PGP of halotolerant bacteria effect in chia (Salvia hispanica L.) seeds germination under salinity conditions

YÁÑEZ YAZLLE, MARÍA FLORENCIA; ACRECHE, MARTÍN M.; CRUZ, MERCEDES C.; IRAZUSTA, VERÓNICA P.; LOCATELLI, MICHELANGELO; RAJAL, VERÓNICA B.

San Luis

Congreso; XIII Congreso Argentino de Microbiología General; 2018

Bad agriculture practices increased saline soils. These soils are a serious problem for agriculture since they interfere with the adequate growth of most crops. The high content of soluble salts in the soil exchange complex, produces a negative effect by increasing its osmotic pressure, decreasing available water for roots, and breaking down its structure. In this sense, halophilic microorganisms with plant growth promoting (PGP) properties constitute an alternative for the re-utilization of these soils.The objective was to evaluate the effect of the inoculation of three halotolerant microorganisms: Micrococcus sp, Bacillus atrophaeus, and Halomonas sp. on the germination of chia in presence of salts.The assay was carried out on water agar plates 1.5% using saline water with different NaCl concentrations: 15 mM (control- non-saline soil), 50 mM, 100 mM and 150 mM. The experimental strains were: Micrococcus sp SA211, Bacillus atrophaeus HX11 and Halomonas sp. SFsal. Six bacterial inoculums were used: No bacteria (control), SA211, HX11, SFsal, and two consortiums: C1 (SFsal + SA211) and C2 (HX11 + SA211). The selection of these microorganisms and consortiums was carried out from a previous evaluation of their PGP activities, with and without NaCl. Once selected, antagonism tests were carried out to validate the selection. Seeds were sterilized with 70% ethanol, 3% sodium hypochlorite and distilled water, always under stirring at 150 rpm. Microorganisms were grown in nutritive broth with salt (42 mM NaCl) and the OD was adjusted to 0.6. Sterilized seeds were introduced in the bacterial cultures and were agitated for two hours at 150 rpm. Seeding was done immediately, placing 20 seeds per plate and with four replicates for each treatment. After seven days, the number of germinated seeds, the fresh weight of the seedlings, plant and root length, and root dry weight were recorded.The effect of bacteria at 100 mM and 150 mM was not observed in any of the measured variables for any treatment. Regarding the germination at 15 mM, no differences were observed between the control and the treatments; while at 50 mM an improvement in presence of SA211 and HX11 was observed. Regarding the fresh weight of plants, in 15 mM there was no promoter effect of the bacteria, but in 50 mM there was an increase in the treatments with SA211 and HX11. In the case of root dry weight, a significant increase was observed in SA211 and HX11 compared to the control at 15 mM. Growing at 50 mM of NaCl, the length of the plants increased significantly when the seeds were inoculated with HX11 and to a lesser extent in C2. Inoculation with HX11 produced a positive effect on the elongation of roots under salinity conditions. We were able to observe by fluorescence microscopy, the presence of bacteria in the roots of the treatments at the end of the experiment. The use of halotolerant microorganisms could help chia seeds to germinate in saline soils.