Effects of exogenous proline and a natural ventilation system on the in vitro growth of orchids

Abstract

ABSTRACT:Micropropagation is an alternative to produce orchid plants in large scale. However, this process presents losses during acclimatization. Exogenous proline use in vitro plant tissue culture can reduce the stress of the plant acclimatization phase. We aimed to verify the growth of orchids in different micropropagation systems with the addition of proline in the culture medium. Cattleya walkeriana plants were obtained from the germination of seeds in culture medium. Seeds were germinated in MS medium, added 20 g. L -1 of sucrose, solidified with 6 g. L -1 of agar and pH adjusted for 5,8. The cultures were incubated in a growth room with temperature of 24 ± 2 0 C, under photoperiod of 16 h. After 5 months, 1-cm long seedlings were placed in a culture vessel according to the treatments, which were composed of two micropropagation systems (conventional and natural ventilation) and three proline concentrations (0, 1, and 2 g·L -1 ). The experiment was carried out in an entirely randomized design consisting of a 2 × 3 factorial, for a total of 6 treatments, each with 5 replicates. The natural ventilation system with the use of proline (1 g·L -1 ) promoted higher dry mass accumulation and better control of water loss by plants.

Biorreator na micropropagação de abacaxi ornamental

“…Similar results were found by Moreira et al (2013), who compared micropropagation systems in orchid cultivation and found that plants growing in a temporary immersion bioreactor had a higher dry matter, reaching 0.032 g, followed by the natural ventilation system, which were superior to conventional micropropagation. Silva et al (2016) verified a greater dry matter accumulation in orchid plants growing in natural ventilation systems, when compared to conventional micropropagation. This result is in agreement with those observed in this study, where it was observed that the plants maintained in NVS had 66% greater dry mass accumulation than the plants in CM ( Figure 2C).…”

“…2, 2018 p. 182-187 2010). The beneficial effects of natural ventilation are due to the reduction in in vitro relative humidity (IVANOVA and VAN STADEN, 2010;SILVA et al, 2016), to the increase in gas exchange with the external atmosphere (MOHAMED and ALSADON, 2010;SILVA et al, 2016) and the reduction in water availability, besides producing more rustic in vitro plants, reducing seedling losses during the acclimatization phase (SILVA et al, 2016).…”

Influência da luz, ventilação natural e tamanho do frasco no crescimento e desenvolvimento de denphal (Orchidaceae)

“…E para os frascos em sistema convencional foram observadas as menores médias para essas variáveis (Tabela 1). Os resultados observados estão relacionados à utilização do sistema de ventilação natural que permite trocas gasosas entre o interior do frasco e o ar atmosférico, influenciando o crescimento das plantas in vitro (Silva et al, 2016). Esses resultados corroboram com os de Silva et al (2014) onde plantas de Cattleya walkeriana Gardner, cultivadas em frascos vedados com tampas que proporcionaram ventilação, apresentaram características de crescimento superiores àquelas cultivadas em ambiente hermético.…”

“…No entanto, quando as plantas foram cultivadas em frascos com sistema convencional, apresentaram maior NB (5,16 brotos), resultado que pode estar relacionado com o maior NF, também encontrado nesse tratamento (Tabela 1). Este fato pode ser decorrente da presença de gás etileno e de elevadas concentrações de CO 2 no ambiente hermético de cultivo, que podem diminuir o crescimento das plantas e conteúdo de pigmentos fotossintéticos (Silva et al, 2014;Silva et al, 2016;Teixeira da Silva et al, 2017). E neste trabalho contribuindo para formação de brotos e folhas.…”

“…Ao verificar a Figura 1, pode-se constatar que, para plântulas de denphal, a utilização de frascos maiores e do sistema de ventilação natural, foram fatores que proporcionaram condições favoráveis na promoção do crescimento in vitro. Uma explicação para este fato, de acordo com Silva et al (2016), é que sistemas de micropropagação que permitem trocas gasosas entre o microambiente dentro do frasco e o ar atmosférico, acabam por diminuir o acúmulo de gás etileno e CO 2 , favorecendo o crescimento das partes das plantas no cultivo in vitro.…”