Effects of allelochemicals from Juniperus phoenicea L. needles on the germination and growth of chosen agricultural crops

In this study, we examined the allelopathic potential of Juniperus phoenicea L. needles on the seed germination and seedling growth of various crops. The investigation focused on the phytotoxic effects of Juniperus phoenicea L. needles, encompassing leachate, aqueous, and organic extracts, on radish, lettuce, barley, and tomato crops. To comprehensively assess their impact, we established pot cultures by incorporating needle powder into the soil at rates of 50 and 100 g/kg, accompanied by irrigation with leachate and aqueous extracts at concentrations corresponding to IC50 (50 % growth inhibition) and the minimum inhibitory concentration (MIC, resulting in 100 % growth inhibition). The volatile components of petroleum ether, chloroform, and acetone extracts were subjected to gas chromatography–mass spectrometry (GC–MS) analysis to elucidate their chemical composition. The germination index underwent significant reduction due to the influence of the needle extract and leachate. Concerning growth, the needle extract exhibited maximum toxicity at a concentration of 40 g/L. Remarkably, the needle leachate exerted a pronounced inhibitory effect on the growth of radish, tomato, and lettuce seedlings, notably at a concentration of 200 g/L. In the context of organic extracts, all three fractions displayed substantial toxicity at a concentration of 30 mg/kg. Incorporating residues into the soil at a rate of 100 g/kg led to a notable decrease in the root and shoot length of the target crops. Soil irrigation with aqueous needle extracts and leachate adversely affected radish, lettuce, and tomato. The biomass of J. phoenicea L. emerges as a potential source of herbicidal substances, offering a promising avenue for integration into agricultural systems to achieve effective and sustainable weed control. However, to solidify these findings within authentic field conditions and to identify specific bioactive compounds for the development of sustainable weed management strategies, further research is imperative.