Some factors affecting glassiness in carnation meristem tip cultures

Abstract

A study was made of the effect of agar concentration on glassiness during meristem tip culture of carnation. Increasing the agar concentration from the usual 6 g/1 to 12 g/1 decreased glassiness, but at the same time reduced plant growth. A concentration of 8 or 10 g/1 reconciled these conflicting effects. The type of closure of the tubes was also found to affect glassiness, the looser types (cotton wool, metal caps, steri stops) being better than the tighter ones (aluminium foil and parafilm). In the first days after excision of the meristem tip a period existed in which a rather high temperature of 26 ~ favoured the development of normal plants later. The positive response to high temperature was around 3 days after excision.

Controle da vitrificação do cravo (Dianthus caryophyllus L.) in vitro

“…De igual modo, o ágar reduziu a taxa de propagação para 50% em relação ao uso de "Gelrite". HAKKAART & VERSLUIJS (1983) também reduziram a vitrificação em cravo a níveis bastante significantes ao substituírem tampas de papel alumínio por tampas de algodão, o que implicou no baixo desenvolvimento das plantas. Esse efeito pode ser atribuído às perdas de água no meio pela evaporação sob condições de baixa umidade restringindo a disponibilidade de água e nutrientes do meio de cultura (DEBERGH et al, 1981).…”

“…Os eventuais fatores da vitrificação têm sido atribuídos ao potencial osmótico (DEBERGH et al, 1981;HAKKAART & VERSLUIJS, 1983;PASQUALETO et al, 1988), concentração dos reguladores de crescimento, especialmente a citocinina (LESHEM et al, 1988a;1988b), umidade e a concentração salina do meio de cultura (DAGUIN & LETOUZÉ, 1986). Pára contribuir ao estudo dessa questão é que foi conduzido o presente trabalho tendo em vista determinar as condições controladoras da vitrifícação do cravo in vitro.…”

Vitrification in Micropropagation

“…There is also some evidence that the reduction of agar concentration or its avoidance (liquid culture instead of solid ones) causes vitrification (Hauzinska 1974;Davis et al 1977;Sutter and Langhans 1979;Debergh 1983;Hakkaart and Versluijs 1983;Druart et al 1984;Kevers et al 1984;Boxus 1984, 1987b;John 1986). However, many data suggest that the control of water potential is not the only way in which agar concentration affects vitrification (Debergh 1983;Bornman and Vogelmann 1984;Vieitez et al 1985).…”

“…The size and type of culture vessel, the type of closure, the concentration of agar, and the climate parameters of the culture room all influence vitrification (Hakkaart and Versluijs 1983;Debergh and Maene 1984).…”

“…My feeling, however, is that the excess of ethylene produced by plants placed in vitrifying conditions, which accumulates to some extent in the flask atmosphere (Kevers and Gaspar 1985b) is partly responsible for the morphological changes in these plants: exogenously supplied ethylene induces identical morphological traits (stem thickening, reduction of internode length) in several systems (Gaspar et al 1989); better gas exchange of the culture atmospheres (Hakkaart and Versluijs 1983) and reduced ethylene emission using inhibitors of ethylene biosynthesis (Gaspar and Kevers 1985) reduce or suppress vitrification.…”