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Project

Within- and among-variability of root trait responses to N availability in two forage legumes (WINLEG)

Main research question/goal

How do forage legumes divide their carbon assimilates between the first-formed roots and shoots? Does the root architecture affects the formation of the desired nodules where N fixation takes place? These fundamental questions are studied within the WINLEG research project, and can lead to useful applications within forage legume breeding. Forage legumes are often grown in combination - and hence in competition - with forage grasses. Such grass-legume mixtures produce high forage yields with a high protein content, but require less nitrogen (N) fertilization. However, successful grass-legume mixtures require a quick establishment of the legume component. Quick establishment of legume seedlings and their competition for nitrogen could be better controlled if we better understand the rooting process. In forage legumes such as red clover or alfalfa, the early fases of rooting have been little studied untill now. 


Research approach

We focus on two major forage legumes: red clover and alfalfa. Five varieties from each crop are evaluated. A total of 19 seedlings per variety are phenotyped for root architecture (root elongation potential, branching capacity, shoot-root allocation) under high and low N conditions using the 4PMI phenotyping facility at INRA Dijon (FR). Rhizotube technology coupled with image acquisition systems (RGB images) makes it possible to obtain regular high resolution images (42 microns) from shoots and root systems. Using the images, the growht of each individual plant is modeled in a growing curve where the growth of above-ground and below-ground plant parts are displayed. The balance between investing in above-ground and below-ground plant parts is determined for each plant. The N division within plants is investigated through 15N analyses. 


Relevance/Valorisation

This fundamental research project has generated insight into the competitive potential of forage legumes. The newly acquired knowledge can help breeders in red clover and alfalfa aiming to develop varieties adapted to the growing conditions of tomorrow. Researchers have collected and analyzed large amounts of data: over 180 000 images were obtained in the 50 days after sowing. Growing curves for rooting and above-ground plant growth have been modelled for all varieties. Different growing patterns were observed both between and within varieties. An allometric analysis revealed that in the seedling stage, alfalfa invests more in rooting than does red clover. After finalization of the project, the images will be used to study various additional traits, such as root density, root depth and the total leaf surface. A NIRS analysis on the harvested leaf material should provide more insight in the leaf/stem ratio. A biochemical analysis on the harvested roots reveal how both crops react to nitrogen fertilization in the seedling stage. We expect at least two scientific publications on root traits and the N response in both legume crops. 

Date:1 Sep 2020 →  31 Aug 2021
Disciplines:Agricultural spatial analysis and modelling, Crop science