Allelopathic effects of Prosopis juliflora (SW.) DC on improving the vegetative traits of Acacia oerfota (Forssk.) Schweinf and Acacia tortilis (Forssk) Hayne seeds under laboratory conditions

Allelopathy is the interaction between plants that stimulates or inhibits the growth and germination of other species. Non-native species of (Prosopis juliflora (SW.) DC) is one of the species known as invasive species with allelopathic effects that can inhibit the growth and growth of species by producing allopathic compounds such as phenols, alkaloids into the environment. Two important species of Hormoozgan province are Acacia oerfota and Acacia tortilis which P.juliflora was observed with them in the natural forests, Therefore, the correct selection of tree species in forest plantation should be done with caution in order to inhibit negative effects on native species. The aim of this study was to investigate the allelopathic effects of different organs of p. juliflora on germinatin, radicle and plumule length of Ac. tortilis and A. oerfota.

For this purpose, the organs (root, bark and leaf) of P.juliflora were collected and different extract concentration (0, 2, 4, 6 and 8%) were prepared were added on A.tortilis and A. oerfota (4 replications, n=60) in growth chamber, and after recording germination, the plumule and radicle length were meausered after 30 days. Factorial experiment was performed through completely randomized design and was analyzed by two-way variance analyses.

Results showed that the lowest gemination percentage in A.tortilis was observed at 8% concentration with the amount of 16.11%. The plumule length of A. tortilis and A. oerfota in aquatic extraction of leaves (1.73 and 3.9 cm) was significantly lower than other organs. Also, the plumule length of A. tortilis (3.58 cm) and A. oerfota (5 cm) had the highest amounts in control. The interaction effects of organ × concentration showed that plumule and radicle length in A.tortilis and A. oerfota had the significant differences. The interactions of organ × concentration on radicle and plumule length in A.tortilis and A. oerfota species were also significantly different. The radicle and plumule length of A. tortilis and A. oerfota in leaf organ with values of 1.25, 1.73 cm and 1.98 and 3.9 cm were significantly less than bark and roots, respectively.

The results showed that there were inhibitory effects of aqueous extract of Prosopis juliflora root, bark and leaves on the germination percentage, root length and stem length of two important species of Acacia tortilis and Acacia oerfota in laboratory condition. Among the three studied organs, the leaf organ had the most inhibitory effects, which due to the high volume of litter under the canopy of this species in the environment and the entry of toxic compounds into the surface soil due to decomposition, prevents the growth of Acacia tortilis and Acacia oerfota that P. juliflora is seen with these species and overcome on them. Also, the root had the lowest inhibitory In according to the results, P.juliflora has allelopathic effects on native species. Therefore, it is recommended to choose non-native species for afforestation more carefully and using native species for reforestation and afforestation in the south fragile ecosystem of Iran is more suitable option.