Seed and Biomass Yield Responses of Blessed Thistle to Nitrogen and Density

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.

Rhizobacterial species richness improves sorghum growth and soil nutrient synergism in a nutrient-poor greenhouse soil

“…The plant density is a key determinant of agro- and natural-ecosystems productivity while it influences the quality and quantity of important agro-ecological traits 63 – 65 . Nevertheless, the higher plant density, as we observed in the rhizobacterial treatments, is considered a good indicator of plants agronomic traits and productivity under marginal soil conditions 66 , 67 .…”