Abstract
The allelopathic impact of Eucalyptus spp is a pivotal factor in plant-plant interactions, particularly in arid and semi-arid ecosystems. The consideration of sowing depth in plant species becomes increasingly significant when examining allelopathic effects. This study aimed to assess the allelopathic effects of Eucalyptus camaldulensis leaf powder in conjunction with sowing depth on the germination and growth behavior of Agropyron desertorum and Onobrychis sativa. Seeds of these species were collected from Yazd province, Iran. An experimental design was implemented employing a completely randomized design (CRD) with four replications and two factors. The first factor (allelopathy) comprised five levels: 0 (control), 5%, 1%, 2%, and 3% leaf powder of E. camaldulensis in 1000 g of soil. The second factor (sowing depth) included four levels: 0.5 (control), 1.5, 3, and 4.5 cm. Data analysis utilized one-way ANOVA and Duncan’s multiple range tests. The results indicated that both allelopathy and sowing depth significantly impeded the growth of A. desertorum and O. sativa. Additionally, findings revealed that 3% leaf powder of eucalyptus exerted the most pronounced impact on the number of germinated seeds, stem length, and shoot weight in both species. Furthermore, a sowing depth of 4.5 cm was observed to be more inhibitory on the germination, shoot length, and shoot weight of A. desertorum and O. sativa compared to other depths. In conclusion, the study established that the interactions between allelopathy and sowing depth significantly constrained the growth and performance of A. desertorum and O. sativa.