Effect of factors on growth and development of Dendrobium officinale Kimura et Migo cultured in vitro and ex vitro

Dendrobium officinate Kimura et Migo, a species of orchid for beautiful flowers, is used in traditional medicine in many Asian countries because there are many important pharmaceuticals (chrysotoxene, erianin, confusarin, polysaccharide, alkaloid ...) in anti-cancer, anti-aging, boosting immunity and vasodilation, etc. In recent years, more than 4,000 hectares of Dendrobium officinate Kimura et Migo artificial planting has been available in China and the price of dry product was around ¥ 80,000/kg. Currently, plantlet quality is an important factor influencing the acclimatization stage, growth, and development of plants in the greenhouse. In this study, the effect of a number of factors medium, plant regulator, ventilation, and substrate to improve plantlet quality as well as further growth and development in the greenhouse conditions were investigated. The results showed that SH medium was suitable for in vitro shoot growth in terms of monitoring parameters after 90 days of culture. In shoot multiplication stage, the shoots culture on SH medium supplemented with 2 mg/L BA, 30 g/L sucrose, 9 g/L agar, 1g /L activated charcoal (AC) gave the best results with 4.53 shoots/per shoot. The SH medium supplemented with 1.0 mg/L NAA, 30 g/L sucrose, 9 g/L agar, 1.0 g/L AC combined with ventilation conditions was suitable for rooting stage with plant height (5.73 cm), number of roots (4.77), root length (5.00 cm), fresh weight (3.36 g), dry weight (0,31 g), and total chlorophyll (SPAD) (45.76 nmol/cm2). Plantlets derived from culture ventilation conditions cultivated on the mixture of pine bark and fern fiber (50:50) was the highest survival rate (100%) and growth after 12 months in the greenhouse.

Improved in vitro rooting and acclimatization of “Violetta” Artichoke and “Green Globe” Artichoke

Artichoke (Cynara scolymus L.), a medicinal plant with high economic value, contains high levels of phenolic compounds; especially cynarine, which plays an important role in preventing cancer, cardiovascular disease, osteoporosis, diabetes and neurodegeneration, etc. Currently, Artichoke micropropagation has achieved some success; however, the rooting efficiency and plantlet quality are still limited. In this study, improving the quality of Artichoke plantlet related to the shoot quality and suitable substrates in in vitro rooting stage was studied on “Violetta” Artichoke (VA) and “Green Globe” Artichoke (GA). The results showed that shoots (1.5 cm) cultured on MS medium supplemented 0.5 mg/L KIN were most suitable to shoot multiplication of VA with the number of shoots/explant (3.67 shoots), number of shoots ≥ 2 cm (3 shoots); while, 1.0 mg/L BA was suitable to shoot multiplication of GA (5.33 shoots; 5.00 shoots; respectively) after 4 weeks of culture. Besides, the in vitro rooting was improved using 8 g/L commercial agar for VA; meanwwhile, 3 g/L gelrite for GA. In addition, the nylon bag culture system (120 mm × 250 mm) has potential in plantlet production (15 plants/bag) and can be applied for large scale micropropagation. In addition, VA and GA plantlets derived from in vitro culture gave the good acclimatization, growth and development after 8, 12 and 20 weeks cultivating at the green house conditions.

In Vitro Germplasm Conservation of Habanero Pepper (Capsicum chinense Jacq.)

To determine the effect of different nitrogen sources and osmotic regulators on minimal growth of Habanero pepper (Capsicum chinense Jacq.) germplasm for in vitro conservation, different concentrations of nitrate, sucrose, mannitol, and sorbitol were evaluated. The micropropagation system based on Santana-Buzzy et al. (2006) culture medium was modified in its nitrate concentrations: reduced to 50% and increased to 150%, and osmoregulators were added to the basal culture media: sucrose (6% and 8%), mannitol (2%, 4%, and 8%), or sorbitol (2%, 4%, and 8%). The apical meristems of germinated plants were cultivated in the different treatments for 35 weeks without subculture. Results have demonstrated that mannitol at 2% had the better effect on minimal growth of the plantlets and did not affect the plant physiology and quality. The plantlets remained small in size, turgent, with green leaves and stems and looked like normal plants until to the end of the evaluation period. Changes in nitrogen media concentration did not prove to be adequate for conserving because they affected the plantlet quality (they became chlorotic). The presence of sorbitol and high osmolite concentrations induced minimal growth but reduced the plant quality. Sucrose at mid or low concentrations did not induce minimal growth.

Effects of Light Quality on Growth and Quality of in Vitro Plantlets during Low-temperature Storage

Broccoli `Green Duke' plantlets, which were ready for transplanting after 2 weeks of photoautotrophic (sugar-free) culture under the conditions of 1100 μmol·mol–1 CO2 (outside the vessel), 22±4C air temperature, and 140 μmol·m–2·s–1 photosynthetic photon flux (PPF), were stored for 6 weeks at 5C in darkness or in white, red, or blue light at 2 μmol·m–2·s–1 PPF. Photoperiod was set at 24 h/day during storage. Spectral quality significantly affected plantlet quality: stem length was longer and chlorophyll concentration of leaves was lower in red or in blue light than in white light or in darkness after 6 weeks in storage. Regardless of the spectral quality, light in storage maintained plantlet dry weight at a level comparable to that before storage, while dry weight was reduced significantly in dark-stored plantlets. Spectral quality did not significantly affect the photosynthetic and regrowth potential of plantlets. All plantlets stored in light, regardless of light spectra, showed comparably high photosynthetic ability after storage and had similar dry weight, number of leaves, and stem length after 9 weeks of transplanting to the greenhouse under natural light.

LOW-TEMPERATURE STORAGE OF MICROPROPAGATED PLANTLETS UNDER SELECTED LMHT SPECTRA

`Green Duke' broccoli plantlets, which were ready for transplanting after 2 weeks of photoautotrophic (sugar free) culture under the conditions of 1100 μmol·mol–l CO2 (outside the vessel), 22 + 4C air temperature, and 140 μmol·m–2·s–1 photosynthetic photon flux (PPF), were stored for 6 weeks at 5C in darkness or in white, red, or blue light at 2 μmol·m–2·s–l PPF (light compensation point at 5C). Photoperiod was set at 24 hour/day during storage. Spectral quality significantly affected plantlet quality: stem length was longer and chlorophyll concentration of leaves was lower in red or in blue light than in white light or in darkness after 6 weeks in storage. Regardless of the spectral quality, light in storage maintained plantlet dry weight at a level comparable to that before storage; dry weight was reduced significantly in dark-stored plantlets. Spectral quality did not significantly affect the photosynthetic and regrowth potential of plantlets. All plantlets stored in light, regardless of light spectra, grew preferably and had similar dry weight and stem length after 9 weeks of transplanting to the greenhouse under natural light.