Abstract
To ascertain the factors , involved in the low protein content of wheat grain,which is recently a serious issue in northern Kyushu, we investigated the relationship between the protein content of wheat grain and the yield, yield components and climatic conditions using the wheat cultivar ‘Chikugoizumi’ in northern Kyushu cultivatied by the same method from 1993 to 2008 in northern Kyushu. The protein content of grain decreased as the 1000-kernel weight and yield increased, indicating that the protein of grain content was negatively correlated with the yield and 1000-kernel weight. The 1000-kernel weight increased with a decrease in precipitation and an increase in duration of sunshine, and the yield increased with an increase in duration of sunshine during the ripening period of wheat. This indicated that the 1000-kernel weight was negatively correlated with precipitation, and that the yield and 1000-kernel weight were positively correlated with the duration of sunshine during the ripening period. These results suggest that the low protein content of wheat grain was a result of high yield or heavy 1000-kernel weight due to less precipitation and longer duration of sunshine during the ripening period.
