Interactive effects of number of plants and nitrogen fertilization on quality parameters of Salvia officinalis L. cultivated in semi-arid environments

Abstract

This research aimed to elucidate the interplay between number of plants and nitrogen dose on the agronomic attributes, as well as the essential oil yield and composition of Salvia officinalis L. (sage) in the challenging ecological conditions of Mardin, situated in South Eastern Anatolia. A split-plot experimental design was employed during 2018-2019, manipulating the variables of number of plants and nitrogen application rates. The experiment identified camphor, 1,8-cineole, α-thujone, and β-thujone as the major components. The PCA analysis unveiled statistically significant inverse correlations between the concentration of camphor and 1,8-cineole, as well as α- and β-thujone. The results demonstrated that the combination of lower plant number with elevated nitrogen levels yielded higher fresh herb dry herb and dry leaf. While lower plant number and higher nitrogen application independently exerted positive influences on essential oil production and yield, the interactive impact of these treatments yielded inconclusive results. Specifically, nitrogen treatments led to an increase in camphor content while reducing α- and β-thujone contents in the essential oil. Conversely, lower plant numbers resulted in decreased camphor content and an increase in thujone content within the oil. In light of these findings, it is recommended that, under semi-arid conditions, optimal yields can be achieved by employing plant number of 50000 plants ha−1 and a nitrogen fertilizer rate of 120 kg ha−1. This research sheds light on the intricate relationship between agronomic factors and the quality of sage cultivation, offering valuable insights into sustainable agricultural practices in semi-arid regions.