Winter oilseed rape : analysis of yield formation and crop type design for higher yield potential

Abstract

The study described in this thesis focuses on quantifying the seed yield formation of winter oilseed rape and on identifying crop traits and combinations of traits for increasing seed yield potential in North-West Europe, by combining experimental research with crop growth simulation. The experimental research yielded quantitative detailed data on pod formation, seed set and seed filling. Results on light absorption, light use efficiency and crop growth showed that the first two of these explain much of the variation in crop dry matter production. An empirical model was developed to describe the phenological development of the crop in relation to environmental factors. Comparison of its predictions of various developmental stages with data recorded in Germany, the Netherlands and France, showed that much of the variation in duration of the various developmental phases is attributable to the combined effect of temperature (including vernalization) and photoperiod or to the effect of temperature only. Key processes of crop growth, phenological development and partitioning of assimilates to the seeds were integrated in a simple crop growth model, whose performance was evaluated with data used for parameterization and with independent data. The model recognizably reproduced the observed variation in various crop characteristics, such as total dry matter production, pod density, seed density and seed yield resulting from different sowing dates and growing seasons. Differences between sowing dates were simulated better than differences between years. The model was used to identify options for increasing seed yield potential. Comparison with the higher-yielding reference crop, winter wheat, showed that light absorption, light use efficiency and harvest index were relatively weak yielddetermining components. Crop traits and combinations of traits were identified to obtain higher values in these components. Finally, high-yielding crop types were designed and tested in simulations for various locations in North-West Europe and showed good prospects for increasing seed yield potential