Comparative Phytochemical Analysis and Allelopathic Potential of Juniperus phoenicea L. in Ashnishan and Satlunah Sites, Al-Jabal Al-Akhdar, Libya

Abstract

This study compared the ecological and phytochemical status of Juniperus phoenicea in two areas of Al Jabal Al Akhdar, Libya: Ashnishan (monospecific stands) and Satlunah (mixed maquis), and evaluated the allelopathic activity of aqueous leaf extracts on seed germination. Composite leaf samples from each site were analyzed for flavonoids, total alkaloids, total phenolics, and protein content. Aqueous extracts at concentrations of 0, 5, 10, 20, 50, 75, and 100% were tested in a completely randomized design with three replicates to assess germination percentage, germination inhibition, shoot length, root length, fresh weight, dry weight, and water content. Phytochemical analysis revealed higher concentrations of all measured constituents in the Ashnishan population than in Satlunah: flavonoids (2.17 vs. 1.81 mg/100 g), alkaloids (129.80 vs. 114.30 µg ml⁻¹), total phenolics (393.80 vs. 369.10 µg GAE/100 g), and protein (5.10% vs. 4.72%). Bioassay results showed that increasing extract concentration significantly (P ≤ 0.05) reduced seed germination. In Ashnishan extracts, germination declined from 90% (control) to 20% at ≥20% concentration, with inhibition reaching 78%. In Satlunah extracts, germination dropped from 100% to 20% at 75–100% concentration, with inhibition up to 80%. Root growth was the most sensitive parameter; complete inhibition occurred at ≥50% Ashnishan extract and ≥75% Satlunah extract. Fresh weight, dry weight, and water content also decreased significantly with rising extract concentration. The results indicate that the allelopathic activity of J. phoenicea is concentration dependent and varies between populations. The stronger phytotoxic effect of the Ashnishan extract corresponded with its higher phenolic, flavonoid, and alkaloid content, suggesting that geographical variation in phytochemical composition may influence the allelopathic potential of J. phoenicea in Mediterranean ecosystems.