Modeling cotton growth and phenology in response to temperature

Cotton (Gossypium hirsutum L.) is grown in a wide range of temperatures throughout the world. These crops experience temperature fluctuations ranging from 5°C to 45°C during the season, which diversely influence growth and development. Minimum, maximum and optimum temperatures also vary with the stage of plant development and physiological processes involved. However, most cotton simulation models have been developed with data collected from a narrow temperature range, and hence have limited predictive capabilities under temperature extremes. Several studies on cotton growth under high CO2 conditions have examined the plants' response to a wide range of temperatures, including both high and low temperature extremes. A data set derived from these studies was used to construct a model of cotton growth and development. The rates of approach to fruit initiation, flowering and boll opening were modeled as a function of temperature. The daily increment for new node formation was a function of temperature and physiological stress of the plant. The rates of prefruiting and fruiting leaf expansion were modeled as functions of temperature and existing area of the corresponding leaf structures. The model has been validated and incorporated into cotton simulation models that are being used for cotton crop management.