Mass propagation of date palm through indirect somatic embryogenesis or organogenesis has attracted the interest of commercial producers. But, this technique still faces some problems that hindered the production of date palm plantlets in vitro. Tissue browning is one of the serious problems that reduce callus growth and shoot regeneration. So the objective of the present study is to investigate the effect of cold pretreatment on callus growth, shoot regeneration, and polyphenol oxidase (PPO) activity during the callus culture. Results showed that a high survival rate of callus cultures (100%) were obtained when cultures were incubated in low temperature (cold treatment) for 45 and 75 days. On the other hand, total amount on phenolic compounds was also reduced to 0.47 and 0.53 mg GAE/g after same period of incubation (45 and 75 days respectively) at low temperature. In additional, our results showed that the highest frequency of shoot formation (66.67 and 73.34, %) and the highest shoot numbers (7.8 and 8.6 shoots/100 mg) were obtained from callus treated with low temperature for 45 and 75 days, respectively.

Present study was investigate the effect of different UV-doses on morphological defending system features of two palm species Phoenix dactylifera L. and Washingtonia filifera (Lindl.) H. Wendl. The results showed that the morphological and biomass traits of both palm species grown for 30 days under UV-B with a rate of 2 hrs.day-1 were almost improved. Where, the highest leaf width was recorded (1.1 and 0.7 cm) respectively. Conversely, UV-treatment (4-10 hrs.day-1) has adversely affected on almost morphological and biomass features of both species. Where, the less leaf widths were recorded 0.95, 0.8, 0.73, 0.45, 0.43 and 0.40 cm in both palm species. Besides, results also spotted changes in leaf’s surface appearances. However, present investigation concluded that morphological features and biomass of both species were unaffected with low dose of UV-radiation (2 hrs.day-1). But, date palm (P. dactylifera L.) was capable to survive at high dose of radiation conditions reaches 8 hrs.day-1 for 30 days.

أجريت الدراسة في مختبر زراعة الأنسجة النباتية العائد لقسم البستنة وهندسة الحدائق / كلية الزراعة / جامعة الكوفة ، لدراسة تأثير الإجهاد الملحي في انتاج الدرنات الدقيقة والصفات النوعية لها باستخدام تراكيز مختلفة من كلوريد الصوديوم 0 ،50 ،100 و150 ملي مول ، تم أضافتها إلى الوسط الغذائي MS المزود بـ 5 ملغم . لتر-1 BA  و1 ملغم . لتر-1 ثايمين و0.5 ملغم . لتر-1 بايريدوكسين و0.5 ملغم . لتر-1 حامض النيكوتين و100 ملغم . لتر-1  Myo-inositol و80 غم . لتر-1 سكروز و7 غم . لتر-1 أكار الخاص بإنتاج الدرنات الدقيقة، أظهرت النتائج تفوق التركيز 50 ملي مول NaCl  الذي حقق اعلى معدل في عدد وقطر الدرنات الدقيقة 2.49) ، 3.31 ملم) على الترتيب ، بينما ازداد محتوى الدرنات الدقيقة من البرولين والسكريات الذائبة الكلية بإضافة 150 ملي مول NaCl  اذ بلغت (0.616   ،0.268 ملغم.غم-1) على الترتيب. واظهر الصنف  Eigenheimer تفوق واضح في الصفات الكميه والنوعية عدا معدل قطر الدرنات الدقيقة الذي ازداد في الصنف  Bintje. كما اثر التداخل بين الصنف والتراكيز الملحية معنويا في مؤشرات نمو الدرنات الدقيقة ومحتواها من البرولين والسكريات الذائبة، اذ أعطت معامله التداخل بين الصنف Eigenheimer والتركيز 50 ملي مول اعلى معدل لعدد الدرنات الدقيقة بلغ 2.66 ، واعلى معدل من البرولين والسكريات الذائبة الكلية عند تداخل الصنف نفسه مع التركيز 150 ملي مول 0.877 ،0.277 ملغم.غم-1 على الترتيب. اعتمادا على المؤشرات المظهرية ومحتوى الخلايا من الذائبات العضوية  (البرولين والسكريات الذائبة الكلية ) يمكن الاستنتاج إنَ الصنف Eigenheimer هو الأكثر تحملا للإجهاد الملحي من الصنف  . Bintje

Salinity is one of the serious and crucial problem facias the plant in this planet. Fortunately, plants have different lines of defending system that help to overcome such environmental stress. This study uses a different NaCl level to investigate the behavior of date palm microshoots at two stages (multiplication and elongation) of micropropagation protocol. Study found the salinity stress effect on multiplied and elongated shoots at high levels of salt 150 and 200mM. At these levels the morphological and physiological aspects are changed in compression with control and other salt treatments (25-100mM). The physiological aspects recorded elevation in the rates of carbohydrate, proline and abscisic acid when NaCl concentration increasing. However, study concluded the salinity may help to improve some morphological aspect like shoot diameter that help to increase the plant survival during acclimation stage.  stage. Concentrations.