Effects of auxins on in vitro reserve compounds of Phalaenopsis amabilis (Orchidaceae)

The effects of auxin and the endogenous levels of reserve compounds of Phalaenopsis amabilis (L.) Blume (Orchidaceae) were analyzed in vitro. Rootless plants were inoculated in modified MS media supplemented with IBA or NAA (0.0, 0.2, 1.0 and 5.0 mg L-1) and with 2,4-D (0.000, 0.032, 0.160 and 0.800 mg L-1). The biochemical parameters of endogenous levels of soluble carbohydrates and starch and of total soluble protein in roots, leaves and shoots were analyzed after 30 and 120 days. Carbohydrate levels in leaves showed similar patterns for all treatments. At 30 days, there was an increase in the endogenous carbohydrate level along with an increase in the concentration of auxins. At 120 days, the endogenous carbohydrate level in leaves had decreased, while the auxin concentration had continued to increase, demonstrating the mobilization of the carbohydrates. The leaf carbohydrate levels decreased from day 30 to 120; for both IBA and 2,4-D treatments, there was starch accumulation in roots as a function of the collection date. The 2,4-D concentration of 0.0032 mg L-1 decreased the level of total soluble protein in roots. The in vitro plants exhibit different growth patterns depending on the classes and concentrations of growth regulators. Biochemical analyses exhibited that metabolic activity and the degradation and accumulation of substances occurs in leaves, roots and shoots, demonstrating that roots contribute to the maintenance of plant metabolism and also act as reserve organs, even in epiphytic plants.Keywords: Storage compounds, soluble carbohydrates, starch, soluble proteins.African Journal of Biotechnology, Vol 13(12, 1467-147

Orchid in vitro growth as affected by nitrogen levels in the culture medium

O cultivo in vitro de plantas é o principal método de propagação das plantas da família Orchidaceae, sendo o nitrogênio o nutriente de maior importância dos meios de cultivo. O estudo teve como objetivo avaliar o efeito de diferentes concentrações de N através de balanço iônico do meio de Murashige & Skoog (MS-1962) no crescimento in vitro da orquídea Phalaenopsis amabilis. Plantas com 360 dias foram cultivadas em meio MS líquido, modificado com 7,5, 15, 30, 45 e 60 mM N. Após 180 dias avaliou-se o comprimento da planta, número de folhas e raízes, comprimento da raiz e as massas fresca e seca de folhas, raízes e total. Os tratamentos foram dispostos em delineamento inteiramente casualizado, com quatro repetições e parcelas de cinco frascos, com três explantes cada. A menor concentração de N (7,5 mM) no meio MS induziu o desenvolvimento de raízes em comprimento, número e massas fresca e seca. A concentração de 30 mM de N estimulou a emissão de folhas e o acúmulo de massa seca de folhas. A concentração original de nitrogênio no meio MS (60 mM) mostrou ser excessiva para o crescimento de P. amabilis cultivada in vitro.In vitro cultivation is the main propagation method for the family Orchidaceae, whereas nitrogen is the most important nutrient in the culture media. This work was carried out to study the influence of different nitrogen concentrations on the in vitro growth of the orchid Phalaenopsis amabilis. Nitrogen concentrations varied by altering the ionic balance of the Murashige & Skoog (MS) culture medium. Plants, 360 days old, were cultivated in liquid MS, modified with 7.5, 15, 30, 45, and 60 mM N. After 180 days, we assessed plant and root length, number of leaves and roots, and fresh and dry weight of leaves, roots and plants. Treatments were assigned to completely randomized plots, with four replications. Plots consisted of five three-plant flasks. The lowest nitrogen level (7.5 mM) in the medium induced root development in length, number, and fresh and dry weight. The concentration 30 mM N stimulated both emission and dry weight accumulation of leaves. The original nitrogen concentration in the MS medium (60 mM) was excessive for the in vitro growth of P. amabilis.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Efeito da aplicação de ácido giberélico no crescimento da palmeira-ráfia Effect of gibbeerllic acid application on lady palm growth

A palmeira-ráfia possui grande importância econômica devido ao seu interesse comercial. É uma planta ornamental muito apreciada por sua beleza e utilização em ambiente interno, crescendo bem em locais com sombra e apresentando resistência à exposição solar. O valor econômico dessa planta está relacionado à altura e número de hastes. O objetivo do trabalho foi promover o crescimento da planta, através da aplicação do regulador de crescimento ácido giberélico (GA3). Mudas de palmeira-ráfia com aproximadamente um ano de idade foram aspergidas a cada 21 dias (quatro aplicações) com solução de ácido giberélico nas concentrações de 0; 75; 150; 225; e 300 mg.L-1. Os resultados indicaram que a aplicação do ácido giberélico foi eficiente na promoção do crescimento da espécie, sendo esse incremento significativo nas variáveis: comprimento dos pecíolos, lâminas foliares e altura da planta. Não se observou diferença no acúmulo de matéria seca ou fresca do pecíolo entre os tratamentos, e plantas do tratamento-controle foram superiores às dos tratamentos 225 e 300 mg L-1, nas variáveis diâmetro do colo e massa fresca e seca das raízes. Devido ao incremento na altura das mudas e à alteração da disposição das folhas da palmeira, a utilização do ácido giberélico pode ser recomendada para a produção de mudas de alta qualidade.<br>Lady Palm is of great economic importance due its commercial interest. It is an ornamental plant growing in shadowy places, resistant to sun exposure and very appreciated for its beauty and ornamental value. Its commercial value is associated to plant height and shoot number. The aim of this work was to stimulate lady palm growth by applying the plant growth regulator gibberellic acid. Plantlets of R. excelsa approximately one year old were sprayed every 21 days (4 applications) with gibberellic acid solution at concentrations of 0; 75; 150; 225 and 300 mg L-1. The results showed that gibberellic acid was efficient in promoting the growth of the species and was statistically significant for petioles, leaf length and plant height. Petiole dry and fresh mass did not show any significant difference between treatments for stem diameter, with root dry and fresh mass having a higher value for the control than for the 225 and 300 mg L-1 treatments. Due to the higher height and leaf architecture changes observed, gibberellic acid can be used as a tool to stimulate Lady Palm growth, adding commercial value to the plantlets