الفهرس 
LITERATURE REVIEWOnly 14 pages are availabe for public view
Abstract
SUMMMARY
This investigation was carried out to study the impact of foliar spraying with Bacillus subtilis suspension and/or Spirulina platensis extract alone /or in combination as bio-stimulants to alleviate the toxic effect of different concentrations of salinity (75 and 150 mM NaCl) on common bean plants. The seeds were divided into three groups and each group was irrigated with a certain concentration of sodium chloride (0, 75 and 150 mM). Each group was divided into four subgroups. Plants in the first group served as control in which no biostimulants were applied, while the second and third groups were sprayed with bacteria and algal extracts respectively, the fourth group was treated with combined bacteria and algal extract.
Morphological and biochemical studies were carried out on plant shoots, roots and seeds during the different stages of growth.
The main experimental results can be summarized in the following:
1- Salinity concentrations (75 and 150 mM NaCl) caused a significant decrease in the morphological parameters of common bean plant, shoot and root lengths as well as fresh and dry weight, number of leaves/ plants and assimilating area during the vegetative and flowering stages. In addition, treatment with biostimulants (bacterial suspension, algal extract and their mixture) led to a significant increment in the morphological parameters of the treated plants as compared with control.
2- Treatment with different concentrations of salinity led to a decrease in the photosynthetic pigments content such as chlorophyll a and b, carotenoids and the total content of pigments. Biostimulants (bacterial suspension, algal extract and their mixture) led to an increase in the same content in treated plants individually or in combination with different concentrations of salinity.
3- Irrigation of plants with salinity concentration (75 and 150 mM NaCl) caused a decrease in the soluble sugar content of the shoot and root in the vegetative and flowering stages. On the contrary, salinity increased the content of free amino acids and proline contents. The results also showed a significant improvement in the content of sugars, free amino acids and proline content in response to treatment with biostimulants.
4- Salinity concentrations (75 and 150 mM NaCl) caused an increase in the content of anthocyanins, α-tocopherol and ascorbic acid in common bean shoot and root. In addition, treatment with biostimulants (bacterial suspension, algal extract and their mixture) increased the previous mentioned.
5- The shoot and root contents of some enzymatic antioxidants (polyphenol oxidase, peroxidase and catalase) were also studied, salinity induced a significant increment in studded enzymes while further increment in plants treated with biostimulants compared to the untreated plants was recorded.
6- The results also showed an increase in the content of phenols and flavonoids in shoot and root of plants treated with biostimulants in both salinity stressed and unstressed plants.
7- The salinity concentrations (75 and 150 mM NaCl) caused elevation in H2O2 and MDA content in the shoot and root of common bean plants. On the contrary, treatment with biostimulants (bacterial suspension, algal extract and their mixture) decreased H2O2 and MDA contents.
8- The mineral contents of the root and shoot as well as the seeds of common bean were also studied. The results indicate that the content of potassium, phosphorous, calcium, magnesium, nitrogen, zinc and iron were decreased as a result of treating the plant with different concentrations of salinity compared with the unstressed plants. At the same time, the concentration of both sodium and chlorine ions were increased under the influence of the same treatment. The results also indicate that the effect of biostimulants alone or in combination with salt concentrations (75 and 150 mM NaCl) led to an improvement in the content of potassium, phosphorous, calcium, magnesium, nitrogen, zinc and iron in plants, as well as a decrease in the concentration of sodium and chlorine ions.
9- The results showed that salinity stress induced a significant decrease in the number of pods/ plants, the dry and fresh weight of the pods, the length of the pods and the weight of 1000 seeds, as well as a decrease in the total content of protein and soluble sugars in the seeds. The results also showed the positive effect of biostimulants in plant productivity enhancement as compared with the control plants.
10- Based on our results, we recommend using biostimulants to help improve the growth of plants grown under salt stress and mitigate the negative effects of stress.