Carlos Henrique Carvalho de Sousa

The carnauba palm trees in the Caatinga ecosystem, in Northeast Brazil, have been impacted by invasive species, particularly in areas subject to flooding. This study aimed to evaluate morphological, physiological, and nutritional responses of Copernicia prunifera (native) and Cryptostegia madagascariensis (invasive) seedlings exposed to flooding stress. The experiment was conducted in a randomized complete block design, with a split-plot arrangement and five replicates. The treatments were formed by two species and five periods of flood stress (0, 8, 12, 16, and 20 days). Flooding significantly reduced shoot dry mass in both species; however, the reduction was more pronounced in the invasive species (27%) compared to the native palm (20%). The invasive species showed strong use of resources, with higher values for leaf mineral nutrient, net photosynthesis, growth rate, and leaf area, regardless of the water regime. Under flooding, the invasive species produced adventitious roots, and the net photosynthetic rate was less impacted, despite greater sodium accumulation in the leaves. The results indicate that the characteristics of C. prunifera, such as slow growth rate, low specific leaf area, and morphological adaptations of the root system, may ensure greater stability in net carbon assimilation in the whole plant under flooding. However, the rapid growth and high absorption of soil resources of C. madagascariensis pose a significant threat to the establishment of C. prunifera seedlings, directly jeopardizing the long-term renewal of carnauba palm groves in the Caatinga ecosystem.

One of the techniques developed for the reclamation and incorporation of areas affected by salinity and sodicity is the implementation of subsurface drainage systems combinedwith proper irrigation management, aiming to improve production conditions. This research evaluated the hydraulic performance of a subsurface drainage system, soil water transmission properties, soil chemical attributes, and the profitability of dwarf coconut cultivation in a family farming area that has been undergoingsaline-sodic soil reclamation for 13 years.The research was conducted during the 2023 growing season in the Brazilian semi-arid region, within the Curu Pentecoste Irrigation Project, Ceará. The research results showed that the groundwater flow network highlighted the central region of the area as having higher total potential values, thus functioning as a groundwater divide. The water table drawdown profiles reflect the low water transmission capacityin the soil. The soil chemical attributes indicate that salinity and sodicity levels remain virtually unchangedafter the saline-sodic soil reclamation process.Thewater source used for irrigation poses no risk to the soil or the coconut crop, with the subsurface drainage system playing a vital role in salt removal. The 0.4-hectare pilot area allows the smallholder farmer to reach the level of social reproduction, which is only made possible through financing and the absence of intermediaries in the commercialization process.

The objective of this work was to evaluate the effect of the application of different doses of hydrogel and irrigation levels on the morphophysiological and productive behavior of a bell pepper cultivar, in a protected environment. Four doses of hydrogel (0.0, 0.6, 1.2, and, 2.4 g per plant) and four irrigation levels (50, 75, 100, and, 125%) were used, on the basis of the daily evapotranspiration of a bell pepper crop grown in a sandy soil. Height, stem diameter, and leaf area were measured at 70 and 100 days. At the end of the experiment, bell pepper yield and water use efficiency were estimated. Hydrogel associated with irrigation increases leaf area, productivity, and irrigation-water use efficiency. The applied water deficit (132.8 and 199.26 mm), associated with the hydrogel doses, does not affect the plants morphologically.

Brazil has significant potential for floodplain areas which are suitable for cultivation after the rainy season, with water supply from the water table. Short-cycle crops with shallow root systems are more suitable for these conditions. On this subject, the objective of this study was to determine the responses of the lettuce crop to rising damp rates and water table depth levels. The variables of production, gas exchange, and SEW₃₀ values (sum of excess water above 0.30 m depth) were analyzed. A physical model of seven drainage lysimeters was used; in six, the only water supply occurred by capillary rise from the water table (0.10; 0.15; 0.20; 0.25; 0.30 and 0.35 m depth) and, in the remaining lysimeter, irrigation was performed with no water table. The water table level maintained at 0.20 m from the soil surface was able to supply the water demanded by a sandy soil. The factor-product ratio indicates this depth as the most viable option in terms of crop response. Among the analyzed cultivars and under conditions of excess water in the soil, preference should be given to the establishment of the Gloriosa cultivar, for higher yields.

O VALOR DA ÁGUA NO SISTEMA DE PRODUÇÃO DO MELÃO FERTIRRIGADO MANOEL VALNIR JÚNIOR1; ALDÊNIA MENDES MASCENA DE ALMEIDA2; VALDELÂNIA RIPARDO NASCIMENTO3; MARIA JOSIELY RODRIGUES BRITO4; CLAYTON MOURA DE CARVALHO5 E CARLOS HENRIQUE CARVALHO DE SOUSA6 1 Doutor, Professor, Instituto Federal de Educação, Ciência e Tecnologia do Ceará – IFCE, Campus Sobral, Av. Dr. Guarani, 317 - Derby Clube, Sobral - CE, 62042-030, e-mail: valnir@ifce.edu.br 2 Doutora, Pesquisadora Bolsista, Fundação Cearense de Apoio ao Desenvolvimento Científico e Tecnológico – FUNCAP, Av. Dr. Guarani, 317 - Derby Clube, Sobral - CE, 62042-030, e-mail: ald_m_m@hotmail.com 3 Discente em Tecnologia de Irrigação e Drenagem, Instituto Federal de Educação, Ciência e Tecnologia do Ceará – IFCE, Campus Sobral, Av. Dr. Guarani, 317 - Derby Clube, Sobral - CE, 62042-030, e-mail: valdelaniaripardo83@gmail.com 4 Mestranda em Engenharia Agrícola, Universidade Federal do Ceará – UFC, Centro de Ciências Agrárias - CCA/UFC, Bloco 804, s/n - Pici, Fortaleza - CE, 60455-760, e-mail: josielyrodriguesedif@gmail.com 5 Doutor, Pesquisador Bolsista, Fundação Cearense de Apoio ao Desenvolvimento Científico e Tecnológico – FUNCAP, Av. Dr. Guarani, 317 - Derby Clube, Sobral - CE, 62042-030, e-mail: carvalho_cmc@yahoo.com.br 6 Doutor, Professor, Faculdade Ieducare - FIED, R. Cons. João Lourenço, n 406 - Centro, Tianguá - CE, 62320-000 e-mail: sousaibiapina@gmail.com 1 RESUMO O trabalho tem por objetivo avaliar o valor da água no sistema de produção do melão em diferentes manejos de irrigação. O experimento foi realizado em um lote localizado no DIBAU, no qual todos os tratos culturais foram iguais diferindo apenas quanto ao uso da água. Os manejos de irrigação avaliados foram dois, M1 e M2 comandados pelo sistema Ômega que utiliza a evaporação do tanque Classe A, que adotam kt igual a 1,0 e 0,75, respectivamente e o M3 por uma planilha com esquema de irrigação usada pelos produtores locais. O custo total (CT) de produção foi em média de R$ 27.897,41 ha-1, com variação de R$ 276,06 entre os manejos, embora o M1 tenha utilizado menos da metade da água do M3. Os custos fixos, com insumos e mão de obra, representam mais de 90% do custo total. Já os custos que envolvem a irrigação (água + energia) representaram de 1 a 2% do CT entre os tratamentos. Conclui-se que o sistema de produção requer um considerável investimento para cobrir os custos de produção e que embora a água seja um recurso essencial aos sistemas irrigados, esta tem pouca expressividade sobre o CT, independente dá quantidade de água aplicada. Palavras-chave: Manejo de irrigação, Cucumis melo L., Custo de produção. VALNIR JÚNIOR, M; ALMEIDA, A. M. M.; NASCIMENTO, V. R.; BRITO, M. J. R.; CARVALHO, C. M.; SOUSA, C. H. C. THE VALUE OF WATER IN THE FERTIRRIGATED MELON PRODUCTION SYSTEM 2 ABSTRACT The aim of this work was to evaluate the value of water in melon production systems under different irrigation management practices. The experiment was carried out on a plot located in DIBAU, in which all the culture treatments were the same and differed only in terms of water use. Two irrigation systems, M1 and M2, controlled by the Omega system, which uses evaporation from the Class A tank and adopts kt values equal to 1.0 and 0.75, respectively, were evaluated, and M3 was controlled by a spreadsheet with an irrigation scheme used by local producers. The total cost (CT) of production averaged R$ 27,897.41 ha -1, with a variation of R$ 276.06 between management practices, although M1 used less than half the water of M3. Fixed costs, with inputs and labor, represent more than 90% of the total cost. The costs of irrigation (water + energy) represented 1 to 2% of the total costs of the CT treatment. It is concluded that the production system requires a considerable investment to cover production costs and that although water is an essential resource for irrigated systems, it has little influence on CT, regardless of the amount of water applied. Keywords: Irrigation management, Cucumis melo L., Production cost.

There is no consensus on how much N can be applied to plants under salt stress. In our research we tested the hypothesis that such response depends on salt tolerance of the plant species. So, this study aimed to evaluate the uses and losses of N by cotton (salt-tolerant) and maize (moderately salt-sensitive) irrigated with waters of different electrical conductivity (0.5, 2.0, 4.0, and 6.0 dS m⁻¹) and fertilized with nitrogen (60, 100, and 140% of the recommended dose for each crop). We found that nitrogen doses beyond the recommended values exacerbated the negative effects of salinity on growth and photosynthetic rates, especially in maize plants growing under moderate to high salinity. N rates over the recommended dose did not increase leaf nitrogenous compounds, believed to attenuate the negative impacts of salt stress. Our results indicate that the responses to additional nitrogen fertilization depend on crop salt tolerance and on the level of saline stress imposed. Increasing N rates beyond crop needs under salinity only increased leaching losses and reduced the nitrogen-use efficiency, indicating that such practice would result in economic losses and environmental N overload, especially when a supplemental dose is applied to a salt-sensitive crop.

Soil drainage is an important technique in the construction of a sports lawn and information about the sensitivity of the crop to excess water influences the design of the project. Assuming that excess water affects the development of the grass and that the indices SEW30 (Sum of Excess Water above 0.30 m depth) and SDI (Stress-Day Index) are sensitive to the variables of development of the crop, the objective was to identify the sensitivity of Bermuda grass to the excess of water. The experimental design was completely randomized with five treatments and four repetitions. The treatments consisted of groundwater elevations: 0 cm d (at the level of the drains - control); 180 cm d (at 0.20 m from the soil surface); 270 cm d (at 0.15 m from the soil surface); 360 cm d (at 0.10 m from the soil surface); and 450 cm d (at 0.05 m from the soil surface), carried out fortnightly, lasting three days. The variables used to test the treatment were root length, photosynthesis rate, dry mass of roots, stolons, rhizomes, culms and leaves and dry mass of grass clippings. Stress caused by excess water near the soil surface reduced root length, dry mass of culms and leaves, and photosynthesis rate; Bermuda grass was more sensitive to excess water in its initial vegetative stage, which occurs until 42 days after planting; and the photosynthesis rate in the treatment with highest stress level decreased by approximately by 2/3 when compared to the condition of no water table.

The objective of this study was to evaluate the influence of irrigation with brackish water on the production of bamboo seedlings (Bambusa vulgaris). The experiment was carried out at the Fazenda Experimental Piroás, in the municipality of Redenção, CE, Brazil (4° 14’ 53” S, 38° 45’ 10” W, and altitude of 230 m), in a completely randomized design with five treatments and six repetitions. The treatments consisted of five irrigation water electrical conductivity (ECw): 0.5 (control); 1.5; 2.5; 3.5 and 4.5 dS m-1. At 120 days after the beginning of the application of the treatments the leaf gas exchange, relative chlorophyll index (RCI), plant height (H), shoot dry matter (SDM), H/SDM ratio, and the concentrations of Na+ and K+ in stems and leaves were evaluated. Salt tolerance indexes were calculated based on SDM, H, photosynthesis rate and RCI. The increase in the ECw reduced leaf gas exchange, and the reduction in the photosynthesis rate was caused by stomatal and non-stomatal effects. The salinity affected negatively the growth and quality of bamboo seedlings, with the greatest effects being with ECw equal to or greater than 2.5 dS m-1. Bamboo seedlings present Na+ retention in the stems and low Na+/K+ ratio in the leaves. Bamboo seedlings are tolerant to salinity up to 1.5 dS m-1, indicating that waters with this salinity can be used for seedling production of this species, without loss of growth and quality.

The objective of this study was to evaluate the growth of forest species under conditions of salinity and water deficit. The experimental design was completely randomized in a triple factorial scheme with four forest species (Neem - Azadirachta indica A. Juss, ‘Aroeira’ - Myracrodruon urundeuva Fr Allemão, ‘Ipê’ - Tabebuia impetiginosa (Mart. ex. DC.) Standl and ‘Sabiá’ - Mimosa caesalpiniifoliaBenth), two salinity levels (1.2 and 8.6 dS m^-1) and two water regimes (with and without water restriction). Plant height, stem diameter, number of leaves, shoot dry matter, root dry matter and total dry matter were measured. For all the studied variables, there was statistical significance for the factors species (A) and salinity (B), individually. However, water deficit (Factor C) and the interaction among factors (A x B x C) did not cause any statistical effect. The 50% reduction in water replacement for the four species studied was not enough to cause significant damage to plant growth, with a mean reduction in dry matter production lower than 10%. It was observed that the tolerance index found varied according to the imposition of the stresses, being caused mainly by salinity. Based on shoot dry matter production, the species Neem behaved as moderately tolerant, while the other species were moderately sensitive to salinity. The applied water deficit was not enough to intensify the effects of the salt stress under the conditions of the present study.