7 research outputs found
Influence of Water Stress on Seed Germination Characteristics in Invasive Diplotaxis harra (Forssk.) Boiss (Brassicaceae) in Arid zone of Tunisia
Diplotaxis harra (Forssk.) Boiss (Brassicaceae) has a wide ecological and geographical amplitudes in Tunisia and grows under a variety of environmental conditions. A laboratory experiment was performed to evaluate the effect of water potential on seed germination and recovery responses after transfer to distilled water. The germination responses of seeds at 15ĂâĂ°C in complete darkness were determined over a wide range of PEG-6000 solutions of different osmotic potentials: 0 to Ă¹ùâÂŹĂąâŹĆ1 MPa. Greatest germination was obtained in distilled water (71%), and increases in osmolality of solutions progressively inhibited seed germination, less than 10% of the seeds germinated at Ă¹ùâÂŹĂąâŹĆ0.8 MPa. No germination was observed for the treatment of Ă¹ùâÂŹĂąâŹĆ1 MPa. The rate of germination decreased as osmotic potential decreased. When seeds were transferred to distilled water after 20 days of water stress, the recovery of germination increased with an increase in pretransfer PEG-6000 treatments. Seeds subjected to high osmotic potential had higher recovery percentages. ĂâĂ
Facteurs influençant la germination des graines de Cleome ambyocarpa Barr. & Murb. (Capparidaceae) dans le Sud tunisien
Cleome amblyocarpa Barr. & Murb. is an annual herb in the family of Capparidaceae.
It is abundant in sandy environments, and the gravel and stony grounds in Tunisian arid areas. Laboratory
experiments were carried out to assess the effects of temperature (10 to 40° C) on seed germination in
complete darkness. The osmotic stress simulated by NaCl at different concentrations (0 to 200 mM) or
polyethylene glycol 6000 (PEG-6000) at different osmotic potentials (0 to -1 MPa) was evaluated at the
most suitable temperature found. Greatest germination percentage and rate of germination were obtained
at 25° C, but germination was inhibited by either an increase or decrease in temperature from the optimal
temperature. The increase in osmolality of solutions induced by NaCl or PEG progressively inhibited seed
germination. At 150 mM NaCl or osmotic potential of -0.6 MPa, germination was completely inhibited.
There was a decrease in the rate of germination as osmotic stress was intensified. These findings suggest that
C. amblyocarpa was able to tolerate well osmotically- and saline-stressful habitats of the arid ecosystems
during germination stageCleome amblyocarpa Barr. & Murb. est une plante herbacée annuelle de la famille des Capparidaceae. Elle est abondante dans les environnements sableux, les sols secs et pierreux, ainsi que les alluvions de gravier dans les
zones arides tunisiennes. Des expériences conduites au laboratoire ont été effectuées pour évaluer les effets de la température (10 à 40° C) à l'obscurité. Le stress osmotique simulé par le NaCl à différentes concentrations (0 à 200 mM) ou le polyéthylÚne glycol 6000 (PEG-6000) à différents
potentiels osmotiques (0 à -1 MPa) a été évalué à la température optimale trouvée. Les meilleurs pourcentages et vitesses de germination ont été obtenus à 25° C, mais la germination est inhibée au-dessus et en deçà de cette température. L'augmentation de l'osmolarité des solutions induites
par le NaCl ou le PEG inhibe progressivement la germination des graines. à 150 mM NaCl ou un potentiel osmotique de -0,6 MPa, la germination est complÚtement inhibée. On assiste à une diminution de l'indice de germination au fur et à mesure que le stress osmotique est accentué. Ces résultats
suggÚrent que C. amblyocarpa semble bien tolérer la salinité et la sécheresse des écosystÚmes arides durant la phase germinative
Factors influencing seed germination of Cleome amblyocarpa Barr. et Murb. (Capparidaceae) occurring in southern Tunisia
Cleome amblyocarpa Barr. & Murb. is an annual herb in the family of Capparidaceae. It is abundant in sandy environments, and the gravel and stony grounds in Tunisian arid areas. Laboratory experiments were carried out to assess the effects of temperature (10 to 40° C) on seed germination in complete darkness. The osmotic stress simulated by NaCl at different concentrations (0 to 200 mM) or polyethylene glycol 6000 (PEG-6000) at different osmotic potentials (0 to -1 MPa) was evaluated at the most suitable temperature found. Greatest germination percentage and rate of germination were obtained at 25° C, but germination was inhibited by either an increase or decrease in temperature from the optimal temperature. The increase in osmolality of solutions induced by NaCl or PEG progressively inhibited seed germination. At 150 mM NaCl or osmotic potential of -0.6 MPa, germination was completely inhibited. There was a decrease in the rate of germination as osmotic stress was intensified. These findings suggest that C. amblyocarpa was able to tolerate well osmotically-and saline-stressful habitats of the arid ecosystems during germination stage.Facteurs influençant la germination des graines de Cleome ambyocarpa Barr. & Murb.
(Capparidaceae) dans le Sud tunisien.
Cleome amblyocarpa Barr. & Murb. est une plante herbacĂ©e annuelle de la famille des Capparidaceae. Elle est abondante dans les environnements sableux, les sols secs et pierreux, ainsi que les alluvions de gravier dans les zones arides tunisiennes. Des expĂ©riences conduites au laboratoire ont Ă©tĂ© effectuĂ©es pour Ă©valuer les effets de la tempĂ©rature (10 Ă 40° C) Ă lâobscuritĂ©. Le stress osmotique simulĂ© par le NaCl Ă diffĂ©rentes concentrations (0 Ă 200 mM) ou le polyĂ©thylĂšne glycol 6000 (PEG-6000) Ă diffĂ©rents potentiels osmotiques (0 Ă -1 MPa) a Ă©tĂ© Ă©valuĂ© Ă la tempĂ©rature optimale trouvĂ©e. Les meilleurs pourcentages et vitesses de germination ont Ă©tĂ© obtenus Ă 25° C, mais la germination est inhibĂ©e au-dessus et en deçà de cette tempĂ©rature. Lâaugmentation de lâosmolaritĂ© des solutions induites par le NaCl ou le PEG inhibe progressivement la germination des graines. Ă 150 mM NaCl ou un potentiel osmotique de -0,6 MPa, la germination est complĂštement inhibĂ©e. On assiste Ă une diminution de lâindice de germination au fur et Ă mesure que le stress osmotique est accentuĂ©. Ces rĂ©sultats suggĂšrent que C. amblyocarpa semble bien tolĂ©rer la salinitĂ© et la sĂ©cheresse des Ă©cosystĂšmes arides durant la phase germinative.Tlig Tahar, Gorai Mustapha, Neffati Mohamed. Factors influencing seed germination of Cleome amblyocarpa Barr. et Murb. (Capparidaceae) occurring in southern Tunisia. In: Revue d'Ăcologie (La Terre et La Vie), tome 67, n°3, 2012. pp. 305-312
Ătude expĂ©rimentale de la compĂ©tition entre lâadventice Diplotaxis harra (Forssk.) Boiss. et lâorge (Hordeum vulgare var. Ardhaoui)
Interspecific competition between the weed
Diplotaxis harra (Forssk.) Boiss. and barley (Hordeum vulgare var. Ardhaoui) was studied in pots. Seeds of D. harra were sown in pots in association with the barley variety âArdhaouiâ
cultivated on a large scale in arid Tunisia. This study was conducted for varying density of weed. The results show that D. harra hasnât got a significant competitive effect on the growth parameters of barley as the dry total biomass and the maximum height. Similarly, the presence of D. harra did not significantly affect the parameters of barley yield as the number of ears / feet and the number of seeds / spike. Field barley invasions by this weed cannot be attributed to its competitive power. So rather allelopathic behavior of the species or its massive seed set that appears to play a key role in invasiveness.La compĂ©tition interspĂ©cifique entre lâadventice
Diplotaxis harra (Forssk.) Boiss. et lâorge (Hordeum vulgare var. Ardhaoui) a Ă©tĂ© Ă©tudiĂ©e en pot. Les graines de D. harra ont Ă©tĂ© semĂ©es dans des pots en association avec la variĂ©tĂ© dâorge «Ardhaoui» cultivĂ©e Ă grande Ă©chelle dans les zones arides tunisiennes. Cette Ă©tude a Ă©tĂ© conduite pour des densitĂ©s variables dâadventice. Les rĂ©sultats montrent que D. harra nâa pas un effet compĂ©titif significatif sur les paramĂštres de croissance de lâorge comme la biomasse sĂšche totale et la hauteur maximale. De la mĂȘme maniĂšre, la prĂ©sence de D. harra nâa pas significativement affectĂ© les paramĂštres du rendement de lâorge comme le nombre dâĂ©pis/pied et le nombre de graines/Ă©pi. Lâenvahissement des champs dâorge par cette adventice ne peut donc pas ĂȘtre attribuĂ© Ă son pouvoir compĂ©titif. Câest ainsi plutĂŽt le comportement allĂ©lopathique de lâespĂšce ou sa grenaison massive qui semblerait jouer un rĂŽle primordial dans son caractĂšre envahissant.Tlig Tahar, Gorai Mustapha, Neffati Mohamed. Ătude expĂ©rimentale de la compĂ©tition entre lâadventice Diplotaxis harra (Forssk.) Boiss. et lâorge (Hordeum vulgare var. Ardhaoui). In: Ecologia mediterranea, tome 38 n°1, 2012. pp. 89-95
Effet de la durée de conservation, de la couleur et de la période de récolte des semences sur la germination de Diplotaxis harra (Forssk.) Boiss., plante envahissante en Tunisie méridionale
Seeds of Diplotaxis harra (Forssk.) Boiss., an invasive plant species of Southern Tunisia, were collected in July 2007, January 2008 and, April 2008 and stored under laboratory conditions. Directly after collection and each three months, germination experiments were conducted in darkness at 15°C, which corresponds to the thermal optimum for the germination of this species. The results show that seed color did not significantly affect the germination pattern of
D. harra. Seeds, notably those collected in summer, maintained a high germination rate even after 18-month storage period. These germination characterisitics could partly explain the invasive behaviour of this species.Les semences de Diplotaxis harra (Forssk.) Boiss., espĂšce envahissante de la Tunisie mĂ©ridionale, ont Ă©tĂ© rĂ©coltĂ©es en juillet 2007, janvier 2008 et avril 2008 et ensuite conservĂ©es dans les conditions ambiantes du laboratoire. Ă la rĂ©colte, et tous les trois mois, des essais de germination ont Ă©tĂ© conduits Ă lâobscuritĂ© et Ă 15°C, ce qui correspond Ă lâoptimum thermique pour la germination de cette espĂšce. Les rĂ©sultats obtenus montrent que la couleur des semences nâa pas dâeffet significatif sur les aptitudes germinatives de cette espĂšce. Les semences, notamment celles collectĂ©es en Ă©tĂ©, gardent un taux de germination trĂšs Ă©levĂ© mĂȘme aprĂšs une conservation de 18 mois. Ces aptitudes germinatives expliquent, du moins en partie, le caractĂšre envahissant de cette espĂšce.Tlig Tahar, Gorai Mustapha, Neffati Mohamed. Effet de la durĂ©e de conservation, de la couleur et de la pĂ©riode de rĂ©colte des semences sur la germination de Diplotaxis harra (Forssk.) Boiss., plante envahissante en Tunisie mĂ©ridionale. In: Ecologia mediterranea, tome 37 n°1, 2011. pp. 83-89