Prediction of harvest time of lettuce [Lactuca sativa] by nonparametric DVR method

It is important for the stable lettuce production to predict the exact harvest time. We examined the relation between the lettuce growth and the day average temperature, and predicted the harvest time of lettuce by the nonparametric DVR (developmental rate) method. The nonparametric DVR method gave more precise information than the integrating effective temperature method. The DVR patterns of cultivars used in this study differed each other, and the DVR in spring cropping differed from that in summer to autumn cropping. Using the data on the growth in different cropping seasons over three years, the prediction system for the lettuce harvest time by the nonparametric DVR method could be more reliable.