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.

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.

The growing competition for good-quality water is forcing the use of saline water for irrigation in several areas around the world. The objective of this study was to evaluate the influence of different electrical conductivities of irrigation water on the maize production aspects. The study was conducted in the field from August to December 2017 at the Experimental Farm of the Universidade da Integração Internacional da Lusofonia Afro-Brasileira (UNILAB), Redenção, CE, Brazil. A randomized complete block design with five irrigation water salinity (1.0, 2.0, 3.0, 4.0 and 5.0 dS m-1) and four repetitions was used. The evaluated variables were: unhusked and husked ear weights, husked ear length and diameter, cob weight, 1000-grain weight and yield. The increase of salt concentration in irrigation water reduced the unhusked and husked ear weights, cob weight, 1000-grain weight and yield. Ear length and diameter were not influenced by the increase in water salinity.

O melão (Cucumis melo) apresenta elevados gastos com adubos minerais, evidenciando a possibilidade da utilização de produtos alternativos como os biofertilizantes. Este experimento teve como objetivo avaliar a produtividade e a pós-colheita da cultura do melão cultivar Mirage seguimento Harper, submetida a doses e tipos de biofertilizantes na presença e ausência de adubação mineral. O delineamento experimental foi em blocos casualizados no arranjo fatorial 4×2+2, referentes a quatro doses de biofertilizantes (0,5, 1,0, 1,5 e 2,0 L/semana), dois tipos de biofertilizantes líquidos (misto de fermentação aeróbica e bovino simples de fermentação anaeróbica) com dois tratamentos adicionais: controle e adubação mineral recomendada. As variáveis analisadas foram produtividade, massa média de frutos, diâmetro de frutos, sólidos solúveis, acidez titulável, firmeza, espessura da polpa e cavidade da polpa. O biofertilizante misto mostrou-se mais eficiente do que o bovino na maioria das variáveis analisadas. A maior produtividade do meloeiro (32,62 t/ha) foi alcançada com a dose de 1,08 L/planta/semana para o biofertilizante misto e com 1,41 L/planta/semana para o bovino (25,87 t/ha). O biofertilizante misto e bovino com a dose 2,0 L/planta/semana foi melhor que o controle e a adubação mineral para espessura e cavidade de polpa.

Água salina e biofertilizantes de esterco bovino e caprino na salinidade do solo, crescimento e fisiologia da fava - DOI:10.5039/agraria.v14i3a5672

Under water deficit and/or salt stress conditions, crops suffer from several physiological disturbances, which lead to the reduction in growth and, consequently, decreases in their yields. Thus, the objective of this study was to evaluate the physiological responses of lima bean, cultivar Espírito Santo, under different irrigation water salinity associated to two water regimes. The experiment was carried out in the experimental area of the Universidade Federal do Ceará, Brazil, from September to November 2017, and it was carried out in pots in full sun, under a completely randomized design in split plots, where water salinities (1.1, 2.1, 3.1, 4.1 and 5.1 dS m-1) were considered as the plots, and the treatments of water regime (50 and 100% of the reference evapotranspiration - ETo) were considered as the subplots. At 45 days after sowing, leaf gas exchanges and relative index of total chlorophyll (SPAD index) were evaluated. In general, the increase of salt concentration in irrigation water causes reductions in the physiological responses of lima beans. Under a water regime of 50% ETo, the instantaneous and intrinsic water use efficiency is higher.