Abstract:

Aims Accurate simulation of green area index is critical for reliable prediction of crop growth and yield using a crop growth model. Our study was undertaken to develop a process-based simulation model for predicting dynamic green area index, including leaf area index (LAI) and pod area index (PAI), in winter rapeseed (Brassica napus).

Methods Leaf area expansion was simulated through the relationship between LAI and source- or sink-limited dry matter. Daily leaf expansion rate increased in an S-shaped growth curve under source limitation, as influenced by temperature, water and nitrogen levels. Under the sink limitation, leaf area expansion was quantified on the basis of specific leaf area. Pod area was calculated from specific pod area and pod dry matter. The specific leaf area and specific pod area were determined from physiological development time and genotype. We calibrated and validated the model using experimental data from different varieties, sowing dates and nitrogen fertilization rates.

Important findings Root mean square error (RMSE) values of LAI were 11.15%, 15.57% and 16.87% at three N levels, and the average RMSE value of PAI in two varieties was 12.92%. Plotting the 1∶1 relationship between the simulated and observed values inLAI and PAI growth dynamics indicated a good fit. Our model of green area index in winter rapeseed shows a high accuracy and applicability under different conditions.

Key words: leaf area index (LAI), pod area index (PAI), specific pod area, specific leaf area, simulation model, rapeseed