Change in Wheat Quality with Ripening : I. Grain dry weight and grain water content

Abstract

To obtain basic data for the change in wheat grain quality with ripening in the Tokachi district of Hokkaido, Japan, we examined the changes in dry weight, water content and water percentage in developing grain using two winter and two spring wheat cultivars in 1992 and 1993. The time of maximum grain dry matter accumulation (Tmax), when grain dry weight was not different significantly (P<0.01) from its maximum, was estimated by analysis of variance. The change in grain dry weight varied for years and cultivars. The Tmax was 30 to 36 days after anthesis for the spring cultivars harvested in 1992 and the winter cultivars in 1992 and 1993, but it was 42 to 45 days for the spring cultivars harvested in 1993. For the spring cultivars harvested in 1993, the change in grain dry weight was probably affected by low temperatures, and the grain dry weight increased slightly after Tmax. However, the grain dry weight did not increase after Tmax for the other cases. In all cases, the grain water content held almost constant until Tmax, and then decreased rapidly thereafter. From the changes in grain dry weight and water content, it is believed that grain dry matter accumulation ceased at Tmax, because grain dry matter accumulation ceased with the rapid decrease in grain water content. The grain water percentages were approximately 40% of Tmax for all cultivars and years examined.