INITIAL GROWTH OF SEEDLINGS OF Eucalyptus dunnii Maiden AS INFLUENCED BY THE ADDITION OF NATURAL POLYMER AND FARMING SUBSTRATES

Abstract

-This study aimed to test different concentrations of natural polymer combined with different substrates in order to maximize the production and quality of Eucalyptus dunnii Maiden as well as the influence of the physical and chemical properties of the substrates. Experiments were conducted in a greenhouse in a randomized design with a 4 x 4 factorial arrangement for different substrates (factor "A") and water-retaining polymer concentrations (factor "B"). The physical and chemical properties of the substrates were also analyzed in each treatment. The seedlings height (H), neck diameter (D), shoot dry matter (SDM), root dry matter (RDM), total dry matter (TDM), H/D ratio and Dickson quality index (DQI) were measured after 90 days of sowing. Both the physical and chemical properties of the substrates have improved by the addition of hydrogel, especially those regarding to porosity, water availability and water holding capacity. In general, the water-retaining polymer concentrations of 2 and 4 g L -1 provided a better seedling growth. Seedlings largest neck diameter was observed at a hydrogel concentration of 6 g L -1. The use of hydrogel has resulted in higher height and neck diameter values when carbonized rice hulls were used as substrate. Therefore, hydrogel concentrations of 2 and 4 g L -1may increase the quality of Eucalyptus dunnii seedlings and reduce their nursery time.Keywords: Seedling production; Water holding capacity; Hydrogel. CRESCIMENTO INICIAL DE MUDAS DE Eucalyptus dunnii Maiden COM UTILIZAÇÃO DE POLÍMERO NATURAL E SUBSTRATOS DE CULTIVORESUMO -O objetivo deste estudo foi testar diferentes doses do polímero à base de amido de milho combinado com diferentes substratos, visando à maximização da produção e qualidade de mudas de Eucalyptus dunnii Maiden e a influência das características físicas e químicas dos substratos. O experimento foi conduzido em casa de vegetação, utilizando delineamento inteiramente casualizado em arranjo fatorial 4 x 4, em que os níveis do fator "A" referiram-se aos diferentes subtratos e os níveis do fator "B" às doses do hidroretentor. Para cada tratamento realizou-se análise física e química do substrato. Após 90 dias da semeadura avaliouse a altura, diâmetro do colo, MMSPA, MMSR, MMST e o cálculo da relação h/dc e do IQD. A adição do hidrogel melhorou as características físicas e químicas dos substratos, principalmente às relacionadas com porosidade, disponibilidade de água e capacidade de retenção de água. As dosagens de 2 e 4 g L-1 do hidroretentor proporcionaram melhor crescimento das mudas. O maior diâmetro de coleto foi observado 628Revista Árvore, Viçosa-MG, v.40, n.4, p.627-637, 2016 NAVROSKI, M.C. et al. do hidrogel. Quando a casca de arroz carbonizada foi utilizada, o uso do hidrogel proporcionou elevação da altura e diâmetro de coleto. Assim, o hidrogel, em dosagens entre 2 e 4 g L -1pode melhorar a qualidade das mudas de Eucalyptus dunnii diminuindo o tempo de permanência no viveiro.Palavras-chave: Mudas; Retenção de água; Hidrogel.

Hydrogel Changes the Air-Water Ratio of Plant Substrates

“…When the sample is dehydrated, instead of water, the pores remain. This fact was also observed by Navroski et al (2016b) in which total porosity as risen for all substrates tested as the hydrogel concentration increased.…”

“…However, the water retention capacity of hydrogels can be influenced by several factors, such as its physical and chemical composition, particle size, texture, pH and density, as well as the soluble salts present in the environment (AZEVEDO et al, 2019). This fact was observed by Navroski et al (2016b) in that the behavior of the hydrogel vary according to the composition of the substrate used. In such a study the available water increased with the increase in the concentration of the hydro polymer for the commercial substrate and its mixture with carbonized rice husk, but remained stable or slightly decreased when the commercial substrate was mixed with vermiculite, or mixed with vermiculite and rice husk.…”

“…The seedling production aims to obtain quality seedlings for different purposes (AZEVEDO et al, 2019) because the final performance of the plants in the field depends on the quality of the seedlings produced (NAVROSKI et al, 2016b). The superiority in relation to seedling quality can be achieved using appropriate techniques, some are based on substrate properties, mainly physical and chemical characteristics (SILVA et al, 2014;NAVROSKI et al, 2015a).…”

Allometry and morphophysiology of papaya seedlings in a substrate with polymer under irrigation with saline water

“…It is then highlighted that the irrigation frequency modifies the effects of salinities, which are intensified under a lower frequency, probably due to the effect of lower salt dilution. Regarding the water-absorbing polymer, the beneficial effect in the production of papaya seedlings is limited to its concentration in the substrate, as also observed in seedlings of Eucalyptus dunnii (Navroski et al, 2016). This behavior can be attributed to the reduction of water losses and, consequently, to the mitigation of water stress provided by the water-retaining polymer, thus causing greater production and accumulation of total mass by the seedlings.…”

Ácido indolbutírico (AIB) e substratos na propagação vegetativa de Jatobá (Hymenaea courbaril L.) por miniestaquia

“…Em relação à aplicação do AIB, o comportamento das miniestacas se mostrou, mais uma vez, prejudicado com a aplicação do regulador de crescimento, comprovados pelos valores superiores de 0,053 e 0,085 para as testemunhas nos substratos BIO e VFC respectivamente (Figura 3J). Os valores de IQD120 observados no presente estudo estão de acordo com os encontrados por Navroski et al (2016) para Eucalyptus dunnii, e por Marana et al (2015) para Jacaratia spinosa. Mudas vigorosas, com sistema radicular mais desenvolvido, apresentam maior probabilidade de sobreviver e crescer mais rápido em condições adversas de campo (Sampaio et al, 2010).…”