Biochar successfully replaces activated charcoal for in vitro culture of two white poplar clones reducing ethylene concentration

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Tissue culture of ornamental cacti

Cacti species are plants that are well adapted to growing in arid and semiarid regions where the main problem is water availability. Cacti have developed a series of adaptations to cope with water scarcity, such as reduced leaf surface via morphological modifications including spines, cereous cuticles, extended root systems and stem tissue modifications to increase water storage, and crassulacean acid metabolism to reduce transpiration and water loss. Furthermore, seeds of these plants very often exhibit dormancy, a phenomenon that helps to prevent germination when the availability of water is reduced. In general, cactus species exhibit a low growth rate that makes their rapid propagation difficult. Cacti are much appreciated as ornamental plants due to their great variety and diversity of forms and their beautiful short-life flowers; however, due to difficulties in propagating them rapidly to meet market demand, they are very often over-collected in their natural habitats, which leads to numerous species being threatened, endangered or becoming extinct. Therefore, plant tissue culture techniques may facilitate their propagation over a shorter time period than conventional techniques used for commercial purposes; or may help to recover populations of endangered or threatened species for their re-introduction in the wild; or may also be of value to the preservation and conservation of the genetic resources of this important family. Herein we present the state-of-the-art of tissue culture techniques used for ornamental cacti and selected suggestions for solving a number of the problems faced by members of the Cactaceae family

Micropropagação de cebola a partir de bulbinhos induzidos in vitro Micropropagation of onion from in vitro induced bulblet

Visando determinar um método para micropropagação a partir de bulbinhos in vitro, de cultivares de cebola (Allium cepa L.), foram realizados três experimentos, avaliando-se a influência do 6-benzilaminopurina (BAP) x ácido naftalenoacético (ANA) e posição do explante no meio de cultura, a influência de bulbinhos desenvolvidos em diversas concentrações de sacarose e o efeito do diâmetro dos bulbinhos sobre a taxa de multiplicação in vitro. Pelos resultados, a posição vertical dos explantes mostrou maior tendência para porcentagem de regeneração nos cultivares Pira Ouro e Pirana Precoce. 0 efeito das concentrações de fitorreguladores na porcentagem de regeneração não foi verificado para o 'Pira Ouro', enquanto para o 'Pirana Precoce', porcentagem mais elevada foi obtida em 4,0 mg/L de BAP x 0,5 mg/L de ANA. Maior taxa de multiplicação foi observada para os dois cultivares em BAP (2,0 mg/L) x ANA (0,25 mg/L). Bulbinhos do cultivar Pira Ouro e híbrido entre Pira Ouro e Pirana Precoce, desenvolvidos em 120 g/L de sacarose, mostraram-se mais adequados à micropropagação in vitro no material utilizado. Com relação ao diâmetro inicial do explante, o 'Pira Ouro' não mostrou diferença estatística para os parâmetros avaliados, enquanto no 'Pirana Precoce' maior porcentagem de regeneração foi obtida nos diâmetros M (5 a 10 mm) e P (< 5 mm), e maior número de brotos no diâmetro M.<br>Series of three different experiments were carried out, in order to study the optimization of the use of bulblets obtained in vitro, in the micropropagation of the onion (Allium cepa L.). Initially, it was evaluated the effects of the interaction between two doais of 6-benzylaminopurine (BAP) and naphthaleneacetic acid (NAA), and the position of the explant in the medium, for the cultivara Pira Ouro and Pirana Precoce. For 'Pira Ouro' the phytohormone concentrations did not affect the percentage of regeneration; however, for 'Pirana Precoce', the rates of 4.0 mg/L of BAP and 0.5 mg/L of NAA gave the best results. The highest multiplication rate, measured by the number of shoots obtained, for both cultivars, was observed with 2.0 mg/L of BAP and 0.25 mg/L of NAA. The vertical position of the explant showed a tendency of increasing the percentage of regeneration for the two genotypes. Explants from bulblets obtained with the sucrose concentration of 120 g/L were best fitted for the regeneration process, as showed by the second experiment, carried out with the Pira Ouro cultivar and the hybrid Pira Ouro x Pirana Precoce. The size of the bulblet, measured as its diameter, utilized as the source of the explants was studied in the third one, for the same cultivars utilized in the first experiment. For 'Pira Ouro', there was no influente, both, for the percentage of regeneration and the number of shoots obtained. The small diameter (P: < 5 mm) and the medium one (M: 5 a 10 mm), in the Pirana cultivar, had higher percentage of regeneration; the highest number of shoots was obtained with M diameter