This study was carried out to investigate the effects of silicon (Si) 3.6 mM (as calcium silicate) under drought stress induced by polyethylene glycol "PEG" at 15% (MW 8000), in addition to the control treatment on growth and some biochemical constituents of date palm cv. Barhee cultured in vitro. Drought stress (15% PEG) depressed the growth of shoot and decreased protein content and chlorophyll concentration. Addition of 3.6 mM Si could improve the growth of shoot and increase the protein content and leaf chlorophyll concentrations of stressed plants. The inclusion of Si to the PEG containing medium significantly increased the catalase (CAT) and superoxide dismutase (SOD) activity in regenerated shoot, compared to other treatments. As well as drought stress 15% PEG induced significant accumulation of shoots proline, which were decreased by added silicon. Moreover, the results were also supported by the observation that PEG stress-induced decrease the response percentage of root induction and root lengths was reversed by added silicon. Addition of Si obviously significantly increased the wax content in leaves, response percentage of root induction and root lengths of plantlets under drought stress. The results of this study indicate that the application of silicon improved growth attributes, effectively mitigate the adverse effect of drought, and increase tolerance of date palm plants for drought stress during the course of date palm tissue cultures.

This study was carried out to investigate the effects of copper sulphate and cobalt chloride on propagation of date palm cv. Ashgar in vitro. The rate of callus proliferation was significantly higher in the medium supplemented with 2 µM copper sulphate and 2 µM cobalt chloride together (p<0.05). Addition of copper sulphate and Cobalt chloride to the medium was most effective for shoots regeneration from callus and enhanced regeneration frequency as well as number of shoots obtained per explant, the best result (7.12 shoot/explant) was obtained by using copper sulphate and Cobalt chloride at 2.0 µM. Also the results of this experiment indicates that the maximum induction of roots can be achieved in the media containing both additives at 0.5 µM. The callus exhibited a decline in carbohydrate contents, proteins, whereas total phenol content increased at high concentration of Cu and Co. The greatest formation of chlorophylls a, b and total chlorophyll was obtained in plantlets grown in the media containing both additives at 0.5 µM. As well as Maximum survivability was noticed for plants cultured in media that containing both copper sulphate and Cobalt chloride at 0.5 µM.

The objective of the present study is to determine the effect of light source on enhancement of shoot multiplication, phytochemicals, as well as, antioxidant enzyme activities of in vitro cultures of date palm cv. Alshakr. In vitro-grown buds were cultured on Murashige and Skoog (MS) medium and incubated under a conventional white fluorescent light (control), and combinations of red + blue light emitting diode (18:2) (CRB-LED). Results revealed that the treatment of CRB-LED showed a significant increase in the number of shoots compared with the white florescent light. Total soluble carbohydrate "TSCH" (7.10 mg g(-1) DW.), starch (1.63 mg g(-1) DW.) and free amino acids (2.90 mg g(-1) DW.) were significantly higher in CRB-LED (p < 0.05). Additionally, CRB-LED induced a higher peroxidase activity (25.50 U ml(-1)) compared with the white fluorescent light treatment (19.74 U ml(-1)) as control treatment. Potassium, magnesium and sodium contents in (3.62, 13.99 and 2.76 mg g(-1) DW.) were increased in in vitro shoots under CRB-LED treatment in comparison with fluorescent light (p < 0.05). Protein profile showed the appearance of newly bands with the molecular weight of 38 and 60 kDa at the treatment CRB-LED compared with control treatment. Our results demonstrate the positive effects of CRB-LED light during the course of date palm tissue cultures.

There are some major obstacles in practical applications of date palm tissue culture in the laboratory such as reduced number of shoots, vitrification of tissues, and browning of cultured tissues. The objective of the present study is to determine the effect of boron (B) and calcium (Ca) on enhancing organogenesis of buds from callus, shoot multiplication, and phytochemicals of in vitro cultures of date palm ‘Barhee’. Addition of calcium chloride and boric acid to the medium was most effective on callus for shoot regeneration and number of shoots per jar, where the best result (88.89%, 8.2 shoots per jar, respectively) was obtained by using 660 mg L−1 Ca + 9.3 mg L−1 B, compared with other treatments. It was observed that the interaction between 660 mg L−1 Ca + 9.3 mg L−1 B resulted in the highest tissue content of B [(4.75 mg L−1 dry weight (DW)]. The highest medium calcium chloride level (880 mg L−1) increased Ca content in the shoots. The combined application had the effect in reducing the vitrification. Application of Ca and B induced synthesis of proteins bands with molecular weights of 88.0, 55.6, 52.8, 43.0, 41.1, 38.3, 28.3, and 16.6 KDa in a medium supplemented with 660 mg L−1 Ca + 9.3 mg L−1 B.

No abstract