Oil productivity of seven Romanian linseed varieties as affected by weather conditions

• New descriptors (quality coefficient, cultivar efficiency) were introduced to globally assess yield and quality of seven linseed varieties.
• According to oil unsaturation degree, linseed cultivars were classified into three groups.
• Rainfall in late May–June is a key factor for obtaining improved cultivar efficiencies.
• High temperatures and low amounts of rainfall in July and August are beneficial.

In order to meet the linseed (Linum usitatissimum L.) oil growing demand it is necessary to understand the factors that influence the oil productivity. Among these factors, weather conditions (temperature and rainfall regime) may have an important effect on the development of the linseed plant in different growth stages and eventually on the oil productivity, in the context of a rational water use in drought susceptible agricultural areas. The aim of this study was to establish the influence of weather conditions on linseed oil yield and quality through an extensive field study carried on seven Romanian linseed cultivars grown in the South-Eastern agricultural area of Romania. Nine consecutive crops were analyzed in terms of seed production, seed oil content, oil production, fatty acids profile and iodine index. In order to have a global perspective on the oil production (both quantitatively and qualitatively), two new descriptors (quality coefficient and cultivar efficiency) were defined and computed. Linseed cultivars were classified according to the oil unsaturation degree by means of Principal Component and Linear Discriminant Analysis techniques. The influence of the weather conditions on the linseed crop was analyzed on the basis of a multivariate regression equation correlating cultivar efficiencies with temperatures and rainfall levels (globally expressed as Sielianinov hydrothermal coefficients) within each oil unsaturation group. Based on the results, the May–June period was found critical for the linseed development, because of the accelerated plant growth both in terms of height and branching; during this period, rainfalls are a key factor for obtaining good crops. On the contrary, pronounced drought during May–June may compromise the crop, therefore irrigation is recommended. Irrigation is not necessary during July–August since high temperatures and low levels of precipitations were found beneficial for obtaining good linseed productivities.