Secondary Metabolites and Their Antioxidant Activity Enhance the Tolerance to Water Deficit on Clover Lotus corniculatus L. through Different Seasonal Times

This study aimed to evaluate the effects of a water limitation in different ecotypes and one variety of Lotus corniculatus L. on the production of secondary metabolites and their antioxidant activity in response to a water deficit (WD) through other seasonal times. A randomized block experimental design with three replicates was used. Two levels of soil water content and five genotypes were arranged in a factorial way (2 × 5) with ten treatments for replication. The 255301 ecotype showed significantly higher (p ≤ 0.05) concentrations of total phenols, with a concentration of 86.6 mg Gallic Acid Equivalent (GAE)/gram of fresh weight (gFW); total flavonoids, with a concentration of 63.2 mg Quercetin Equivalent (QE)/gFW); total tannins (71.7 mg GAE/gFW); and radical scavenging activity, with an average of 200 mg Trolox Equivalent Antioxidant Capacity (TEAC)/gFW) in winter under a WD. The 255305 ecotype showed an increase in radical scavenging activity of 230 mg (TEAC)/gFW) and a total tannin concentration of 65.3 mg GAE/gFW in winter and spring, respectively, under a WD. The 255301 ecotype showed an increase in the concentration of total saponins (254.8 mg saponins/gFW) in summer under a WD. All these responses were triggered to mitigate a water deficit and extreme temperatures.