A cardinal temperature-based phenotyping method for rice

Rice is one of the major food crops in the world. It is characterized by a wide diversity of growing conditions through latitude and altitude. Temperature is one of the most important factors determining plant growth, development and yield. In the context of climate change, thermal constraint (cold and chilling) could highly affect rice production. To breed rice varieties better adapted to these new environments, a better knowledge of thermal response in rice varieties is needed. The Cirad Orytage project involving NARS and IRC partners aims at developing an international phenotyping network for rice adaptation to thermal stresses, further aiming at gene discovery and genetic mapping, closely linked to the GCP network. Reaching this goal requires to improve methods for high throughput phenotyping. In case of thermal stress, plant elongation was used to phenotype plant responses to temperatures. From a beta function (Yin, 1995; Wang, 1998), cardinal temperatures (Topt, Tmax and Tmin) were determined using a normalized method. The goal of this work was to study the genetic diversity of the cardinal temperatures in the Oryza sativa japonica tropical group.