Introduction

The areas considered to have high agricultural potential aridity in 43% of the total area of the world (^{Rueda et al., 2003}). In Mexico solonchaks soils are combined with calcisols and it is estimated that around 1.7 million hectares of the 6.2 million ha of irrigation problems presented average high salinity. Also, these areas are characterized by large quantity of salts dissolved carbonate type, sulphates and gypsum at a depth of 8 to 10 mm in the soil, and water wells for agricultural use, with high salt content (^{SEMARNAT, 1999}). These soils are located in the Chihuahuan Desert and in the states of Aguascalientes, Baja California, Baja California Sur, Chihuahua, Coahuila, Durango, Nuevo Leon, Sonora, Zacatecas and San Luis Potosi (^{INEGI, 2013}). In the state of San Luis Potosi, Mexico, there are problems areas with medium to high salinity (4-8 g L of water), a situation that has affected the productivity of conventional farming.

With the presence of these salts the establishment of traditional crops is limited by decreasing their yields, which are required to supply the food needs of the population, with plants that tolerate high salt concentrations of both soil and water, and thus incorporate agricultural or low production harvestable crop development systems land.

An alternative may be the halophytes, which grow naturally in saline arid environments. A representative genus with exploitable potential is Salicornia bigelovii, which has been proposed as an alternative for agro-arid areas and use of brackish water. However, to develop it as a monoculture requires a nitrogenous chemical application ranging from 1 000-1 500 kg distributed in three stages of phenology; these high applications of chemical fertilizers bring high salinization due to agricultural soils in arid areas such as the area of San Luis Potosi state (^{Martinez, 1996}). An alternative solution to the above plan is the application of promoting bacteria plant growth, which have the particularity to fix atmospheric nitrogen in addition to produce and / or act as inducers in the synthesis of plant hormones, which include auxin and gibberellins (AG₃) that promote germination, f lowering and fruiting plants. In order to expand the knowledge of the behavior of Salicornia bigelovii with the interaction of beneficial bacteria under saline conditions set out to evaluate the effect of inoculation of Azospirillum halopraeferens and Klebsiella pneumoniae and an uninoculated control in two genotypes of Salicornia bigelovii (improved genotype SOS-7 and wild genotype Bahia Kino= BK=) in the stages of germination and early development of seedlings developing it in saline conditions: sodium chloride (NaCl) and calcium sulfate (Ca₂SO₄+2H₂O) to 0.5 molar and 1 molar. The variables evaluated were: percentage and germination rate, height of seedling.

Methodology

This work was conducted in two phenological stages: germination and early seedling greenhouses agroindustrial area of the faculty of engineering of the Autonomous University of San Luis Potosi (UASLP).

Results and discussion

According to the methodology referred above, the results shown below.

Germination of genotypes of Salicornia bigelvii (Bahia de Kino= BK= and SOS-7) with inoculation of Azospirillum halopraeferens (Ah) and Klebsiella pneumoniae (Kp) under conditions of salinity (0.5 and 1 M sodium chloride= NaCl= and calcium sulfate= Ca₂SO₄+2H₂O.

The results obtained by making use of a salt chloride of sodium (0.5 M) on the two genotypes of Salicornia bigelovii (BK and SOS-7) with the inoculation of bacteria, the SOS-7 genotype showed the best germination percentage (91.3%) inoculated with Kp, following him in the background, the same genotype SOS-7 with 82.9 inoculated with Ah (Figure 1); similar behavior to the wild genotype was observed (BK), that inoculated with protruding Kp compared Ah (79.2 against 77.6%, respectively). Regarding the use of calcium sulphate (0.5 of Ca₂SO₄+2H₂O), SOS-7 showed values of 80.1 against 79.3, inoculated with Kp and Ah, respectively. While BK ecotype was lower compared SOS-7, yielding values of 69.1 and 68.3, both inoculated with Kp and ah, respectively. Meanwhile uninoculated ecotypes in both saline solutions showed the lowest values (Figure 1).

Figure 1 Percentage of germination of Salicornia bigelovii genotypes (wild material Kino Bay= BK and improved material SOS- 7), inoculated with bacteria Klebsiella pneumoniae= kp= y Ah= Azospirillum halopraeferens to 0.5 and 1 M of NaCl and 0.5 and 1 Ca₂SO₄+2H₂O. The letters indicate significant differences (p< 0.005). 

To a salinity of 1 M of NaCl, genotype uninoculated BK, reduced the percentage of germination up to 75% compared to 0.5M. However, being inoculated with beneficial bacteria, the germination percentage is even reduced by 50% (48.2% with 45.3K pand with Ah). With regard to vegetative material SOS-7, 1 M of NaCl, who was not inoculated was significantly affected germination, achieving only 10% germination. However, to be innoculated percentage of germination was favored by 55.3 and 57.2 with Ah and Kp, respectively. The same genotype BK 1M of CaSO4 (inoculated with Kp and Ah) reduced the percentage of germination by 55%, compared with 0.5 M of Ca₂SO₄+2H₂O. However, SOS-7 uninoculated was affected up to 74% less (18%).

Regarding SOS-7, subjected to 1 M of Ca₂SO₄+2H₂O, there were no significant differences between SOS-7 inoculated with Kp and Ah (35.1 against 34.2), respectively. SOS-7 uninoculated, reduced germination up to 60% less (11%) compared with the inoculated Kp and Ah. The results of inoculation match ^{Bashan and Holguin (1997)}; ^{Meza et al. (2015)}, which indicate the use of bacterium induces germination because phytohormone synthesis released. Another factor observed in this study and which other research glisten (^{Besnier, 1988}; ^{Camacho, 1994}), is the germination inhibition effect of some abiotic factors such as temperature, humidity, light and salinity. The latter is an important factor that did not allow the genotypes in study Salicornia bigelovii germinate properly as salinity increased (^{Allison et al., 1980}; ^{Ungar, 2000}).

Germination rate of genotypes of Salicornia bigelovii (Bahia Kino= BK= and SOS-7) with the inoculation of bacteria (Azospirillum halopraeferens (Ah) and Klebsiella pneumoniae (Kp)) to 0.5 M of NaCl and Ca₂SO₄+2H₂O.

The behavior of the different treatments on the germination rate at a salinity of 0.5 M of NaCl, the KB genotype inoculated with Kp, behaved significantly higher compared with the same genotype inoculated with Ah and SOS-7 with two inoculants as the tenth day reached its highest percentage (79.2%). However, it is important to note that the maximum percentage of germination was achieved by SOS-7 inoculated with Kp (91.3%) at 15 days after planting. Meanwhile genotypes (BK and SOS-7) uninoculated, where germination rate showed no favored dynamic, initiating the germination process on the sixth day.

Regarding the germination rate at a salinity of 0.5 M of CaSO₄, the behavior was similar to 0.5 M of NaCl; i.e. the BK genotype inoculated with Kp showed an initial germination on the fourth day and ending at the twelfth day to 69.1%. For its part inoculated BK with Ah, she started sprouting on the fifth day, totaling 68.3% with no significant difference with BK + Kp. Notwithstanding the foregoing, even when SOS-7, in its germination rate has not been observed favored the eighth day showed a final germination of 80.1 by Kp against 79.3 inoculated with Ah, not having shown statistical differences between these two treatments. Those dynamically uninoculated treatments showed not favored in the germination rate.

Germination rate of genotypes of Salicornia bigelovii (Bahia Kino= BK= and SOS-7) with the inoculation of bacteria (Azospirillum halopraeferens (Ah) and Klebsiella pneumoniae (Kp) to 1 M of NaCl and Ca₂SO₄+2H₂O.

According to the germination rate of both genotypes (Bahia de Kino= BK= and improved genotype SOS-7), subject to a salinity of 1 M of NaCl and CaSO₄ and inoculated with Ah and Kp, wild genotype SOS-7+Kp , behaved higher germination rate with 57.2% of germinated seeds 12 days after sowing in the NaCl solution compared the remaining genotypes. The SOS-7+Ah, genotype showed maximum germination percentage in the 13 days to 1 M of NaCl. Moreover, this same salinity (1 M of NaCl), treatments with genotype BK, inoculated with Kp and Ah, initiated germination on the ninth day and finalizing on the fourteenth day with a 48.2 and 45.3%, respectively. The uninoculated treatments showed dynamically lower compared to those inoculated. With regard to the dynamics of germination 1M solution Ca₂SO₄+2H₂O, it was similar to those treatments to 1 M of NaCl, but with significant results in the final percentage of germination behavior. In salinities applied to the genotypes of Salicornia bigelovii clearly seen where bacteria promoted seed germination. According to ^{Lira (2003)}, it indicates that hormones, specifically gibberellins and auxins in germination are synthesized in seeds; coupled with the production of the same by bacteria, the effect on the rate and % of germination is intrinsically expressed as the rate of cell division increases (mitosis) (^{Fallik et al., 2000}).

Seedling height and root length of Salicornia bigelovii genotypes (Kino Bay= BK= and SOS-7), inoculated with bacteria Klebsiella pneumoniae and Azospirillum halopraeferens 0.5 and 1 M of NaCl and Ca₂SO₄+2H₂O.

The height of the genotypes studied at a salinity of 0.5 M of NaCl, BK+Kp showed the highest values (38.2 mm) compared BK+Ah, SOS-7+Ah, SOS-7-Kp with 32.3, 35.4 and 35.7 mm, respectively. A similar behavior was observed with Ca₂SO₄+2H₂O to the 0.5 M solution; there were no significant differences, however, the highest numerical values were genotyped for the BK+Kp with 33.2 mm compared BK+Ah, SOS-7+Ah, SOS-7-Kp with 29.3, 30.4 and 31.4, respectively . To this salt concentration, there were no significant differences between the type of salt; But not this, was identified genotypes in solving Ca₂SO₄+2H₂O numerical values are lower compared NaCl. The uninoculated treatments showed 25% less in the variable height 0.5M conditions both salts, compared to those inoculated.

Meanwhile, the same variable height, at a salinity of 1 M of NaCl, genotype BK+Kp showed the highest values (18.1 mm) compared BK+Ah, SOS-7+Ah, SOS-7-Kp with 12.2, 15.3 and 15.4, respectively. A similar behavior was observed with Ca₂SO₄+2H₂O solution 1M with no significant differences, however, higher values were genotyped for the BK+Kp with 13.1 mm compared BK+Ah, SOS-7+Ah, SOS-7-Kp with 9.1, 10.4 and 11.4, respectively. Just as in the concentration of this salt concentration 0.5M, there was no significant difference between the types of salt; but not this, was identified genotypes in solving Ca₂SO₄+2H₂O, numerical values were lower compared NaCl. The uninoculated treatments were lower in height variable conditions 1M both salts. With regard to root length, SOS- 7+Ah (62.9 mm) genotype showed significant higher values compared to SOS-7+Kp and SOS-7 (44.12 and 41.09 mm respectively) at 0.5 M of NaCl, without significant differences between solutions (SOS-7+Ah (59.7 mm) revealed significant higher values compared to SOS-7+Kp and SOS-7 (39.11 and 38.02 mm, respectively). with regard to the concentration of 1 M of NaCl and Ca₂SO₄+2H₂O to 1M, treatment with BK+Kp was the one that presented greater root length (35.8 mm) compared BK+Ah, SOS-7-Kp and SOS-7+Ah, with 15.1, 12.7 and 11.2 mm respectively. the uninoculated treatments showed similar numerically to SOS-7+Ah treatment 11.01 and 11.00 mm (BK and SOS-7, respectively). the previously mentioned values generated significant results with p< 0.05 between salt concentrations (0.5 with 1M).

According to the results, genotypes as SOS BK-7 and the Ah and Kp bacteria can clearly see the effect on height growth and root length were taken into the salt concentrations. These findings by the effect of bacteria correspond to that in other studies, which show that auxins, cytokinins and gibberellins produced by microorganisms, as well as inducing them in vegetative organs such as seeds, exhibit strong regulating properties growth and each with its particular structure and active at very low concentrations in the plant (^{Bashan et al., 2000}; ^{Lira, 2003}; ^{Rueda et al., 2004}).

Cool and dry weight seedling genotypes of Salicornia bigelovii (Bahia Kino= BK= and SOS-7), inoculated with bacteria (Klebsiella pneumoniae and Azospirillum halopraeferens) at 0.5 and 1 M of NaCl and Ca₂SO₄+2H₂O.

In the variables fresh weight, considering the treatments with inoculants inoculants 0.5 M of NaCl, genotype presented the highest values was the BK+Kp, with an average of 0.0335 mg, followed in second order SOS-7+Kp with 0.0329 mg. Those inoculated with Ah, were numerically lower than those inoculated with Kb, without significant differences. Meanwhile treatments without inoculants 0.5 M of NaCl, genotype presented the highest values was the BK, with an average of 0.0242 mg, followed in second order SOS-7. The results show no significant differences between inoculated and uninoculated treatments. Relative to 0.5M of Ca₂SO₄+2H₂O solution, the results show no significant difference between the type of salt (NaCl against Ca₂SO₄+2H₂O) to 0.5M. Low and values presented for those not inoculated (Bk and SOS-7 with 0.0191 and 0.0188 mg respectively).

Also, the concentration of 1 M of NaCl against Ca₂SO₄+2H₂O, between treatments inoculated bacteria with Kp, similarly Bk continued to behave superior compared to the other genotypes (fresh weight= 0.0274 mg, dry weight= 0.0032 mg). Regarding Ah inoculation, the levels obtained were fresh weight for SOS-7 genotype, while for higher dry weight was again Bk.

Conclusion

Salicornia bigelovii a halophyte that develops off the coast of Baja California Sur and Sonora in sight for the immediate future as an option to contribute to the agricultural economy in states with salinity problems and a potential positive impact on regional development of the sector agricultural. Although states like San Luis Potosi not develop naturally this halophyte, soils rich in salts such as chlorides and sulfates and brackish waters above 6 g of dissolved solids, allow agriculture with halophytes agroindustrial importance, they can be implemented in the agricultural sector. The results obtained in this research contribute to expand knowledge on possible alternative agricultural production and effects on the application of biofertilizers in new plant materials with productive potential of socio-economic interest to states with problems of availability of good quality water, as is the state of San Luis Potosi. The results suggest the feasibility of that in the germination stage, the use of plant growth promoting bacteria, it contributes significantly to the germination of Salicornia bigelovii genotypes. Also, the type of salt and concentration thereof, affects the germination. However, it evaluated phenological stage is mitigated when the genotypes studied (Bahia de Kino and SOS-7) Salicornia bigelovii, are inoculated with Klebsiella pneumoniae and Azospirillum halopraeferens. Notwithstanding the foregoing, as studies concerning possible bio-fertilizers, they are necessary in subsequent different phenological stages with both genotypes, who for this phenological stage, turned out to have expectations.