Marcos Alfonso Lastiri-Hernández

Soil salinity is one of the most important factors reducing agricultural productivity worldwide. Halophilic plant growth-promoting bacteria (H-PGPB) represent an alternative method of alleviating saline stress in crops of agricultural interest. In this study, the following halophilic bacteria were evaluated: Bacillus sp. SVHM1.1, Halomonas sp. SVCN6, Halomonas sp. SVHM8, and a consortium. They were grown under greenhouse conditions in Solanum lycopersicum at different salinity concentrations in irrigation water (0, 20, 60, and 100 mM NaCl) to determine the effects on germination, fruit quality, yield, and concentration of osmoprotectors in plant tissue. Our results demonstrate the influence of halophilic bacteria with the capacity to promote plant growth on the germination and development of Solanum lycopersicum at higher salinity levels. The germination percentage was improved at the highest concentration by the inoculated treatments (from 37 to 47%), as were the length of the radicle (30% at 20 mM) and plumule of the germinated seed, this bacterium also increased the weight of the plumule (97% at 100 mM). They also improved the yield. The dry weight of the plant, in addition to having an influence on the quality of the fruit and the concentration of osmoprotectors (Bacillus sp. SVHM 1.1) had the greatest effect on fruit yield (1.5 kg/plant at 20 mM), by the otherhand, Halomonas sp. SVHM8 provided the best fruit quality characteristics at 100 mM. According to the above results, the efficiency of halophilic PGPB in the attenuation of salt stress in Solanum lycopersicum has been proven.

The aim of this research was to evaluate the phytoremediative potential of Epipremnum aureum and Bacopa monnieri to improve the chemical properties of irrigation water exposed to the following two saline concentrations: highly saline (EC 2000 μS cm⁻¹) and severely saline (EC 4000 μS cm⁻¹). The artificial wetlands used in this experiment were of the free water surface type, considering a hydraulic retention time of 42 days. The evaluated treatments were configured as follows: T1 (B. monnieri [control, 300 μS cm⁻¹]), T2 (B. monnieri [2000 μS cm⁻¹]), T3 (B. monnieri [4000 μS cm⁻¹]), T4 (E. aureum [control, 300 μS cm⁻¹]), T5 (E. aureum [2000 μS cm⁻¹]), T6 (E. aureum [4000 μS cm⁻¹]), T7 (B. monnieri + E. aureum [control, 300 μS cm⁻¹]), T8 (B. monnieri + E. aureum [2000 μS cm⁻¹]), and T9 (B. monnieri + E. aureum [4000 μS cm⁻¹]). The results showed that the species B. monnieri and E. aureum (both separately and together) showed a good ability to reduce the salinity of the irrigation water. However, B. monnieri showed a greater ability of phytoremediation, to the point of improving its chemical properties and reducing potential damage to the soil to use this water. In the highly saline group, B. monnieri accumulated 7.992 g per experimental unit and achieved to reduce of the pH from 7.96 to 7.75, EC from 2000 μS cm⁻¹ to 670 μS cm⁻¹, SAR from 13.54 to 3.91 and ESP from 20.17 to 5.83, which allowed it to go from (C3-S3) to (C3-S1). In the severely saline group, B. monnieri accumulated 13.494 g per experimental unit and achieved to reduce the pH from 8.14 to 7.91, EC from 4000 μS cm⁻¹ to 1730 μS cm⁻¹, SAR from 27.35 to 8.73, ESP from 40.35 to 13.01, which allowed it to go from (C4-S4) to (C3-S2).