The use of plant-growth-promoting rhizobacteria (PGPR) can be one option for mitigating the impact of abiotic constraints on different cropping systems in the tropical semi-arid region. Studies suggest that these bacteria have mechanisms to mitigate the effects of water stress and to promote more significant growth in plant species. These mechanisms involve phenotypic changes in growth, water conservation, plant cell protection, and damage restoration through the integration of phytohormone modulation, stress-induced enzyme apparatus, and metabolites. The aim of this study was to evaluate the growth, leaf gas exchange, and yield in maize (Zea mays L.—BRS Caatingueiro) inoculated with Bacillus aryabhattai and subjected to water and salt stress. The experiment followed a randomised block design, in a split-plot arrangement, with six repetitions. The plots comprised two levels of electrical conductivity of the irrigation water (0.3 dS m⁻¹ and 3.0 dS m⁻¹); the subplots consisted of three irrigation depths (50%, 75%, and 100% of the crop evapotranspiration (ETc)); while the sub-subplots included the presence or absence of B. aryabhattai inoculant. A water deficit of 50% of the ETc resulted in the principal negative effects on growth, reducing the leaf area and stem diameter. The use of B. aryabhattai mitigated salt stress and promoted better leaf gas exchange by increasing the CO₂ assimilation rate, stomatal conductance, and internal CO₂ concentration. However, irrigation with brackish water (3.0 dS m⁻¹) reduced the instantaneous water-use efficiency of the maize. Our results showed that inoculation wiht PGPR mitigates the effect of abiotic stress (salt and water) in maize plants, making it an option in regions with a scarcity of low-salinity water.

The objective of this research was to define the potential of brackish groundwater for 15 systems of biosaline agriculture in a representative area of the Brazilian semi-arid region. The study was conducted using a database of the State of Ceará, with 6284 wells having brackish water (EC ≥ 0.8 dS m⁻¹ and discharge rate ≥ 0.5 m³ h⁻¹). Our results show that the potential of brackish groundwater resources depends on the set of data: (i) production system (crop salt tolerance and water demand) and (ii) water source (salinity and well discharge rate). The joint analysis of these data shows that plant production systems with lesser water requirements, even with moderate tolerance levels to salt stress, present better results than more tolerant species, including halophytes and coconut orchards. About 41, 43, 58, 69, and 82% of wells have enough discharge rates to irrigate forage cactus (1.0 ha), sorghum (1.0 ha with supplemental irrigation), hydroponic cultivation, cashew seedlings, and coconut seedlings, respectively, without restrictions in terms of salinity. Otherwise, 65.8 and 71.2% of wells do not have enough water yield to irrigate an area of 1.0 ha with halophytes and coconut palm trees, respectively, butmore than 98.3 and 90.7% do not reach the water salinity threshold for these crops. Our study also indicates the need for diversification and use of multiple systems on farms (intercropping, association of fish/shrimp with plants), to reach the sustainability of biosaline agriculture in tropical drylands, especially for family farming.

The excess of salts can affect several processes in the crops, and nitrogen (N) can attenuate the depressive effect of salinity. The objective was to evaluate the influence of nitrogen doses on the growth and gas exchange of corn crop irrigated with saline water. The experiment was conducted from June to September 2019 at the University of International Integration of Afro-Brazilian Lusophony, Redenção, CE, Brazil. The experimental design was completely randomized, in a 2 x 3 factorial scheme (supply water of 0.3 dS m-1 and saline solution of 3.0 dS m-1) and three nitrogen doses, 0, 80, and 160 kg ha-1, corresponding to 0, 50, and 100% of the recommended dose respectively, with six repetitions. At 30 and 45 days after sowing (DAS), plant height, leaf area, number of leaves, photosynthesis, transpiration, and stomatal conductance were evaluated. Saline stress affects plant height, leaf area, photosynthesis, transpiration, and conductance at 30 DAS. The doses of 80 and 160 kg ha-1 provide greater performance in plant height, leaf area, photosynthesis, transpiration, and conductance at 30 DAS. The use of low salinity water and doses of 80 and 160 kg ha-1 were more efficient in terms of plant height, leaf area, photosynthesis, transpiration, and conductance at 45 DAS. The dose of 160 kg ha-1 of N attenuates the harmful effects of salts in AG 1051 hybrid maize plants, providing higher values of photosynthesis, transpiration, and stomatal conductance at 45 DAS when irrigated with water of 3.0 dS m-1.

Semi-arid regions present the inherent problem of accumulation of salts in the soil due to the use of brackish water for irrigation, and water deficit compromises the growth and physiological indices of crops. This study evaluated the effect of salt and water stress on growth and gas exchange in the zucchini cv. Caserta crop. The study was conducted at the University of International Integration of Afro-Brazilian Lusophony, Redenção, Ceará State, Brazil. The experimental design was completely randomized, in a 5 × 2 factorial scheme with five levels of electrical conductivity of the irrigation water - ECw (0.5, 1.0, 1.5, 2.0, and 2.5 dS m-1) and two water regimes (50 and 100% of the potential crop evapotranspiration - ETc), with five replicates. At 36 days after sowing, the following traits were evaluated: CO2 assimilation rate, transpiration, stomatal conductance, internal carbon concentration, leaf temperature, relative chlorophyll index, and water use efficiency. At 45 days after sowing, the plant height, stem diameter, number of leaves, and leaf area were also evaluated. The use of brackish water (1 to 2.5 dS m-1) reduced the growth parameters of zucchini cv. Caserta. The increase in ECw caused a decline in the physiological traits. Under 100% ETc, higher values of CO2 assimilation rate, transpiration, and instantaneous water use efficiency were recorded, and there was 50% ETc for internal carbon concentration, even with the increase in ECw.

Das espécies do gênero Phaseolus, a fava é a mais tolerante à seca se comparada com os feijões comuns. Apesar da sua importância, ela tem sido pouco estudada, necessitando de pesquisas aplicadas à cultura para maior compreensão dos mecanismos envolvidos na resposta ao déficit hídrico. Este estudo avalia a tolerância de quatro genótipos de fava cultivados no Ceará quanto a sua resistência ao estresse hídrico. O experimento foi realizado em um delineamento inteira­mente casualizado, no esquema fatorial 4 x 3 em que o primeiro fator foi constituído pelos genótipos: ‘Branca’, ‘Mulatinha’, ‘Preta’ e ‘Coquinho Laranja’; o segundo por três regimes hídricos: irrigado, déficit moderado e déficit severo; com cinco repetições. As plantas foram conduzidas em vasos até o estádio fenológico V₃ onde foram avaliados os seguintes parâmetros fisiológicos: taxa fotossintética (A), condutância estomática (gs), relação Ci/Ca, Transpiração (E), eficiência no uso da água (EUA), eficiência no uso da água intrínseca (EUA int), eficiência instantânea de carboxi­la­ção (EiC) e taxa de transferência de elétrons (ETR). Sem comprometer seu metabolismo, o genótipo Coquinho Laran­ja foi mais tolerante ao déficit hídrico, evidenciando maior produtividade fotossintética, associadas à alta eficiência no uso da água pelo fechamento dos seus estômatos com redução da transpiração.

A utilização de água salina na agricultura irrigada pode causar desequilíbrio nutricional e inibição competitiva na absorção de nutrientes. O objetivo deste trabalho foi avaliar os efeitos da salinidade da água de irrigação sobre o acúmulo, os totais extraídos e a distribuição de nutrientes em plantas de milho. O estudo foi conduzido em condições de campo em um Argissolo Vermelho Amarelo na estação seca, no delineamento em blocos ao acaso, com cinco repetições, de setembro a dezembro de 2007, em Fortaleza, CE. As plantas de milho foram coletadas aos 90 dias após a semeadura e realizadas as seguintes avaliações: teores, extração e distribuição de elementos minerais nas diferentes partes da planta (folha, colmo, grão e sabugo). O aumento da salinidade da água de irrigação aos 90 dias após a semeadura, inibiu o acúmulo de potássio nas folhas e de magnésio e fósforo nos grãos. A extração dos nutrientes e sódio pelas plantas irrigadas com água de salinidade variando de 0,8 a 3,6 dS m-1 obedeceu à seguinte ordem decrescente: K > Mg > Ca > P > Na; no tratamento de maior salinidade (5,0 dS m-1) a sequência de extração foi: K > Ca > Na > P > Mg.