A protocol for fast in vitro propagation of Impatiens hawkeri cv. Sweeties Blue Star, an important ornamental-cover species

Impatiens hawkeri is among the three important bedding plants in the world. There is no efficient protocol for fast micropropagation of Impatiens hawkeri cv. Sweeties Blue Star. Single nodes were germinated on Murashige and Skoog (MS) medium supplemented with 1-naphthaleneacetic acid (NAA; 0.00, 0.10 and 0.50 mg l-1), 6-benzyladenine (BA; 0.00, 0.10, 0.50 and 1.00 mg l-1) and kinetin (KIN; 0.00, 0.10, 0.50 and 1.00 mg l-1). The shoot length was highest in medium containing 0.10 mg l-1 NAA and control. The largest number of shoots (14.06 and 14.00 per explant) was produced in media supplemented with 1.00 mg l-1 BA, 0.50 mg l-1 NAA and 1.00 mg l-1 BA, 0.10 mg l-1 NAA, respectively. The 0.10 mg l-1 NAA along with 1.00 mg l-1 BA was found to be superior for production of leaf (57.13). Maximum root length (33.80 mm) and root number (29.13) were obtained on medium supplemented with 0.10 mg l-1 NAA without BA and KIN. Plantlets were transplanted to pots filled with perlite and peat moss (in ratio of 1:1) and transferred to the greenhouse for acclimatization. Regenerated plantlets were morphologically identical with mother plants. Upon ex vitro transfer, 100% of plants survived.

Influence of Polyethylene Glycol on Leaf Anatomy, Stomatal Behavior, Water Loss, and Some Physiological Traits of Date Palm Plantlets Grown In Vitro and Ex Vitro

Few reports explain the mechanism of PEG action on stomatal behavior and anatomical structure and analyze the photosynthetic pigments of in vitro date palm plantlets for better tolerance to ex vitro exposure. The main challenge for in vitro micropropagation of date palm techniques remains restricted to high survival rates and vigorous growth after ex vitro transplantation. In vitro hardening is induced by Polyethylene glycol PEG (0.0, 10, 20, 30 g L−1) for 4 weeks. Leaf anatomy, stomatal behavior, water loss %, photosynthetic pigments, and reducing sugars were examined in date palm plantlets (Phoenix dactylifera L.) cv. (Sewi) after 4 weeks from in vitro PEG treatment and after 4 weeks from ex vitro transplanting to the greenhouse. Leaf anatomy and the surface ultrastructure of in vitro untreated leaves showed a thin cuticle layer, wide opened malfunctioning stomata, and abnormal leaf anatomy. Furthermore, addition of PEG resulted in increasing cuticle thickness, epicuticular wax depositions, and plastids density, improving the stomatal ability to close and decreasing the stomatal aperture length while reducing the substomatal chambers and intercellular spaces in the mesophyll. As a result, a significant reduction in water loss % was observed in both in vitro and ex vitro PEG treated leaves as compared to untreated ones, which exhibited rapid wilting when exposed to low humidity for 4 h. PEG application significantly increased Chlorophylls a, b and carotenoids concentrations, especially 10, 20 g L−1 treatments, which were sequentially reflected in increasing the reducing sugar concentration. However, leaves of plantlets treated with PEG at 30 g L−1 became yellow and had necrosis ends with death. In vitro hardening by 20 g L−1 PEG increased the survival rate of plantlets to 90% after ex vitro transfer compared to 63% recorded for the untreated plantlets. Therefore, this application provides normal date palm plantlets developed faster and enhances survival after ex vitro transfer.