Effects of chitosan and titanium dioxide (bulk and nano) foliar application on yield and biochemical responses of Silybum marianum (L. Gaertn.) ecotypes

Milk thistle (Silybum marianum (L. Gaertn.)) is a plant with various medicinal uses which is adapted to different climates. To investigate the effects of different concentrations of chitosan (CS) and titanium dioxide (TiO2) on increasing yield and biochemical indices of milk thistle ecotypes, a farm factorial experiment was conducted in a randomized complete block design with three replications during two crop years. Experimental treatments included milk thistle ecotype at five levels (Budakalazi, Sari, Khomein, Khorramabad, and Ahvaz) and type and elicitor concentration at nine levels (foliar application of distilled water (control), bulk CS (50 and 100 mg L-1), nano CS (50 and 100 mg L-1), bulk TiO2 (50 and 100 mg L-1), and nano TiO2 (50 and 100 mg L-1)). The results showed that foliar application of CS and TiO2 (bulk and nano) effectively increased yield and defense enzymes. In all these traits, foliar application of CS and TiO2 in nano form was more effective compared to the bulk form and control. Based on the mean comparisons results, the plant yield increased with foliar application of nano CS at the concentration of 50 mg L-1. Also, foliar application of nano CS at the concentration of 100 mg L-1 increased the activity of defense enzymes. In general, foliar application of nano CS increased the yield as well as improved the biochemical traits of milk thistle ecotypes, especially the Budakalazi one, which could be considered as a suitable way to increase the yield of this plant. Considering the higher yield of Budakalazi ecotype, it could be also recommended to be used in breeding programs.