2006 Volume 75 Issue 4 Pages 526-534
The water content and dry-matter weight of kernel were measured in two cultivars ‘Norin61’ and ‘Shirogane-komugi’ grown at different temperatures to develop a method of estimating the maturation stage in wheat from meteorological data. A logistic equation fitted to the dry matter increase showed that high temperatures during maturation reduced the final grain weight mainly through early cessation of kernel growth. The water content of kernel at physiological maturity was about 41% and was not affected by temperature, water deficit or cultivar. This indicated that the previously suggested value of around 40% could be useful as a trait of physiological maturity in wheat under various environment conditions. A positive linear relationship was observed between maturation temperature and developmental rate (DVR). In addition, the decrease of water content of kernel was associated with the increase of dry-matter in kernel and was correlated with the developmental index (DVI). Using these equations, we could estimate the date of physiological maturity and the water content of kernel under field conditions with root mean square error of 2.1 days and 3.1%, respectively. Furthermore, we compared the reported data on the morphological stages of embryo and endosperm with our results, and the results suggested that the seed dormancy starts when the water content of kernel decreased to approximately 50%.
