Figure 3.

Relative allelopathic effect (RAE) on seed germination of Lactuca sativa (a, b, and c) and Linum strictum (d, e, and f) according to Pinus halepensis VOC source (a, d), dose (b, e) and substrate type (c, f). Values are mean ± SE. Different letters denote significant differences between treatments with a > b > c. Negative values of RAE indicate an inhibitory effect, whereas positive values indicate a stimulatory effect. GN, green needle; FP, filter paper; NL, needle litter; SN, senescent needle