Brassinosteroide e fungo micorrízico arbuscular na produção do porta-enxerto tangerineira ‘Cleópatra’

Abstract

RESUMOTanto o brassinosteroide quanto a inoculação com fungos micorrízicos arbusculares (FMA) favorecem o crescimento e a absorção de nutrientes pelas plantas. Entretanto, não há relatos de experimentos testando a combinação desses insumos em mudas de Citrus reshni (tangerineira 'Cleópatra'). Assim, o objetivo deste trabalho foi avaliar o efeito da aplicação desses dois insumos sobre o crescimento e o estado nutricional de mudas de tangerineira 'Cleópatra', na fase final do enviveiramento. O experimento foi conduzido em delineamento casualizado em blocos, com esquema fatorial 5 x 2, sendo cinco concentrações de brassinosteroide (0,0; 0,1; 0,5; 0,75 e 1,00 mg L -1 ) e dois tratamentos de FMA (sem inoculação e inoculado com Acaulospora scrobiculata Trappe), com quatro repetições. Foram avaliados parâmetros de crescimento como altura, número de folhas e diâmetro do caule, a cada 20 dias após o transplantio das mudas e, ao final da fase de enviveiramento, a área foliar, a matéria seca da parte aérea e das raízes e o estado nutricional das mudas. O brassinosteroide não proporcionou efeito para as características de crescimento das mudas. A simbiose com A. scrobiculata promoveu aumento na altura no número de folhas, no conteúdo e no teor de Fe e Mn na massa seca das folhas de mudas de tangerineira 'Cleópatra'. Palavras-chave: Acaulospora, Citrus reshni, nutrição de plantas, propagação de plantas Brassinosteroid and arbuscular mycorrhizal fungi in the production of rootstock 'Cleopatra' ABSTRACTThe brassinosteroid belong to the class of plant hormone with diverse effects on plant physiology, including effects on growth and nutritional status. Allied to this substance, inoculation with mycorrhizal fungi can enhance growth and nutrient uptake in plants grown in containers. The objective of this study was to evaluate the effect of brassinosteroid and inoculation with arbuscular mycorrhizal fungi (AMF) on growth and nutritional status of Citrus reshni ('Cleopatra') at the stage of transplanting the tubes to pots. The experiment was conducted in a randomized block design in a 5 x 2 factorial arrangement with five doses of brassinosteroid (0.0; 0.1; 0.5; 0.75 and 1.00 mg L -1 ) and two AMF of treatments (without inoculation and inoculated with Acaulospora scrobiculata Trappe) with four replications. We evaluated the growth (height, number of leaves and stem diameter) every 20 days after transplanting of seedlings and at the end of the experiment (130 days after transplant) was assessed leaf area, shoot dry matter of roots and nutritional status of the plants. The brassinosteroid provided no effect on the characteristics of seedling growth. Inoculation with A. scrobiculata increased the height, number of leaves, the content and the content of Fe and Mn in the leaf dry weight of 'Cleopatra'.

Absorption of nutrients by soursop seedlings in response to mycorrhizal inoculation and addition of organic compost1

“…'Cleopatra' mandarin seedlings inoculated with A. scrobiculata provided increases of 11.9 % and 15.6 % in the Fe and Mn contents, when compared to the control treatment (Freitas et al 2015). Divergent results were reported for inoculation with Rhizophagus clarus, which reduced the Cu contents in 'Paulsen 103' grapevine plants (Rosa et al 2016).…”

Humic acids and brassinosteroid application effects on pineapple plantlet growth and nutrition during the aclimatization phase

“…These results are in agreement with those reported by Freitas et al (2012), who verified that brassinosteroid doses exhibited a significant effect on nitrogen content, with an increasing linear behavior, with 1.0 mg L -1 providing an 11.1% increase in the nutritional content of pineapple plantlets when compared to the controls. Freitas et al (2015), when working with 'Cleopatra' mandarin plantlets, reported that 1.0 mg L -1 brassinosteroids associated with arbuscular mycorrhizal fungi led to a 15.4% increase in the aerial dry mass nitrogen content. Diniz et al (1999) evaluated in vitro macronutrient absorption by banana explants, and reported that nitrogen content was higher during the first 10 days, decreasing as a function of culture time.…”

Nitrogen metabolism in maize plants submitted to drought, brassinosteroids and azospirillum

“…Brassinosteroids are a class of plant steroid hormones that act on cell elongation, allowing the growth of plants (Baghel et al, 2019). However, its effect depends on the growth stage of the plant (Freitas et al, 2015), the applied concentration (Freitas et al, 2014;Wei and Li, 2016) and the presence or absence of environmental stress (Tanveer et al, 2019). It is efficient in increasing resistance, especially at high temperatures, drought and salinity (Vardhini, 2012).…”