SUMMARYOrchid fertilization is fundamental for a satisfactory plant growth and development for commercial orchid production as well as in collections. Mineral and/or organic sources can be used for fertilization. The objective of this study was to evaluate the effect of the use of organic and/or mineral fertilizers on the nutrition and growth of orchid (Laelia purpurata 'werkhanserii' x L. lobata 'Jeni') seedlings in greenhouse. The following fertilizers were tested: an NPK fertilizer + micronutrients; a Ca source in the form of calcium nitrate; two organic fertilizers, one prepared with a mixture of bone meal, castor meal and ash, and a similar commercial fertilizer. The organic fertilizers were distributed on the surface of the pots every two months and the minerals were applied weekly to the substrate in 25 mL aliquots of a solution containing 1 g L -1 of the respective fertilizer. The plant response to the application of mineral together with organic fertilizer was better, with higher dry matter production than by the isolated application of each fertilizer (organic or mineral). The treatments with calcium nitrate + NPK fertilizer did not differ significantly from the use of NPK fertilizer, probably due to the S deficiency detected in a mineral analysis of the tissues. Commercial organic fertilizer had a very elevated B level, leading to toxicity symptoms, reduced growth and necrotized tips of the older leaves in all fertilized treatments. Index terms: orchidaceae, fertilizer, B toxicity, bone meal, castor meal, ash.

RESUMO Esterilização química na propagação in vitro de Arundina bambusifolia Lindl. e Epidendrum ibaguense KunthHá uma grande demanda por técnicas de laboratório mais simples, e de menor custo, e por procedimentos mais acessíveis, por parte de orquidófilos que não têm o embasamento teórico necessário à utilização de métodos usuais de produção, seminífera e clonal, de orquídeas, in vitro. O objetivo deste trabalho foi avaliar a eficiência da aplicação de hipoclorito de sódio (NaClO), para a descontaminação, no processo de inoculação de explantes de orquídeas das espécies Arundina bambusifolia e Epidendrum ibaguenses. As soluções de NaClO (1.200; 2.400; 3.600; 4.800 e 6.000 mg L -1 -equivalentes a 50; 100; 150; 200 e 250 mL L -1 de água sanitária comercial -ASC) foram borrifadas (1,0 mL) sobre explantes e meio de cultura (GB5), na ausência ou na presença de carvão ativado (2 g L -1). Os explantes utilizados foram segmentos nodais de plantas adultas, cultivadas a campo. Os procedimentos para inoculação dos explantes foram

Concentrações e composições químicas do meio nutritivo para o cultivo in vitro de orquídeaRev. Ceres, Viçosa, v. 59, n.1, p. 1-8, jan/fev, 2012 RESUMO ABSTRACT Chemical composition and component concentrations of culture medium for the in vitro growth of orchidOrchid seedlings grown in vitro respond differently to the different culture media used for this technique. This study compares the traditional Knudson (KC) medium used in orchid in vitro cultivation with a new medium formulation based on the KC medium with modifications, which was named Novais medium (NM), and two other media prepared with NPK fertilizer in the formulations 10-30-20 + micronutrients and 30-10-10 + micronutrients. The media were tested for the in vitro growth of six-month-old orchid seedlings derived from the cross Cattleya walkeriana x Cattleya loddigesii 'Etibaia' and germinated in Knudson C medium. The KC medium was tested in the concentration of 2.0 g L -1 , and the other three media were tested in the concentrations of 0.25; 0.50; 1.00; 1.75; and 2.25 g L -1 . All the media were added with 20 g L -1 of sucrose, solidified with 10 g L -1 agar and pH adjusted to 5.7. NM and Peters ® media were added with 2 g L -1 of activated charcoal and 200 ml L -1 of coconut water. The seedlings were cultured in 320 mL glass jars containing 35 mL of medium. The experiment was maintained in a growth room at 27±2 °C, 16/8 h photoperiod with 48 ì mol m -2 s -1 irradiance. The best responses for production of fresh matter were obtained using NPK fertilizers, in comparison with KC and NM medium. The fresh matter production increased linearly with increasing nutrients doses in both MN and KC media. The orchid seedlings grown in Knudson medium had the lowest means for the variables evaluated. Plântulas de orquídeas cultivadas in vitro respondem de forma distinta aos vários meios de cultura empregados nessa técnica. Este trabalho comparou o meio nutritivo Knudson C, utilizado no cultivo de orquídeas, com o denominado MN e outros dois meios preparados com fertilizantes Peters ® : NPK 10-30-20 + micronutrientes e NPK 30-10-10 + micronutrientes para o cultivo in vitro de plântulas do híbrido Etibaia (Cattleya walkeriana x C. loddigesii), com seis meses de idade, germinadas sobre o meio Knudson C. Os três últimos meios foram testados com as seguintes doses de sais: 0,25; 0,50; 1,00; 1,75; e 2,25 g L -1 , e o meio Knudson C, 2,0 g L -1 . A todos os meios adicionaram-se 20 g L -1 de sacarose, solidificado com 10 g L -1 de ágar, e o pH foi ajustado a 5,7. Aos meios MN e Peters ® foram acrescentados 2 g L -1 de carvão ativado e 200 ml L -1 de água de coco. Foram utilizados frascos de vidro de 320 mL contendo 35 mL de meio nutritivo, e o experimento foi mantido em sala de crescimento a 27 ± 2 ºC, 16/8 h luz/escuro e irrdiância de 48 µmol m -2 s -1 . Melhores respostas para produção de matéria fresca foram obtidas com os fertilizantes NPK, em comparação com os meios Knudson C e MN. A produção de matéria fresca aumentou linearmente com o aumento da dose de nutrientes n...

In the best cultivation methods of orchids, in particular of the genus Phalaenopsis, liming is a common practice. The objective of this study was to evaluate the influence of lime rates (0.0; 1.0; 2.0; 3.0; 4.0; and 5.0 g dm -3 of substrate) applied to the cultivation substrate (xaxim) on the growth of Epidendrum ibaguense seedlings. In a greenhouse, 1-L plastic pots filled with 0.8 dm 3 of xaxim were irrigated such that no leachate was lost during the experiment. N, P, K, Ca, Mg, S, Fe, Zn, B, and Mn contents in roots, stems and leaves were measured. Leachate was collected by applying a sufficient water volume to obtain 25 mL from each pot. Fourteen days after lime application of 3 g dm -3 , the pH of the collected leachate reached values above 7 and a value of 6.29 with the highest lime rate at the end of the experiment. The lime rate did not influence plant height, probably due to a Zn deficiency at high pH levels and a Ca deficiency in the control. Nevertheless, there was a large increase in leaf production, for number as well as for dry matter mass. There was no statistical difference between treatments in root dry matter production. Maximum dry matter production was obtained at a lime rate of 4.09 g dm (0,0; 1,0; 2,0; 3,0; 4,0 e 5,0 g dm -3

In vitro cultivation of orchid seedlings in media with differents concentrations of mineral fertilizerThere are a number of medium formulations for growth of orchid seedlings in vitro, with different compositions and concentrations of salts, leading to varying plant responses to them. The objective of this work was to evaluate in vitro growth of orchid (Cattleya walkeriana Gardner) seedlings subjected to different rates of a NPK fertilizer added to the growth medium. The fertilizer Peters ® was used in the formulation NPK 10-30-20+Mg+micronutrients in the rates of 0.0; 1.0; 2.0; 3.0; 4.0; 5.0; and 10.0 g L -1 medium, with coconut milk (150 mL L -1 ), sucrose (20 g L -1 ) and activated charcoal (2 g L -1 ) and pH adjusted to 5.6. Six-month-old seedlings, previously germinated in Knudson C medium were transferred to 320 mL glass jars containing 35 mL of medium, using 10 plants per jar. The maximum production of dry matter from the aerial part at six months of age was estimated at 0.255 g/jar, with the medium added of 5.22 g L -1 of fertilizer. Considering the possibility of high salt concentration in the medium for some orchid species, the fertilizer rate needed to obtain 90% of maximum production was estimate at 3.55 g L -1 . There was a drastic growth reduction in root growth when using high fertilizer concentrations, producing fewer roots and shorter.