Linseed as a dual-purpose crop: evaluation of cultivar suitability and analysis of yield determinants

Linseed is enjoying renewed popularity worldwide thanks to emerging market opportunities for raw material derived from seeds and stems. The dual-purpose cultivation is particularly attractive to growers for its capacity to yield both seed/oil and straw/fibre; however, field-based research is necessary to identify suitable cultivars to meet modern production goals. Under these premises, a 3-year experimental campaign was conducted to evaluate 18 linseed cultivars potentially interesting for dual-purpose cultivation in Northern Italy. Cultivar performance was evaluated in terms of seed, straw and fibre yield, oil composition and stem fibre content. Inter-annual weather variability explained the largest portion of the total variance. However, the 'cultivar x year' interaction was not significant except for seed oil content and composition. Stability analysis showed that at least half of the cultivars were unstable for oil content and alpha-linolenic acid fraction. A Structural Equation Model was developed to investigate causal relationships between the productive performance and factors such as environmental variables, phenological traits, plant size and density. Rainfall was beneficial to seed yield, both before and after flowering, whereas higher post-flowering air temperature had a depressive effect. A higher oil content was favoured by pre-flowering rainfall. Plant height was negatively associated with seed yield and oil content, but it was positively associated with straw and fibre yield. Plant density was critical for fibre yield since below 500 plants/m(2) the increased plant branching makes it difficult to extract fibre. Together with plant density, plant height could be used to manipulate the seed/straw ratio according to production goals.