The quality of agricultural products is influenced in various ways by the production system. This occurs through the type and quantity of fertilization, or indirectly through plant-related measures that alter the competitiveness of crops against weeds or pests. In cultivation systems without pesticides (NOcsPS), it can be expected that plants are subjected to increased stress due to enhanced weed growth as well as pathogen infestation. In both cases, imbalances can arise in the supply of nutrients, photosynthesis products, and water to plant metabolism, which in turn affect the quality of harvested products. This particularly concerns products whose quality depends on the composition of primary metabolites (proteins, organic acids, sugars), as their distribution is strongly influenced by source/sink ratios within the plant and can be rapidly altered under stress.

While the external quality is demanded by consumers and the internal quality by the processing industry, health aspects also need to be considered. The successful establishment and acceptance of NOcsPS cultivation systems is only possible if these systems are capable of producing products with good or better quality, which also meet the technical requirements for product processing in the long term.

The aim of this subproject is to examine whether the NOcsPS cultivation system, especially for potatoes, can achieve consistently adequate or even better product qualities in the long term compared to conventional production. For this purpose, key parameters of both external and internal quality are to be investigated. The potassium concentration, which significantly contributes to tuber quality and also serves as an indicator of root nutrient acquisition, is intended to be determined. Furthermore, the concentration of ascorbic acid (Vitamin C) in the tubers will be captured, and cooking darkening will be tested as a processing parameter.

The products to be sampled include those from the cultivation trials of the State School of Horticulture or Staatsschule für Gartenbau (SfG) and Heidfeldhof in Hohenheim. The investigations focus on two culinary potato varieties (Almonda and Belana). After harvest, yield data and the proportion of marketable produce are recorded. After three and six months of storage, the following quality parameters will be sampled: calcium, potassium, Vitamin C levels, and cooking darkening.

Expected outcomes:

The internal quality of the harvested products will be assessed, as well as the presentation of marketability and external quality of the products from both cultivation systems (NOcsPS/conventional). Additionally, the identification of cause-and-effect relationships between competition, stress, and potato quality will be carried out concerning the measured nutrient and Vitamin C levels.