Poor Ripening of Wheat Due to Abnormally Early Ripening in Natajima Region of Yamaguchi Prefecture in Relation to Grain Growth and Sugar Content of Shoot

Abstract

Poor ripening due to abnormally early ripening (AER) of wheat (Triticum aestivum L.) in farmers’ fields in Natajima region, Yamaguchi Prefecture, was investigated in two seasons (2004/2005 and 2005/2006). Grain weight and sugar content of straws were also measured at maturity. The symptom of AER was consistently severer in Norin 61 than in Nishinokaori in both seasons. Although the AER appeared in both fields with and without pre-anthesis waterlogging, the AER symptom was severer in the field with pre-anthesis waterlogging. The grain weight decreased with increase in extent of AER symptoms. The sugar content of straws was high in the field scored as serious AER. The number of fields with AER and that with pre-anthesis waterlogging were low in “Shin-kaisaku” area developed in 1774 and high in “Shouwa-kaisaku” area developed in 1930. The AER fields did not always show the symptom of AER every year. The sugar content of straws showed a negative relationship with grain weight in Norin 61 plants with AER. These results confirmed that light grains at the mature stage have ceased its growth earlier leaving a large amount of reserves unutilized in straw.