific stage such as meiosis, in the field. In this model, the leaf age at transplanting, time of panicle formation and flowering time were used as the initial values. Usefulness of the method was verified by the field experiments at Morioka, Towada, Hachinohe and Aomori in 1999, 2001 and 2003. The peak of the glumous flowers at the stage sensitive to cool-weather damage appeared 2-3 days later than that at the meiosis stage. In the year with cool-weather damage, 2003, productive panicles at the meiosis stage and glumous flowers at the dangerous stage were observed for a longer period than in 1999 and 2001. The time of flowering was 2-3 days later than that of heading. In 2001, with cool temperature during heading and flowering, the period of heading and flowering was longer than in 2003 with cool-weather damages. Estimation by this method showed that even in 2001 and 2003, when ripening was retarded by cold temperature, a part of the reproductive panicles and caryopses in the field were ripened. The number of days with a dangerous cool temperature was zero and the sterility was low in 1999, but both the number and the sterility were high in 2001 and 2003, In conclusion, we can estimate the variation of growth stages in the field by this method.
