No abstract

No abstract

No abstract

Core Ideas This is the first report of blessed thistle response to nitrogen and plant density. Optimizing nitrogen and density improved quality and quantity of blessed thistle seed. Under low yielding conditions, the actual yield of blessed thistle is acceptable. Blessed thistle is rich in polyunsaturated fatty acids such as linoleic acid. Developing alternative oilseed crops with acceptable seed yield and biomass production in low‐yielding environments could be a part of sustainable agriculture management strategies. Field experiments were conducted in a semiarid region of Iran in 2013 and 2014 to determine the effects of N fertilizer rates and plant densities on growth, seed yield and quality of blessed thistle (Cnicus benedictus L.) under low yielding conditions. Randomized complete‐block design with factorial arrangement of treatments was used in three replicates. Treatments consisted of four N rates (0, 50, 100, and 150 kg N ha−1) combined with five plant densities (5, 10, 15, 20, and 25 plants m−2). According to quadratic functions, the maximum seed yield (913 kg ha−1) was achieved with 122 kg N ha−1 and 16 plants m−2. Although the seed oil content decreased with increasing N rates, increased seed yield partially compensated for the reduction in oil content. Higher seed protein was obtained from low plant densities (5–10 plants m−2) and high N rates (100–150 kg N ha−1). Nitrogen harvest index (NHI) decreased by 30 to 40% as a result of increased plant density across all N rates. Plant density and N did not affect seed fatty acid profiles, even though N rate by year interaction affected the profile. Linoleic acid was the predominant fatty acid comprising 62.5 to 66.2% of the total fatty acids. The study demonstrates that blessed thistle could be a promising oil crop for cultivation in low yielding soils, although breeding work is needed to enhance its prospects as a viable oil crop.

Exploring the saline-adapted species and the mechanisms by which they have evolved in saline conditions would be a feasible way to utilize saline soils. Based on this approach, this study aimed to evaluate the seed germination and seedling responses of the five abundant Asteraceae species to salinity stress and determine the antioxidant defense strategies by which these species demonstrated variations in the tolerance of salinity. Milk thistle (Silybum marianum), blessed thistle (Cnicus benedictus), pot marigold (Calendula officinalis), safflower (Carthamus tinctorius), and cardoon (Cynara cardunculus) were subjected to 0 (control), 50, 100, 150, 200 and 250 Mm NaCl concentrations. Calendula officinalis (CO) showed the highest, Silybum marianum (SM) and Cnicus benedictus (CB) moderate, and Carthamus tinctorius (CT) followed by Cynara cardunculus (CC) the least inhibition of seed germination and seedling growth at all given salinity levels. Each species utilized different antioxidant mechanisms in response to salinity. Peroxidase (POX) was the major antioxidative enzyme in resistance species, CT and CC, while catalase (CAT) and superoxide dismutase (SOD) were more pronounced in moderate, SM and CB, and susceptible, CO, species, respectively. Besides, all species expressed a great ability to accumulate considerable amounts of proline in response to salinity, which was more evident in the 150 and 200 Mm NaCl concentrations. From the results, it can be concluded that CT and CC with longer seedling roots, higher POX activity and proline accumulation coupled with lower cellular damage under increased salinity demonstrated a more saline-tolerance capacity in comparison to other species.