ABSTRACT. This study evaluated the effects of fertigation, banana biomass as a soil covering under drip and micro-sprinkler irrigation system on the root growth and distribution and their relations with chemical soil attributes, soil water availability, and productivity. This work was conducted in a field with banana 2.5 × 2.0 m spacing and irrigated every two days using a drip and micro-sprinkler irrigation system during the first crop cycle. The experiment followed a random block design with six treatments, two irrigation systems, two fertilization methods of fertigation and side-dressing, as well as two cultivation types with and without soil covering. Roots were collected from each plot using soil monoliths and digitalization allowed the determination of root length density, and diameter at several distances from the plant and at different soil depths. Total root length, density, and distribution by diameter were evaluated based on the treatment interactions with respect to the distance from the plant and the soil depth. Our results showed that the combination of the irrigation system, fertilizer application and soil covering influenced root growth and distribution. In addition, we found that the better soil conditions for root growth were in drip or micro-sprinkler systems with fertigation and cultivated biomass covering.

RESUMO O objetivo desse trabalho foi avaliar o efeito de substâncias húmicas (ácido húmico e fúlvico) aplicadas via fertirrigação com e sem extratos vegetais a base de saponinas nas variáveis de crescimento e produção da bananeira BRS Princesa (Musa sp.). O pomar foi instalado em espaçamento de 2,0 m x 2,5 m, em Latossolo Amarelo Distrocoeso, sob regime de fertirrigação por gotejamento, no Recôncavo da Bahia, Brasil. Os tratamentos consistiram em cinco doses de substância húmicas (0,0; 21,14; 31,71; 42,28 e 63,42 L ha-1ciclo-1) com e sem aplicação de extratos vegetais, a base de saponinas. O delineamento experimental adotado foi o de blocos casualizados, em esquema de parcelas subdivididas no espaço com cinco repetições. Foram efetuadas análises biométricas na ocasião da floração e da colheita, sendo avaliados o crescimento e a produção acumulada, respectivamente. Mediante análise estatística foi verificado que, quando as substâncias húmicas foram associadas aos extratos vegetais, ocorreram influências significativas sobre a produtividade de pencas, comprimento e diâmetro de frutos e quando as substâncias húmicas foram aplicadas de forma isolada ocorreram efeitos significativos, apenas, sobre a altura de plantas.

ABSTRACT The use of humic substances and plant extract has been increasing mainly in organic crop systems without scientific-based recommendations. Research is necessary to evaluate the feasibility and the recommendations of these substances. The objective of this work was to evaluate the effect of humic substances (humic and fulvic acids) applied by fertigation with and without saponin-based plant extracts on growth and yield of ‘BRS Princesa’ banana. The experiment was carried out using the banana cultivar ‘BRS Princesa’, at a spacing of 2.0 × 2.5 m, fertigated by drip irrigation in a Dystric Densic Xantic Ferralsol, at the Recôncavo da Bahia, Brazil. Treatments consisted of five doses of humic substances (0.0; 70; 105; 140, and 210 L ha-1cycle-1) applied with and without a saponin-based plant extract in a randomized block design in split-plot scheme. The following growth variables were evaluated: number of leaves, pseudostem height, pseudostem diameter, and length and width of the third leaf. The number of fruits/hand and hands/bunch, hand and bunch yield, and length and fruit diameter of the second central hand were evaluated during harvest. The doses of humic substances influenced only pseudostem height. Hand yield, as well as fruit length and diameter of ‘BRS Princesa’ banana were higher in plants fertigated with humic substance and plant extract in comparison with plants fertigated with only humic substance.

RESUMO. O trabalho teve como objetivo avaliar efeitos de substância húmica aplicada com e sem adição de extrato vegetal via fertirrigação no sistema radicular da bananeira cultivar 'BRS Princesa'. A bananeira foi cultivada no espaçamento 2,0 x 2,5 m, fertirrigada por gotejamento em Latossolo Amarelo Distrocoeso. O delineamento experimental foi em blocos casualizados em esquema de parcelas subsubdivididas com cinco repetições, sendo os fatores: doses de substancia húmica, presença de uma formulação de extrato vegetal. Usou-se cinco doses de uma formulação de substâncias húmicas, baseadas na dose de referência correspondente a 14,14 L ha-1 ciclo-1 de substancias húmicas, na presença e ausência de extrato vegetal. A variável comprimento de raízes (cm) foi submetida a análises de variância para avaliação do efeito isolado da dose de substancia húmica ou em interação com uma formulação de extrato vegetal e com a profundidade do solo. O uso do extrato vegetal potencializou o efeito da substancia húmica no comprimento das raízes, entretanto ofuscou seu efeito para as diferentes doses de substancia húmica. Na profundidade 0 - 0,40 m o comprimento de raízes não foi sensível ao aumento da dose da substancia húmica com extrato vegetal até 42,42 L ha-1.

ABSTRACT. This study aimed to evaluate the effects of fertigation with humic substances, with and without the addition of plant extracts, on the root system of the 'BRS Princesa' banana cultivar. The banana crop was cultivated at a spacing of 2.0 x 2.5 m and fertigated using a drip system in a dystrocohesive Yellow Latosol. The experimental design was randomized blocks, in a split-split-plot scheme with five replicates, for the following factors: humic substance doses and presence of a plant extract formulation. The treatments consisted of five doses of humic substances, based on a reference dose of 14.14 L ha-1 cycle-1, in the presence and absence of plant extract. The variable root length (cm) was subjected to variance analyses to evaluate the effect of the humic substances, either isolated or in interaction with plant extract and soil depth. The use of the plant extract increased the effect of the humic substance on root length but overshadowed its effect for the different doses of humic substance. Root length was not sensitive to increasing humic substance dose with plant extract for doses of up to 42.42 L ha-1at 0 - 0.40 m depth.

RESUMO A fertirrigação com produtos à base de substâncias húmicas vem sendo adotada em plantios comerciais de bananeiras. No entanto, tal procedimento ainda carece de mais estudos para comprovar sua viabilidade técnica. Objetivou-se avaliar os efeitos da fertirrigação com substâncias húmicas nos atributos químicos de um Latossolo Amarelo distrocoeso cultivado com bananeira 'BRS Princesa' e no desempenho agronômico do pomar. O experimento foi conduzido em delineamento de blocos casualizados, com seis tratamentos e quatro repetições. Os tratamentos consistiram da aplicação mensal de doses de substâncias húmicas, calculadas a partir da dose de referência (12,09 kg ha-1 ciclo-1) recomendada comercialmente para o cultivo da bananeira. As doses utilizadas foram equivalentes a porcentagens da dose de referência (100 %, 150 %, 200 %, 250 % e 300 %), além da testemunha. Não foram observados efeitos significativos da fertirrigação com substâncias húmicas que justificassem o emprego do insumo nas doses avaliadas sobre os atributos químicos do solo, crescimento e produção das bananeiras.

ABSTRACT Fertigation with humic substances products has been adopted in commercial banana tree plantations. However, there are few studies on the procedure to confirm its technical feasibility. This study aimed at assessing the effects of fertigation with humic substances on the chemical attributes of a Dystric Densic Xantic Ferralsol cultivated with the 'BRS Princesa' banana tree cultivar and on the agronomic performance of the orchard. The experiment was conducted using a randomized blocks design, with six treatments and four replications. Treatments consisted of a monthly application of humic substances doses based on the commercially recommended reference dose for the banana plantation (12.09 kg ha-1 cycle-1). The doses used were equivalent to percentages of the reference dose (100 %, 150 %, 200 %, 250 % and 300 %), in addition to the control. No significant effects of the fertigation with humic substances that could justify the use of the product at the doses assessed were observed on the soil chemical attributes, banana growth and yield.