Abstract
We analyzed the effects of climatic fluctuations on wheat (Triticum aestivum) cultivar ‘Norin 61’ grown by the same cultivation method on an experimental field in Saitama Prefecture from 1951 to 1996. The heading and maturity had become earlier and the number of days from heading to maturity increased during the 45 years. No trends were observed, however, in the culm length, yield, or yield components. Multiple-regression analysis was performed on the relationships between climatic fluctuations and the wheat growth and yield across the study period. The number of days from seeding to heading was significantly reduced by increase in mean air temperature from November to April. The number of days from seeding to maturity was also significantly reduced by the increase in mean air temperature for the same period and in May. The culm length was significantly increased under higher total precipitation from January to April and higher mean air temperature in March. Yield was reduced by higher mean air temperature from November to December and greater precipitation in the period from heading to maturity. The yield reduction was attributed to the reduced number of grains per spike due to the increased mean air temperature from November to December and increased precipitation in May. These results highlighted the number of grains per spike as a critical trait for stable wheat production against climatic fluctuations.
