Abstract The objective of this work was to evaluate the effect of the use of plastic mulch and percolation barrier on the growth and distribution of pineapple roots. The BRS Imperial cultivar was cultivated using plastic as mulching material and a percolation barrier. The evaluated variables were: relative and absolute root growth rates, root length distribution, and root length density. The use of plastic mulch resulted in a greater accumulation of root dry matter, with or without the percolation barrier. Under drip irrigation, mulching promoted a greater root development. The highest root growth rate occurred from 360 to 450 days after planting. The amount of roots was from 64.1 to 66.7% on the stem, and from 34 to 36% distributed in the 0.10 and 0.20 m soil layer. Black plastic, as mulch or a percolation barrier, contributes to increase the root development of 'BRS Imperial' pineapple under drip irrigation.

Resumo O objetivo deste trabalho foi avaliar o efeito do uso de cobertura plástica e barreira de percolação no crescimento e na distribuição de raízes de abacaxizeiro. A cultivar BRS Imperial de abacaxizeiro foi cultivada com uso de plástico como cobertura do solo e como impedimento à percolação. As variáveis avaliadas foram: taxas de crescimento radicular relativo e absoluto, distribuição do comprimento das raízes e densidade do comprimento radicular. O uso do plástico como cobertura do solo resultou em maior acúmulo de matéria seca das raízes, com ou sem impedimento de percolação. Sob irrigação por gotejamento, o uso do plástico como cobertura do solo promoveu maior desenvolvimento das raizes. A maior taxa de crescimento radicular ocorreu dos 360 aos 450 dias após o plantio. A quantidade de raízes foi de 64,1 a 66,7% no caule, e de 34 a 36% distribuídas na camada de 0,10 a 0,20 m do solo. O plástico preto, tanto como cobertura do solo quanto como impedimento de percolação, contribui para aumentar o desenvolvimento radicular do abacaxizeiro 'BRS Imperial' sob irrigação por gotejamento.

Abstract The objective of this work was to determine the fruit yield and water productivity of the 'Prata Anã' banana plant, under different combinations of planting densities and irrigation depths in its fourth production cycle. The experiment was designed in randomized complete blocks in a split-plot arrangement with four replicates, with the following factors: two levels of irrigation depth (50 and 100% crop evapotranspiration) in the plots and four levels of planting density (1,666, 2,083, 2,666, and 3,333 plants per hectare) in the subplots. Crop evapotranspiration and yield characteristics were evaluated. Reductions in the mass of hands, number of hands, and number of fruits were observed as planting density increased, as well as increments in the yield of hands and in water productivity and a reduction in water footprint. It is possible to increase the yield of the banana plant by increasing its planting density and reducing the irrigation depth applied in its fourth production cycle.

Resumo O objetivo deste trabalho foi determinar a produtividade de frutos e da água em bananeira 'Prata Anã', sob diferentes combinações de densidades de plantio e lâminas de irrigação no seu quarto ciclo de produção. O experimento foi delineado em blocos ao acaso, em arranjo de parcelas subdivididas, com quatro repetições, com os seguintes fatores: dois níveis de lâmina de irrigação (50 e 100% da evapotranspiração da cultura) nas parcelas e quatro níveis de densidade de plantio (1.666, 2.083, 2.666 e 3.333 plantas por hectare) nas subparcelas. Foram avaliadas a evapotranspiração e as características de produtividade da cultura. Foram observadas reduções na massa de pencas, no número de pencas e no número de frutos à medida que aumentou a densidade de plantio, bem como incrementos no rendimento de pencas e na produtividade hídrica e redução na pegada hídrica. É possível aumentar a produtividade da bananeira ao aumentar sua densidade de plantio e reduzir a lâmina de irrigação aplicada no seu quarto ciclo de produção.

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 trabalho objetivou-se em avaliar dois sistemas de irrigação, por gotejamento e microjatos difusores, dois tipos de fertirrigação, por pulverização na base da planta e no solo, e dois tipos de enraizadores no desenvolvimento e na produção do abacaxizeiro ‘BRS Imperial’. O sistema de gotejamento promoveu maior desenvolvimento radicular que o sistema de microjato difusor. Grande parte do sistema radicular concentrou-se no talo e no solo até 0,1 m de profundidade, em que o sistema de gotejo promoveu uma maior porcentagem relativa de crescimento de raiz no talo em relação ao microjato. Os enraizadores promoveram maior crescimento de raízes no talo que no solo. Sendo que o uso do enraizador à base de ácidos húmicos e fúlvicos não foi significativo, enquanto o uso do enraizador a base de ácido fosfórico e aminas foi significativo no crescimento radicular apenas no sistema de microjato. A aplicação de fertilizantes por pulverização na base da planta promoveu maior crescimento radicular e produtividade em comparação ao uso de fertirrigação. O sistema de gotejamento apresentou maior eficiência de produtividade da água de irrigação e da cultura para o abacaxizeiro ‘BRS Imperial’.

Abstract The objective of this work was to evaluate two irrigation systems, by drip and diffuser microjets, two types of fertigation, by spraying at the base of the plant and in the soil, and two types of root enhancers in the development and production of the pineapple ‘BRS Imperial’. The drip system promoted greater root development than the diffuser microjet system. Much of the root system was concentrated in the stalk and soil up to 0.1 m depth, where the drip system promoted a higher relative percentage of root growth in the stalk compared to the microjet. The root enhancers promoted greater root growth in the stalk than in the soil. The use of the root enhancers based on humic and fulvic acids was not significant, while the use of the root enhancers based on phosphoric acid and amines was significant for root growth only in the microjet system. Application of fertilizers by spraying at the base of the plant promoted root growth and increased yield compared to the use of fertigation. The drip system showed higher efficiency of crop and irrigation water productivity for ‘BRS Imperial’ pineapple.

Abstract Background: Lupus nephritis (LN) is a major source of morbidity and mortality in patients with systemic lupus erythematosus (SLE), with 10–25% of patients progressing to end-stage renal disease (ESRD). Objective: This study aims to elucidate the predictive capabilities of 24-h proteinuria (24PTU) and serum creatinine (sCr) after 12 months of treatment with respect to long-term renal outcomes in LN in a single-center cohort of LN patients. Methods: A retrospective analysis was performed on 214 patients diagnosed with LN followed in our center. Values of 24PTU and sCr were assessed at baseline and after 3, 6 and 12 months, and after 5 years and/or the last evaluation. Chronic kidney disease (CKD) was defined as an estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m2 for 3 months or longer. End-stage renal disease (ESRD) was defined as the need for permanent dialysis. Receiver operating characteristics curves (ROC) were used to test the best cut-off value of 24PTU and sCr at 12 months who predict bad long-term renal outcomes. Results: The mean follow-up period was 11.2 ± 7.2 years. The best cut-off values for 24PTU and sCr as predictor of CKD were, respectively, 0.9 g/24 h and 0.9 mg/dL. ROC curve for 24PTU had a slightly lower performance than ROC curve for sCr as predictor for CKD (PTU AUC = 0.68; sCr AUC = 0.70), but sensitivity and specificity were better for 24PTU (24PTU: sensitivity = 63.5%, specificity = 71.2%; sCr: sensitivity = 54.8%, specificity = 75.3%). When the outcome was ESRD the best cut-off points were 0.9 g/24hs and 1.3 mg/dL for 24PTU and sCr, respectively, and the curve performance was better for 24PTU (PTU AUC = 0.72; sCr AUC = 0.61). Conclusions: In this ethnically diverse population with LN followed for a long time (> 10 years), levels of 24PTU > 0.9/day at 12 months was a good predictor of bad long-term renal outcome. The serum creatinine > 0.9 mg/dL and > 1.3 mg/dL at 12 months were also good predictors of CKD and ESRD, respectively. Patients with 24PTU < 0.9 g/day and sCr < 1.3 mg/dL at 12 months are not likely to develop ESRD because of the high negative predictive values (NPV) (93.2% and 82%). 24PTU and sCr are relevant as components for a treat-to-target strategy for LN treatment, since their high NPV corroborates their importance as good predictors of long-term renal outcome.

Resumo O objetivo deste trabalho foi estimar a concentração de nitrato e potássio na solução do solo, em lisímetro de drenagem com o uso dos modelos matemáticos desenvolvidos por Vogeler et al. (1996) e Muñoz-Carpena et al. (2005) e do modelo computacional Hydrus-2D e comparar os dados simulados e observados usando parâmetros estatísticos. A cultivar utilizada para o estudo foi a ‘Prata Gorutuba’. As parcelas experimentais foram seis lisímetros de drenagem. A fertirrigação foi realizada semanalmente. Os modelos matemáticos desenvolvidos por Vogeler et al. (1996) e Muñoz-Carpena et al. (2005), foram utilizados para determinar a concentração específica de um determinado íon (Ci). O software Hydrus foi utilizado para simular a dinâmica de nutrientes. As concentrações de nitrato e potássio na solução do solo, estimados por meio do modelo de Vogeler et al. (1996) adaptado para a relação CEw-Ci do tipo linear e simulado pelo modelo Hydrus apresentou uma caracterização aceitável da distribuição desses nutrientes.

Abstract This study estimated the nitrate and potassium concentration in the soil solution of drainage lysimeter using the mathematical models developed by Vogeler et al. (1996) and Muñoz-Carpena et al. (2005) and the computational model Hydrus-2D, while comparing the simulated and observed data using statistical parameters. The cultivar used for the study was ‘Prata Gorutuba’. The experimental plots were six lysimeters of drainage. Fertigation was performed weekly. The mathematical models developed by Vogeler et al. (1996) and Muñoz-Carpena et al. (2005) were used to determine the specific concentration of a given ion (Ci). The Hydrus software was used to simulate the dynamics of nutrients. The concentrations of nitrate and potassium in the soil solution were estimated by the model of Vogeler et al. (1996), adapted to the linear type CEw-Ci ratio and simulated by the Hydrus model, resulting in an acceptable characterization of the distribution of these nutrients.

Resumo Conhecimento preciso e exato da percolação é uma chave para a determinação confiável do balanço de água no solo e da eficiência no uso da água pelas culturas. Este trabalho objetivou avaliar uma aproximação para estimar a quantidade de água percolada na zona radicular usando dados de umidade do solo (SWC) medidos em diferentes intervalos de tempo. A aproximação se baseou na diferença de umidade do solo dentro e abaixo da camada efetiva do sistema radicular de bananeiras em diferentes intervalos de tempo. Um lisímetro de drenagem foi utilizado para comparar os dados de percolação medida e estimada. A aproximação foi então utilizada em um bananal sob irrigação por gotejamento e por micro aspersão, com e sem cobertura do solo. O armazenamento de água no solo na zona radicular efetiva da bananeira foi avaliado em um perfil bidimensional do solo com sensores de reflectometria no domínio do tempo (TDR). A percolação média medida em lisímetro não diferiu do valor estimado pela aproximação, utilizando intervalos entre medidas de umidade do solo iguais ou superiores a 6 horas a partir do final do evento de irrigação. Estimativas de percolação sob gotejamento e micro aspersão em campo, com e sem cobertura do solo, foram consistentes com aquelas dos lisímetro, considerando o intervalo de 6 horas entre medições de umidade do solo. A percolação foi maior sob gotejamento com cobertura do solo. A quantidade de água percolada não foi influenciada pela presença da cobertura do solo sob irrigação por micro aspersão.

Abstract Precise, accurate knowledge of percolation is key to reliable determination of soil water balance and a crop’s water-use efficiency. This work evaluated an approach to estimate the amount of water percolated in the root zone using soil water content (SWC) data measured at different time intervals. The approach was based on the difference of soil water content within and below the effective root zone of banana plants at different time intervals. A drainage lysimeter was used to compare the measured and estimated percolation data. The approach was then used in a banana orchard under drip and micro sprinkler irrigation, with and without the use of mulch. The soil water storage in the banana’s root zone was evaluated within a two-dimensional soil profile with time domain reflectometry (TDR). Mean percolation measured in the lysimeters did not differ from the approach’s estimates using intervals between SWC readings equal to or longer than 6 h from the end of an irrigation event. Percolation estimates under drip and micro sprinkler irrigation in the field, with and without mulch, were consistent with those measured in the lysimeters, considering the 6-h interval of SWC measurements. Percolation was greater under the drip irrigation system with mulch. The amount of water percolated was not influenced by the presence of mulch under the micro sprinkler system.

ABSTRACT: Climatic uncertainties have compromised water resources, which influences irrigated agriculture. Irrigation is an important alternative to mitigate the effects of water scarcity. Partial root-zone drying (PRD) is a rational use of irrigation water. This study aimed to evaluate PRD for irrigation management of banana crop, cv BRS Princesa, under semi-arid conditions in Brazil. A field experiment was carried out with five treatments: one control (full irrigation) and four with 50 % reduction of water irrigation depth (WID) and frequencies alternating the side to be irrigated of the plant row of 0, 7, 14 and 21 days. Stomatal conductance, growth, yield and soil water status were evaluated. Results indicated that banana crop cv. BRS Princesa shows shoot physiological regulation for 50 % reduction of soil water and vapor pressure deficit between 1.92 and 2.25 kPa. Decrease in yields of treatments with WID reduction compared to full irrigation is due to the reduction of root uptake rate, which is related to vapor pressure deficit and soil water availability. Partial root-zone drying saves 50 % of irrigation water and increases water use efficiency of banana cv. BRS Princesa crop by 78 %.

Resumo Importante parcela da produção de mamão de Minas Gerais origina-se de cultivos irrigados, sendo o manejo da irrigação com uso da técnica de secamento parcial radicular (SPR) uma alternativa fundamental para redução de desperdício da água. Objetivou-se avaliar a qualidade de mamão ‘Tainung 1’ produzido sob SPR em condições semiáridas do norte Minas Gerais. Os tratamentos por SPR foram constituídos pela redução da lâmina calculada de irrigação (lci) em 50%, aplicada em um dos lados da linha de irrigação, com alternância de 7; 14 e 21 dias ou sem alternância e irrigação plena, aplicando-se 100% da lci. Cada parcela experimental foi constituída por dez plantas, sendo que das seis centrais se colheram os frutos para as avaliações no ponto de colheita e quando maduros. No ponto de colheita, os frutos têm cor da casca, acidez titulável, ratio, tamanho e espessura da polpa semelhantes àqueles produzidos sem déficit hídrico. A firmeza, o teor de sólidos solúveis, a massa fresca e o diâmetro da cavidade central são distintos em função da condição de SPR. Quando maduros, somente a firmeza varia em função dos tratamentos por SPR. A qualidade do mamão ‘Tainung 1’, produzido por secamento parcial do sistema radicular, em condições semiáridas, não foi comprometida.

Resumo A significant portion of papaya production in the state of Minas Gerais originates from irrigated crops, and irrigation management using the partial root zone drying technique (PRD) is a fundamental alternative to reduce water waste. This study aimed to evaluate the quality of ‘Tainung 1’ papaya produced under PRD in semi-arid conditions of northern state of Minas Gerais. PRD treatments were composed of reduction of the calculated irrigation water (CIW) by 50%, applied on one side of the irrigation line, with alternation of 7, 14 and 21 days or without alternation and full irrigation, applying 100 % CIW in both lateral plant rows. Each experimental plot consisted of ten plants, and from six plants, fruits were harvested for evaluations at harvest point and when ripe. At harvest point, fruits had peel color, titratable acidity, ratio, pulp size and thickness similar to those produced without water deficit. Firmness, soluble solids content, fresh mass and central cavity diameter are distinct as a function of PRD condition. When ripe, only firmness varied according to PRD treatments. The quality of ‘Tainung 1’ papaya produced by partial root zone drying in semi-arid conditions was not compromised.

Resumo O conhecimento da transpiração é de fundamental importância para aprimoramento do manejo da irrigação. Objetivou-se com o presente trabalho determinar o fluxo de seiva da mangueira ‘Tommy Atkins’ utilizando o método da sonda de dissipação térmica de Granier, sob irrigação com déficit controlado. O trabalho foi desenvolvido em um pomar de mangueira ‘Tommy Atkins’ com 10 anos de idade, irrigado por microaspersão, localizada no Perímetro Irrigado de Ceraíma, no município de Guanambi, Bahia. A determinação do fluxo de seiva foi realizada em três dias consecutivos em plantas sob irrigação com déficit controlado, com redução de 30 e 60% da evapotranspiração da cultura em três fases de desenvolvimento do fruto, início da floração ao pegamento dos frutos (Fase I), fase de expansão do fruto (Fase II) e fase de maturação fisiológica do fruto (Fase III). Verificou-se que o déficit hídrico controlado causa redução no fluxo de seiva em mangueiras ‘Tommy Atkins’.

Abstract Knowledge of transpiration is of fundamental importance for improving irrigation management. This study measured sap flow of the 'Tommy Atkins' mango tree using Granier’s thermal dissipation probe method under regulated deficit irrigation. The work was conducted in a 10-year-old ‘Tommy Atkins’ mango orchard, irrigated by micro sprinkler, located in the Irrigated Perimeter of Ceraíma, in Guanambi, Bahia, Brazil. Sap flow measurements were carried out on three consecutive days in plants under regulated deficit irrigation, with reductions of 30 and 60% of crop evapotranspiration in three phases of fruit development; beginning of flowering to early fruit growth (Phase I), fruit expansion (Phase II) and physiological maturation of fruits (Phase III). Regulated deficit irrigation led to reduced sap flow in ‘Tommy Atkins’ mango tree.

ABSTRACT: The knowledge on spatial and temporal variations of soil water storage in the root zone of crops is essential to guide the studies to determine soil water balance, verify the effective zone of water extraction in the soil and indicate the correct region for the management of water, fertilizers and pesticides. The objectives of this study were: (i) to indicate the zones of highest root activity for banana in different development stages; (ii) to determine, inside the zone of highest root activity, the adequate position for the installation of soil moisture sensors. A 5.0 m3 drainage lysimeter was installed in the center of an experimental area of 320 m2. Water extraction was quantified inside the lysimeter using a 72 TDR probe. The concept of time stability was applied to indicate the position for sensor installation within the limits of effective water extraction. There are two patterns of water extraction distribution during the development of banana and the point of installation of sensors for irrigation management inside the zone of highest root activity is not constant along the crop development.

RESUMO: O objetivo deste trabalho foi o de avaliar a influência da salinidade sobre a absorção e utilização de nutrientes pela mandioca. Para o estudo, as plantas foram submetidas a quatro concentrações salinas: 0, 20, 40 e 60mM de NaCl. Os resultados mostraram que a absorção de todos os nutrientes, exceto o nitrogênio (N), foi reduzida pela salinidade, com maior redução para o potássio (K). No entanto, todos os nutrientes foram mantidos em concentrações que não indicaram problema de deficiência mineral. A concentração anormal de cálcio nas raízes tuberosas pode ter sido um dos fatores que contribuíram para o menor crescimento desse órgão e da planta como um todo. Os transportes de nitrogênio, potássio, fósforo e enxofre da raiz para a parte aérea foram maiores sob tratamento com salinidade. A eficiência no uso de todos os nutrientes, principalmente N, foi reduzida devido à salinidade. Considerando que: (i) a absorção de K foi a mais prejudicada, (ii) houve acúmulo anormal de Ca nas raízes tuberosas e (iii) a eficiência no uso de N foi a mais afetada, sugere-se priorizar estudos sobre estas três questões, como forma de melhor entender os aspectos relacionados à tolerância/sensibilidade das plantas de mandioca à salinidade.

ABSTRACT: The objective of this research was to evaluate the influence of salinity on the absorption and utilization of nutrients by cassava. For the study, cassava was submitted to four saline concentrations: 0, 20, 40, and 60mM NaCl. Results showed that the absorption of all nutrients, except nitrogen (N), was reduced by salinity, with highest reduction for potassium (K). However, all nutrients were maintained at concentrations which did not indicate mineral deficiency problem. The abnormal concentration of calcium in the tuberous roots may have been one of the factors that contributed to the lower growth of this organ and of the plant as a whole. Transports of nitrogen, potassium, phosphorus and sulfur from root to the aerial part was higher under salinity treatment. Efficiency in the use of all the nutrients, mainly N, was reduced due to salinity. Given that: (i) the absorption of K was the most impaired, (ii) there was abnormal accumulation of Ca in tuberous roots, and (iii) the efficiency in the use of N was the most affected, it is suggested to prioritize studies on these three issues, as a way to better understand the aspects related to the tolerance/sensitivity of cassava plants to salinity.

RESUMO. Esse estudo foi desenvolvido para avaliar os efeitos da salinidade sobre as trocas gasosas e crescimento da mandioca, cultivar Verdinha. Quatro concentrações de NaCl, em mM, foram utilizadas: 0, 20, 40 e 60. A menor concentração de Na+ foi observada nas raízes tuberosas; entretanto, a matéria seca dessa parte da planta foi reduzida pela aplicação de apenas 20 mM de NaCl. O índice de colheita foi reduzido em até 50% pela salinidade. A aplicação de NaCl reduziu a assimilação de carbono (A), condutância estomática ( gs ), transpiração (E) e eficiência no uso de água (EUA). A correlação entre gs e A foi alta e positiva, evidenciando que o movimento estomático foi um dos responsáveis pela menor A. Sob salinidade também existiu aumento na concentração interna de CO2, indicando que o NaCl pode ter inibido o metabolismo de carbono das plantas. Com base na redução do acúmulo de matéria seca das raízes tuberosas (redução de 81% sob 60 mM de NaCl) é concluído que essa cultivar de mandioca é bastante sensível à presença de NaCl na solução do solo. A sensibilidade da mandioca esteve relacionada à alta sensibilidade das raízes tuberosas aos efeitos iônicos e/ou osmótico do NaCl. Assim, as raízes tuberosas podem ser o órgão alvo em estudos que visem melhorar a tolerância da mandioca à salinidade.

ABSTRACT. This study was developed to evaluate the effects of salinity on the growth and gas exchange of cassava plants, cultivar Verdinha. The four concentrations of NaCl (mM) were as follows: 0, 20, 40, and 60. Under salinity, the lowest concentration of Na+ ions was observed in the tuberous roots; however, the dry matter of tuberous roots was reduced with an application of just 20 mM NaCl. The harvest index was reduced 50% with the highest salt concentration. Salinity reduced carbon assimilation (A), stomatal conductance ( gs ), transpiration, and the instantaneous water use efficiency. The correlation between gs and A was high and positive, showing that stomatal movement was one of the responsible for the lower A. Under salt stress, there was an increase in intercellular CO2 concentration, indicating the impairment of carbon metabolism. Based on the reduction of dry matter of the tuberous roots (reduction of 81% under 60 mM NaCl), it was concluded that cassava is sensitive to salinity. The growth of shoots and the absorbing roots were minimally affected by salinity, even in the situation where A was reduced; therefore, the sensitivity of cassava was related to the high sensitivity of the tuberous roots to the ionic and/or osmotic effects of salinity. Thus, tuberous roots can be the target organ in studies that aim to improve the tolerance of cassava to salinity.

Resumen El objetivo del estudio fue evaluar las características fisiológicas del banano 'Princesa' bajo riego lateralmente alternado (RLA). El diseño experimental fue de bloques al azar, con cinco tratamientos y cinco repeticiones: 1 - reducción del 50% en la lámina de riego (LR) con el lado de frecuencia de la conmutación de la planta (FC) 7 días durante todo el ciclo de producción; 2 - 50% de LR y 14 días de FC en el ciclo; 3 - 50% de LR y FC 21 días; 4 - 50% con un LR de riego fijo (sólo una de las alas en un lado de la planta) y 5 - riego completo (dos líneas laterales con registros abiertos) durante el ciclo. La conductancia estomática - gs fue menor en las plantas regadas con 50% de ETc en sistema de riego fijo. Incluso con déficit de agua en el suelo, con el RLA con 50% de ETc, Fotosíntesis -A, Transpiración - E; Temperatura de la hoja - Tl, la concentración interna de CO2 - Ci; conductancia estomática - gs; Radiación fotosintéticamente activa - Qleaf; eficiencia de carboxilación - A/Ci; La eficiencia cuántica de la fotosíntesis - A/Qleaf; y la eficiencia instantánea del uso del agua -A/E en el banano 'Princesa' no difiere entre los tratamientos, lo que pone de relieve la importancia de la técnica de gestión de riego, con el ahorro de agua y sin cambios fisiológicos de las plantas.

Abstract This research aimed to evaluate physiological characteristics of 'BRS Princesa' banana under partial rootzone drying irrigation, PRD. The five treatments, 1 - 50% of reduction in water depth (WD) with a frequency alternation of irrigation side (FA) of seven days during the whole production cycle; 2 - 50% of WD and FA of 14 days in the cycle; 3 - 50% of WD and FA of 21 days; 4 - 50% of WD with a fixed irrigation (only one lateral line on one side of the plant); and 5 - full irrigation (two lateral lines with open shutoff valve) throughout the cycle, they were arranged in a randomized block design with five replicates. There is a reduction in photosynthetic rates and water use efficiency as a result of enzymatic impairment or stomatal closure, due to the increased of leaf temperature. The stomatal conductance - gs was lower in plants irrigated with 50% of ETc with fixed irrigation in one side of the plant. Even with water deficit in the soil, using the PRD with 50% of ETc, Photosynthesis - A Transpiration - E; Leaf temperature - Tleaf, internal concentration of CO2 - Ci; stomatal conductance - gs; photosynthetically active radiation - Qleaf; carboxylation efficiency - A/Ci; Quantum efficiency of Photosynthesis - A/Qleaf; and instantaneous water use efficiency - WUE 'BRS Princesa' banana were similar among strategies, highlighting the possibility of use of the irrigation management technique with PRD, saving water, and no physiological changes in the plants.

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.