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The efficiency of plant growth promoting rhizobacteria (PGPR) on yield and yield components of two varieties of wheat in salinity condition.

The amount of salt that affected land world wide is estimated to be 900 million ha, it's 6% of the global total land mass (Flowers 2004). Soil salinity limited plant growth and crop production in many parts of the world, particularly in arid and semi-arid areas (Shannon 1984). Stalinization can result from the natural phenomena (for example rainfall limited) or human activities (such as unsuitable agricultural functions). Leaching salt downward in to the deeper layer with excess water is the most common method to lower soil salt content in the root zone (Qadir et al. 2003). However, soil leaching is not feasible for locations that are distant from water resources of for those with poor drainage. In these sites, high evaporation also results in soil salinity. Soil salinity is defined as the concentration of dissolvable salts extracted from soil by water (Richards 1954). Soil salinity prevents plant growth and development with adverse effects such as osmotic stress, [Na.sup.+] and [Cl.sup.-] toxicity, ethylene production, plasmolysis, nutrient imbalance and interference with photosynthesis (Sairam and Tyagi 2004). Decrease of photosynthetic capacity due to the osmotic stress and partial closure of stomata (Drew et al. 1990). Plant growth promoting rhizobacteria (PGPR) are a group of bacteria that can actively colonize plant roots and increase plant growth (Kloepper and Schroth 1978). PGPR may improve plant growth and yield by direct and indirect mechanisms (Noel et al. 1996). Indirect mechanisms have been observed with most PGPR strains. Direct mechanisms may act on the plant itself and affect growth (Kloepper and Schroth 1978) by means of plant growth regulators, solubilization of minerals and fixation of atmospheric nitrogen. PGPR can inhibit the harmful effects of phytopathogenic organisms and environmental stresses. Woitke (2004) reported that a high salinity treatment with Bacillus subtilis had even a lower yield despit improved vegetative plant growth. PGPR produce plant growth promoting compounds including phytohormones; auxins, cytokinins and gibberellins (Dashti et al. 2000), antibacterial peptides that prevent pathogenic strains (Maurhofer et al. 1992), and enzyme of ACC deaminase, this enzyme enables these micro organisms to utilize ACC as a sole nitrogen source by metabolizing in to ammonia and [alpha]-ketobutyrate.

Rhizobacteria can attach to the surface of plant roots or seeds and can take up some of the ACC exuded by the plant and degrade it through the action of ACC deaminase (Glick et al. 1998). Ethylene is required for many plants for seed germination but high levels of ethylene can impede plant growth. PGPR that contain ACC deaminase, when bound to the seed coat of a developing seedling, act as a mechanism for ensuring that the ethylene level dose not become raised to the point where root growth is impaired.

The objective in this study was to investigate the effect of PGPR on yield and yield components of two varieties in saline soil.

Materials and methods

In this experiment we used two varieties of wheat (T. aestivum ssp. Variety falat as sensitive genotype and T. aestivum ssp. Variety Bam4 as tolerant genotype). Wheat seeds were sterilized in 2% sodium hypochlorite for 3 min, And then rinsed 4 times with distilled water. Sixteen seed were sown in each pots (25 cm diameter and 15 cm deep) in a greenhouse under 12000-14000 lux light condition (that created by using sodium and helium lamps), at temperature of 30[degrees]C and 20[degrees]C in day and night, respectively. After sowing, seedlings numbers in any pots were decreased to ten. Soil samples were collected from farm and then transferred to the greenhouse. The soil used was Entisols. The soil characteristics were pH 7.9, EC 0.9 dS [m.sup.-1], total nitrogen 0.025 mg [kg.sup.-1], K 148, P 7.2, Mn 9.84, Zn 0.32, Fe 2.48, and Cu 0.82 mg [kg.sup.-1]. [P.sub.2][o.sub.5] and K2o fertilizer was applied according to the soil analysis. The PGPR effect on salinity levels was conducted by using 4 salinity levels (1, 4, 8 and 12 dS [m.sup.-1]). These saline solutions were prepared by NaCl and Ca[Cl.sub.2] and were applied after two leaves step. Before planting, one drop of Arabic gum added to 15 gr seeds for each pot and then inoculation was performed with 1 gr of inoculum. All plants were harvested after many of panicles were reached.

Four strains of rhizobacteria including Pseudomonas fluorescens 153, 169, Pseudomonas putida 108 and 4 were selected from the microbial bank of soil biology research department of khorasan razavi soil and water research institute. Perlit was used as vector for inoculum preparation. Cell density in Pseudomonas fluorescence 153, 169, Pseudomonas putida 108 and 4 were 1.3 x 109, 1.25 x 109, 1.2 x 109 and 1.01 x 109 per 1 ml, respectively.

After harvesting a total of five traits consist of grain yield, shoot dry weight (biologic yield), grain per panicle, 1000-grain weight and tiller number were evaluated.

The experiment was conducted in completely randomized design (CRD) with split factorial arrangement with 3 replications. The analysis of variance (ANOVA) was performed using the software MSTATC and treatment means were compared by tucky test.

Results and discussion

To alleviate the negative effect of soil salinity on wheat yield and yield components were inoculated four strains of PGPR, Pseudomonas fluorescens 153, 169, Pseudomonas putida 108 and 4.

Results of the measurements on yield and yield components are given in table 1 and 2.

All traits were significantly increased by inoculation with PGPR. We observed significantly differences for all traits under non-salinity and salinity stress. Under non-salinity stress, the grain yield, biologic yield, grain per panicle, 1000-grain weight and tiller number was increased by 26, 29.12, 23, 28.6 and 23.9%, respectively, in comparison to the bacterial control treatment. The grain yield(Fig. 1), biologic yield, grain per panicle, 1000-grain weight(Fig. 2) and tiller number of wheat varieties under salinity stress (EC 12 dS [m.sup.-1]) was also increased by 126, 138, 127, 76 and 66.9% in the PGPR strain treatments compared to the control condition. Grain yield in treatment containing Pseudomonas putida 108 was increased 10.14% compared to the non-salinity stress condition. The reduction of plant yield caused by salinity stress is the most common phenomenon of plants under stress.

[FIGURE 1 OMITTED]

Discussion

We also observed significantly difference between two wheat varieties in bacterial levels for all traits except tiller number. The reduction of yield by salinity stress is the most common reaction of plants under stress condition. This reduction is result of many alterations in physiological activities in the plant. PGPR improved plant yield in saline soils. This promotion effect, however, varied with varieties and soil salinity. The Bam4 variety treated with PGPR had higher yield and yield components than the non-PGPR plants in soil. In this study, inoculation with

The grain yield, biologic yield, grain per panicle, 1000-grain weight and tiller number of wheat varieties under salinity stress (EC 12 dS [m.sup.-1]) was also increased and these findings have been reported by others researchers (Hilali et al. 2000; Weller and Cook 1986; Vasudevan et al. 2002; Cheng 2007) for PGPR effects on yield and yield components. Hilali et al (2000) reported that grain yield of wheat inoculated by rhizoctonia leguminosarum bv. Trifolii were increased in comparison to the control treatment. PGPR strains increased yield and yield components of plant in comparison to the non-inoculated control treatment, and the inoculation with PGPR strains under soil salinity conditions improved yield and yield components compared to the non-inoculated control.

[FIGURE 2 OMITTED]

In conclusion, PGPR promoted phytoremediation was confirmed to be a feasible and effective remediation technique for soils with moderate salinity.

Acknowledgments

We thank the soil and water section of Agriculture and Natural Resource Research Institute in Mashhad for supporting and cooporation in this thesis.

Reference

Cheng, Z., E. Park, B.R. Glick, 2007. 1-Aminocyclopropane-1-carboxylate deaminase from Pseudomonas putida UW4 facilitates the growth of canola in the presence of salt. Canadian Journal of Microbiology, 53: 912918.

Dashti, N., B. Prithiviraj, X. Zhou, R.K. Hynes and D.L. Smith, 2000. Combined effects of plant growth promoting rhizobacteria and genistein on nitrogen fixation in soybean at sub optimal root zone temperatures. J. Plant Nutrition, 23: 593-604.

Drew, M.C., P.S. Hole and G.A. Picchioni, 1990. Inhibition by NaCl of net C[O.sub.2] fixation and yield of cucumber. J. Amer. Society Horticulture Science, 115: 472-477.

Flowers, T., 2004. Improving crop salt tolerance. Journal of Experimental Botany, 55: 307-19.

Glick, B.R., D.M. Penrose and J. Li, 1998. A model for the lowering of plant ethylene concentrations by plant growth-promoting bacteria. Journal of Theoretical Biology, 190: 63-8.

Hilali, A., D. PrZvost, W.J. Broughton and H. Antoun, 2000. Potential use of Rhizobium leguminosarum bv. trifolii as plant growth promoting rhizobacteria with wheat. Abstract. 17th North American Conference on Symbiotic Nitrogen Fixation. Laval University, Quebec, Canada 23-28 July 2000.

Kloepper, J.W., M.N. Schroth, 1978. Plant growth promoting rhizobacteria on radishes. IV International Conference on Plant Pathogenic Bacteria. Angers France, 2: 879-882.

Maurhofer, M., C. Keel, U. Schnider, C. Voisard, D. Hass and G. Defago, 1992. Influence of enhanced antibiotic production in Pseudomonas fluorescens strain CHAO on its disease suppressive capacity. Phytopathology, 82: 190-195.

Noel, T.C., C. Sheng, C.K. Yost, R.P. Pharis and M.F. Hynes, 1996. Rhizobium legominosarum as a plant growth promoting rhizobacterium: direct growth promotion of canola and lettuce. Canadian Journal of Microbiol., 42: 279-283.

Qadir, M., D. Steffens, F. Yan and S. Schubert, 2003. Proton release by N2-fixing plant roots: A possible contribution to phytoremediation of calcareous sodic soils. Journal of Plant Nutrition and Soil Science, 166: 14-22.

Richards, L.A., 1954. Diagnosis and improvement of saline and alkaline soils. United States Salinity Laboratory, California, USA.

Sairam, R.K., A. Tyagi, 2004. Physiology and molecular biology of salinity stress tolerance in plants. Current Science, 86: 407-421.

Shannon, M.C., 1984. Breeding, Selection, and the Genetics of salt Tolerance. Pages 231-254 in J. Wiley, eds. Salinity Tolerance in Plants Strategies for Crop Improvement, New York, USA.

Vasudevan, P., M.S. Reddy, S. Kavitha, P. Velusamy, D. Paul, R.S. Raj, S.M. Purushothaman, Brindha V. Priyadarisini, S. Bharathkumar, J.W. Kloepper and S.S. Gnanamanickam, 2002. Role of biological preparation in enhancement of rice seedling growth and grain yield. Current Science, 83(9): 1140-1143.

Weller, D.M., R.J. Cook, 1986. Increased growth of wheat by seed treatments with fluorescent pseudomonads, and implication of Pythium control. Canadian Journal of Plant Pathology, 8: 328-334.

Woitke, M.H., H. Junge and W.H. Schnitzler, 2004. Bacillus subtilis as growth promoter in hydroponically grown tomatoes under saline conditions. Acta Horticulturae, 659: 363-369.

(1) Abolfazl Abbaspoor, (2) Hamid Reza Zabihi, (3) Sadeq Movafegh and (4) Mohammad Hossein Akbari Asl

(1) Soil Science Department, Agriculture and Natural Resources Research Institute, Khorasan Razavi, Mashhad, Iran

(2) Soil Science Department, Agriculture and Natural Resources Research Institute, Khorasan Razavi, Mashhad, Iran

(3) Jolge Rokh Department, Agriculture and Natural Resources Research Institute, Khorasan Razavi, Mashhad, Iran

(4) Toroq Department, Agriculture and Natural Resources Research Institute, Khorasan Razavi, Mashhad, Iran

Corresponding Author: Abolfazl Abbaspoor, Razavi Khorasan Agriculture and Natural Resources Research Institute Toroq section, Razavi Khorasan Agriculture and Natural Resources Research Institute, Mashhad, Iran.

E- mail: Abolfazl.abbaspour@yahoo.com,

Tel. Number: +98 511 38 22378, Fax Number: +98 511 38 22390
Table 1: Variance analysis of tiller number, grain per panicle,
1000-grain weight, grain yield and shoot dry weight (biologic yield)

               Tiller number     Grain per         1000-grain
                                 panicle           weight

Cultivar(A)                      165.769 **        42.459 *
Error          0.292             2.223             4.732
Salinity(B)    0.879             2116.024          593.750
(A*B)                                              0.003
PGPR(C)        1.350 **          855.745 **        362.549 **
(A*C)                                              0.003
(B*C)          0.916 **          83.562 **         35.186 **
(A*B*C)                                            0.003
Error          0.210             9.614             1.976

               Grain yield       Biologic
                                 yield

Cultivar(A)    39.71             2.085
Error          10.06             72.570
Salinity(B)    613.342           7561.716 **
(A*B)          0.076             0.039
PGPR(C)        607.629 **        5281.731 **
(A*C)          0.075             0.058
(B*C)          20.053 *          139.875 *
(A*B*C)        0.075             0.017
Error          8.489             80.383

* and ** significant at 95% and 99% confidence

Table 2: Measuring results of yield components

Traits                              Variety                 Salinity
                                                            (dS [m.
                                                            sup.-1])

                                    Bam         Falat       1

Tiller number                       1.754       1.754       1.95
Grain per panicle                   40.473      38.122      50.198
1000-grain weight                   33.072      31.882      37.827
Grain yield (g [plant.sup.-1])      26.947      25.796      31.216
Biologic yield (g [plant.sup.-1])   76.884      77.148      95.14

Traits                              Salinity (dS [m.sup.-1])

                                    4           8           12

Tiller number                       1.845       1.601       1.621
Grain per panicle                   43.234      36.519      30.133
1000-grain weight                   34.324      29.732      28.026
Grain yield (g [plant.sup.-1])      28.289      25.37       20.611
Biologic yield (g [plant.sup.-1])   82.339      73.183      57.403

Traits                              Bacteria

                                    Control     PF153       PF169

Tiller number                       1.553       1.519       1.814
Grain per panicle                   32.118      34.008      42.329
1000-grain weight                   27.873      29.315      34.062
Grain yield (g [plant.sup.-1])      20.864      22.611      27.993
Biologic yield (g [plant.sup.-1])   61.435      63.78       84.502

Traits                              Bacteria

                                    PP108       PP4

Tiller number                       2.108       1.776
Grain per panicle                   46.18       41.849
1000-grain weight                   37.518      33.618
Grain yield (g [plant.sup.-1])      33.726      26.662
Biologic yield (g [plant.sup.-1])   97.163      78.201

PF153, Pseudomonas fluorescens 153,
PF169, Pseudomonas fluorescens 169
PP108, Pseudomonas putida 108
PP4, Pseudomonas putida 4
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Title Annotation:Original Articles
Author:Abbaspoor, Abolfazl; Zabihi, Hamid Reza; Movafegh, Sadeq; Asl, Mohammad Hossein Akbari
Publication:American-Eurasian Journal of Sustainable Agriculture
Article Type:Report
Geographic Code:7IRAN
Date:Dec 1, 2009
Words:2294
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