Variabilidade genética e alterações morfológicas em progênies de polinização aberta de Eucalyptus grandis sob o efeito de paclobutrazol

Abstract

ResumoO presente trabalho teve como objetivo estudar a variabilidade genética e as alterações das características morfológicas em progênies de polinização aberta de Eucalyptus grandis sob o efeito do biorregulador de crescimento paclobutrazol. O experimento foi instalado no delineamento em blocos casualizados. As modificações que ocorreram antes e durante a indução floral das plantas foram estudadas e os parâmetros genéticos estimados para altura de plantas e diâmetro do caule. O regulador paclobutrazol causou modificações morfológicas durante o desenvolvimento das plantas; que foram intensas logo após a aplicação do regulador e foram diminuindo seu efeito ao longo das avaliações. Os coeficientes de variação mostraram haver maior variabilidade genética dentro do que entre progênies, para as características estudadas, apontando para maior eficiência na seleção dentro das progênies em programas de melhoramento do Eucalyptus grandis.Palavras-chave adicionais: eucalipto; parâmetros genéticos; regulador vegetal. AbstractThe research objective was to study the genetic diversity of morphological traits in Eucalyptus grandis progenies growing under paclobutrazol regulator effects. The progeny trail was set up through design of randomized blocks. The morphological changes occurred before and during the plant flowering were analyzed. The estimation of genetic parameters were for plant height and stem diameter. The paclobutrazol have caused changes on plant development being strong by the beginning and becoming lightening through the evaluations. The coefficients of variation have shown there is higher genetic diversity within than among progenies for the studied traits. Therefore, it can have high efficiency on selection within progenies in the Eucalyptus grandis breeding program.

Modulation of the initial growth of Eucalyptus clones using paclobutrazol: when smaller is better

“…Low inhibition effectiveness on SD is related to the lack of gibberellin biosynthesis in the vascular cambium (Leopold and Kriedemann, 1975) and to the lower expression of secondary growth during the change in the growth phase. Reduced SD due to the application of PBZ has also been reported in Pinus nigra, Betula papyrifera (Chorbadjian et al, 2011), Eucalyptus camaldulensis and Eucalyptus tereticornis (Varghese et al, 2008)as well as E. grandis during the initial growth stage (Moraes et al, 2014). Similar reductions (25.24%) in lateral shoot number (LSN) were observed in plants treated with PBZ concentrations of 116 ppm and in control plants (Fig.1c).…”

“…Compared with the H of control plants, the H of plants treated with PBZ was at most 51.67% lower; this maximum was achieved using a PBZ concentration of 140 ppm (Fig.1a). Reduced H is a common effect of PBZ application in some Eucalyptus species and is associated with shortened internodes (Moraes et al, 2012;Moraes et al, 2014).…”

“…Changes promoted by PBZ depend on species, variety and plant development stage as well as PBZ concentration and application method (Silva and Faria Jr, 2011). Regarding Eucalyptus cultivation, PBZ shortens the juvenile stage and stimulates the reproductive phase, resulting in early flowering (initiation of flower buds) (Moraes et al,2014;Gardner et al, 2016;Klocko et al, 2016;Potts et al, 2008). The effects of PBZ on Eucalyptus growth were first reported in the 1990s (Willians et al, 1999;Griffin et al, 1993).…”

Reproductive and vegetative behavior of hybrid jabuticaba tree under flowering induction

“…Bioregulators are a kind of synthetic chemical compost used in agriculture to modify morphological and physiological characteristics and to promote or suppress vegetative development (Leite & Crusciol 2008). In woody angiosperms, the use of bioregulators directly influences the vegetative and reproductive growth, since some of them block the gibberellin biosynthesis, a hormone that promotes cell stretching and meristem division (Moraes et al 2014), while other bioregulators are ethylene precursors (Cunha 2005).…”

“…The bioregulators that are most common and well understood are calcium carbide (Brescasin et al 2013), ethephon (Cunha 2005, Schmidt et al 2009, Moraes et al 2012) and paclobutrazol (Cavatte et al 2012, Moraes et al 2012, Oliveira et al 2012, Moraes et al 2014. These chemicals are largely used to promote flowering in mango trees (Mangifera indica) (Cardoso et al 2007, Akram et al 2013, apple trees (Malus domestica) (Schimidt et al 2009), grapevines (Vitis sp.)…”