Genotype and plant density effects on oil content and fatty acid composition of safflower
Safflower (Carthamus tinctorius L.) is a multipurpose oilseed crop that is tolerant to drought, saline, heat and cold conditions; and yields high quality edible seed oil. The objective of this study was to evaluate the effect of plant density and genotypes on oil content and fatty acid composition of safflower. A field experiment was conducted in the years 2015 and 2016, during winter and summer seasons. Treatments included five safflower genotypes and six plant densities. Genotype and plant density significantly interacted (P < 0.05) to influence oil content and fatty acid composition of safflower. Increasing plant density from 62,500 to 100,000 plants ha-1 significantly (P < 0.05) increased the oil concentration from 16 to 54%, depending on the interaction between genotype and plant density and genotype by environment (winter and summer seasons). However, as plant density increased from 100,000 to 200,000 plants ha-1, safflower oil content significantly (P < 0.05) decreased in all genotypes. The lowest and highest oil contents was produced by genotype ‘Gila’ planted at density 62,500 or 200,000; and ‘Sina’, ‘Pi 537 636’ at 100 000 or 125, 000 plants ha-1 in winter or summer, respectively. Fatty acid composition was significantly influenced by genotype and plant density interactions during the two growing seasons. The main fatty acids identified included linoleic, oleic, stearic and palmatic. There was a significant (P < 0.05) increase in linoleic acid content and a decrease in oleic, palmatic and stearic as plant density increased from 62,500 to 100,000 plants ha-1, depending on genotype or growing season. Genotype ‘Sina’ at 100,000 plants ha-1 produced the highest oil content and with high unsaturated fatty acid concentrations.