The most important producers of tea are China, India, and tropical southern Asia. In Brazil, this plant is cultivated in Vale do Ribeira region, São Paulo state, to produce mainly black tea.
The success of tea productions depends on a uniform stand of plants that are propagated by cuttings, because sexual propagation cannot guarantee high yield and quality. However, tea plants are considered a difficult-to-root species (Wei et al., 2013). The difficulty of rooting can be caused by external factors, such as light and temperature, and internal factors, such as nutrition, age, and plant hormonal balance (Hartmann et al., 2011). Furthermore, the physiological age of the plant material affects the promotion of adventitious roots in some species. According to Gomes et al. (2002), guava plants (Psidium guajava) have increased rooting in softwood cuttings, whereas in litchi (Litchi chinensis), optimal rooting was in semihardwood cuttings (Carvalho et al., 2005). The impact of physiological age of tea on rooting capacity has not been reported.
Auxins as promoters of the development of adventitious roots on stems are widely known. Many woody species have early preformed adventitious root primordia on their stems, which remain dormant, unless they receive auxin stimulus (Salisbury and Ross, 1992). IBA is among the exogenous auxins applied for rooting of cuttings because it presents greater resistance to photodegradation, inactivation by biological action, and adherence to the cutting (Hartmann et al., 2011). However, the beneficial effects of exogenous auxins are concentration dependent. The application of auxin promotes rooting growth when used in a certain concentration; the effect becomes inhibitory when concentrations are higher. The ideal concentration for the treatment of cuttings varies according to the species and varieties (Zietemann and Roberto, 2007).
The use of this growth regulator has been promising in the rooting of cuttings of several species such as peach [Prunus persica (Mindêllo Neto, 2005)], guava [Psidium guajava (da Costa et al., 2003)], and vanilla [Vanilla planifolia (Silva et al., 2009)].
In Brazil, few studies have been performed on the effects of cutting age, growth regulator application, and collection season of cuttings for tea propagation. The objectives of this study were to evaluate the rooting of softwood and semihardwood cuttings in two botanical varieties of tea under different concentrations of IBA.
Balasaravanan, T., Pius, P.K., Raj Kumar, R., Muraleedharan, N. & Shasany, A.K. 2003 Genetic diversity among south Indian tea germplasm (Camellia sinensis, C. assamica and C. assamica spp. Lasiocalyx) using AFLP markers Plant Sci. 165 365 372
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da Costa, W.H. Jr, Scarpare Filho, J.A. & Bastos, D.C. 2003 Estiolamento da planta matriz e uso de ácido indolbutírico no enraizamento de estacas de goiabeiras Rev. Bras. Frutic. 25 301 304
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Lima, D.J., Bolfarini, A.C.B., Silva, S.H.M.G. & Moraes, W.S. 2013 Propagação de Camellia sinensis: Efeito do genótipo, estaca, substrato, recipiente e ácido indolbutírico Hortic. Bras. 31 74 79
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Wei, K., Wang, L., Cheng, H., Zhang, C., Ma, C., Zhang, L., Gong, W. & Wu, L. 2013 Identification of genes involved in indole-3-butyric acid-induced adventitious root formation in nodal cuttings of Camellia sinensis (L.) by suppression subtractive hybridization Gene 514 91 98
Zietemann, C. & Roberto, R. 2007 Efeito de diferentes substratos e épocas de coleta no enraizamento de estacas herbáceas de goiabeira, cvs Paluma e Século XXI Rev. Bras. Frutic. 29 31 36