Growth-active gibberellins overcome the very slow shoot growth of Hancornia speciosa, an important fruit tree from the Brazilian “Cerrado”

Abstract

Shoot elongation of Hancornia speciosa, an endangered tree from the Brazilian savannah ''Cerrado'', is very slow, thus limiting nursery production of plants. Gibberellins (GAs) A 1 , A 3 , and A 5 , and two inhibitors of GA biosynthesis, trinexapac-ethyl and ancymidol were applied to shoots of Hancornia seedlings. GA 1 and GA 3 significantly stimulated shoot elongation, while GA 5 had no significant effect. Trinexapac-ethyl and ancymidol, both at 100 lg per seedling, inhibited shoot elongation up to 45 days after treatment, though the effect was statistically significant only for ancymidol. Somewhat surprisingly, exogenous GA 3 more effectively stimulated shoot elongation in SD-grown plants, than in LD-grown plants. The results from exogenous application of GAs and inhibitors of GA biosynthesis imply that Hancornia shoot growth is controlled by GAs, and that level of endogenous growthactive GAs is likely to be the limiting factor for shoot elongation in Hancornia. Application of GAs thus offer a practical method for nursery production of Hancornia seedlings for outplanting into the field.

Selectivity of the plant growth regulators trinexapac-ethyl and sulfometuron-methyl to cultivated species

“…Trinexapac is an acylcyclehexanedione (Caldas et al, 2009;Rademacher, 2000) that, in Poaceae species, such as wheat and rye, causes a reduction in the internode length and, consequently, in plant height. This has been used to reduce plant lodging (MAPA, 2011b;Espindula et al, 2009;Zagonel and Fernandes, 2007).…”

“…This has been used to reduce plant lodging (MAPA, 2011b;Espindula et al, 2009;Zagonel and Fernandes, 2007). This effect is explained by the trinexapac action on the synthesis of gibberellins, starting from the GA 12 aldehyde which, among other functions, is responsible for cell elongation (Caldas et al, 2009;Dalley and Richard Junior, 2010;Rademacher, 2000). As a consequence of becoming incapable of synthesizing active gibberellins, the plants start to synthesize and accumulate biologically less efficient gibberellins and this causes reductions in cell elongation (Rademacher, 2000;Taiz and Zeiger, 2006).…”

Trinexapac-Ethyl and Sulfometuron-Methyl Selectivity to Young Eucalyptus Plants

“…T r i n e x a p a c -e t h y l i s a n acylcyclohexanedione (Radamacher, 2000;Caldas et al, 2009) that in poaceae species such as wheat, barley and rice, causes reduction in internode length and thus plant height, being favorable to avoid their layering (Zagonel & Fernandes, 2007;Espindula et al, 2009;Nascimento et al, 2009;Moddus, 2014). This effect can be explained by the mode of action of trinexapac-ethyl, which acts on the metabolism of gibberellins synthesis from GA 12 -aldehyde, a hormone that, among other functions, promotes cell elongation (Radamacher, 2000;Caldas et al, 2009;Dalley & Richard Júnior, 2010). In response, the plants have difficulty forming active gibberellins and begin to synthesize and accumulate gibberellins biologically that less efficient, causing reduction in cell elongation (Radamacher, 2000;Taiz & Zeiger, 2010).…”

Trinexapac-ethyl causes stimulatory effect on eucalyptus initial growth under nutritional deficiency

“…Trinexapac-ethyl is a plant growth regulator (acylcyclohexanedione), which is used as a ripener in sugar cane. Because it reduces internode elongation, this product is also used to lower the risk of lodging in wheat and other cereal species (Caldas et al 2009;Nascimento et al 2009;Rademacher 2015). The main activity of this compound is reducing the levels of active gibberellins (mainly GA 1 ) in response to competition with structurally related 2-oxogluterate.…”