Variations in carbon and nitrogen ratios and their effects on seed germination in Cupressus sempervirens populations

Abstract

This study investigated the variations in the carbon (C), nitrogen (N), and C/N ratios in the seeds of the Mediterranean Cypress (Cupressus sempervirens L.), a typical forest tree of the Mediterranean Region. The data were gathered from populations distributed across Turkey. We also evaluated the relationship between these variations and germination parameters such as the germination percentage (GP) and mean germination time (MGT). All of the evaluated characteristics demonstrated statistically significant variations among the populations. The GPs were generally low and varied between 14% in Datca and 51% in the Koprulu Kanyon. The MGTs ranged from 14.9 in the Koprulu Kanyon to 18.9 in Marmaris. In addition, the C ratios varied between 46% in Marmaris and 52% in the Koprulu Kanyon, while the N ratios ranged from 1.1% in Beycik and Goksu to 1.8% in the Koprulu Kanyon. Furthermore, we observed a positive correlation between the GP and the C and N contents (R-2 = 0.51 and R-2 = 0.49, respectively) but found a negative correlation between the MGT and the C and N contents (R-2 = 0.56 and R-2 = 0.32, respectively). Moreover, with regard to the combined C and N seed ratios of the regression models, R-2 = 0.95 for the GP and R-2 = 0.87 for the MGT, and the populations with higher quantities of C and N in their seeds had shorter MGTs and higher GPs.