Towards utilizing Asteraceae alternative oilseed species on marginal lands: Agronomic performance, fatty acid composition, oil biocompounds, and oil physicochemical properties of Asteraceae species

Including alternative and drought-resilient oilseeds in marginal lands, where conventional oilseed production is threatened, could be an effective measure to restore marginal lands and improve sustainable seed oil production. Based on this approach, the present study aimed to evaluate the potential of some new and neglected Asteraceae species as alternative oil seed crops in marginal lands. The agronomic performance, fatty acid profile, seed oil biocompounds, and physicochemical properties of blessed thistle (Cnicus benedictus), cardoon (Cynara cardunculus), milk thistle (Silybum marianum), niger seed (Guizotia abyssinica), pot marigold (Calendula officinalis) and safflower (Carthamus tinctorius) were studied under a marginal land condition (semi-dry poor soils) in two growing years. Niger seed possessed the highest oil content (39.45%), while the highest oil yield (470.21 kg ha−1) was noted in safflower. The GC and HLPC analysis indicated that all the species of seed oils were rich linoleic acid sources (51.65–73.45%). However, some species, such as safflower, also contained a high amount of oleic acid (25.41%) proportion. Pot marigold seed oils had high levels of calendic acid (more than 50% of total fatty acids). The tocopherol and phenol biocompounds as essential micronutrients for human health were abundant in the species studied, which the highest tocopherol contents recorded for blessed thistle (670.43 mg/kg) and safflower (655.75 mg/kg) oils, respectively. Accordingly, the antioxidant activity of the oilseeds followed the same trends, being the highest in blessed thistle and safflower oils. The high concentration of oleic acid in safflower oil was associated with decreasing oil density, saponification, peroxidase, and increasing viscosity indicating its high oil oxidative stability. According to agronomic and oilseed quality properties, most species, especially safflower and blessed thistle, can be considered promising alternative oilseed crops in marginal lands.