2 By Mohamed Abd El-Aal Lotfy Sadek Potential Impacts of the Invasive Ipomoea carnea Jacq. on Plant Diversity Along Canal and Drain Banks of the Nile Delta, EgyptByMohamed Abd El-Aal Lotfy SadekLecturer of Plant EcologyBotany Department, Faculty of ScienceMansoura University, Egypt
3 Invasive plant species pose a threat that negatively impacting biodiversity or abundance of native plant communities and ecosystems (McGeoch et al., 2010).In Nile Delta, Egypt the introduced invasive species Ipomoea carnea Jacq. become in pure and/or mixed stands with poor associates along banks of canals and drains forming a dense aboveground patches.Introduction
4 Ipomoea carnea JacqPerennial dicot shrub belonging to Family ConvolvulaceaeIt is native to Tropical South America and was introduced to Egypt in 1932 as an ornamental plant for its luxuriant vegetative growth and attractive large pink flowers.Recently, it is recorded as a naturalized species along canals and drains, road sides, railways, wastelands and field edges in the Nile Delta (Shaltout et al., 2010).
6 The problems created by I. carnea block water flow in the open water zone of drainage & irrigation systemInterfering with fishering & navigationPolluting water suppliesIncreasing sedimentation & water lossCause severe nervous disorders when ingested by cattles & goats or sheepThe growing season of it encompasses most of the year.
7 The objective of this work 1) To demonstrate the impacts of I. carnea invasion on plant species diversity.2) To identify the reasons for its dominance in the canal and drain banks.
8 Study areaFigure. Map of the Nile Delta (Egypt) indicated the location of sampling sites. Source Google Earth
9 Materials and Methods1) Measurement of plant diversity in invaded and uninvaded stands2) Soil analysis3)Assessment of allelopathic potential of I. carnea (root, stem, leaf, fruit) aqueous extracts with different concentrations (2,4,6,8,10%)against a) Portulaca oleracea L.b) Echinochloa crus-galli (L.) P. Beauv4)Phytochemical analyses of I. carnea
10 Results Effect of I. carnea on species diversity Invaded Uninvaded 27 50Species Number0.9050.940Species Richness0.8130.861Evenness
11 Effect of I. carnea on soil chemical properties Two-way ANOVA indicated significant negative effect for I. carnea invasion on sulphates, phosphorous and sodium (P≤ 0.05).
12 Impact of aqueous extracts of I Impact of aqueous extracts of I. carnea on seed germination and seedling growth of the tested speciesAll aqueous extracts of I. carnea significantly (P≤ 0.05) inhibited seed germination and seedling growth of P. oleracea and E. crus-galli at both high and low concentrations.The leaf aqueous extract was the most effective one where it completely inhibited the germination of P. oleracea at concentrations ranged between 6, 8 and 10 gl-1, and at concentration of 10 g/L for E. crus-galli.
13 The decline in germination percentages was a function of type and concentration of the extract. At a concentration of 10% aqueous leaf extract, shoot length was reduced by 63.57% in P. oleracea and by % in E. crus-galli, while root length was reduced by 53.39% in P. oleracea and by 69.44% in E. crus-galli.
14 concentration (mg/g dry weight plant material) Bioactive chemical compounds of I. carneaPlant organPhenolicsFlavonoidsTanninsAlkaloidsconcentration (mg/g dry weight plant material)Root70.52±0.507.78±0.4522.63±0.7541.95±0.77Stem63.53±1.017.60±0.6520.33±0.3838.43±0.42Leaf110.16±0.7839.09±0.3139.30±0.4650.54±0.71Fruit79.15±1.4312.29±0.5330.66±0.2924.27±0.62Leaf extract contained the highest values of phenol contents, flavonoids, tannins and alkaloids, while stem extract showed the lowest contents of phenols, flavonoids and tannins.
15 DiscussionI. carnea invasion has a potential threat to plant diversity and certain soil chemical properties along the banks of canals and drains in the Nile Delta.The plant I. carnea caused a negative impact on species richness and evenness of associated species beneath, as compared with uninvaded stands.
16 Competition for available nutrients I. carnea abundancehigh rate of reproduction, quick spread, unpalatability and wide ecological amplitudeCompetition for available nutrientsAllelopathic Effect
17 The root, stem, leaf and fruit of I The root, stem, leaf and fruit of I. carnea extracted in water have inhibitory effects upon seed germination and seedlings growth of the tested species, P. oleracea and E. crus-galli.Phytochemical analysis of I. carnea revealed the presence of some bioactive compounds, particularly phenolic compounds, flavonoids, tannins and alkaloids. These bioactive chemical compounds have been described as allelochemicals (Cheema et al., 2012).
18 In the present study, the inhibitory effects of I In the present study, the inhibitory effects of I. carnea extracts followed a gradient: leaf > fruit > root > stem. Also, the degree of inhibition was dependent on the concentration of extracts.The high allelopathic activity of leaf extract may be attributed to the presence of many inhibitory bioactive secondary metabolites in higher concentration compared to fruit, root and stem extracts as shown in the results.The aqueous leaf extract (10 g/L) was the most potent inhibitor of seed germination and seedling growth of the assayed species.
19 ConclusionI. carnea dominated the community in the canal and drain banks in the Nile Delta, Egypt and become in pure and/or mixed stands with poor associates.The allelopathic effect of I. carnea coupled with its competitive effect on soil nutrients could contribute to the successful invasion and attainment of pure population.The management strategy should be focused on eliminating the population of I. carnea which currently established in the canal and drain banks for prevention of biodiversity loss and changes in habitat conditions.
20 The present results suggest that, aqueous leaf extract of I The present results suggest that, aqueous leaf extract of I. carnea could be used at 10 gL-1 for management of Echinochloa crus-galli and Portulaca oleracea as an alternative biocontrol method.Further work is needed for characterization of the causative allelochemical (s) of I. carnea water extract.