علیرضا امینی حاجی آبادی

The demand for wheat as the most important grain used by humans is increasing. Due to climate change and improper soil and water management, salinity stress reduces wheat yield. The use of plant growth promoting rhizobacteria is a nature-friendly way to reduce the effects of salinity stress on wheat yield. The aim of this study was to evaluate the effect of plant growth promoting bacteria isolated from the rhizosphere of several saline plants in Yazd province on total biomass and yield components of wheat (var. Ghods).

Plant growth promoting characteristics and salinity resistance of bacteria isolated from rhizosphere of Atriplex lentiformis, Seidlitzea rosmarinus, Tamarix ramosissima and Halostachys belangeriana were investigated. Wheat seeds were inoculated with superior bacteria including Bacillus safensis, B. pumilus and Zhihengliuella halotolerans and after planting in the pots in greenhouse conditions was irrigated with water with salinities of 4, 8, and 16 ds/m.

All three bacteria were able to produce auxin. The highest amount of auxin production was measured in B. safensis (29.72 μg / ml). All three bacteria were able to produce hydrogen cyanide and the highest amount of hydrogen cyanide production was observed in Z. halotolerans with grade 5 (very high). All three bacteria were able to produce siderophore. ACC deaminase production was observed in all three bacteria and the highest amount was measured in B. pumilus at 8 μg / ml. Ability to dissolve phosphate in Z. halotolerans was more than twice that of B. safensis. Salinity reduced all the measured indices in wheat. In bacterial inoculated treatments at all salinity stress levels (4, 8 and 16 ds/m), the average of total biomass, amylose and amylopectin increased up to 52.5, 21.3 and 10.3%, respectively, compared to the average of these indices in control treatments (without bacteria) in the same salinity levels. Also, bacteria in these levels increased spike weight, seed weight and number of seeds up to a maximum of 22, 74.6 and 66.6%, respectively, compared to the control (without bacteria) of these salinity levels.

the plant growth promoting bacteria increased yield components of wheat under salinity stress, therefore to reduce the effects of salinity on wheat under saline irrigation conditions; the bacteria studied in this experiment can be used. Z. halotolerans was more efficient than other two bacteria in all of the studied indices. Since the experiment was performed under greenhouse conditions, it is recommended that this experiment be performed in the field.

Reducing wheat production due to salinity stress is one of the most important food security challenges worldwide. Plant rhizosphere bacteria reduce the effect of salinity stress on plants, including wheat, by mechanisms such as modulating plant hormones, making nutrients available to the plant, and combating pathogens. This study was designed and performed with the aim of increasing the salinity resistance of wheat (var. Ghods) using salinity-resistant growth-promoting bacteria isolated from the rhizosphere of several halophyte plants in Yazd province.

Growth-promoting traits and salinity resistance of bacteria isolated from rhizosphere of plants Atriplex lentiformis (Torr.) S. Watson، Tamarix ramosissima Ledeb. Seidlitzia rosmarinus Ehrenb. ex Bois and Halostachys belangeriana (Moq.) Botsch. were investigated. Wheat seeds were inoculated with superior bacteria in terms of growth-promoting traits and salinity resistance, including Bacillus safensis, Bacillus pumilus and Zhihengliuella halotolerans. During the growth period, physiological parameters of chlorophyll a, chlorophyll b and total chlorophyll, proline, enzymatic activity of antioxidants, phenol and total soluble sugars in the leaves were measured.

All three bacteria were able to produce auxin. The highest amount of auxin production was measured in B. safensis (29.72 μg / ml). All three bacteria were able to produce hydrogen cyanide and the highest amount of hydrogen cyanide production was observed in Z. halotolerans with grade 5 (very high). All three bacteria were able to produce siderophore. ACC deaminase production was observed in all three bacteria and the highest amount was measured in B. pumilus at 8 μg / ml. Ability to dissolve phosphate in Z. halotolerans was more than twice that of B. safensis. The results of wheat leaf analysis showed that with increasing salinity, (without bacteria inouculation) chlorophyll content in all treatments decreased, instead the amount of proline, antioxidant activity, the amount of phenol and the amount of soluble sugars decreased compared to the control (0.2 ds/m). The use of bacteria increases chlorophyll a, chlorophyll b, total chlorophyll, proline, total phenol, total antioxidants and total soluble sugar compared to without bacteria inoculation treatment.

The growth-promoting bacteria under study with a set of growth-promoting mechanisms significantly improved the resistance of wheat to salinity stress. Therefore, the bacteria studied in this experiment can be used to reduce the effects of salinity on wheat var Qhods under saline irrigation. B. safensis, in salinity of 8 ds/m, more than the other two bacteria, improved the physiological indices of salinity resistance of Qods wheat. Since this experiment was performed under greenhouse conditions, it is recommended that this experiment be performed in field conditions to complete the findings.

Salinity stress is an important challenge for wheat production in the world. Plant growth promoting rhizosphere bacteria, isolated from halophytic plants, can increase the tolerance of crop plants to salinity by direct and indirect mechanisms. In this study, plant growth-promoting traits of bacterial strains (Bacillus safensis, Bacillus pumilus and Zhihengliuella halotolerans), isolated from the rhizosphere of several halophyte plants, were deterimined and their effects on some vegetative traits and ionic content of wheat plant irrigated with saline water ( 0.2, as control,  4, 8 and 16 dS/m) were measured. Result showed that all three bacteria were able to produce auxin, hydrogen cyanide, siderophore, 1-aminocyclopropane-1-carboxylic acid deaminase and soluble phosphate. The increase in salinity levels caused increase in the concentration of sodium and decrease in the concentration of potassium, calcium and phosphorus in wheat leaves, as well as decrease in stem length, shoot and root dry weight, root to shoot dry weight ratio and total biomass. In wheat plants irrigated with saline water and inoculated with the bacterial strains, sodium concentration decreased up to 17.7% and concentrations of potassium, calcium, phosphorus and potassium to sodium ratio increased up to 33, 25.7, 200.4 and 41%, respectively. The most efficient bacterium was found to be Z. halotolerans. All bacterial isolates also increased stem length, shoot and root dry weight, root to shoot dry weight ratio and total biomass by 17, 58.6, 137, 88 and 66 %, respectively. The results of this study showed that the plant growth-promoting bacteria of rangeland halophytic plants potentionally improve the growth indices of wheat plants in saline conditions. These results also showed that the rhizosphere of halophytic plants in rangelands can be a good source for the isolation of salinity-resistant bacteria to improve the resistance of wheat plants to salinity.

A number of halophytic species as Salicornia europea, Halocnemum strobilaceum, Aeluropus lagopoides, and Aeluropus littoralis were found to occupy a significant portion of the total vegetation of the surrounding area at the Zayande-Roud inlet to Gavkhoony wetland. However, their ecological demands and bioenvironmental factors by which vegetation community composition has been affected is not undestood. A compehensive knowledge of the establishment is essential for future improvements in using the above species on salanized regions. In this paper, using the ordination method. The establishment pattern of  these four species in a range of varied habitats is evaluated based on the recongition of the relative  significance of habitat soil chemical properties and vegetion crown cover to the establishment of the four species. For this purpose, 48 plants meansurements were taken along a transect, having more species variation in term of vegetation cover percentage. Furthermore, 48 soil samples were taken from the plot along the same transect in a one-year period in 1999. The soil samples were analysed for PH, EC, available Na, K, Ca and Mg as well as clay, and silt contents. The ground and field vegetation data were analysed using the Principlas Components Analysis (PCA), and Canonical Correspondence Analysis (CCA) to produce summary vectors (PCA axes) of both the soil chemistry and habitat vegetation structure datasets. The summary of ordination method quantified the degree to which soil variables and species cover were related to variability in ground vegetation composition. variation in community composition (type and percentage) was significantly related to gradient of the aforementioned soil factors. Generally, the vegatation community composition in this experiment could be considered as a key component to expand the growth and development patterns of these species to similar salinised regions.