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.

Agriculture in semiarid regions commonly face problems because of salt and availability of irrigation water. Considering this, studies on cultures resistant to salt and water stresses involving sweet sorghum are required. Therefore, the aim was to evaluate the growth and other mechanisms of tolerance to salinity and water deficit in BRS 506 sweet sorghum. The experimental design was conducted in Upanema-RN, Brazil, in randomized blocks, where the isolated and interactive effect of 3 salinity levels, expressed as the electrical conductivity of irrigation water (1.5, 3.8, and 6.0 dS m⁻¹), and 3 irrigation depths (55, 83, and 110% of crop evapotranspiration) were evaluated. During the cycle, sorghum adapted to the salinity and deficit irrigation depth, since stem height reduced only −5.5% with increasing salinity and −11.95% with decreasing irrigation depth, and aerial dry mass was affected by interaction only at the end of the cycle. Proline, total amino acids, and total soluble sugars were not differenced by stresses. Additionally, around 68.71% of total Na⁺ was at roots at the end of the cycle. In summary, sorghum BRS 506 was more tolerant to salt than water stress and used Na⁺ compartmentalization in root cells as the main tolerance mechanism.

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

The objective of this study was to evaluate the performance of three rice cultivars under saline water irrigation. The experiment was carried out in full sun at the Experimental Farm of the Unilab, in Redenção, Ceará, Brazil, in January 2016. The experimental design was completely randomized (CRD), in a 5 x 3 factorial scheme [irrigation water electrical conductivity (ECw: 0.5, 1.0, 2.0, 3.0 and 4.0 dS m^-1) versus three rice cultivars (C1 - Ligeirinho, C2 - Casado and C3 - Meruinho)], totaling 15 treatments, with 4 replicates of 30 seeds per cultivar. After 21 days, the following variables were evaluated: emergence percentage (EP), emergence speed index (ESI), mean time of emergence (MTE), mean speed of emergence (MSE), shoot dry matter (SDM), root dry matter (RDM) and total dry matter (TDM). The cultivar Ligeirinho showed higher tolerance to saline stress with respect to the emergence percentage, emergence speed index and mean speed of emergence. The cultivar Casado showed higher tolerance to saline stress for shoot dry matter, root dry matter and total dry matter in comparison to the other cultivars.

The use of plant growth-promoting bacteria can be one option for mitigating the impact of abiotic constraints on different cropping systems in the tropical semi-arid region. The aim of this study was to evaluate growth, leaf gas exchange and yield in maize 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 for the irrigation water (ECw): 0.3 dS m-1 and 3.0 dS m-1; the subplots consisted of three irrigation depths (ID1: 50%, ID2: 75%, and ID3: 100% of the crop evapotranspiration (ETc)); while the sub-subplots included the presence or absence of Bacillus 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 Bacillus 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. Inoculation partially reduced the effects of abiotic stress due to morpho-physiological traits, and increased yield potential under water deficit with no salt stress.

The study hypothesis proposes that the use of Trichoderma, associated with fertilization with 100% of the recommended phosphorus, may mitigate saline stress and maximize the productivity and quality of the tuberous root. This study aims to evaluate the mitigating effects of phosphate fertilization and Trichoderma harzianum in beet plants under salt stress, by measuring the initial growth, leaf gas exchange, productivity and quality of the beet. The experimental design used was entirely randomized, in a 3 × 2 × 2 factorial scheme, referring to three doses of phosphate fertilization (25%, 50% and 100%), with and without the use of Trichoderma-based inoculation, and two levels of electrical conductivity of the irrigation water (0.5 and 6.2 dS m⁻¹). Salt stress negatively affected the leaf area of the beet. The shoots’ dry mass was reduced as the electrical conductivity of the irrigation water increased, especially in the treatment with the 25% P₂O₅ dose. Salt stress reduced photosynthesis to a greater extent at the 25% P₂O₅ dose and in the absence of Trichoderma harzianum. Increasing the electrical conductivity of the irrigation water reduced transpiration and increased leaf temperature at the 25% P₂O₅ dose and in the presence of Trichoderma harzianum. The 25% P₂O₅ dose increased the stomatal conductance of the beet. The higher electrical conductivity of the irrigation water negatively affected water use efficiency, most significantly at the 25% P₂O₅ dose. Our data showed that the doses of 50% and 100% P₂O₅ were more efficient at increasing the productivity and quality of the beet, with the tuberous root diameter being higher under the lower electrical conductivity of the water and the absence of Trichoderma harzianum. The pH was high under the lowest electrical conductivity of the water, with a dose of 25% P₂O₅ and the absence of Trichoderma harzianum.