Influence of climatic factors on "crop situation index" of wheat and barley in Okayama prefecture

The influences of air temperature, precipitation, number of rainy days and sunshine duration on the crop situation index of wheat, six-rowed barley and two-rowed barley in Okayama prefecture were analyzed by using the data for the 30-year-period of 1966-1995. The crop situation index of these three crops showed high negative correlation with the precipitation in April and a positive correlation with sunshine duration in April. Precipitation over 150 mm or lesser sunshine duration under 190 hrs in April seems to reduce the yield of wheat and barley in Okayama.