Increasing sustainability and nitrogen use efficiency by improving peas for crop rotation

This project focuses on identifying efficient pea varieties with superior photosynthetic performance, nitrogen fixation capacity, and protein yield. Using advanced field phenotyping technology, researchers will screen pea lines for photosynthetic efficiency and assess the technology’s ability to detect high-performing breeding lines. Rather than optimizing fertilizer use, the project explores an alternative approach to improving nitrogen use efficiency at the farm level by integrating legumes into crop rotations or enhancing existing legume varieties.

Plant-based protein production is a key issue to decrease the environmental footprint of agriculture and to improve human nutrition - especially in Europe. Protein production from grain legumes such as pea, beans or chickpeas provides a lot of benefits compared to protein production from other plant species such as cereals. Most importantly, Nitrogen (N) fertilization is not required due to the symbiosis of legumes with N-fixing bacteria. This decreases N pollution into the air and water, making nitrogen use efficiency one of the most important goals towards sustainable agriculture. Throughout the last decades, grain legumes have been optimized for animal feed used for inefficient animal protein production. With increased demand for alternative meat products, new grain legume varieties are required with high protein content and quality. The N fixation of legumes produces sustainable protein. However, the process cannot directly be monitored and therefore it is difficult for breeders to select for. Fueled by photosynthates, N-fixation could be indirectly selected for when measuring photosynthetic performance. Photosynthesis is highly dynamic under fluctuating field conditions, but a powerful indicator of plant growth and N fixation, when it can be measured in high temporal resolution.

Monitoring of photosynthesis in breeding nurseries using a field robot offers the chance to identify superior pea breeding lines and varieties in terms of protein production. In the Eschikon field site, more than 100 pea lines will be grown and monitored for photosynthesis throughout the growing season. Yield and protein content can be evaluated with conventional methods. Then, the relationship between photosynthetic efficiency and protein content will be investigated and superior lines can be identified. The best lines will be placed into farmers’ fields and the N fixation, N use efficiency and protein production under realistic conditions will be measured and compared to a standard variety. This research project provides the opportunity to explore automated monitoring of photosynthesis in the field in a wide set of pea varieties and to calculate their N use efficiency. Establishment of such a workflow will be the cornerstone for breeding more N efficient varieties. These varieties will be attractive to farmers and their share of legumes in crop rotation will increase, along with N use efficiency, food security and sustainable protein production.