RESUMO No semiárido brasileiro o déficit hídrico é um dos principais fatores que compromete o crescimento e o rendimento produtivo das culturas, inclusive do maracujazeiro- amarelo, devido à limitação da assimilação de carbono pela atividade fotossintética dos vegetais. Diante disso, faz-se necessário o manejo do solo com tecnologias que possam reduzir a perda de água no solo e que amenize os efeitos do déficit hídrico às plantas de maracujazeiro-amarelo cultivadas em condições de semiaridez. Objetivou-se avaliar a aplicação no solo de doses de hidrogel e mulching sob os aspectos fisiológicos do cultivo de maracujazeiro-amarelo irrigado. O experimento foi desenvolvido em delineamento em blocos casualizados, no esquema fatorial 5 × 2, referente às cinco doses de hidrogel (0,0, 0,5, 1,0, 1,5 e 2,0 g dm−3 de solo) no solo sem e com cobertura vegetal oriunda braquiária (Brachiaria decumbens L.). As variáveis analisadas foram índices de clorofila, fluorescências (inicial, máxima e variável) e trocas gasosas. O índice de clorofila total foi elevado com a aplicação de 1,5 g dm−3 e uso de mulching, ao se aplicar doses de 2,0 g dm−3 de hidrogel a taxa fotossintética das plantas de maracujazeiro-amarelo aumentou, já a taxa de transpiração das plantas foi incrementada com o uso de cobertura vegetal e doses de hidrogel, como consequência houve redução na eficiência do uso da água.

ABSTRACT In the Brazilian semi-arid region, water deficit is one of the main factors that compromise the growth and productive yield of crops, including yellow passion fruit, due to the limitation of carbon assimilation by the photosynthetic activity of plants. Therefore, it is necessary to manage the soil with technologies that can reduce the loss of water in the soil and mitigate the effects of water deficit on yellow passion fruit plants cultivated under semi-arid conditions. The objective of this study was to evaluate the application of hydrogel doses and mulching to the soil on the physiological aspects of irrigated yellow passion fruit cultivation. The experiment was carried out in a randomized block design, in a 5 × 2 factorial scheme, referring to five doses of hydrogel (0.0, 0.5, 1.0, 1.5 and 2.0 g dm−3 of soil) in soil without and with mulching from signal grass (Brachiaria decumbens L.). The variables analyzed were chlorophyll indices, fluorescence (initial, maximum and variable) and gas exchange. The total chlorophyll index was increased with the application of 1.5 g dm−3 of hydrogel and the use of mulching; when applying hydrogel doses of 2.0 g dm−3 the photosynthetic rate of yellow passion fruit plants increased, whereas their transpiration rate increased with the use of mulching and doses of hydrogel; as a consequence, there was a reduction in water use efficiency.

ABSTRACT The yellow passion fruit is grown under different edaphoclimatic conditions. Irrigation standardizes and increases the development and productivity of the plants. The objective of this study was to evaluate the physiological and productive aspects of yellow passion fruit with application of hydroabsorbent polymer at different irrigation depths. The experimental design was in randomized blocks in a 2 × 5 factorial arrangement. The treatments were soil with and without polymer and five dephts of irrigation (60 to 100% of crop evapotranspiration). Initial, maximum, and variable chlorophyll fluorescence, physiology (photosynthetic rate, internal carbon concentration, transpiration, stomatal conductance, water use efficiency, and instantaneous carboxylation efficiency) and production of yellow passion fruit were the variables analyzed. The hydrogel probably retained water in its structure, reducing the ability to dissipate excess energy. Setting the irrigation depth at an estimated 82% of crop evapotranspiration increased photosynthetic rate, stomatal conductance, and water use efficiency of yellow passion fruit plants. Maximum yield was 17.2 t ha-1 in irrigated plants at 100% evapotranspiration (ETc) in soil without hydrogel.

RESUMO A goiabeira é uma frutífera cultivada mundialmente, destacando-se pela grande aceitação no mercado consumidor. Entretanto, para que a cultura explore o seu máximo potencial produtivo e mantenha a qualidade dos frutos, é necessária a adequada adubação mineral para elevar a disponibilidade de nutrientes no solo e aumentar sua absorção pelas plantas. Objetivou-se, com este trabalho, avaliar os efeitos da adubação com doses de potássio, na presença e na ausência de cálcio, no estado nutricional e na produção da goiabeira 'Paluma'. O experimento foi desenvolvido de agosto de 2015 a maio de 2016, no município de Remígio, Paraíba. As variáveis analisadas foram: teores foliares de macro e de micronutrientes, número de frutos por planta, massa média de frutos, produção de frutos por planta e produtividade. As plantas da goiabeira estavam adequadamente supridas em nitrogênio, fósforo, potássio, cálcio, magnésio, boro, ferro, manganês e deficientes em enxofre, cobre e zinco. A adubação com cálcio incrementou os teores foliares de P, K, Ca, S, B, Mn e Zn e reduziu o número de frutos por planta e a produtividade da goiabeira 'Paluma'. A adubação potássica sem adição de cálcio, nas doses entre 101 e 143 g planta-1 ano-1 de K2O, aos 16 meses de idade, proporcionou a maior produtividade da goiabeira 'Paluma'.

ABSTRACT The guava is a fruit cultivated worldwide, distinguished by the great acceptance in the consumer market. However, so that the crop exploits its maximum productive potential and maintains the quality of the fruits it is necessary an adequate mineral fertilization to raise the availability of nutrients in the soil and to increase the absorption by plants. The objective of the work was to evaluate the effects of fertilization with potassium doses, in the presence and absence of calcium, on the nutritional status and on the production of 'Paluma' guava. The experiment was carried out from August 2015 to May 2016, in the municipality of Remígio-PB, Brazil. The variables analyzed were: macro and micronutrient leaf contents, number of fruits per plant, average fruit mass, fruit yield per plant and productivity. Guava plants were adequately supplied with nitrogen, phosphorus, potassium, calcium, magnesium, boron, iron and manganese, and deficient in sulfur, copper and zinc. Calcium fertilization increased the leaf content of P, K, Ca, S, B, Mn and Zn, but reduced the number of fruits per plant and the yield of 'Paluma' guava. Potassium fertilization without calcium addition at doses between 101 and 143 g plant-1 year-1 K2O at 16 months of age provides the highest productivity of 'Paluma' guava.

RESUMEN El umbuzeiro (Spondias tuberosa Arr. Cam.) es un árbol frutal originario del bioma Caatinga con gran aceptación en el mercado para consumo in natura o productos industrializados. Debido a esto, su cultivo ha adquirido gran importancia para la región del Nordeste brasileño. El objetivo fue evaluar el crecimiento, temperatura del sustrato e índices de clorofila en plántulas de umbuzeiro en niveles de compuestos orgánicos en el sustrato y aplicación foliar de fertilizante foliar orgánico (EcoLife®). El delineamiento experimental utilizado fue en bloques al azar, con arreglo factorial de 5x2, con cuatro repeticiones y tres plantas por unidad experimental. Los factores corresponden a las proporciones de compuesto orgánico a los sustratos (0, 25, 50, 75 y 100%) en el sustrato con y sin aplicación foliar de fertilizante foliar orgánico a 1%. El crecimiento, área foliar e índices de clorofila de plántulas de umbuzeiro fue mayor en los tratamientos con compuesto orgánico y aplicación foliar de fertilizante orgánico.

ABSTRACT The umbuzeiro (Spondias tuberosa Arr. Cam.) is a fruit tree originating from the Caatinga biome that enjoys high acceptance in the market for in natura consumption or industrialized products; as a result, its cultivation has become of great importance for the region of Northeast Brazil. The objective was to evaluate growth, substrate temperature and chlorophyll indices in umbuzeiro seedlings at organic substrate levels and with organic foliar fertilizer (EcoLife®) applications. The experimental design was a randomized block with a factorial arrangement of 5x2, with four replicates and three plants per experiment unit. The factors corresponded to the proportions of the organic compost to the substrates (0, 25, 50, 75 and 100%), with and without foliar applications of 1% organic foliar fertilizer. The growth, leaf area and chlorophyll indices of the umbuzeiro seedlings were higher in the treatments with organic compost and foliar applications of organic foliar fertilizer.

ABSTRACT Guava is a perennial fruit, highly preferred by the Brazilian consumer and in increasing commercial exploitation in almost all the national territory. The most required nutrients are nitrogen, followed by potassium and calcium with great participation in the growth and physiology of guava. The objective of this study was to evaluate the effects of potassium doses in the soil without and with calcium in the physiology of Paluma guava plants. The experiment was carried out in a randomized complete block design in a 5 × 2 factorial arrangement, with K2O of 0, 45, 90, 135 and 180 g plant-1 year-1, without and with 120 g plant-1 year-1 calcium from calcium nitrate. The variables analyzed were chlorophyll indices (a, b and total), chlorophyll fluorescence and gas exchange. The results were submitted to analysis of variance by the “F” test and the potassium doses were submitted to regression analysis, using SAS© software version 9.3. Guava plants fertilized with only potassium in the soil had higher photosynthetic rate, water use efficiency and instantaneous carboxylation efficiency. The addition of calcium and potassium to the soil increased chlorophyll a, b, total, variable fluorescence, maximum fluorescence, quantum efficiency, stomatal conductance, transpiration rate and internal carbon concentration in guava.

RESUMEN La guayaba es una planta perenne, de alta preferencia por los consumidores brasileños y generando esto un crecimiento operacional en su comercio en casi todo el territorio nacional. Nutricionalmente, los nutrientes más necesarios son nitrógeno, potasio y calcio, con gran participación en el crecimiento y fisiología de la guayaba. Teniendo en cuenta lo anterior, el objetivo fue evaluar los efectos de dosis de potasio en el suelo con y sin calcio en la fisiología de la guayaba con la variedad Paluma. El experimento se realizó en un bloque completamente aleatorizado con arreglo factorial 5 × 2, relativo al suelo con dosis de K2O de 0, 45, 90, 135 y 180 g planta-1 año-1 y sin y con 120 g planta-1 año-1 de calcio derivado del nitrato de calcio. Las variables analizadas fueron las tasas de clorofila (a, b, y total) fluorescencia de la clorofila y el intercambio gaseoso. Los resultados fueron sometidos a la prueba por análisis de varianza “F” y las doses de potasio fueron sometidos a análisis de regresión, utilizando el software SAS versión 9.3 ©. Las plantas de guayaba fertilizados solamente con el potasio en el suelo, mostraron una mayor tasa de fotosíntesis, el uso eficiente del agua y la eficiencia instantánea de carboxilación. La adición de calcio y potasio en el suelo aumentó los índices de clorofila a, b, total, fluorescencia variable, el máximo rendimiento cuántico de fluorescencia, conductancia estomática, tasa de transpiración e concentración interna de carbono en la planta de guayaba.