Role of Microbial Inoculants and Organic Carriers in Enhancing the Biological Response of Grass Pea (Lathyrus sativus L.) under Diesel-Contaminated Soil Conditions

• Zainab Adnan Hussein * 1, Faris Mohammed Suhail 2

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This study analyzed how microbial inoculants and organic carriers improve the biological response of grass peas (Lathyrus sativus L.) in soil polluted by gasoil (diesel). A Randomized Complete Block Design (RCBD) factorial field experiment used 24 treatments from interactions of biological treatments (Rhizobium and Bacillus on biochar or cocopeat, and the mycorrhizal fungus Glomus mosseae), two gasoil levels (0 and 1%), and two biochar levels (0 and 1%), in three replications (72 units). Results showed significant effects on most studied traits. The triple interaction among mycorrhizae, gasoil, and biochar yielded highest values in growth traits: plant height (100 cm), shoot dry weight (30.11 g. plant⁻¹), and root dry weight (1.81 g. plant⁻¹). Furthermore, Rhizobium on biochar combined with gasoil and biochar excelled in active root nodules (31.33 nodules plant⁻¹), while Rhizobium on cocopeat with gasoil and biochar recorded highest leaf nitrogen (5.94%). Mycorrhizae demonstrated clear superiority in colonization percentage (averaging 83.08%, increasing to 87.17% with gasoil and 85.83% with biochar). Biochar improved mycorrhizal colonization, whereas gasoil alone had no significant effect on it. Overall, integrating microbial inoculants and organic carriers particularly mycorrhizae and Rhizobium with biochar significantly improved grass pea growth and biological response under gasoil pollution, supporting their potential to enhance biological systems in petroleum-affected soils.

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