2023/12/05 by Bagot, Patrick, Salvi, Frédéric, Gombert, Julien
#AMMI #Abiotic stress #Azodyn #CTPS #Colza #Diacol #Ecovalence #IFT #INN #ITK #Oilseed rape #PLS Regression #Relative N concentration #Régression PLS #Réseau d’essais #Stress abiotique #Technical practices #Trial network #VATE #VCUS
paper · doi:10.17180/de25-bf61
One of the main aims selected by the group “Adopting sustainable modes of production and consumptions” gathered during the “Grenelle on the environment”, was to promote plant varieties which present a low dependence towards inputs. In order to reach this goal, a workgroup was set up within the section of the Technical and Permanent Committee for Selection (CTPS) for oilseed rape and other crucifers. In order to deepen this complex issue, this workgroup, gathering the partners of the sector, undertook an important work on the available data within the Grouping of Study and Control of the Varieties and Seeds (GEVES), confronted with those of the CETIOM, should be introduced. The objective of this approach was first to establish the current situation of the intrinsic variability of the trial network, in terms of agropedoclimatic areas and technical practices. The trial network set up within the framework of the studies of Value for Cultivation, Use and Sustainability (VCUS or VATE) is composed of about twenty locations. It is mainly located on the Charente - Lorraine diagonal, which is the main area of oilseed rape production in France. It completely meets its double objective of research for contrasting pedoclimatic situations and good representativeness of the various production areas. The average figures and the distribution of the Index of Frequency Treatment (IFT) according to the categories as well as the diversity of situations observed on the different locations were really consistent with the national average practices. The average level of the crop protection in the trial network was level 1 or "reasoned" according to the Ecophyto R*D classification. The observed fertilization practices were completely in accordance with the national practices, in terms of technical supply and doses. The technical practices (ITK) in the network were not uniform and represented at best the diversity of the French practices, under constraint of variety testing. In order to characterize the locations, indicators were looked for and were focused on abiotic stresses. Combination of a model (AZODYN) and a tool of diagnosis (DIACOL) was used to characterize the situations in climate terms and nitrogen status (relative N Concentration) a posteriori. Output indicators of both tools matched well enough between them and between to the experts thinking for the studied year, which had been atypical and marked by a strong spring water stress, leading a nitrogen stress. The researched indicators of variety behavior were mainly focused on the analysis of the Interactions x Genotypes x Environment x Practices (IGEC). The Additive Main effect and Multiplicative Interaction (AMMI) method led to good results to segregate the variety behaviors and the observed environmental situations (4 or 5 according to the trial series) without being able to explain them. Though, it was possible to identify ecovalence as a synthetic indicator to characterize the environmental and varieties levels of interactions. The Partial Least Square regression (PLSR) made it possible to identify limiting factors for the tested year and especially to measure their impacts on the locations and varieties with a very good precision. However, this analysis did not permit to characterize the varieties in the locations with the same limiting factors, the trial number for each situation being too low.