Prediction of Harvest Stage of the Garlic Cultivar ‘Fukuchi White’ in Aomori Prefecture

Abstract

We experimentally cultivated the garlic variety ‘Fukuchi White’ on transparent mulch in Aomori Prefecture, Japan, from 2011 to 2021. The dates of snow disappearance, scale differentiation stage, and harvesting stage when the yield of high-quality product was at its maximal were March 7th, April 19th, and June 30th, respectively. The cumulative daily mean air temperature from the snow disappearance date to the scale differentiation stage was approximately 220°C. The cumulative air temperature from the scale differentiation stage to harvesting stage was approximately 1010°C. To predict the harvesting stage, the actual-measured air temperature was used in the summation to determine the cumulative air temperature, with the smallest error level falling between the estimated and actual-measured values at the harvesting stage. The root mean square error (RMSE) between the estimated harvesting stage (date when the cumulative air temperature became 1240°C after the disappearance of snow) and measured harvesting stage was 4.15 days. RMSE between the estimated harvesting stage (date when the cumulative air temperature became 1010°C after the scale differentiation stage) and measured harvesting stage was 4.00 days. To predict the current year harvesting stage, RMSE between the predicted and measured harvesting stage was determined from the actual-measured air temperature and annual average value. RMSE was approximately 4 days when the annual average temperature from 90 days after the snow disappearance date to harvesting stage was used. RMSE was approximately 3 days when the annual average temperature from 50 days after the scale differentiation stage to harvesting stage was used.