Geographic variation in phytochemical constituents and allelopathic potential of Pinus halepensis barks

Aqueous extracts (10, 20, 30 and 40 g/L) of Pinus halepensis barks, collected from Bizerte (B), Tabarka (T), Seliana (S) and Oueslatia (O) to elucidate the influence of ecological sites on allelopathic potential. Aqueous barks extracts from (S) and (O) have revealed a higher rate of phenolic acids than those from (T) and (B), respectively 13.23, 13.8, 11.63 and 10.37 mg/mL. Alep pin barks were analyzed using HPLC/UV for the identification and quantification of the phenolic compounds, among which in particular the catechin acetate, the gallic acid, the rutine hydrate, luteolin 7 glucoside and the cinnamic acid. In fact, the aqueous extract of barks from (S) revealed a highest level, respectively 2.61, 1.74, 1.61, 1.36, and 1.21 mg/mL. The Pinus halepensis barks was analyzed by GC and GC-MS. As a result, 29 compounds were identified representing 89% made up basically by β-caryophyllene, α-humulene. As for allelopathic activity, aqueous extracts of barks significantly delayed germination, reduced its rate and affected the seedling growth mainly the (S) and (O) extracts. The root growth of the two targets has shown a high sensibility compared to the shoot lengths. Pot cultures were conducted by the incorporation of barks powder (50 and 100 g/kg) or the irrigation with their aqueous extracts at 20 and 40 g/L. Pinus halepensis barks and its extracts have shown a high herbicide potent, particularly the one collected from (S) and (O), may be favorably used for incorporating in agricultural systems for sustainable weed management