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 , 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 -1 at 0 -0.40 m depth.

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.

Trickle irrigation has been largely used for banana in Brazil, mainly due to the increase in water and fertilizer use efficiency. These irrigation systems have different options concerning number, type and flow rate of emitters as well as for hydraulics, number and location of lateral lines. The small area of soil wetted by these systems limits root spatial distribution of crops. This study aimed to evaluate the effect of different trickle irrigation systems on the root spatial growth and root spatial distribution of banana cv. Prata Gorutuba. Root length density and root length were evaluated in soil profiles of three micro-sprinkler systems, with emitter flow rates of 35, 53 and 70 L h-1 and of two drip irrigation systems, with one and two lateral lines per crop row. Trickle irrigation systems influence root spatial distribution, favoring a greater or smaller distribution of roots at different depth and distance from the plant according to micro-sprinkler flow rate and to the number of lateral lines per crop row. The effect on root spatial distribution is more accentuated for micro-sprinkler systems than for drip systems. The majority of the total root length (80%) was observed in the soil profiles from 0.33 to 0.57 m depth and at distances from the plants of 0.75 to 0.83 m.

Occurrence of more frequent events of prolonged periods of low rainfall (drought) in worldwide cacao (Theobroma cacao L.) production zones has not only compromised productivity of small farmers but also crop survival. This study aimed to evaluate how and to what extent cacao tree mortality in dry years is related with variations in soil and physiographic features. The rate of mortality of cacao trees cultivated under an agroforestry system was evaluated over three periods (1994-1995, 2009-2013, and 2015-2019) on 36 plots of a farm in Bahia, Brazil, which has a wide diversity of soils and is established in a region with a subhumid to dry climate. Correlation analyses (single and multiple), cluster analysis, and Tukey tests were performed. The explanatory variables studied were the attributes of two soil layers (physical, mineralogical, and chemical), the diagnostic horizon, and the physiographic attributes (slope, terrain orientation in relation to the sun, and crop shading). The edaphic attributes most related to cacao tree mortality were physical (granulometry, porosity, and density) and mineralogical (Ki), mainly in the subsurface layer. The lowest mortality was observed in Oxisols and on slopes facing south and east. It was possible to establish recommend limits of the most suitable edaphic attributes to ensure greater survival of cacao trees cultivated in regions subject to recurrent water deficit similar to the conditions of this study. These findings can be used to guide farmers on how to mitigate the effect of drought. INTRODUCTIONIncrease in the frequency of drought events in the cacao (Theobroma cacao L.) production regions of the world has Abbreviations: BD, bulk density; BS, base saturation; CEC, cation exchange capacity; Ki, SiO 2 /Al 2 O 3 molar ratio; Kr, SiO 2 /(Fe 2 O 3 +Al 2 O 3 ) molar ratio; PCA, principal components analysis; PDP, percentage of dead plants; P rem , remaining P; S-value, sum of basic cations; Sl, terrain slope; SLAI, shading leaf area index; SORS, slope orientation in relation to the sun; TOC, total organic carbon; TP, total porosity.

RESUMO Submitted on February 29th, 2016 The use of humic substances and plant extract has been increasing mainly in organic crop systems without scientificbased 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. ) 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. Key words: Fertirrigação da bananeira 'BRS Princesa' com substâncias húmicas e extratos vegetais a base de saponinasO 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 -1 ciclo -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.Palavras-chave: Extratos de plantas; irrigação por gotejamento; matéria orgânica; Musa sp.