Light effects on in vitro rooting of pear cultivars of different rhizogenic ability

Abstract

The effect of varying light regimes on in vitro rooting ofmicrocuttings of two pear (Pyrus communis L.) cultivars was investigated. Cultures of the easy-to-root 'Conference' and the difficult-to-root 'Doyenne d'Hiver' were incubated for 21 days with or without indole-3-butyric acid (IBA) in the medium in darkness or under continuous far-red (8 /~.mol m -2 s -1 , blue, white or red (15 or 36 #mol m -2 s -~) light. 'Conference' rooted without IBA when exposed to red, blue or white light while no rooting was observed under far-red light and in darkness. The high rooting efficiency under red and, by contrast, the inhibition under far-red light and darkness suggest the involvement of the phytochrome system in rhizogenesis. The addition of IBA to the culture medium enhanced root production under all light regimes in both cultivars. Red light, especially at the lower photon fluence rate, had a positive effect by increasing root extension (number x length of roots) and stimulating secondary root formation.

Effect of polyvinyl alcohol on in vitro rooting capacity of shoots in pear clones (Pyrus communis L.) of different ploidy

“…In this paper, the in vitro rooting capacity of polyploids originated from the diploid cultivar 'Fertility' showed different responses to exogenous auxins in our earlier observations, with the diploid control clone being easy to root and the polyploid and mixploid clones being difficult to root. Rooting methods for other Pyrus species that had been published (Bertazza et al 1995;Barros et al 2005;Dolcet-Sanjuan et al 1990;Liu et al 2004;Luo et al 2006;Marino 1988;Marks and Simpson 2000;Shibli et al 1997) were not effective for the polyploid clones in our preliminary experiments. It had been reported that PVA had been used for seed coating or pretreatment seed to improve seed germination, seedling growth or resistance to salt (Lin et al 2003;Guo et al 1989;Hong and Zhao 1997;Ruan and Xue 2002;Xiong 1998), to increase chlorophyll content in peas (Czeczuga and Nowak 1962), or used in soil to reduce runoff and soil losses (Marsh and Groenevelt 1992) and to stabilize soil (Stefanson 1973;Oades 1976).…”

“…Losses at this step will have vast economic consequences. The ability of in vitro shoots to form roots is affected by several factors, including differences between genotypes (Bertazza et al 1995;Barros et al 2005), culture procedures (Anirudh and Kanwar 2008;Bertazza et al 1995;Barros et al 2005;DolcetSanjuan et al 1990), mineral nutrition (Liu et al 2004;Ramage and Williams 2002), subculture times (Banno et al 1989;Tang et al 2006), the level of tissue maturity (Olivier 2004), and physiological age ). Due to these factors, in vitro shoots showing a variety of rooting responses have resulted in plants being variously described as easy-to-root (ETR), or difficult-to-root (DTR) (Marks and Simpson 2000).…”

Biology of Root Formation and Development

“…The high rooting efficiency under red and white light, and the inhibition of rooting under far-red and darkness, suggest the involvement of the phytochrome system in rhizogenesis (Bertazza et al, 1995;Letouze and Beauchesne, 1969;Rossi et aL, 1993). Phytochrome induction of rhizogenesis may occur in part through modulation of auxin levels, as reported for phytochrome regulation of stem growth (Behringer et aL, 1992).…”

Pyroligneous Acid Improves In Vitro Rooting of Japanese Pear Cultivars

“…Many studies have been undertaken to improve rooting in Pyrus sp. (Bertazza et al, 1995;Reed, 1995;Rodríguez Pyroligneous acid (PA) (wood vinegar) is a dark brown solution obtained as a by-product of wood carbonization. It contains over 200 components, such as acids, alcohols, phenols, and neutrals (Jodai et al, 1989;Shirakawa et al, 1995b;Yatagai et al, 1988).…”