ABSTRACT Tahiti lime is a species of great economic importance worldwide. In Brazil, production is concentrated in the states of São Paulo and Pará, where it is usually grafted onto the Rangpur lime. This study aimed to analyze the effects of different irrigation depths on the fruit yield, phenology, and gas exchange of Tahiti lime trees grafted onto Swingle citrumelo. Irrigation was performed during the first year at four different irrigation depths in a random block design with five blocks and four treatments to maintain the soil matric potential in the following ranges: T1: below -50 kPa, T2: from -30 to -50 kPa, T3: from -10 to -30 kPa, and T4: above -10 kPa. The flowering, carbon assimilation rate (A), stomatal conductance (gs), transpiration (E), and fruit yield were measured. Fruits were harvested earlier in the most irrigated treatment, T4, and the yield increased from 2.22 to 6.89 kg per plant from T1 to T4. The average fruit weight escalated from 78.6 to 96.1 g from T1 to T4, and carbon assimilation increased from 6.89 to 9.51 μmol CO2m-2s-1 from T1 to T4.

RESUMO A lima ácida Tahiti é uma espécie de grande importância econômica em todo o mundo. Em território brasileiro, a produção concentra-se nos estados de São Paulo e Pará, onde geralmente é enxertada em limão-cravo. Este estudo tem como objetivo analisar o efeito de diferentes lâminas de irrigação na produção de frutos, fenologia e trocas gasosas de lima ácida Tahiti enxertada em citrumelo Swingle. A irrigação foi realizada durante o primeiro ano, com quatro lâminas de irrigação diferentes em um delineamento de blocos ao acaso com 5 blocos e 4 tratamentos, para manter o potencial matricial do solo nas seguintes faixas: T1: abaixo de -50 kPa, T2: de -30 a -50 kPa , T3: de -10 a -30 kPa e T4: acima de -10 kPa. Foram medidos florescimento, taxa de assimilação de carbono (A), condutância estomática (gs), transpiração (E) e produção de frutos. Os frutos foram colhidos mais cedo no tratamento mais irrigado, T4, e a produtividade aumentou de 2,22 para 6,89 kg por planta de T1 para T4. O peso médio dos frutos aumentou de 78,6 para 96,1 g de T1 para T4. A assimilação de carbono aumentou de 6,89 para 9,51 μmol CO2 m-2 s-1 de T1 para T4.

Resumo Investiga-se o balanço de radiação e energia sobre um pomar de limão na Amazônia Oriental e como ele se relaciona com as condições ambientais. Foi descoberto que a lima ácida Tahiti com idades entre 6 e 7 anos refletem de 11,0% a 14,5% da radiação de ondas curtas recebidas, e o fluxo de calor latente corresponde a 57,6% e 66,6% do saldo de radiação diária nos períodos secos (agosto a novembro) de 2020 e 2021, respectivamente. O fluxo de calor do solo representa de 1% a 2% do saldo de radiação diário. A evapotranspiração foi muito menor que a evapotranspiração de referência de agosto a novembro em 2019 e 2020. A evapotranspiração aumentou proporcionalmente à evapotranspiração de referência de agosto a novembro de 2021. Esse aumento pode ser explicado pelas condições climáticas, como as chuvas frequentes durante o período seco de 2021, no mesmo período em que a energia para evapotranspiração é maior. Além disso, a alta umidade relativa entre agosto e novembro de 2021 pode ter favorecido a abertura dos estômatos, aumentando a evapotranspiração do pomar. O coeficiente de cultura variou entre 0,74 e 0,84.

Abstract We investigate the balance of radiation and energy over a lime orchard in Eastern Amazon and how it relates to environmental conditions. We found that lime trees aged between 6 and 7 years old reflect 11.0% to 14.5% of incoming shortwave radiation, and the latent heat flux corresponds to 57.6% and 66.6% of the daily net radiation in the dry season (August - November) of 2020, and 2021, respectively. The soil heat flux represents 1% to 2% of the daily net radiation. Evapotranspiration was much lower than the reference evapotranspiration from August to November in 2019 and 2020. Evapotranspiration increased proportionally to the reference evapotranspiration from August to November 2021. This increase may be explained by weather conditions, such as the frequent rainfall during the dry season of 2021, in the same period when the energy for evapotranspiration is higher. Also, the high relative humidity between August and November 2021 may have favored the opening of stomata, increasing the orchard's evapotranspiration. The crop coefficient ranges between 0.74 and 0.84.

ABSTRACT. The use of empirical agrometeorological models that can be adjusted to the climatic conditions of different regions has become increasingly necessary to improve water management in grain-producing municipalities. The aim of this work is to examine the correlation between various reference evapotranspiration (ETo) estimation methods and the standard FAO 56 Penman-Monteith method, as well as to determine correction factors, when necessary, for crop-producing municipalities in the northeast of Pará, during both the rainy and dry seasons. We compared simpler methods of ETo estimation to the FAO 56 Penman-Monteith method. For this purpose, meteorological data from Tracuateua, Bragança, Capitão Poço and Castanhal, provided by the National Institute of Meteorology (INMET), were used. The calibration of equations was performed through linear regression. The accuracy of different estimation methods was examined. The Turc, FAO 24 Blaney-Criddle and regression methods presented the best results for all statistical criteria; the Priestley-Taylor, Makkink and FAO 24 Radiation methods presented excellent results after calibration. The methods of Camargo and Hargreaves-Samani produced the worst results for all the criteria.

RESUMO O objetivo deste trabalho foi estimar o consumo hídrico em pomar de mangueiras durante as suas fases fenológicas, na região nordeste do Estado do Pará. Para isso, foi instalada e instrumentada uma torre micrometeorológica em um pomar de mangueiras cv. Tommy Atkins de 22 anos de idade, com os dados coletados durante o período reprodutivo das safras de 2010/2011, e de 2011/2012. A evapotranspiração atual de cultura foi estimada pelo balanço de energia através da técnica da razão de Bowen. As safras ocorreram em condições meteorológicas distintas, com menor quantidade de chuva na safra 2, tendo como consequência diferenças significativas na razão de Bowen. A evapotranspiração também sofreu influência das condições meteorológicas ocorridas no período. A evapotranspiração atual da cultura variou entre 402,9 e 420 mm, apresentando um consumo médio diário de 3,8 mm na fase floração, de 4,25 mm na fase de queda, de 3,56 mm na fase formação, de 3,0 mm na fase de maturação e de 3,73 mm para toda a fase reprodutiva.

ABSTRACT The aim of this study was to estimate the water consumption in mango orchard during its phenological stages in the northeastern of the State of Pará, Brazil. For this purpose, it was installed and instrumented a micrometeorological tower in a mango orchard, cv. Tommy Atkins, of 22 years old, with data collected during the crops of 2010/2011 and of 2011/2012. The actual crop evapotranspiration was estimated from the energy balance using the Bowen ratio technique. The crops were subjected to different weather conditions, consequently, some differences in the Bowen ration values were observed. The evapotranspiration suffered influences of meteorological conditions during the period. The actual crop evapotranspiration during its reproductive period ranged between 402.9 and 420 mm with a mean daily water consumption of 3.8 mm at flowering, of 4.25 mm at fruit fall, of 3.56 mm at fruit formation, of 3.0 mm at fruit maturation and of 3.73 mm for the whole period.

Crop evapotranspiration (ETc) is essential for irrigation scheduling. The amount of water consumed can be estimated by multiplying the reference evapotranspiration (ET0) by a crop coefficient (Kc); the value of Kc is usually obtained from FAO Paper nr 56. In table grapes (Vitis vinifera L.), Kc are obtained from experiments in vines trained on trellis systems; however in Chile, the most used is the overhead trellis system (parronal). Therefore, the objective was to determine water requirements and Kc values of a table grape orchard cv. Thompson Seedless trained on an overhead trellis system in Calle Larga (32°52’40" S, 70°37’45" W, 795 m a.s.l.), Aconcagua Valley, Chile, using the Eddy covariance method. During the 2008/2009 and 2009/2010 seasons, the instruments required for ET0 and ETc measurement were installed on a 4 m tower above the soil (2 m above vine canopy). The ET0 was estimated according to the FAO Penman-Monteith equation and ETc by the Eddy covariance method. The Kc was obtained by ratio between ETc and ET0. The maximum ETc was 7 mm d-1 and total water consumption was 810 mm. The season maximum Kc value of 1.2 was obtained near harvest during the first season, and 20 d before veraison in the second season. The Kc increased linearly with the percentage of intercepted solar radiation (IRS) by the vine canopy at noon, suggesting that an equation to convert the IRS to Kc is more useful than Kc tabulated according to phenology. The equation obtained in this experiment was Kc = 0.012 IRS - 0.1029, R² = 0.85.

An experiment was carried out to evaluate the effects of different levels of pruning and water application on vegetative growth, yield and berry composition of grapevines (Vitis vinifera L.), located in Pencahue Valley, Maule Region, Chile (35º22' S lat; 71º47' W long), during the 2003-2004 and 2004-2005 growing seasons. The cultivar used was a 10 yr-old Cabernet Sauvignon, drip irrigated and trained on a vertical shoot positioned system. Pruning levels were 12, 18 and 24 buds per plant. Irrigation levels applied were 40, 70 and 100% of real evapotranspiration of the vineyard (ETv) from setting to harvest. Results showed that increasing pruning severity resulted in a decrease in the Ravaz index from 4.3 to 2.9 in the first season, and a severe reduction of yield (between 41 and 53%) in both seasons. Only in the second season, did the reduction in the water application decrease the yield from 3.0 to 1.8 kg pl-1 and increase the total anthocyanin content in berries from 1290 to 1520 mg L-1. There was no significant interaction between pruning and irrigation levels for any of the seasons under evaluation.

Se llevó a cabo un experimento para evaluar el efecto de distintos niveles de poda y reposición hídrica sobre el crecimiento vegetativo, rendimiento y composición de bayas en un viñedo (Vitis vinifera L.) ubicado en el Valle de Pencahue, Región del Maule, Chile (35º22' lat. Sur; 71º47' long. Oeste), durante las temporadas de crecimiento 2003-2004 y 2004-2005. Se usó un cultivar Cabernet Sauvignon de 10 años de edad, regado por goteo y conducido en espaldera vertical simple. Los distintos niveles de poda fueron 12, 18 y 24 yemas por planta. Por otro lado, los niveles de riego consistieron en la reposición del 40, 70 y 100% de la evapotranspiración real de la vid (ETv) aplicado durante el período de cuaja a cosecha. Los resultados mostraron que al incrementar la severidad de poda se obtuvo una disminución del índice de Ravaz desde 4,3 a 2,9 en la primera temporada y una reducción severa del rendimiento (entre un 41 y 53%) en ambas temporadas. Sólo en la segunda temporada, la reducción en la reposición hídrica disminuyo en forma significativa el rendimiento desde 3,0 a 1,8 kg pl-1 e incremento el contenido de antocianas totales (desde 1290 a 1520 mg L-1) en las bayas. En ninguna de las dos temporadas de evaluación se registraron interacciones positivas importantes entre los factores poda y riego.

A study was carried out to evaluate the effect of four levels of water application on the yield and quality of a tomato (Lycopersicon esculentum Mill.) cv. Presto produced in a greenhouse at the Panguilemo Experimental Station, of the University of Talca (35º23´ S lat; 71º W long; 110 m.a.s.l.), during the period August 2000 and January 2001. The irrigation treatments were application of 60 (T1), 100 (T2) and 140% (T3) of the actual evapotranspiration (ETreal) and a control (T4) was the irrigation level that farmers traditionally apply in the region. The results indicated that the largest total yield (180 t ha-1) was obtained by treatment T3, followed by treatment T4. The largest commercial yields were observed in treatments T3 and T4, which corresponded to 129.8 and 120.3 t ha-1, respectively. The diameter and weight of fruit were reduced as the water application decreased, but soluble solids and dry matter increased. The treatment T3 was the best combination of yield and quality of greenhouse tomatoes with a 72% reduction of water application in comparison with T4.

Se realizó una investigación para evaluar el efecto de cuatro láminas de agua sobre el rendimiento y calidad de un cultivo de tomates (Lycopersicon esculentum Mill.) cv. Presto, producido en invernadero en la Estación Experimental Panguilemo de la Universidad de Talca (35º 23’ lat. Sur; 71º 40’ long. Oeste; 110 m.s.n.m), durante los meses de agosto de 2000 a enero de 2001. Los tratamientos de riego correspondieron a una reposición de 60 (T1), 100 (T2) y 140% (T3) de la evapotranspiración real (ETreal) y un testigo (T4) que correspondió a las láminas de agua que los agricultores utilizan tradicionalmente en la zona. Los resultados indicaron que el mayor rendimiento total (180 t ha-1) fue obtenido en el tratamiento T3, seguido por el testigo. Los mayores rendimientos comerciales fueron observados en los tratamientos T3 y T4, los cuales correspondieron a 129,8 y 120,3 t ha-1, respectivamente. El diámetro y peso de los frutos fueron reducidos a medida que se aplicaron cantidades de agua menores; por el contrario, los sólidos solubles y el peso seco fueron aumentados. El tratamiento T3 presento la mejor combinación de rendimiento y calidad para el cultivo de tomate producido en invernadero, con una reducción de un 72% en la aplicación de agua en comparación al tratamiento T4.

A study was performed in three orchards of San Fernando, VI Region, Chile, in order to develop a predictive table of apple size (Malus domestica Borkh.) using a logistical equation, whose main variable was accumulated degree days (GDA). To this end, data were collected on fruit equatorial diameter and air temperature for the 1989/90 and 1992/93 seasons in three apple orchards cv. Granny Smith. Sampling was carried out from 80 GDA until harvest, selecting 5 trees in each orchard, in which 40 fruit/tree were chosen, covering all the size ranges, at a height approximately 1.0 to 2.0 meters about the soil. At harvest, the evaluated fruit was grouped according to four ranges of diameter (63-68, 69-74, 75-80, and 81-86 mm), to develop the logistic growth models as a function of GDA. The results of this study indicated that the implemented models were able to estimate apple sizes with a coefficient of determination (r²), absolute error (Ea) and standard error of estimate (SEE) ranging from 0.91 to 0.94; 5.8 and 6.7%; and 3.0 to 3.6 mm, respectively. Based on these statistical results a predictive table able to predict apple size as a function of GDA was constructed, which presented an Ea of 5% starting at 600 GDA.

Se desarrolló un estudio en tres huertos de la zona de San Fernando, VI Región, Chile, para elaborar una tabla de pronóstico de diámetro de manzanas (Malus domestica Borkh.) utilizando la ecuación logística, cuya variable de entrada fueron los grados días acumulados (GDA). Para ello, se recolectaron datos de diámetro ecuatorial de fruto y temperatura del aire entre las temporadas 1989/90 y 1992/93 en tres huertos de manzanos cv. Granny Smith. El muestreo de frutos se realizó a partir de los 80 GDA y hasta la cosecha, seleccionando en cada huerto 5 árboles, en los cuales se marcaron 40 frutos/árbol, cubriendo todos los rangos de tamaño, a una altura aproximada de 1,0 a 2,0 m desde la superficie del suelo. A la cosecha, los frutos evaluados fueron agrupados según cuatro rangos de diámetro (63-68, 69-74, 75-80 y 81-86 mm) para desarrollar los modelos de crecimiento logístico en función de los GDA. Los resultados de este estudio indican que los modelos implementados presentaron un coeficiente de determinación (r²), error absoluto (Ea) y desviación estándar del error (DEE) que fluctuaron entre 0,91 y 0,94; 5,8 y 6,7%; y 3,0 y 3,6 mm, respectivamente. En base a estos resultados estadísticos se construyó una tabla predictiva de tamaño de manzanas en función de los GDA, que presenta un Ea menor al 5% a partir de los 600 GDA.

A study was carried out from January to July 1997 in a greenhouse at the Panguilemo Experimental Station of the University of Talca, Chile (35°23’ S lat, 71°40’ W long, 110 m.s.n.m) to evaluate the effect of different levels of irrigation water on the yield and quality of tomatoes (Lycopersicon esculentum Mill.) cv. FA-144. The drip irrigation treatments were the application of 70% (T1), 100% (T2) and 150% (T3) of the real crop evapotranspiration (ETreal) and the control was the irrigation level that farmers usually apply in the region. The ETreal was estimated using the evaporation of a modified tray (diameter = 50 cm and depth = 25 cm), whose values were corrected by a local tray coefficient and the tomato crop coefficient. The results indicated that the total yield decreased with lower quantities of water with the highest production being reached by T3 and the control. Furthermore, fruit size was significantly larger with T3 than with the other treatments. Regarding the diameter, average weight and dry matter percentage no significant differences were observed among the treatments. On the other hand, soluble solids and fruit pulp pressure increased significantly with the reduction of water.

Se realizó una investigación en la Estación Experimental Panguilemo de la Universidad de Talca (35°23’ lat. Sur, 71°40’ long. Oeste, 110 m.s.n.m) con el objeto de evaluar el efecto de cuatro láminas de agua sobre el rendimiento y calidad de un cultivo de tomates (Lycopersicon esculentum L.) cv. FA-144, regado por cintas, durante los meses de enero a julio de 1997. Los tratamientos correspondieron a una reposición de 70, 100 y 150% de la evapotranspiración real (ETreal), T1, T2 y T3, respectivamente, y un testigo que correspondió a las láminas de agua que el agricultor utiliza tradicionalmente en la zona. La ETreal del tomate se estimó usando la evaporación de una bandeja modificada (diámetro = 50 cm y altura = 25 cm), cuyos valores fueron corregidos por un coeficiente de bandeja local y el coeficiente de cultivo del tomate. Los resultados de este estudio indicaron que el rendimiento total y comercial disminuyó a medida que se aplicaron cantidades de agua menores, siendo el testigo y el tratamiento de 150% de la ETreal (T3) los que alcanzaron las mayores producciones totales. Por otra parte, la producción de frutos de calibre extra y primera fue significativamente superior en T3 que en el resto de los tratamientos. En cuanto al diámetro ecuatorial y polar, y peso promedio, no se observaron diferencias significativas entre las distintas láminas de agua evaluadas; similar situación se observó en el porcentaje de materia seca. Por otro lado, los sólidos solubles y presión de pulpa de los frutos aumentaron significativamente con la reducción del agua.