Characterisation and optimisation of the registration scheme for winter pea varieties in 2007, 2008 and 2009

The aim of the study was to adapt the method for diagnosing limiting factors—originally developed for wheat—to peas, drawing on the registration network for conventional hr winter pea varieties (non-photoperiod-responsive) and the new network of photoperiod-responsive Hr winter pea varieties (which can be sown earlier). One of the objectives was therefore also to discuss the development of this new network. The use of existing agronomic models or those developed as part of the study was necessary to calculate the descriptive variables of certain limiting factors, in particular to estimate the date of occurrence of certain growth stages (flower initiation, onset of grain filling), and to describe limiting factors such as winter frost, water stress, nitrogen deficiency and pressure from ascochytosis. The assessments of limiting factors carried out on four control varieties (three of the hr type, 1 of the Hr type) explained between 51 and 66 per cent of the variation in yield with 3 to 6 limiting factors, and between 43 and 84 per cent of the variation in protein yield with 3 to 7 limiting factors, figures very close to those for yield. We highlighted the predominant influence of ascochytosis, high temperatures between the start of flowering and the start of grain filling (which have a less pronounced effect on protein yield), drought and lack of sunlight during the same period (which have a more pronounced effect on protein yield). Limiting factors at the start of the growing season (plant losses, delayed emergence, and, in mountainous areas, frost between floral initiation and the start of flowering) particularly affected early-sown winter peas. The Hr network was structured using four factors limiting yield losses. This highlights the specific characteristics of certain environments and suggests increasing the diversity of limiting factors by selecting new sites or by varying cultivation practices. The use of at least two control varieties is also desirable to increase this diversity.