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Physiologique D'une Halophyte, Atriplex, Aux Conditions Arides

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Physiologique D'une Halophyte, Atriplex, Aux Conditions Arides REPUBLIQUE ALGERIENNE DEMOCRATIQUE ET POPULAIRE MINISTERE DE L’ENSEIGNEMENT SUPERIEUR ET DE LA RECHERCHE SCIENTIFIQUE FACULTE DES SCIENCES DE LA NATURE ET DE LA VIE DEPARTEMENT DE BIOLOGIE THESE En vue de l’obtention du DOCTORAT EN SCIENCES BIOLOGIQUES Spécialité : Physiologie Végétale Thème : Caractérisation morpho- physiologique d’une halophyte, atriplex, aux conditions arides Présenté par : ZIDANE DJERROUDI Ouiza Soutenue le : 12 Janvier 2017 Devant le jury composé de : Présidente Prof BENNACEUR Malika Université Oran I ABB Examinateur Prof HADJADJ AOUL Seghir Université Oran I ABB Examinateur Prof BENHASSAINI Hachemi Université de Sidi Bel Abbès Examinateur Prof BENABADJI Noury Université de Tlemcen Examinateur Prof MILOUDI Ali Université de Mascara Directeur de Thèse Prof BELKHODJA Moulay Université Oran I ABB 2015-2016 Caractérisation morpho- physiologique d’une halophyte, atriplex, aux conditions arides Résumé: Cette étude a permis de déterminer les effets de l’acide salicylique en absence ou en présence du chlorure de sodium, sur la tolérance à la salinité de deux espèces d’atriplex (Atriplex halimus L. et d’Atriplex canescens (Pursh) Nutt.) à travers divers paramètres. La réponse des graines au cours de la germination a été d’abord appréciée par application de quatre concentrations d’acide salicylique (0.25, 0.5, 0.75 et 1 mM) et de deux concentrations de chlorure de sodium (300 et 600 meq.l-1). Le traitement 0,5 mM AS a induit un taux de germination et une valeur germinative maximales des graines d’Atriplex halimus L., alors que pour les graines d’Atriplex canescens (Pursh) Nutt., le TGF et la VG sont nettement élevé respectivement sous l’effet de 1 mM d’AS et sous 0,75 mM l-1 d’AS. La salinité réduite a permis une germination importante des graines des deux espèces. Les deux concentrations d’AS 0, 5 et 1 mM associées à 300 et 600 meq.l-1 NaCl montrent une grande variation du TGF et de la VG qui est en fonction de l’espèce, de la concentration d’AS et du NaCl. Ainsi, les traitements 0,5 mM d’AS combiné à 600 meq.l-1 NaCl et 1 mM d’AS + 300 meq.l-1 NaCl ont permis d’éliminer les effets inhibiteurs de la salinité et ont améliorer la germination finale et la valeur germinative des graines de l’Atriplex halimus L. et l’Atriplex canescens (Pursh) Nutt. respectivement. Les résultats relatifs à la réponse hydrique et biochimique des jeunes plantes d’atriplex âgées de 120 jours et stressées durant une semaine en présence ou non de l’AS, ont montré que sous stress salin seul ; la teneur en eau des feuilles, la teneur relative en eau, la biomasse aérienne et la teneur en K+ dans les deux organes ont diminué. Alors que, le déficit hydrique en eau des feuilles, la teneur en proline et en sodium, les ratios Na+/K+ des feuilles et des racines, ainsi que l’indice de sensibilité relative au sel ont sensiblement augmenté. L’application exogène de l’AS dans les milieux stressés a atténué les dommages de la salinité en comparaison aux plantes stressées uniquement au sel correspondant. L’apport de 1 mM d’AS associé à 600 meq.l-1 NaCl et à 300 meq.l-1 NaCl a provoqué une élévation de la teneur en eau respectivement chez Atriplex canescens (Pursh) Nutt. et chez Atriplex halimus L. Cependant, la teneur relative en eau s’est améliorée sous le traitement 0,5 mM d’AS +600 meq.l-1 NaCl chez Atriplex canescens (Pursh) Nutt. Ce dernier traitement a par contre réduit le déficit hydrique de saturation chez les deux espèces. En présence de 0,5 mM d’AS, la croissance des jeunes plantes d’atriplex a été stimulée, la teneur en proline au niveau des feuilles a augmenté sous 300 meq.l-1 NaCl chez Atriplex halimus L. et sous 600 meq.l-1 NaCl pour Atriplex canescens (Pursh) Nutt. L’absorption du K+ est également favorisée en présence de 300 meq.l-1 NaCl chez Atriplex canescens (Pursh) Nutt., dans les feuilles et les racines. Or, la teneur en Na+ des feuilles, l’indice de sensibilité et le ratio Na+/K+ ont diminué chez les deux espèces. Mots clés : Atriplex, stress salin, acide salicylique, NaCl, germination, paramètres hydrique, ajustement osmotique. الخصائص المورفو- فييزيولوجية لنبات ملحي atriplex تحت ظروف المناطق الجافة الملخص : تهدف هذه الدراسة لمعرفة تأثير حمض سالسليك في غياب ووجود كلور الصوديوم على تحمل الملوحة لنوعين من نبات Atriplex halimus L.) atriplex و .Atriplex canescens (Pursh) Nutt( من خﻻل العديد من المعايير . ان تقدير استجابة البذور اثناء اﻻنبات و ذلك بعد معاملتها بواسطة اربع تراكيز من حامض السالسليك ) 0.25, 0.5, 0.75 و 1 ملي مول ( و تركيزين من كلور الصوديوم )300 وmeq.l-1600 (. بالنسبة للمعاملة 0.5 ملي مول من حامض سالسيليك فقد ادت الى الحصول على اعلى نسبة و قيمة من اﻻنبات عند بذور Atriplex halimus في حين انه عند بذورAtriplex canescens فان نسبة اﻻنبات النهائي و سرعة اﻻنبات كانت عالية تحت تاثير كﻻ التركيز 1 و0.75 ملي مول من حامض السالسليك كما ان التركيز القليل من كلور الصوديوم ادى الى نسبة انبات مهمة عند كل من النوعين . اما عند المعاملتين 1 و0.5 ملي مول من حامض السالسليك مع التركيزين 600 وmeq.l-1 300 من كلور الصوديوم فقد كانت هناك اختﻻف معنوي في زيادة نسبة اﻻنبات النهائي و سرعة اﻻنبات وذلك حسب نوع النبات و تركيز حمض السالسليك وكلور الصوديوم كذلك. باﻹضافة الى ان التركيز 0.5 ملي مول من حامض السالسليك مع التركيز meq.l-1 600 من كلور الصوديوم و التركيز 1 ملي مول من حامض السالسليك و meq.l-1 300 من كلور الصوديوم سمح بالقضاء على الثاثير التثبيطي للملوحة و سمح بتحسين نسبة وعدد انبات بذور .Atriplex halimus L و.Atriplex canescens (Pursh) Nutt النتائج المرتبطة باستجابة المحتوى المائي والبيوكيميائي لنباتات ذات عمر 120 يوم مع اجهاد لمدة اسبوع بوجود حامض السالسليك وغيابه ﻻحظنا ان تحت تأثير اﻻجهاد الملحي فقط فان المحتوى المائي للورقة و محتوى الماء النسبي , الكتلة اﻻحيائية للجزء الخضري الطري والجاف باﻹضافة الى نسبة +K في الساق والجذور تناقصت، في حين ان المحتوى المائي للورقة و نسبة البرولين والصوديوم نسبة +Na+/K في اﻻوراق و الجذور باﻹضافة الى مؤشر للحساسية النسبي للملح قد كانت زيادتهم واضحة . ان التطبيق الخارجي لحمض السالسليك في الوسط المجهد ادى الى تخفيف الضرر الذي سببه اﻻجهاد الملحى على النباتات بالمقارنة مع تلك الموجودة في وسط المجهد بالملح فقط دون اضافة حامض السالسليك . ان اضافة 1 ملي مول من حامض السالسليك و meq.l-1 600 و meq.l-1300 من كلور الصوديوم ادت الى ارتفاع نسبة الماء عند Atriplex canescens (Pursh) Nutt. و.Atriplex halimus L على التوالي مع انه نسب الماء قد تحسنت عند 0,5 ملي مول من حامض السالسليك وmeq.l-1 600 من كلور الصوديوم عندAtriplex canescens وهذه اﻻخير قد ادت كذلك على انخفاض نسبة العجز المائي عند النوعين. اما عند المعاملة 0.5 ملي مول من حامض السالسليك فقد ادت الى تحفيز نمو نبات atriplex، نسبة البرولين في الورقة سجلت زيادة وذلك عند المعاملة meq.l-1300 من كلور الصوديوم عند Atriplex halimus، و تحت meq.l-1 600 بالنسبة لنوع Atriplex . canescens يفضل أيضا امتصاص+ K في وجود meq.l-1 300 كلوريد الصوديوم في اوراق وجذور (Atriplex canescens (Pursh .Nuttومن جهة اخرى فان نسبة+Na في اﻻوراق و مؤشر الحساسية و نسبة +Na+/K تناقصت عند كﻻ النوعين . الكلمات المفتاحية: atriplex ، اﻻجهاد الملحي ، حمض السالسليك ، NaCl، اﻻنبات ، االمعيار المائي ، تعديل اﻻسموزي. A halophyte, atriplex morpho physiological characterization under arid conditions Summary: This study has shown the effects of Salicylic Acid (SA) in the absence or presence of sodium chloride, on both atriplex species (Atriplex halimus L. and Atriplex canescen (Pursh) Nutt salt tolerance through various parameters. The seeds reaction during germination was first appreciated by applying four SA concentrations (0.25, 0.5, 0.75 and 1 mM) and two concentrations of sodium chloride (300 and 600 meq.l-1 NaCl). The 0.5 mM SA treatment induced a maximum germination rate and value among Atriplex halimus L. seeds, whereas the Atriplex canescens ( Pursh) Nutt. seeds , final germination rate (FGR) and the germination value (GV) were significantly high, respectively under the effect of 1 mM and 0.75 mM l-1 SA. Furthermore low salinity is likely to cause major seed germination among both species. both 0.5 and 1 mM SA concentrations associated with 300 and 600 meq.l-1 NaCl caused a large variation of the FGR and GV, depending the species type and the SA and NaCl concentrations. Thus, treatments 0.5 mM AS, combined with 600 meq.l -1 NaCl and 1 mM SA + 300 meq.l -1 NaCl were used to remove the inhibitory effects of salinity and have improved overall final FGR and GV of Atriplex halimus L. and Atriplex canescens ( Pursh) Nutt. respectively. The water and biochemical reaction results of 120 days young atriplex plants to stressing during a week on the presence or absence of SA, showed that only under salt stress: water content of leaves, relative water content, aerial biomass and the potassium content in both organs had decreased. However, the water deficit in the water leaves , the content of proline and sodium, ratios Na+/K+ leaves and roots , and the index relative sensitivity to salt increased significantly .The exogenous application of SA in stressed environments decreased salinity damage in comparison to plants stressed exclusively with salt The addition of 1 mM SA associated with 600 meq.l-1 NaCl and 300 meq.l-1 NaCl improved water content, respectively, in Atriplex canescens (Pursh) Nutt. and in Atriplex halimus L. However, the relative water content has improved under the 0.5 mM AS+600meq.l-1 NaCl treatment in Atriplex canescens (Pursh) Nutt.
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