Abstract
In the present study, an attempt was made to induce rooting from single-node cuttings of hybrid aspen (Populus tremula L. × P. tremuloides Michx.) with different concentrations of Indole-3-acetic acid (IAA), Indole-3-Butytric acid (IBA) and 1-Naphthylacetic acid (NAA). Among the three auxins used, 0.54 mM NAA showed more effective induction on rooting as compared to IAA and IBA at the whole level. Thereafter, 0.54 mM NAA was used further for the anatomical and biochemical investigation. The results showed that it took 12 days from the differentiation of primordium to the appearance of young adventitious roots under NAA application. It was found that endogenous IAA, Zeatin riboside (ZR) and Gibberellic Acid (GA3) levels increased, but Abscisic acid (ABA) decreased in cuttings with NAA treatment. In contrast to the endogenous IAA level, NAA resulted in a decrease in IAA-oxidase (IAAO) activity. Similarly, the decreased peroxidase (POD) activity, consistent with down-regulation of expressed levels of POD1 and POD2, was observed in NAA-treated cuttings. Moreover, NAA resulted in a higher activity in polyphenol oxidase (PPO) compared with control cuttings. Collectively, the study highlighted that 0.54 mM NAA is efficient on rooting in hybrid aspen, and its effect on metabolic changes during rooting was discussed, which can provide valuable information for propagating hybrid aspen.
Highlights
One of the most important challenges at present is the need to replace fossil fuel-based energy sources with renewable energy, such as woody biomass, in order to sequester atmospheric CO2 [1,2]
Among the different concentrations of Indole-3-acetic acid (IAA) used for pretreatment of cuttings, the maximum percentage of rooting was obtained in cuttings treated with 0.57 mM IAA
Among the different concentrations of Indole-3-Butytric acid (IBA) used for pretreatment, the maximum percentage of rooting was observed in cuttings treated with 0.49 mM IBA
Summary
One of the most important challenges at present is the need to replace fossil fuel-based energy sources with renewable energy, such as woody biomass, in order to sequester atmospheric CO2 [1,2]. One way to satisfy the increasing demand for woody biomass is through the establishment of short-rotation forest plantations [3]. It is difficult to root hybrid aspen, propagation through cuttings is the most commonly used asexual method. The successful establishment from stem cuttings, depends upon many factors, such as seasonal and age variation, portion and diameter of stem, growing media, moisture level, nutrient status and temperature, etc. Plant growth regulatory hormones or ‘auxins’ play a vital role in influencing the sprouting and survival of stem cuttings. Adventitious rooting (AR) is a complex developmental process that can be stimulated by exogenously-applied auxins [8], the effect of which is to increase initiation of the root primordium and growth via cell
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