A model for simulating the cotton (Gossypium hirsutum L.) embryo oil and protein accumulation under varying environmental conditions

A mechanistic model was developed to simulate the genotypic and environmental variations in the cotton embryo oil and protein accumulation with the boll development. Three sub-models, cotton boll maturation period model, cotton embryo oil accumulation model and protein accumulation model, were integrated. Genotypic characteristics, effects of temperature and solar radiation, nitrogen (N) supply, and soil water condition were considered. The effect of temperature and solar radiation was expressed by a function of photo-thermal index (PTI). The N supply effect was indicated by subtending leaf N concentration of cotton boll (LNC), while the effect of water condition was indicated by the predawn water potential of functional leaf (PLWP). Based on the relations between the critical LNC/PLWP and the actual LNC/PLWP, effects of N supply and water condition were quantified, respectively. The model calibrations and evaluations were conducted for cotton boll maturation period and the embryo oil and protein accumulation obtained from experiments with 4 cultivars in 2 locations (Nanjing and Anyang) belonging to two cotton growing areas in China. According to the indexes of goodness-of-fit, the model could well explain the observed genotypic and environmental variation in cotton embryo oil and protein accumulation.