Reanalysis of Vernalization Data of Wheat and Carrot

Vernalization is an important determinant of the growth, development, and yield of biennial and perennial crops. Accurate simulation of its response to temperature is thus an important component of successful crop systems modelling. Vernalization has a low optimum temperature compared to other temperature responses of plants, and thus may be difficult to treat using expressions that are appropriate for other plant processes. This paper examines the application of a simple equation that has been used for other processes. It reads as v=V max ( T max - T T max - T opt ) ( T T opt ) T opt T max - T opt , where v is the daily rate of vernalization progress at temperature T, T opt and T max are the optimum and maximum temperatures for vernalization, respectively, and V max is the maximum daily rate of vernalization (the inverse of the minimum number of days required to complete vernalization), which occurs at T opt . The model was applied to published vernalization data for wheat and carrot. The fits to data were good (adjusted R 2 for wheat of 0.94, for carrot 0.98), with estimated T opt and T max being 5.7±0.5 and 21.3±1.4 °C, respectively, for wheat ‘Norin 27’ and 6.6±0.2 and 14.1±0.3 °C for carrot ‘ Chantenay Red Cored’. The estimated parameters, in particular the high T max for wheat, were close to those reported using different analytical approaches. It was suggested that the function would be useful for summarizing vernalization data, and that its use would avoid the abrupt changes that are inevitable when different linear relationships are used for part of the overall response. It was also suggested the high T max should be taken into account when interpreting data obtained with wheat grown under warm conditions.