The green and mature senescent needles of Pinus halepensis from the Tunisian pine forests of Bizerte, Tabarka, Seliana and Oueslatia were evaluated based on their phytochemicals contents for allelopathic potential on seed germination and seedling growth of radish (Raphanus sativus L.) and wheat (Triticum aestivum L.). Aqueous extracts of green needles of Seliana and Oueslatia regions, significantly delayed the germination and adversely affected the seedlings growth. In Pot culture studies, mature and green needles powder or soil treatment with needles aqueous extracts were also very inhibitory to seedling growth. The phenolic acids compositions of green and mature needles were determined using HPLC. Analysis of the needles for their phytochemical content showed that the aqueous extracts of green needles contained higher amount of phenolic acids than in mature needles. The phenolics contents in the needles also varied with ecological sites. Needles from Seliana and Oueslatia regions had higher amount of phenolics than those from Tabarka and Bizerte regions. The aqueous extract of green needles from Seliana region had higher levels of gallic acid and 2, 4-D Pestanal, while, the mature needles from Seliana had higher level of cinnamic acid. The green and mature needle extracts were also analyzed for chemical components by GC and GC-MS and 47-compounds were identified, representing 89% of the total compounds, with beta-caryophyllene, a-pinene and myrcene being the predominant.