Impatiens vitro

Massaro, Raquel, Fadin, Dauri Aparecido, Pedroso-de-Moraes, Cristiano, Vieira, Antônio Sanches & Marteline, Marco Aurélio, 2019, Light quality in vitro growth and acclimatization of two varieties of Phalaenopsis amabilis alba Blume (Orchidaceae), Iheringia, Série Botânica 73 (2), pp. 208-215 : 209-210

In vitro culture

The MS growth medium ( Murashige & Skoog 1962), was prepared, and supplemented with 1 g.L- 1 of active charcoal, 30 g.L- 1 of sucrose with pH adjusted to 5,4 before adding of 7 g.L- 1 banana-agar broth ( Massaro et al. 2012). Next, 25 mL of growth environment was poured into 250 mL bottles and autoclaved at 121°C at 1 atm during 20 minutes ( Arditti & Ernest 1992).

Seeds were disinfected by agitation in eppendorf ® microcentrifug tubes with a hypochlorite sodium solution at 5% during 5 minutes. Next, tubes containing seeds of the two cultivars were dipped in 70% ethanol during 5 minutes and t washed four times in sterilized distilled water with the assistance of a 1 mL syringe. Seeds were deposited in bottles containing the MS growth environment ( Arditti & Ernest 1992). The seeded bottles were closed with a transparent plastic cover and maintained during 180 days in a growth room, at 25±1°C temperature, under 12 hours photoperiod and light intensity of about 35 μmol. m-2. s-1.

After 180 days of cultivation, the germinated seedlings were submitted to sub cultivation, a necessary procedure to ensure a greater biometric uniformity in the bottles. This procedure was performed in new bottles containing the MS growth environment (25 plants per bottle). Each one of the bottles of both cultivars utilized for the experiment of luminous quality presented seedlings approximately 4,0 ± 0,2 cm of high.

For the evaluation of spectral influence the growth of the seedlings, it was selected 20 bottles (10 for each cultivar). Plants were submitted to different light quality: white, blue (465 nm), yellow (485 nm), green (510 nm) and red (700 nm – 0,055 µmol. m-2. s-1), obtained by the utilization of two cellophane paper sheets involving the cultivation bottles ( Araújo et al. 2009), in the same conditions of cultivation. The transmittance of the cellophane papers was determined by spectrophotometer Beckman model DU65, between the wavelengths 400 and 800nm, 40nm intervals ( Almeida & Mundstock 2001).

After 60 days of cultivation, the seedlings were harvested bottles, washed and submitted to multivariable treatments, under 2 X 5 factorial (two cultivars X five treatments).

Acclimatization

After biometrics measures, seedlings were bottled in black plastic containers (1 L). As a drain, it was utilized expanded clay pebbles were surface-sterilized with calcium hypochlorite at 0,5% for 30 minutes followed by three washes in running water, with the objective of avoiding the dissemination of pathogens in the growth environment ( Pedroso-de-Moraes 2000).

For planting in vases it was previously mounted a sphagnum base in the bottom e all around the recipient. Plants were accommodated in parallel lines with sphagnum in the middle of them until the total fulfill of the vase. All the vases were allocated in countertops at 1,5 m from the soil with a spacing of 5 cm between then, procedure that ensures large light exposure to the individuals ( Endsfeldz 1998), and maintained in a greenhouse (mesh type sombrite 70%) of the Orchid Nursery Santa Cruz, in a mean monthly temperature of 28 ± 2°C, air relative humidity of 75% and luminous intensity of about 800 µmol. m-2. s-1 ( Moraes & Almeida 2004). During all the experimental period the seedlings were fertilized with 2 mg.L- 1 Peters ® fertilizer NPK 10-10- 10 in alternated days, having as criteria for the final irrigation the dryness of the substratum ( Pedroso-de-Moraes 2000). This experiment, as well as the germination, was carried out in a factorial scheme 2 X 5 (two varieties X five treatments).

Statistics Avaliations

After two months of growth under several light qualities, the seedlings of the two cultivars of Phal. amabilis alba were submitted to the following biometric evaluation related to growth: Total Seedling Length (TSL), Length of the Air Part (LAP), Dry Mass of the Whole Plant (DMWP), Length of the Larger Leaf (LLL), Number of Roots (NR) and Number of Leaves (NL).

After three months of acclimatization of the seedlings, new biometrics measures were taken, with the objective to verify the influence of several luminous spectra. The variables were analyzed in this experiment were: Seedling Total Length (STL), Length of the Air Part (LAP), Dry Mass of the Whole Plant (DMWP), Dry Mass of the Whole Seedling (DMWS), Length of the Larger Root (LLR), Length of the Larger Leaf (LLL), Number of Roots (NR) and Number of Leaves (NL).

All the measurements were made using a digital caliper rule (Digimess 100A) and an analytical balance (Gehaka BG 400). All data were analyzed by multivariable statistics with the utilization of the application BioEstat 5.3 ( Ayres et al. 2007).