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

FLORENCIA YAÑEZ; LOCATELLI, MICHELANGELO; CRUZ, MERCEDES CECILIA; ACRECHE, MARTÍN; RAJAL, VERONICA BEATRIZ; IRAZUSTA, VERÓNICA PATRICIA

San Luis

Congreso; XIII Congreso Argentino de Microbiología General SAMIGE; 2018

Bad agriculture practices increase salinity in soils. These soils are a serious problem for agriculturesince they interfere with the adequate growth of most crops. The high content of soluble salts in thesoil exchange complex, produces a negative effect by increasing its osmotic pressure, decreasingavailable water for roots, and breaking down its structure. In this sense, halophilic microorganismswith plant growth promoting (PGP) properties constitute an alternative for the re-utilization of thesesoils. 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 ofsalts.The assay was carried out on water agar plates 1.5% using saline water with different NaClconcentrations: 15 mM (control- non-saline soil), 50 mM, 100 mM and 150 mM. The experimentalstrains were: Micrococcus sp SA211, Bacillus atrophaeus HX11 and Halomonas sp. SFsal. Sixbacterial 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 consortiumswas carried out from a previous evaluation of their PGP activities, with and without NaCl. Onceselected, 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 to0.6. Sterilized seeds were introduced in the bacterial cultures and were agitated for two hours at 150rpm. Seeding was done immediately, placing 20 seeds per plate and with four replicates for eachtreatment. After seven days, the number of germinated seeds, the fresh weight of the seedlings, plantand 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 forany treatment. Regarding the germination at 15 mM, no differences were observed between the controland 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 50mM there was an increase in the treatments with SA211 and HX11. In the case of root dry weight, asignificant increase was observed in SA211 and HX11 compared to the control at 15 mM. Growing at50 mM of NaCl, the length of the plants increased significantly when the seeds were inoculated withHX11 and to a lesser extent in C2. Inoculation with HX11 produced a positive effect on the elongationof roots under salinity conditions. We were able to observe by fluorescence microscopy, the presenceof bacteria in the roots of the treatments at the end of the experiment. The use of halotolerantmicroorganisms could help chia seeds to germinate in saline soils.