Changes in anatomy and chlorophyll synthesis in orchids propagated in vitro in the presence of urea

Abstract

ABSTRACT. The environmental and nutritional conditions during plant growth can influence cell differentiation, resulting in anatomical and physiological adaptations. The objective of this study was to investigate the anatomical characteristics and chlorophyll content of L. purpurata during in vitro propagation when different concentrations of urea were applied. After 120 days of culture in a greenhouse, the growth characteristics, chlorophyll content, leaf anatomy and root features were assessed. Plants cultivated in a medium containing 75% urea exhibited modifications in their growth, increase in the number of leaves and roots, changes in the leaf and root dry matter content. There was an increase in the contents of "a" and "b" chlorophyll in plants treated with 50, 75 and 100% urea. An increase in the ratio of chlorophyll a to chlorophyll b ("a/b") was observed in plants treated with 25% urea compared with the controls. In plants treated with 75% urea, increases in the thicknesses of the mesophyll and the leaf blade were observed, and reductions in the number of layers of root cells, the velamen thickness, the exodermis and the vascular cylinder were observed. These results indicate that this species has a tolerance to urea and exhibits higher growth in vitro.Keywords: Laelia purpurata, cultivation in vitro, sources of organic nitrogen.Alterações anatômicas e síntese de clorofila em orquídea propagada in vitro na presença de uréia RESUMO. O ambiente assim como as condições de cultivo e tipo de nutrição podem influenciar na diferenciação celular, resultando em adaptações anatômicas e fisiológicas. O objetivo foi estudar características anatômicas e o teor de clorofila de L. purpurata "carnea" propagadas in vitro quando aplicado diferentes concentrações de uréia. Após 120 dias em sala de crescimento, foram avaliadas características de crescimento, teor de clorofila, aspectos anatômicos foliares e radiculares. Ocorreram modificações nas características de crescimento das plantas cultivadas em meio com 75% de uréia, resultando em aumento do número de folhas, raízes, teor de massa seca foliar e radicular. Houve aumento no teor de clorofila "a" e "b" nos tratamentos com 50, 75 e 100% de uréia. Foi observado aumento da razão de clorofilas "a/b" no tratamento com 25% de uréia, quando comparado com o controle. Na concentração de 75% de uréia foi observado aumento da espessura do mesofilo, limbo foliar, redução do número de camada de células radiculares, espessura do velame, exoderme e cilindro vascular. Tais resultados indicam que a espécie possui tolerância à uréia, possibilitando maior taxa de crescimento em condições in vitro.Palavras-chave: Laelia purpurata, cultivo in vitro, fontes de nitrogênio orgânico.

<b><i>In vitro</i> growth of the bromeliad <i>Alcantarea imperialis</i> (Carrière) Harms with different concentrations of nitrogen

“…Os valores do eixo vertical na seriam com vírgula, já foi corrigido With respect to chlorophyll, four nitrogen atoms are necessary for its composition, suggesting that this molecule could demonstrate the nitrogen status of plants (SALEEM et al, 2010, TAIZ;ZEIGER 2010). At 7.50 mM N, plants of A. imperialis showed a decrease in the concentrations of chlorophyll a and b (Figure 1).…”

“…One of the most important is the nutrient N, the main component of amino acids, proteins, nucleic acids, chlorophyll and coenzymes (SILVA JÚNIOR et al, 2013). According to White and Brown (2010), in their review on mineral nutrition, the N is mentioned as the primary macronutrient essential for plant development.…”

“…According to White and Brown (2010), in their review on mineral nutrition, the N is mentioned as the primary macronutrient essential for plant development. While on deficiency, it is translocated from older leaves, which show chlorosis, to the young leaves that have a lower development (TAIZ;ZEIGER, 2010). N deficiency limits the production, but in excess, it may lead to yield losses, waste of inputs, and causes environmental pollution.…”

“…Guo et al (2010) observed in plants of Abies fabri, an endemic conifer dominant in mountain regions of China, that excessive nitrogen supply had negative effects on plant growth. According to Taiz and Zeiger (2010), when minerals are excessive in the soil, it becomes saline, and plant growth, in general, is reduced. In salt stress, water is osmotically retained in the saline solution.…”

<b>Growth and photosynthetic responses during <i>ex vitro</i> acclimatization of <i>Etlingera elatior</i> (Jack) rm smith (torch ginger)

“…This finding shows that the environmental conditions during plant growth can influence cell differentiation, resulting in anatomical and physiological adaptations. Direct implications in production may occur by modifying growth, increasing the number of leaves and roots, changing the leaf and root dry matter content, varying the contents of "a" and "b" chlorophyll and altering the thickness of mesophyll and leaf blades (SILVA JÚNIOR et al, 2013 …”