Allelopathic Effects Mesquite (Prosopis juliflora Swartz) Aqueous Extracts on Seeds Germination and Seedlings Growth of Alfalfa, Sesame and Sorghum

Abstract

Mesquite plant [Prosopis juliflora (Swartz) DC] is an invasive, evergreen and multi-purpose leguminous tree or shrub, native to South America. Unfortunately, due to deliberate distribution within Sudan, the plant became a threat to agriculture and biodiversity. The observed absence of ground vegetation under its canopy suggests that it has some allopathic potential that may be caused by fallen fruits, leaves, roots exudates or plant leachates. The release of these allelochemicals in t0 the soil may inhibit the germination and growth of agricultural crops. This study which was under taken in the laboratory of plant pathology, Department of Plant Protection, College of Agricultural Studies, Sudan University of Science and Technology during January-February, 2016. It was aimed to elucidate the potential of allopathic effects of aqueous extract of different parts of Mesquite plant,- namely fruits, leaves, bark and roots, on germination percentages and early seedlings growth of Alfalfa ,Sesame and Sorghum. The results obtained revealed that the aqueous extracts of different parts of mesquite screened significantly (P≤0.05) inhibited the seeds germination of the test crops and reduced the early growth of the seedlings with considerable difference compared to control. These suggest that the inhibitory substance(s) were widely distributed -in Mesquite plant but at varying extents. Moreover, the inhibitory -effect on percentages germination and the reduction in early growth of seedlings given by fruits and leaves extracts was more pronounced and consistent than that in bark and roots. This could be attributed to the assumption that the mesquite fruits and leaves aqueous extracts contain or water-soluble allelochemicals than that of roots and bark and hence the inhibitory effect was more pronounced. Accordingly, they gave 0.0%germination in alfalfa and sesame and 47.6% to 86.7% in sorghum, respectively, compared to control. Whereas the length of hypocotyl and radical was reduced to 0.0 cm and up to 2.7 cm depending on the efficacy of extract and the response of the test crop. Thus it is recommended to study the nature of inhibitors which should help to determine whether the Allelopathic is the cause behind the exceptional success of Mesquite on the flat plains of agricultural lands in Sudan.