ABSTRACT Inadequate management of the irrigation system has compromised yield and favoured the degradation and waste of water resources. To ensure efficient irrigation management, providing yield increases, sustainability in the use of water resources and reduction of production costs, studies about the water demand of coconut palms are needed. The objective of this study was to determine the energy partition, crop evapotranspiration (ETc), and the simple crop coefficients (Kc) of the green dwarf coconut palms in Santa Izabel do Pará, Pará, Brazil. The experiment was carried out in a coconut plantation at Reunidas Sococo Farm, with an area of approximately 7 ha in a triangular spacing of 7.5 × 7.5 m, during 2020 and 2021. The ETc was determined by the Bowen ratio method, with measurements of temperature and relative humidity at two levels above the crop canopy and reference evapotranspiration (ETo) by the FAO Penman-Monteith method, using data from the National Institute of Meteorology. The Kc was determined by the ratio between ETc and ETo. The total water demand of the coconut palm was 489 (2020) and 480 mm (2021), with a daily average of 4.21 (2020) and 4.14 mm (2021) for the dry season. The mean value of Kc was 1.06 (± 0.12). Evapotranspiration was driven mainly by energy availability, associated with a control of atmospheric demand on Kc values, suggesting a possible influence of coconut trees on Kc values even under good water availability and small variability in vegetation cover. increases costs needed partition ETc, , (ETc) (Kc Pará Brazil Farm 75 5 7. m 202 2021 method ETo (ETo PenmanMonteith Penman Monteith Meteorology 48 (2020 2021, 421 4 21 4.2 414 14 4.1 (2021 season 106 1 06 1.0 ± ( 0.12. 012 0.12 . 0 12 0.12) cover (ETc 20 (202 42 2 4. 41 10 1. 01 0.1 (20 0. (2

ABSTRACT: The growing demand for coconut water has led to the expansion of irrigated green dwarf coconut cultivation; however, the inefficient use of water has contributed to the degradation and waste of water resources, making fundamental studies aiming to optimize the use of water. The objective of this study was to determine the physical productivity and water productivity of green dwarf coconut palms under the climatic conditions of Santa Izabel do Pará, eastern Amazonia, Brazil. The experiment was carried out from 2020 to 2021, in a green dwarf coconut plantation spaced 7.5 m x 7.5 m in a triangle, at Fazenda Reunidas Sococo, with an area of approximately 7 ha. Water productivity (WP) was determined both in terms of fruit production (WPf) and coconut water production (WPca), through the relationship of fruit productivity (fruit biomass and water volume) with accumulated evapotranspiration. The dwarf coconut tree presented a total production of 105 and 186 fruits plant-1 and 37 and 62 L plant-1 of coconut water in the years 2020 and 2021. The largest volumes of water and the highest weights occurred during the wettest season. WPf was of 1.87 fruits m-3 (2020) and 2.94 fruits m-3 (2021) and WPca 0.66 L m-3 (2020) and 0.98 L m-3 (2021). ABSTRACT cultivation however resources Pará Amazonia Brazil 202 2021 75 5 7. triangle Sococo ha WP (WP (WPf WPca, , (WPca) volume evapotranspiration 10 18 plant1 plant 1 plant- 3 6 season 187 87 1.8 m3 m- (2020 294 2 94 2.9 (2021 066 0 66 0.6 098 98 0.9 . 20 (WPca 8 1. (202 29 9 2. 06 0. 09 (20 (2 (

RESUMO: A crescente demanda por água de coco tem ocasionado a expansão do cultivo de coqueiro-anão-verde irrigado, no entanto, o uso ineficiente da água tem contribuído com a degradação e desperdício dos recursos hídricos, tornando fundamental estudos que visem otimizar o uso da água. Objetivou-se determinar a produtividade física e a produtividade da água do coqueiro-anão-verde, nas condições climáticas de Santa Izabel do Pará, leste da Amazônia, Brasil. O experimento foi realizado no período de 2020 a 2021, em um plantio de coqueiro-anão-verde em espaçamento 7,5 m x 7,5 m em triângulo, na Fazenda Reunidas Sococo, apresentando uma área de aproximadamente 7 ha. A produtividade da água (PA) foi determinada tanto em termos de produção de frutos (PAf) como de produção de água de coco (PAac), através da relação da produtividade de frutos (biomassa do fruto e volume de água) com a evapotranspiração acumulada. O coqueiro-anão apresentou uma produção total de 105 e de 186 frutos planta-1 e de 37 e de 62 L planta-1 de água de coco nos anos de 2020 e 2021. A evapotranspiração total foi de 56,2 m³ (2020) e 53,2 m-3 (2021). A PAf foi de 1,87 frutos m-3 (2020) e 2,94 frutos m-3 (2021) e a PAac de 0,66 L m-3 (2020) e 0,98 L m-3 (2021). RESUMO coqueiroanãoverde coqueiro anão verde irrigado entanto hídricos Objetivouse Objetivou se coqueiroanãoverde, verde, Pará Amazônia Brasil 202 2021 75 5 7, triângulo Sococo ha PA (PA (PAf PAac, , (PAac) biomassa acumulada coqueiroanão 10 18 planta1 planta 1 planta- 3 6 562 56 2 56, (2020 532 53 53, m3 m- . 187 87 1,8 294 94 2,9 (2021 066 0 66 0,6 098 98 0,9 20 (PAac (202 8 1, 29 9 2, 06 0, 09 (20 (2 (

RESUMO O feijão-caupi é uma cultura de grande relevância socioeconômica para as populações do Norte e Nordeste do país, e seu baixo rendimento está comumente relacionado a estresses ambientais, em especial ao hídrico. O objetivo deste estudo foi avaliar o índice de estresse hídrico do feijão-caupi da cultivar BR3 -Tracuateua, submetido a diferentes níveis de irrigação (100, 50, 25 e 0% da ETc) em três estádios fenológicos reprodutivos (R7, R8 e R9), em Castanhal-PA, Brasil. O desenho experimental foi em blocos casualizados, com seis repetições e quatro tratamentos correspondentes a 100, 50, 25 e 0% de reposição diária da evapotranspiração da cultura, durante o período reprodutivo, por meio de um sistema de irrigação. As leituras de temperatura da superfície foram feitas com termômetro infravermelho, durante a fase reprodutiva. As menores diferenças absolutas de temperatura entre o dossel e o ar ocorreram nas fases R7 e R8. Os maiores valores de índice de estresse hídrico (IEHD) foram verificados quando a planta estava sob déficit hídrico, independente dos estádios fenológicos. O efeito do déficit hídrico proporcionou redução na condutância estomática de 58,82% (R7), 83,57% (R8) e 84,87% (R9), transpiração foliar de 45,97% (R7), 64,21% (R8) e 65,90% (R9) e na taxa fotossintética líquida de 40,75% (R7), 66,92% (R8) e 74% (R9). O IEHD variou com a disponibilidade de água, apresentando o maior valor (0,75) no tratamento sem irrigação, no estádio R8. O IEHD se mostrou como bom indicador do status hídrico da planta.

ABSTRACT Cowpea is a crop of great socioeconomic relevance for the populations of the North and Northeast of the country, and its low yield is commonly related to environmental stresses, especially water. The objective of this study was to evaluate the water stress index of cowpea, cultivar BR3 - Tracuateua, subjected to different irrigation levels (100, 50, 25 and 0% of ETc) in three reproductive phenological stages (R7, R8 and R9) in Castanhal-PA, Brazil. The experimental design was in randomized blocks, with six replications and four treatments corresponding to 100, 50, 25 and 0% of daily replacement of crop evapotranspiration, during the reproductive period, through an irrigation system. The surface temperature readings were made with infrared thermometer, during the reproductive stage. The smallest absolute temperature differences between canopy and air occurred in stages R7 and R8. The highest values of water stress index (CWSI) were verified when the plant was under water deficit, regardless of phenological stages. The effect of water deficit caused reductions in stomatal conductance of 58.82% (R7), 83.57% (R8) and 84.87% (R9), in leaf transpiration of 45.97% (R7), 64.21% (R8) and 65.90% (R9) and in the net photosynthetic rate of 40.75% (R7), 66.92% (R8) and 74% (R9). The CWSI varied with the availability of water, showing the highest value (0.75) in the treatment without irrigation, in the R8 stage. The CWSI proved to be a good indicator of the water status of the plant.