Interannual variation in the harvest time of mini cauliflower in the Sanriku coastal region

Abstract

　The Sanriku coastal region of Tohoku, Japan, is characterized by large interannual weather fluctuations, which is an important consideration when scheduling crop cultivation. Therefore, we developed a temperature summation model to predict harvesting time for mini cauliflower (Brassica oleracea var. botrytis). The model parameters were determined from the data obtained during field experiments, and the model was designed using 30-year air temperature records from the AMEDAS observatories. The results indicated that interannual variation at the time of harvest was less when the cauliflower seedlings were transplanted from mid-April through August, but it increased when seedlings were transplanted after September, with the time of harvest often being delayed to mid-winter or later, resulting in severe cold damage to the crop. Based on these results, we concluded that outdoor-cultivated mini cauliflower seedlings should be transplanted before early September in the northern coast and mid-September in the southern coast to ensure harvesting before winter. The effects of greenhouse cover were also evaluated, assuming that the air temperature inside the greenhouse was 2°C-4°C higher than that of outdoors, which showed that greenhouse cultivation decreased the variation in the time of harvest, allowing the time of transplanting to be extended by 2-3 weeks.