Atividade das enzimas invertases e acúmulo de sacarose em cana-de-açúcar sob efeito do nitrato de potássio, etefon e etil-trinexapac

Abstract

RESUMOConduziu-se este trabalho, com o objetivo de avaliar a atividade das enzimas invertases ácida e neutra e sua influência no processo de regulação do acúmulo de sacarose nos colmos da cana-de-açúcar, cultivar RB855453, sob efeito do nitrato de potássio comparado aos maturadores, da classe dos retardantes do crescimento, etefon e etil-trinexapac, buscando contribuir para o entendimento da ação desse composto químico. Os tratamentos constituíram-se da aplicação de quatro maturadores da classe dos retardantes do crescimento, cujos ingredientes ativos são etefon, etil-trinexapac, nitrato de potássio e nitrato de potássio + boro, e a maturação natural como testemunha, em delineamento experimental em blocos casualizados com cinco repetições. Os níveis enzimáticos das invertases ácida e neutra foram afetados de forma e intensidade distintas em função do princípio ativo utilizado como maturador e das condições climáticas; contudo, de forma geral, os níveis da invertase ácida manifestaram-se superiores aos da invertase neutra sem comprometer o acúmulo de sacarose nos colmos da cana-de-açúcar cultivar RB855453. O nitrato de potássio apresentou efeito maturador na cultura da cana-de-açúcar possibilitando o acúmulo de sacarose nos colmos, contudo as condições climáticas afetaram sua eficiência agronômica, tendo em vista que atua como indutor do processo de maturação.Termos para indexação: Saccharum officinarum, etefon, etil-trinexapac, maturadores, nitrato de potássio, reguladores vegetais. ABSTRACTThe objective of this work was to evaluate the acid and neutral invertases enzymes activity and its influence in process of regulation sucrose accumulation in stems of RB855453 variety sugarcane under effect the potassium nitrate in compared with ripeners, of class of retainers growth, ethephon and ethyl-trinexapac, for to contribute the understanding of act this chemical compost. The treatments consisted of four ripeners of class of growth retainers, which active ingredient are ethefon, ethyl-trinexapac, potassium nitrate and potassium nitrate + boron and natural ripener as control, in a randomized block design with five replicates. The acid and neutral invertases enzymes levels were affected of form and intensity differents due active ingredient used as ripening and weather conditions; however, in general, the acid invertase levels were greatest the neutral invertase whitout to compromise the sucrose accumulation in stems of RB855453 cultivar sugarcane. The Potassium nitrate had effect ripener in sugarcane allowing sucrose accumulation in stems, however the weather conditions affected its agronomical efficiency, therefore act as inducers of the ripening process. INTRODUÇÃOOs reguladores vegetais classificados como maturadores referem-se a compostos químicos capazes de modificar a morfologia e fisiologia vegetal, podendo alterar qualitativa e quantitativamente a produção da cana-de-açúcar, sendo utilizados como instrumento auxiliar no planejamento da colheita e no manejo varietal; esses compostos atuam sobre as enzimas (inv...

Gas exchange rates, plant height, yield components, and productivity of upland rice as affected by plant regulators

“…However, there is not much data available regarding the wide spectrum of possibilities that affect carbon balance in tropical plants (Wright et al, 2005;Souza et al, 2008;Fagan et al, 2010). Additionally, in major crops like cotton, sugarcane, wheat and soybeans, plant growth regulators (PGR) have been most commonly used to reduce plant height and to provide greater plant uniformity (Nascimento et al, 2009;Espindula et al, 2011;Leite et al, 2011). Some of these regulators are biosynthesis inhibitors of gibberellins, a plant hormone associated with stem elongation (Buzetti et al, 2006;Nascimento et al, 2009).…”

“…Additionally, in major crops like cotton, sugarcane, wheat and soybeans, plant growth regulators (PGR) have been most commonly used to reduce plant height and to provide greater plant uniformity (Nascimento et al, 2009;Espindula et al, 2011;Leite et al, 2011). Some of these regulators are biosynthesis inhibitors of gibberellins, a plant hormone associated with stem elongation (Buzetti et al, 2006;Nascimento et al, 2009). In rice, these PGR are used to reduce plant height and, as a consequence, to reduce plant lodging.…”

“…Nevertheless, for upland rice cultivation, there is a lack of information regarding the relationship between PGR and physiological aspects involved in plant production, such as carbon gain and gas exchange. Typical studies have only evaluated the effects of PGR on plant height and crop yield (Nascimento et al, 2009), without analyzing photosynthetic relationships. In this sense, mepiquat chloride (PIX), a gibberellins' biosynthesis inhibitor, has been described to reduce photosynthetic capacity, leaf area, and Ribulose-1,5-carboxylase/oxygenase (Rubisco) activity in cotton plants (Reddy et al, 1996).…”