Evaluation of the Effect of a Rain Pulse on the Initial Growth of Prosopis Seedlings

Abstract

Prosopis juliflora is a useful “multi-purpose” tree, but it invades rapidly in arid and semi-arid environments, causing livelihood degradation of local communities. A rain pulse under drought conditions has been reported to be an important factor to promote plant invasion. The purpose of this research was to evaluate the effect of a rain pulse on the invading process of Prosopis juliflora and to propose a feasible plan to control the expansion of this species in Sudan. First, seed germination was examined under eight irrigation conditions, corresponding to 4–32 mm of rainfall. Most seeds imbibed in all the irrigation conditions, about half or more of the imbibed seeds germinated in 12 mm or more of irrigation. Twenty mm or more of irrigation induced seed emergence. Second, initial growth of germinated seeds was examined under ten irrigation conditions (1–32 mm rainfall) over 54 hours or 138 hours of cultivation. Radicle elongated most vigorously in 24 mm irrigation, and extended over 20 cm in length. Allocation to radicle was dominant, and its elongation was promoted in higher soil moisture condition. Based on these results, we propose that seedlings of P. juliflora should be eradicated within a few weeks after a single large rainfall, which might be convenient and effective to control additional expansion of this species in Sudan.

Keywords:

• invasion
• radicle elongation
• Sudan
• wet-dry cycle

Acknowledgments

Thanks are due to Dr. Ian G. Gleadall of Tohoku University for reading the manuscript and valuable comments. We want to thank the editor and anonymous reviewers of the journal for their insightful comments that improved the manuscript.

Additional information

Notes on contributors

Hiroshi Nawata

Hiroshi Nawata is currently associated with the Faculty of International Resource Sciences, Akita University, Akita, Japan.