In cropping systems without pesticides (NOcsPS) it can be expected that plants are exposed to an increased stress level due to intensified weed and pest infestations. Both situations can lead to imbalances in the plants’ supply with nutrients, photosynthates and water, which in turn affect the quality of the harvested product (Zörb et al. 2012).

It is the aim of this subproject to determine, whether optimized fertilization and equidistant row spacing are suitable measures to counterbalance the increased stress level in NOcsPS systems, and to provide sufficient product qualities in the long term.

The following hypotheses will be tested:

• Compared to conventional cropping systems, individual quality parameters of harvest products (e.g. protein composition) will be changed in the NOcsPS system due to higher stress levels.
• In NOcsPS grown cereals, altered temporal accumulation of storage proteins between flowering and corn filling affects the final harvest quality of the seeds.
• Optimized mineral fertilization and equidistant row spacing reduce stress levels in NOcsPS systems, resulting in product qualities which are similar or (due to reduced pesticide residues) even better than those obtained by conventional production; this effect is especially relevant under additional drought conditions.

Experiments will first focus on Cereals (winter wheat) and soybean crops. Samples wll be taken from the cropping system trial and the exact trials in Hohenheim. At harvest time, various quality parameters will be evaluated (e.g. flour properties relevant for baking quality, metabolite profiles, mycotoxins). To evaluate differences in the temporal development of corn quality, corn samples are taken weekly starting at anthesis, and the content and composition of storage protein fractions will be determined.

To investigate options for improving quality by optimized fertilization and equidistant row spacing, similar parameters of quality will be correlated with physiological stress parameters (leakage, malondialdehyde, relative water content, SPAD, osmotic potential) in exact trials.

Harvest product qualities of all trial systems will be recorded in order to illustrate the differences in temporal quality development. In addition, cause-and-effect chains between, competition, stress and quality will be identified.