ABSTRACT
The objective was to study the effectiveness of the growth regulator (ANA + GA3) associated or not to the application of adjuvant and artificial pollination in 'Gefner' atemoya. The experiment was conducted in the experimental orchard at Florida's Tropical Research and Education Center. The experimental design was in a randomized block, with 14 treatments, 10 repetitions and 3 flowers per plot. The highest percentages of fixed fruits were obtained with hand pollination HP and 450 NAA + 1250 GA3 mg L-1 + adjuvant and HP. The use of hand pollination for 'Gefner' atemoya tree proved to be the most efficient method so far. Applying growth regulator without artificial pollination produces parthenocarpic fruits, however with high rate of abortions, and small fruits. Growth regulators together with hand pollination produces small and uneven fruits, and cause reduction in the fruits' titratable acidity. The use of adjuvant caused low fixation and toxicity to fruits, and its use is not recommended.
Subject(s)
Plant Growth Regulators , Annona , PollinationABSTRACT
Uvaia (Eugenia pyriformis) is a fruit tree of the Myrtaceae family. It has recalcitrant seeds of limited longevity, making seed propagation difficult. Micropropagation is an alternative method to obtain a large quantity of progeny plants in a short period of time, by using any part of the plant as explant. The high concentration of phenols associated with the chemical composition of the Myrtaceae, and the presence of microorganisms in the plant material or culture media, can make in vitro propagation difficult and/or impossible. The objective was to evaluate various concentrations of antioxidants affecting the control of microbial contamination and phenol oxidation in vitro in uvaia. A completely randomized design was used, with a 3 (antioxidants PVP, L-cysteine, and ascorbic acid) × 3 (antioxidant concentrations 100, 200, and 300 mg L-1) × 2 (activated charcoal at 0 and 2 g L-1) factorial arrangement + 2 additional variables (absence of antioxidants and activated charcoal; absence of antioxidants with 2 g L-1 activated charcoal), with three repetitions comprising four plants each. The percentage of bacterial and fungal contaminations, along with the number of oxidized explants, was evaluated after 7, 14 and 21 days of in vitro cultivation. It was concluded that, where bacterial and fungal contaminations were concerned, in vitro cultivation of uvaia can be performed without the use of antioxidants. PVP or ascorbic acid must, however be used in the process, at a concentration of 300 mg L-1, along with 2 g L-1 of activated charcoal. This helps to minimize phenol oxidation.
A uvaia Eugenia pyriformis é uma frutífera da família das mirtáceas cujas sementes apresentam longevidade curta e aspecto recalcitrante, fato que dificulta a propagação seminífera. A micropropagação surge como alternativa para obtenção de grande quantidade de mudas em curto período de tempo, por meio da utilização de qualquer parte da planta como explante. A elevada concentração de fenóis associados à composição química das mirtáceas e a presença de microrganismos no material vegetal ou no meio de cultura podem dificultar e/ou impossibilitar a propagação in vitro. Objetivou-se avaliar tipos e concentrações de antioxidantes no controle da contaminação microbiana e da oxidação fenólica in vitro de E. pyriformis. Utilizou-se o delineamento inteiramente casualizado em esquema fatorial 3 (antioxidantes PVP, L-cisteína e ácido ascórbico) x 3 (concentrações - 100, 200 e 300 mg L-1) x 2 (carvão ativado 0 e 2 g L-1) + 2 adicionais (ausência de antioxidantes e de carvão ativado; ausência de antioxidantes com 2 g L-1 de carvão ativado), com três repetições constituídas por quatro plantas. Após sete, 14 e 21 dias do cultivo in vitro foram avaliadas a porcentagem de contaminação bacteriana, fúngica e de explantes oxidados. Conclui-se que o cultivo in vitro de E. pyriformis, em relação as contaminações bacterianas e fúngicas, pode ser efetuado sem a utilização de agentes antioxidantes. Entretanto, para reduzir a oxidação fenólica deve ser utilizado o PVP ou ácido ascórbico, ambos na concentração de 300 mg L-1, associados a 2 g L-1 de carvão ativado.