Abstract:

Photosynthesis and dry matter accumulation are major determinants of the final yield in crop production. Based on eco-physiological processes, a simulation model for photosynthetic production and dry matter accumulation was established for rapeseed. The model used a ‘3 layer model’ for calculating the radiation interception by the layers of flowers, pods and leaves and light absorption by pods and leaves. Gaussian integration method was used to calculate the photosynthesis of pod and leaf layers, and the daily total canopy photosynthesis which was that of all layers of green organs. The effects of physiological age, temperature, nitrogen and water deficit factors on maximum photosynthesis rate were adequately quantified. The model calculated maintenance respiration and growth respiration which consume some photosynthate. Partition index of shoot was quantified by physiological development time (PDT) to calculate shoot dry matter from plant biomass. Then, plant biomass loss due to freezing was quantified by temperature effect. Testing of the model for dry matter accumulation with the field experiments of different genotypes, sowing dates, and nitrogen levels showed a good fit between the observed and simulated data. Thus, the present model appears to be favourable on mechanism explanation and reliable prediction.

Key words: Rapeseed, Canopy distribution, Photosynthesis, Respiration, Dry matter accumulation, Simulation model