Diagnosis of camelina seed yield and quality across an on-farm experimental network

Abstract

Camelina [Camelina sativa (L.) Crantz] is an emerging oilseed crop combining both industrial and agronomic advantages. Camelina seed yield, oil and protein contents, and fatty-acid composition, vary across genotypes, environments, and agricultural practices. However, no studies have been conducted to identify and rank major limiting factors explaining yield and quality variations under on-farm conditions. Camelina performance was measured on 39 experimental strips corresponding to five camelina crop management routes (grown as an intercrop or sole crop), implemented in nine farmers’ fields across northern France in 2017 and 2018. The ranking of candidate limiting factors, defined a priori from scientific literature, was carried out using a model mixing method based on the Akaike Information Criterion. Main limiting factors of camelina yield (ranging from 62 to 2585 kg ha−1) were nitrogen crop status at flowering stage and downy mildew. Camelina yield was indeed positively correlated with the Nitrogen Nutrition Index at flowering stage (R2 = 0.44, p = 0.007). Oil content varied from 36.6 to 46.5 % and was negatively correlated with protein content. Main indicators explaining oil content variations were grain filling duration and downy mildew. Both poly-unsaturated and linolenic acid contents were positively correlated to grain filling duration, and negatively correlated to temperature during grain filling period. Camelina nitrogen status at flowering stage was mainly explained by N uptake of the intercropped species (pea or barley), and the amount of available inorganic nitrogen in the soil between sowing and flowering. Downy mildew was influenced by both weather conditions and the amount of weed biomass.This study showed a large variability in camelina seed yield and quality under on-farm conditions. The identification of the major limiting factors made it possible to pinpoint ways of improving camelina performance namely choosing genotypes with high resistance to mildew, better managing nitrogen fertilization or delaying camelina sowing date. Finally we also identified major research topics to be addressed to support the adoption of this new crop by farmers as the elaboration of the critical nitrogen dilution curve.