The use of brackish water can cause severe effects and irreversible damage to the growth and physiological indices of agricultural crops. Thus, the agricultural environment emerges as an alternative to mitigate saline stress in tomato hybrids (Solanum lycopersicum L.). This study evaluated the gas exchange and growth of tomato hybrids irrigated with brackish water in different environments. The study was carried out in Aratuba, Ceará, Brazil. The experimental design was a randomized block design with split-split plots. The main plots consisted of two environments (protected environment and full sun); the subplots consisted of five levels of irrigation water electrical conductivity (ECw) (1.0, 1.7, 2.4, 3.1, and 3.8 dS m-1) and the sub-subplots consisted of two tomato hybrids (Itaipava and BS DI0014), with five replicates. Salt stress reduced CO2 assimilation rate and instantaneous carboxylation efficiency rates more intensely in the full sun environment, while the use of low electrical conductivity in the protected environment promoted greater stomatal conductance in tomato hybrids. The BS DI0014 hybrid was more tolerant to salt stress in terms of transpiration in the protected environment and in full sun than the Itaipava F1 hybrid. The Itaipava F1 and BS DI0014 hybrids grown in a protected environment had higher internal CO2 concentrations. Keywords: protected cultivation, salinity, Solanum lycopersicum L.

The use of brackish water associated with intercropping is an approach that can enhance the resilience of agriculture in semi-arid regions. Therefore, this study aimed to evaluate irrigation with brackish water as a strategy to ensure the sustainability of forage production in isolated and intercropped systems. The study was conducted under a hot semi-arid climate in the years 2022, 2023, and 2024. Two water scenarios (rainfed and irrigated) and four production systems with forage cactus-FC (Opuntia stricta) and butterfly pea-BP (Clitória ternatea) were evaluated: FC—forage cactus, BP—butterfly pea, FC+1BP—forage cactus intercropped with one row of BP, and FC+2BP—forage cactus intercropped with two rows of BP. Butterfly pea received supplemental irrigation from February to August, while the forage cactus was irrigated during the dry season (July to December). Our results showed that the strategic management of irrigation with brackish water optimizes biomass and protein production in crops adapted to the tropical semi-arid region. The FC+1BP intercropping system (forage palm with a row of butterfly pea) proved to be the most advantageous, mainly in terms of crude protein production and water use efficiency, proving to be an alternative for forage production and food security for livestock in the tropical semi-arid region.

Deficit irrigation strategies are essential for agricultural production in water-scarce regions. However, this study addresses the critical knowledge gap regarding the combined use of this technique with mulching to enhance water use efficiency in crops, such as Capsicum chinense (commonly known as “pimenta de cheiro”). Such studies should also address the need for information on economic and yield-related aspects, which are critical for decision-making by farmers. This study aimed to determine the physiological, production, and economic parameters of Capsicum chinense under partial root drying and deficit irrigation, with and without soil mulching. The study was conducted from 2018 to 2019 in the semiarid region of Ceará State, Brazil. The experiment was arranged in a randomized block split-plot design with four replications. The primary treatment consisted of the following irrigation strategies: full irrigation (FI), deficit irrigation with 70% FI (DI70), deficit irrigation with 40% FI (DI40), and partial root drying zone irrigated with 70% (PRD70) and 40% (PRD40) FI treatment, alternating (every 7 days) the dry and wet sides of the root zone. Subplot treatments consisted of two mulch rates, 0 and 21 t·ha−1. Plants cultivated in mulched soil had a substantially higher water productivity in both seasons, being 26.05% higher (6.29 kg·m−3) in 2018 and 26.17% higher (4.82 kg·m−3) in 2019 than unmulched treatments. The results indicated that FI improved physiological, productive, and economic performance (net present value of 71,486.96 € ha−1). However, under conditions of water shortage, combining DI70 or PRD70 strategies with mulching emerges as a financially viable alternative (net present value of 60,284.99 and 64,598.57 € ha−1, respectively). Irrigation strategies that reduce the volume of applied water by 30%, such as DI70 and PRD70, when combined with mulching, can be effectively used for Capsicum chinense cultivation in semiarid regions.

Sesame (Sesamum indicum L.) cv. BRS Anahí is a promising crop for agricultural diversification in the Brazilian semi-arid region, although saline irrigation can limit its development and productivity. The objective of this study was to evaluate the physiological and productive responses of sesame irrigated with brackish water under different fertilization treatments. The experiment was conducted in a greenhouse at the Federal University of Ceará, using a completely randomized design in a 4 × 2 factorial scheme, with four replications. These corresponded to four fertilization treatments (F1: HomeBiogas liquid biofertilizer from CAGECE; F2: HomeBiogas from food waste; F3: shrimp biofertilizer; and F4: mineral fertilization—NPK) and two irrigation water salinity levels (0.8 and 3.0 dS m−1). Irrigation with 3.0 dS m−1 significantly reduced the analyzed variables; however, the intensity of these effects varied according to the fertilization treatment. Treatment F1 promoted greater physiological activity under saline conditions, partially mitigating saline stress. At low salinity, treatments F1 and F3 showed productivity performance similar to F4, while at high salinity, F3 was less effective. The results highlight the potential of the selected biofertilizers to improve sesame performance under saline irrigation.

Extract of Fava d’Anta (Dimorphandra mollis Benth) alleviates the deleterious effects of saline water. This study evaluates gas exchange and the initial growth of maize under saline stress and the use of Fava d’Anta extract. The experimental design was a randomized block design in a 5 × 4 factorial scheme with three replications. The first factor consisted of five levels of electrical conductivity of irrigation water (ECw = 1.0, 1.5, 3.0, 4.0, and 5.0 dS m⁻¹), and the second factor consisted of four foliar application frequencies of Fava d’Anta extract: F1 – no application; F2 – application every 10 days; F3 – application every 5 days; and F4 – daily application. Increasing salinity of the irrigation water reduced plant height, stem diameter, photosynthesis, stomatal conductance, transpiration, shoot dry mass, and root dry mass. The different application frequencies of the Fava d’Anta extract influenced plant height, photosynthesis, and shoot dry mass. Interactive effects were observed, with better results for the combinations S2 × F2, S3 × F2, and S3 × F2 for photosynthesis, stomatal conductance, and transpiration, respectively. These findings indicate that foliar application of Fava d’Anta extract every 10 days during the vegetative stage has the potential to mitigate the deleterious effects of saline water on maize. Daily application of the extract mitigated the harmful effects of irrigation water with EC of 4.0 dS m⁻¹ on gas exchange parameters. Keywords: Dimorphandra mollis Benth, salinity, Zea mays L.

ECOFISIOLOGIA DA FIGUEIRA 'ROXO DE VALINHOS' NO SEMIÁRIDO: INFLUÊNCIA DE AMBIENTE E ADUBAÇÃO Natanael Santiago Pereira1, Luís Clênio Jário Moreira2, MARLOS ALVES BEZERRA3, Claudivan Feitosa de Lacerda4 1 Instituto Federal do Ceará (IFCE) campus Limoeiro do Norte, rua Estevão Remígio de Freitas, 1145, Monsenhor Otávio, CEP: 62934-006, Limoeiro do Norte, CE, Brasil, ORCID: 0000-0001-7133-4639, Email: natanaelsan@gmail.com. 2 Instituto Federal do Ceará (IFCE) campus Limoeiro do Norte, rua Estevão Remígio de Freitas, 1145, Monsenhor Otávio, CEP: 62934-006, Limoeiro do Norte, CE, Brasil, ORCID: 0000-0001-9918-9744, Email: cleniojario@ifce.edu.br. 3 Empresa Brasileira de Pesquisa Agropecuária - Embrapa Agroindústria Tropical, Rua Dra. Sara Mesquita, 2.270, Planalto do Pici, CEP 60511-110, Fortaleza, CE, Brasil, ORCID: 0000-0002-8622-0770, Email: marlos.bezerra@embrapa.br. 4 Departamento de Engenharia Agrícola, Centro de Ciências Agrárias, Universidade Federal do Ceará (UFC), Campus do PICI, CEP 60440-554, Fortaleza, CE, Brasil, ORCID: 0000-0002-5324-8195, Email: cfeitosa@ufc.br. RESUMO: O objetivo deste trabalho foi avaliar a influência do ambiente de cultivo e de doses de adubação nas características ecofisiológicas da figueira 'Roxo de Valinhos', cultivada na Chapada do Apodi, no semiárido cearense. O experimento utilizou o delineamento em blocos ao acaso, em esquema de faixas com parcelas subdivididas, com quatro repetições. Foram testados dois ambientes (A1 – 50% de sombreamento e A2 – pleno sol) e três doses de adubação por cobertura (D1 - 50%, D2 - 100% e D3 - 150%), por meio de fertirrigação. As trocas gasosas foram avaliadas nos períodos da manhã e da tarde. A avaliação matinal foi mais sensível para capturar o efeito da interação ambiente e as doses de adubação. Em ambos os ambientes, a aplicação da maior dose de adubação (D3-150%) levou a menores concentrações internas de CO2 (Ci) e a uma significativa melhoria na eficiência intrínseca do uso da água (A/gs) quando comparada à dose 1 (50%). Menor valor médio da taxa de transpiração (E) foi observado para a maior dose de adubação (D3 – 150%) na avaliação vespertina, a qual foi associada a uma menor condutância estomática (gs) nessa dose, independentemente do ambiente. Palavras-chaves: Ficus carica, cultivo protegido, fertirrigação ECOPHYSIOLOGY OF 'ROXO DE VALINHOS' FIG TREE IN THE SEMI-ARID REGION: INFLUENCE OF ENVIRONMENT AND FERTILIZATION ABSTRACT: The objective of this study was to evaluate the influence of the cultivation environment and fertilization rates on the ecophysiological characteristics of the 'Roxo de Valinhos' fig tree, which is grown in the Chapada do Apodi region, in semiarid Ceará. The experiment used a randomized block design in a strip-plot scheme with subdivided plots and four replications. Two environments were tested (A1 – 50% shading and A2 – full sun), and three top-dressing fertilization rates (D1 - 50%, D2 - 100%, and D3 - 150%) were applied via fertigation. Gas exchange was evaluated during the morning and afternoon periods. The morning assessment was more sensitive in capturing the effect of the interaction between the environment and the fertilization rate. In both environments, the application of the highest fertilization rate (D3-150%) led to lower internal CO2 concentrations (Ci) and a significant improvement in the intrinsic water use efficiency (A/gs) compared with dose 1 (50%). A lower mean value for the transpiration rate (E) was observed for the highest fertilization rate (D3 – 150%) in the afternoon evaluation, which was associated with lower stomatal conductance (gs) at this dose, regardless of the environment. Keywords: Ficus carica, protected cultivation, fertigation

The consumption of healthy food has become increasingly present and eating fresh, quality fruit is part of this trend. Nevertheless, the scarcity of fresh water and the increasing demand for food have been driving the search for more sustainable agricultural practices worldwide. In this context, cultivation with lower-quality water, characterized by a high concentration of salts, emerges as alternative to enhance water use efficiency and ensure food security in regions prone to water scarcity. In this regard, the aim of this work was to use an NMR-based metabolomics approach to investigate the growth and metabolomic profile of yellow melon fruits and leaf cultivated under water salinity conditions (1.5, 2.5, and 4.5 dS m-1). The research was conducted in a protected environment at Embrapa Agroind & uacute;stria Tropical (3 degrees 44 ' S, 38 degrees 33 ' W, altitude 19.5 m, Fortaleza, Ceara, Brazil). Melon plants (yellow type, inodorous group, non-climacteric) were grown in 12 L pots filled with coconut fiber substrate and irrigated using a drip irrigation system. Salinity reduced fruit weight and metabolic activity, but did not significantly alter soluble solids content. Metabolic profile determinate by NMR showed that essential pathways in the leaves produced metabolites for defense, energy maintenance, and cellular integrity, minimizing the impact on fruit composition. Under salinity, hexoses (glucose and fructose) were more efficiently converted into sucrose, indicating that melon plants maintain its essential metabolism in leaves under saline stress, enhancing tolerance. The increased sucrose content in the fruit, important for consumers, is preserved, making melon a viable option for implementation of efficient water use strategies.

Salinity is one of the primary challenges faced by irrigated agriculture in semi-arid regions. This study aimed to investigate the effects of fertilization on the development of cashew seedlings irrigated with water of varying salinity levels. The research was conducted in a protected environment at Embrapa Agroindústria Tropical, Fortaleza, using grafted seedlings of the BRS 189 clone on CCP 06 rootstock. The treatments resulted from the combination of three levels of NPK fertilization (control - without fertilization, 50% less than conventional nutrition, and 100% of conventional nutrition used by the crop), which was incorporated into the substrate before sowing CCP 06, with four salinity levels (ECa of 0.8, 4.0, 7.0, and 10.0 dS m-1) of the irrigation water for the seedlings. Gas exchange, assimilate accumulation, growth, and nutrient content in the leaves, stems, and roots of the seedlings were evaluated 90 days after grafting. The data were subjected to analysis of variance, and when a significant effect was observed, the Tukey test was performed, while quantitative data were subjected to regression analysis. Overall, fertilization levels did not influence seedling growth. Fertilization did not interfere with photosynthate production, which performed better when the seedlings were subjected to a salinity of 7.0 dS m-1. The application of NPK to the substrate resulted in higher levels of nitrogen in the leaves, while phosphorus content decreased, and foliar potassium was not influenced by fertilization.

The different types of coconut palm, tall, dwarf and hybrid, grow best in coastal areas with a humid tropical climate. In these regions, many biotic and abiotic constraints are serious threats that affect the sustainability of coconut production, and these problems are likely to be exacerbated by global climate change. Thus, ecophysiology studies and the search for coconut genotypes tolerant to different environmental constraints are an important focus to help deal with future challenges. This chapter describes the vegetative and reproductive development of the coconut palm and explores the physiological and productive responses of this crop to the main abiotic and biotic constraints, such as salinity, waterlogging, water deficit, temperature stress, nutrient deficiency, diseases and pests. This text highlights the need to improve water- and fertilizer-use efficiency in coconut production systems worldwide to achieve maximum productivity from this permanent crop.

Lawns play a key role in enhancing public spaces, preventing soil erosion, and acting as barriers against dust and sludge. In Brazil, Paspalum notatum is widely cultivated for its adaptability to the country's ecosystems and the availability of native ecotypes. However, soil salinization, a growing ecological concern, can limit lawn growth due to sodium and chloride ion toxicity. This study aimed to identify the most tolerant among five genotypes (Arua & iacute; and Tiriba cultivars, BRA 010006 and BRA 019178 accessions and the commercial species Axonopus fissifolius) subjected to salinity levels (0.5, 1.5, 3.0, 4.5, and 6.0 dS m(-1)). Analyzed variables included Na and Cl contents in plants, growth parameters (leaf and root dry mass and soil coverage), and morphological symptoms. No significant changes in leaf color or damage compromising aesthetics or functionality at salinity levels from 0.5 to 1.5 dS m(-1), with only occasional yellowing or minor scorch. Higher salinity led to leaf burn and yellowing, particularly in accession BRA 010006 and the control. Sodium and chloride contents, especially sodium, was higher in roots than leaves. Accession BRA 019178, followed by cultivars Arua & iacute; and Tiriba, demonstrated moderate tolerance, maintaining satisfactory soil coverage and dry mass across the tested salinity levels. These findings highlight the importance of selecting native turfgrasses with enhanced salt tolerance for landscaping applications in saline-prone areas.

PRODUTIVIDADE E QUALIDADE DOS FRUTOS DE COCO VERDE SOB LÂMINAS DE IRRIGAÇÃO DEFICITÁRIAS AMANDA SORAYA FREITAS CALVET1; KARINE SILVA PIMENTEL VIDAL2, CLINTON GONÇALVES MOREIRA3; FÁBIO RODRIGUES DE MIRANDA4 E MARLOS ALVES BEZERRA5 [1] Doutora em Agronomia/Fitotecnia pela Universidade Federal do Ceará (UFC). Bolsista Embrapa Agroindústria Tropical. Av. Humberto Monte, s/n, Pici, Fortaleza, Ceará, CEP: 60440-593, Brasil; E-mail: amandasmfc@gmail.com. 2 Graduada em Ciências Biológicas, Mestranda em Engenharia Agrícola, Universidade Federal do Ceará (UFC), Av. Humberto Monte, s/n, Pici, Fortaleza, Ceará, CEP: 60440-593, Brasil; E-mail: karine3pimentel@gmail.com. 3 Mestre em Engenharia Agrícola, Universidade Federal do Ceará (UFC), Av. Humberto Monte, s/n, Pici, Fortaleza - Ceará, CEP: 60440-593, Fortaleza, Ceará, Brasil; E-mail: clinton-paraipaba@hotmail.com. 4 Doutor em Irrigação e Drenagem, Pesquisador, Embrapa Agroindústria Tropical, Fortaleza, Ceará, Rua Pernambuco, 2270, Pici, Fortaleza, Ceará, CEP: 60511-110, Brasil; E-mail: fabio.miranda@embrapa.br. 5 Doutor em Fisiologia Vegetal, Pesquisador, Embrapa Agroindústria Tropical, Fortaleza, Ceará, Rua Pernambuco, 2270, Pici, Fortaleza, Ceará, CEP: 60511-110, Brasil; E-mail: marlos.bezerra@embrapa.br. 1 RESUMO A demanda por coco verde tem aumentado bastante nos últimos tempos e como consequência a área cultivada com coqueiro anão irrigado no Brasil e em particular na região Nordeste teve um aumento significativo. Porém o coqueiro é considerado uma das frutíferas que mais consomem água e seu cultivo no nordeste Brasileiro pode ser comprometido, em função da escassez de água na região. Assim, o presente trabalho teve como objetivo determinar a lâmina de irrigação que permita aumentar a eficiência de utilização da água na irrigação do coqueiro verde em relação à produtividade e qualidade do fruto. O número de cachos, número de frutos e volume de água de coco por planta/ano sofreram influências das lâminas de irrigação, onde a menor lâmina teve o pior desempenho em relação a estas variáveis. Já o teor de sólidos solúveis aumentou conforme diminuiu a quantidade de água disponibilizada para a planta do coqueiro. Quando comparado os dois períodos (chuvoso e seco), no período sem chuva a quantidade de água de coco (ml de água de coco por planta) foi maior nas duas maiores lâminas (100 e 75%), já para o teor de sólidos solúveis ocorreu o inverso, com o melhor valor sendo 4,9 na lâmina 0% em que não ocorreu irrigação. Palavras-chave: Cocos nucifera L., estresse hídrico, produção. CALVET, A. S.F.; VIDAL, K. S. P. L.; MOREIRA, C. G.; MIRANDA, F. R.; BEZERRA, M. A. YIELD AND QUALITY OF GREEN COCONUT FRUITS UNDER DEFICIENT IRRIGATION 2 ABSTRACT The demand for green coconut has increased substantially in recent years, and as a consequence, the cultivated area of irrigated dwarf coconut palm in Brazil, particularly in the Northeast region, has significantly increased in recent years. However, coconut trees are considered to consume the most water during irrigation. Thus, the objective of the present work was to determine the irrigation depth that allows us to increase the efficiency of water use in the irrigation of green coconut trees in relation to the productivity and quality of the fruit. The number of bunches, number of fruits and volume of coconut water per plant/year were influenced by the irrigation depth, where the lowest depth had the worst performance in relation to these variables. The soluble solids content increased as the amount of water available to the coconut plant decreased. When comparing the two periods (rainy and dry), in the period without rain, in relation to the amount of coconut water (ml of coconut water per plant), the highest amount was observed at the two largest depths (100 and 75%), whereas for the soluble solids variable, the opposite occurred; the best solute contents were observed at the 0% depth. Keywords: Cocos nucifera L., Water stress, Yield.

A baixa produtividade dos pomares de cajueiro é fruto de vários fatores, dentre eles a insuficiente oferta de materiais genéticos que tolerem o estresse hídrico. Avaliar a resposta do desenvolvimento inicial de progênies de cajueiro anão precoce submetidas a diferentes regimes hídricos foi o objetivo através deste estudo. O experimento foi conduzido em ambiente semi-controlado, na Embrapa Agroindústria Tropical, Fortaleza–CE, Brasil. As sementes coletadas em jardins dos clones BRS 189, BRS 265, CCP 06, CCP 76 e HB 58 foram semeadas em recipientes com solo (500 mL) e submetidas a três regimes hídricos: 100%, 85% e 70% de água disponível no substrato (ADS), com cinco repetições contendo quatro sementes cada. As variáveis, após teste F em sistema fatorial 5x3, foram submetidas ao teste de Tukey. O regime de ADS influenciou o tempo médio de germinação, alongando o tempo para o nível de 70%. A progênie CCP 06 destacou-se das demais quanto as variáveis de emergência. Para as variáveis de crescimento, o fator ADS só não influenciou significativamente o número de folhas. A progênie BRS 189 apresentou menor porte e menor área foliar em relação às demais progênies. O açúcar solúvel nas folhas foi a única variável que apresentou interação entre os fatores, embora todas as progênies tenham sofrido decréscimo da mesma com a redução da ADS. Assim, as plantas cultivadas sob o regime de 100% de ADS obtiveram um melhor desempenho e se apresentaram mais vigorosas, sem muita diferença varietal para os níveis de redução de água no solo testados.

Avaliar a influência da nutrição mineral e da força da fonte, folhas jovens, na produção e qualidade de frutos de melão amarelo cv Gold mine foi o objetivo através deste trabalho. Plantas desta espécie foram submetidas ao cultivo em vasos sob condições de campo, aplicando-se fertirrigação três vezes por semana, utilizando, de acordo com o tratamento, as seguintes fontes de nutrientes: nitrogênio (Ureia), fósforo (MAP) e potássio (KCl); foram feitas podas de 50% das folhas dos ramos jovens na oitava ou nona semana de crescimento destas plantas. Os seguintes tratamentos foram aplicados, com quatro repetições: fertirrigação com NPK sem poda; com NPK e poda na 8ª semana; com NPK e poda na 9ª semana; com NK sem poda; com NK e poda na 8ª semana; com K sem poda; com K e poda na 8ª semana e com K e poda na 9ª semana. As variáveis analisadas foram: massa seca, área foliar e teor de carboidratos solúveis totais para as folhas e para os frutos teor de sólidos solúveis totais e teor de açúcares. As variáveis com efeitos significativos diferenciados foram: massa seca e área foliar das folhas, com maiores valores nos tratamentos com fonte de NPK sem poda, e menores valores no teor de carboidratos das folhas para o tratamento com fonte de NK sem poda. As variáveis sólidos solúveis totais e teor de sacarose dos frutos no tratamento com aplicação de NK sem poda apresentou maior média e alto valor respectivamente, entre os demais, conferindo-lhe melhor qualidade.

ABSTRACT: This study evaluated the effects of sustained deficit irrigation (SDI) on fruit yield and fruit water quality of dwarf green coconut trees. The experiment was carried out in a commercial orchard located in Camocim, Ceará, Brazil. Four years old coconut trees were irrigated during 29 months, using micro-sprinklers, at irrigation depths equivalent to 55%, 77%, 100% and 131% of crop evapotranspiration (ETc). Green coconut fruits were harvested six months after flower aperture and evaluated for number of fruits per plant, volume of coconut water per fruit and total soluble solids of the coconut water. SDI reduced coconut fruit yield, fruit water volume and coconut water yield. Conversely, SDI increased total soluble solids of the coconut water and irrigation water productivity in terms of fruits and coconut water. Deficit irrigation showed no economic advantage over full irrigation due to the small reduction in irrigation costs compared to the substantial reduction in gross revenue.

Microorganisms, such as growth-promoting bacteria, may favor the obtaining of better-quality banana (Musa spp.) seedlings. This study aimed to evaluate the effect of inoculation with growth-promoting bacteria Bacillus sp. on micropropagated seedlings of banana cv. 'Prata Catarina' in the acclimatization phase. The design was in randomized blocks, with 4 treatments (negative control: no inoculation and no fertilization; positive control: application of slow-release fertilizer; inoculation with Bacillus sp. strain 186; and inoculation with Bacillus sp. strain 109) and 4 replicates (14 experimental units), totaling 224 seedlings. The bacterial population in the rhizosphere was quantified and the growth of seedlings and contents of minerals were evaluated. Seedlings treated with slow-release fertilizer showed better performance for the number of leaves (6.14 +/- 1.44), shoot (3.64 g +/- 1.72) and root (4.76 g +/- 3.23) fresh weight and root dry weight (0.72 g +/- 0.43). Using strains alone did not promote the growth of seedlings, under the conditions of the present study. Nevertheless, the strains were efficient in increasing the nitrogen content in leaves (17.93 g kg(-1) +/- 0.73, strain 109) and potassium and magnesium contents in roots (6.96 g kg(-1) +/- 0.39 and 6.98 g kg(-1) +/- 0.40, strain 186).

Cotton yield under the rainfed farming system in tropical semi-arid regions is significantly decreased by prolonged dry spells. In this context, supplemental irrigation (SI) with treated wastewater emerges as a strategy for the sustainability of agricultural production besides contributing to the reduction of fertilizer costs. The objective of this research was to evaluate the productivity, photosynthetic parameters, fiber quality, and profitability of cotton cultivation, under supplemental irrigation (SI) with municipal treated wastewater (MTW), with and without mineral fertilization. The treatments consisted of three water scenarios (normal, drought, and severe drought), defined by the historical series of precipitation data of 30 years, and two treatments of supplemental irrigation with MTW, with or without NPK fertilization. SI with treated wastewater increased cotton yield in all three scenarios (normal, drought, and severe drought) by approximately 29%, 255%, and 251%. Longer dry spells in drought and severe drought scenarios increased the volume of SI with MTW, resulting in greater nutrient input to the soil, improved photosynthetic response, higher physical water productivity, reduction in fertilizer costs, and higher farmers’ income. Therefore, our results show the importance of using treated wastewater in supplemental irrigation of cotton under scenarios of water scarcity in tropical semi-arid regions.

ABSTRACT This study aimed to evaluate the effects of nitrogen (N) and phosphorus (P) associated with dry and rainy seasons on the photochemical activity of Opuntia ficus-indica (L.) Mill. cv. Gigante. Combinations of N (10.0, 70.0, 100.0, 130.0, and 190.0 kg ha−1 yr−1) and P2O5 (10.0, 70.0, 100.0, 130.0, and 190.0 kg ha−1 yr−1) were evaluated in the dry and rainy seasons in semi-arid regions. A completely randomized block design with split-plot arrangement was adopted with four replications. In Quixadá, the maximum potential quantum efficiency of photosystem II (Fv/Fm) was 0.82, observed in third-order cladodes (rainy season and N/P 75.6/10.0 kg ha−1 yr−1), while in Tejuçuoca, the maximum Fv/Fm was 0.81, found in 2nd/3rd order cladodes (rainy season and N/P 10.0/190.0 kg ha−1 yr−1). In Quixadá, the maximum electron transport rate (ETR) was 31.6 μmol m−2 s−1 in 2nd/3rd order cladodes (rainy season and N/P 10.0/190.0 kg ha−1 yr−1), and in Tejuçuoca, the maximum ETR was 24.1 μmol m−2 s−1, in second-order cladodes (rainy season and N/P 110.1/10.0 kg ha−1 yr−1). In Quixadá and Tejuçuoca, higher values of Fv/Fm and ETR were observed in the rainy season. In Quixadá, the maximum fluorescence decrease ratio (FDR) was 4.04 in third-order cladodes (rainy season and N/P 10.0/114.8 kg ha−1 yr−1), while in Tejuçuoca, the maximum FDR was 6.93, found in 2nd/3rd order cladodes (rainy season and N/P 190.0/10.0 kg ha−1 yr−1). In Quixadá and Tejuçuoca, there was predominance of higher FDR values in the rainy season. Nitrogen, phosphorus, and water status modulate the photochemical efficiency of cladodes of cactus pear cv. Gigante in semi-arid regions.

Dwarf cashew is one of the main crops in northeast of Brazil. Dozens of low-income families, being the main source of income for small farmers, sell cashew nut. Two commercial clones produced by EMBRAPA agroindustry gather good productivity, small size and precocity, called CCP76 and clone BRS226. The grafted plants transferred to black polypropylene conical tubes with extratified substrate. After acclimatization, the control plants received 40ml of distilled water per day and the same volume of saline solutions. The objective was to evaluate the effects of 60mM and 120mM of NaCl on the leaf membranes during 30 days in clones CCP76 and BRS226. Photosynthesis showed decrease of 12% and 23% in 60mM and 120mM in CCP76; in BRS226 the reduction was 38% and 5% in 60mM and 120mM. Transpiration showed a reduction of 2% in 60mM and a 1% increase in 120mM in CCP76. BRS226 there was a decrease of 6% and 1%, respectively, in 60mM and 120mM. Sodium contents showed no variation of the treatments in relation to the control in CCP76, whereas in BRS226 there was a 20% increase in relation to the control in 120mM. The potassium contents increased 16% in 60mM in CCP76 but in 120mM there was no difference. In BRS226, there was a 30% increase in both 60mM and 120mM. Chloride contents showed increase in both clones and treatment, being 38% in 60mM and 120mM of CCP76 and 8% in 60mM and 33% in 120mM of BRS226. Soluble carbohydrates increased 10% and 15% in 60mM in CCP76 and BRS226. In 120mM it decreased 2% and 20% in CCP76 and BRS226. Controls had electrical conductivity lower than the treatments in the clones, but in BRS226 120mM was higher. Total lipids increased 1% and 2% in 60mM and 120mM in CCP76, already in BRS 226 increased 2% and 1% in 60mM and 120mM. Total fatty acids decreased 18:3 31% and 10%, in 60mM and 120mM in CCP76 and of 12% and 36% in 60mM and 120mM in BRS226. Monogalactosildiacilglicerol decreased by 40% in 60mM, increasing 50% in 120mM since Digalactosildiacilglicerol decreased 83% and 34% in 60mM and 120mM in CCP76. Monogalactosildiacilglicerol increased 20% and 83% in 60mM and 120mM, decreasing digalactosildiacilglicerol in 60% and 80% in 60mM and 120mM in BRS226. 16:0 increased in 150% monogalactosylcyglycerol in 60mM decreasing 50% in 120mM Digalactosyldiacylglycerol increased 900% and 100% respectively in 60mM and 120mM in CCP76. 16:0 increased 32% in monogalactosyldiaglycerol in 60mM, unchanged in 120mM. Digalactosyldiacylglycerol increased 10% and 300% in 60mM and 120mM in BRS226. In monogalactosylcyglycerol 18:3 decreased 74% and 94% in 60mM and 120mM in digalactosyldiacilglicerol decreased 70% and 90% in 60mM and 120mM in CCP76. In monogalactosylcyglycerol 18:3 decreased 65% and 90% in 60mM and 120mM in digalactosyldiacilglicerol decreased 58% and 86% in 60mM and 120mM in BRS226. Lipid peroxidation increased 18% in 60mM CCP76, decreasing 18% in 120mM, and decreasing 14% in 60mM increasing 5% in 120mM in BRS226. The results suggest that CCP76 is less susceptible to salinity.

The knowledge of gas exchanges in forage plants is essential for a better understanding of the process of forage biomass production in pasture. This study evaluated the gas exchange in massai grass fertilized with increasing levels of nitrogen fertilizer (control - without nitrogen fertilizer; 400; 800 and 1200 kg ha-1 year-1) and under rotational grazing by sheep, in a completely randomized design with repeated measures in time. The rest period was approximately 1.5 new leaves per tiller, as determined in the pre-test at the beginning of the experiment, providing interval of 22; 18; 16 and 13 days for the levels 0.0 - control; 400; 800 and 1200 kg ha-1 year-1 nitrogen, respectively. The animals used to lower the sward height to the recommended residual height were sheep (½ Morada Nova x ½ undefined breed), placed in paddocks of 42.3 m2. As the animals grazed, the height of the sward was monitored with a ruler until the canopy reached the recommended residual height of approximately 15 cm, corresponding to the residual LAI of exit of the animals from the paddock at approximately 1.5, as determined in a pre-test to set up the experiment. The variables stomatal conductance, leaf photosynthesis rate, leaf carbon dioxide concentration, photosynthesis/transpiration ratio, chlorophyll relative index and nitrogen sufficiency index revealed a positive linear response to nitrogen fertilization. Nitrogen fertilization level at 1200 kg ha-1 year-1 caused an increment of 92.3% in leaf photosynthesis rate in relation to the control. The leaf temperature and photosynthesis/conductance ratio were reduced with increasing nitrogen levels. The leaf transpiration showed a quadratic response with maximum point with increasing nitrogen levels. Nitrogen fertilization favor the gas exchange in massai grass up to the last level tested.