Éxito en la reintroducción en la Reserva Natural de Oued Dekouk, Túnez, de una planta autóctona, Periploca angustifolia

The study evaluates the regeneration success of an autochthonous plant species, Periploca angustifolia Labill. (periploque), using spontaneous (pre-existing) and transplanted (re-introduced from a nursery) plants in the Natural Reserve of Oued Dekouk, southern Tunisia. We compared the growth status of both types of shrubs using morphological and ecophysiological parameters. The results show that spontaneous periploque was more vigorous and appears more adapted to aridity than transplanted periploque. Indeed, spontaneous shrubs have higher growth rates than transplanted ones. They also had higher leaf water potentials, indicating excellent plant water status recovery, and elevated photosynthetic assimilation rate. The better growth of spontaneous shrubs seems to be due to the efficacy of its aridity adaptive mechanisms. They limit water loss through a low leaf area and stomatal density and an efficient stomatal function. Furthermore, spontaneous plants have an efficient water-conducting system less vulnerable to embolism. Transplanted plants may have a less developed root system limiting their ability to absorb soil moisture. The present study indicates that the re-establishment of endangered plant species into areas with limited rainfall maybe more feasible by direct seeding or self regeneration, despite its slowness, than by the hardy and costly transplantation-technique.El estudio evaluó el éxito en la regeneración de una planta autóctona, Periploca angustifolia Labill. (cornical), introducida por la técnica de transplante en la Reserva Natural de Oued Dekouk (sur de Túnez), con un clima mediterráneo supra sahariano. Se llevó a cabo un estudio comparativo entre arbustos espontáneos (pre-existentes) y transplantados (a partir de un vivero) y se midieron varios parámetros morfológicos y ecofisiológicos. Los resultados muestran que los cornicales espontáneos fueron más vigorosos y están mejor adaptados a la aridez que los transplantados. De hecho, los arbustos espontáneos tienen mayores ratios de crecimiento que los transplantados. También mostraron mayor potencial hídrico en las hojas, lo que indica una excelente recuperación del estatus hídrico en la planta, y una elevada tasa de asimilación fotosintética. El mejor crecimiento de los cornicales espontáneos parece ser debido a la eficacia de sus mecanismos de adaptación a la aridez: limitan las pérdidas de agua mediante una menor área de la hoja y de densidad de estomas y una eficiente función de estos. Además, las plantas espontáneas tienen un sistema de conducción de agua eficiente menos vulnerable a la embolia. Las plantas transplantadas pueden tener un sistema de raíces menos desarrollado que limite su capacidad para absorber la humedad del suelo. El presente trabajo indica que la reintroducción de especies en peligro de extinción en áreas con precipitaciones limitadas puede ser  más viable por siembra directa o por auto-regeneración, a pesar de su lentitud, que por la dura y costosa técnica del transplante

Re-introduction success of an autochthonous plant species, Periploca angustifolia, in the Natural Reserve of Oued Dekouk, Tunisia

The study evaluates the regeneration success of an autochthonous plant species, Periploca angustifolia Labill. (periploque), using spontaneous (pre-existing) and transplanted (re-introduced from a nursery) plants in the Natural Reserve of Oued Dekouk, southern Tunisia. We compared the growth status of both types of shrubs using morphological and ecophysiological parameters. The results show that spontaneous periploque was more vigorous and appears more adapted to aridity than transplanted periploque. Indeed, spontaneous shrubs have higher growth rates than transplanted ones. They also had higher leaf water potentials, indicating excellent plant water status recovery, and elevated photosynthetic assimilation rate. The better growth of spontaneous shrubs seems to be due to the efficacy of its aridity adaptive mechanisms. They limit water loss through a low leaf area and stomatal density and an efficient stomatal function. Furthermore, spontaneous plants have an efficient water-conducting system less vulnerable to embolism. Transplanted plants may have a less developed root system limiting their ability to absorb soil moisture. The present study indicates that the re-establishment of endangered plant species into areas with limited rainfall maybe more feasible by direct seeding or self regeneration, despite its slowness, than by the hardy and costly transplantation-technique.El estudio evaluó el éxito en la regeneración de una planta autóctona, Periploca angustifolia Labill. (cornical), introducida por la técnica de transplante en la Reserva Natural de Oued Dekouk (sur de Túnez), con un clima mediterráneo supra sahariano. Se llevó a cabo un estudio comparativo entre arbustos espontáneos (pre-existentes) y transplantados (a partir de un vivero) y se midieron varios parámetros morfológicos y ecofisiológicos. Los resultados muestran que los cornicales espontáneos fueron más vigorosos y están mejor adaptados a la aridez que los transplantados. De hecho, los arbustos espontáneos tienen mayores ratios de crecimiento que los transplantados. También mostraron mayor potencial hídrico en las hojas, lo que indica una excelente recuperación del estatus hídrico en la planta, y una elevada tasa de asimilación fotosintética. El mejor crecimiento de los cornicales espontáneos parece ser debido a la eficacia de sus mecanismos de adaptación a la aridez: limitan las pérdidas de agua mediante una menor área de la hoja y de densidad de estomas y una eficiente función de estos. Además, las plantas espontáneas tienen un sistema de conducción de agua eficiente menos vulnerable a la embolia. Las plantas transplantadas pueden tener un sistema de raíces menos desarrollado que limite su capacidad para absorber la humedad del suelo. El presente trabajo indica que la reintroducción de especies en peligro de extinción en áreas con precipitaciones limitadas puede ser más viable por siembra directa o por auto-regeneración, a pesar de su lentitud, que por la dura y costosa técnica del transplante

Re-introduction success of an autochthonous plant species, Periploca angusttfolia, in the Natural Reserve of Oued Dekouk, Tunisia

The study evaluates the regeneration success of an autochthonous plant species, Periploca angustifolia Labill. (periploque), using spontaneous (pre-existing) and transplanted (re-introduced from a nursery) plants in the Natural Reserve of Oued Dekouk, southern Tunisia. We compared the growth status of both types of shrubs using morphological and ecophysiological parameters. The results show that spontaneous periploque was more vigorous and appears more adapted to aridity than transplanted periploque. Indeed, spontaneous shrubs have higher growth rates than transplanted ones. They also had higher leaf water potentials, indicating excellent plant water status recovery, and elevated photosynthetic assimilation rate. The better growth of spontaneous shrubs seems to be due to the efficacy of its aridity adaptive mechanisms. They limit water loss through a low leaf area and stomatal density and an efficient stomatal function. Furthermore, spontaneous plants have an efficient water-conducting system less vulnerable to embolism. Transplanted plants may have a less developed root system limiting their ability to absorb soil moisture. The present study indicates that the re-establishment of endangered plant species into areas with limited rainfall maybe more feasible by direct seeding or self regeneration, despite its slowness, than by the hardy and costly transplantation-technique

Occurrence of arbuscular mycorrhizal fungi and nodules in the roots of twelve legume species in South-Western Saudi Arabia

The tripartite associations of arbuscular mycorrhizal fungi (AMF), rhizobia and legumes play a vital role in preserving and even restoring fertility of poor and eroded soils. The present study attempted to quantify relationship between legumes and symbiotic microorganisms (rhizobia and mycorrhizal fungi) by describing the mycorrhizal status and the occurrence of nodualtion of legumes growing in different areas of Jazan. The effect of legume species on soil microbial biomass was also investigated. Mycorrhizal and nodulation intensity varied greatly between legume species. The higher number of nodules (14 nodules per plant) and mycorrhization intensity (54%) were registered in root of Argyrolobium arabicum. Rhizosphere soils of all legume species harbored higher AMF fungal spores than bulk soils. Our results suggest also a significant effect of legumes species on soil microbial biomass. Thus, legume species investigated in this study are potentially useful for replanting and soil protection of most degraded regions of Saudi Arabia