Aim : The study was undertaken to investigate the inhibitory effect of pine needle extract (Pinus eldarica) on the vegetative growth of weeds found in bean fields. Methodology : Aqueous extracts [0, 25, 50, 75 and 100% of pine needles were applied to common bean (Phaseolus vulgaris) and weeds (prosomillet and redroot pigweed). The effect extract on seedling growth, physiological and biochemical characteristics were subsequently investigated. The experiment was carried out completely a randomized design with three replicates. Phytochemical compounds of pine needle extracts were determined spectrophotometrically. Results: Extracts of pine needles increased the Chl a, Chl b, total Chl and carotenoid contents of bean varieties in comparison to control; while the level of these pigments were considerably low in weeds. The lowest content of proline and phenolic compounds, as well as the highest peroxidation of biomembrane lipids was detected in redroot pigweed treated with 100% needle extract. Although peroxidase and catalase activities dramatically increased in bean varieties proportional to the extract concentration applied. Auxin oxidase and nitrate reductase activities in both weeds significantly (p<0.05) decreased due to treatment. The sensitivity of weeds to allelochemicals was higher as compared to bean varieties. Content of phenolics and proanthocyanidins were also high in pine needle extracts, which was correlated to the inhibitory effect on the weeds studied. Interpretation: The results of this investigation point to a positive effect of the use of Eldar pine needle extracts as a natural herbicide in comparison to the chemical counter parts.

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