Integrated Assessment of Antioxidant-Related Traits in B. rapa ssp. Oleifera Seeds under Different Sowing Densities

This study investigated the effects of different sowing densities on the antioxidant profile of B. rapa ssp. Oleifera seeds using an integrated analytical approach. Field trials were conducted in a randomized complete block design with four replicates at sowing densities of 150, 200, 250, and 300 seeds m⁻². Total phenolic content, total flavonoid content, DPPH radical scavenging activity, and ferric reducing antioxidant power (FRAP) were measured. Because these parameters were expressed in different units, the data were standardized using the z-score method to enable integrated evaluation. The results showed that antioxidant-related traits responded to sowing density in a parameter-dependent manner rather than following a single common trend. The second sowing density produced the most balanced antioxidant profile, whereas the first density had the highest FRAP value. Total flavonoid content was highest at the third sowing density, while total phenolic content reached its highest level at the fourth density. However, the increase in phenolic content at the highest density was not accompanied by a comparable increase in antioxidant activity. These findings indicate that the optimum sowing density should be evaluated not only in terms of yield, but also with respect to antioxidant-related biochemical quality traits.