الفهرس 
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Abstract
The current work could be summarized in two parts:
A. The first part was carried out at seedling stage to investigate the effect of different osmotic stress levels by NaCl (0.0, -0.3, -0.6, -0.9,-1.2, -1.5 and -1.8 MPa) and interaction with addition either Zn (20 and 200 µM) or Ni (1 and 100 µM) on growth parameters of four wheat cultivars (Sakha 94, Gimiza 11, Gimiza 10 and Giza 168). These cultivars brought from three different breeding programs (Sakha, Gimiza, and International research Centre of agriculture).
B. The second part was conducted to study the effect of different concentrations of osmotic stress levels using NaCl (0.0, -0.3, -0.6, -0.9 and -1.2 MPa) and interaction with addition either Zn (20 and 200 µM) or Ni (1 and 100 µM) on the growth and metabolic sequences in two wheat cultivars (Sakha 94, and Giza 168) during the vegetative and crop yield stages.
The obtained results can be summarized in the following points:
1. At seedling stage, the successive increase in osmotic stress levels induced relative reduction in dry matter of root and shoot of the four wheat tested cultivars.
2. At seedlings stage, results demonstrated that Sakha 94 was the most salt-tolerant cultivar followed by Gimiza11 followed by Gimiza 10 and the most sensitive cultivar was cv. Giza 168.
So the salt tolerance of the four wheat cultivars, during seedling stage ranked as the following:
(cv. Sakha 94 > cv. Gimiza 11 > cv. Gimiza 10 > cv. Giza 168)
3. Zn and Ni application at seedling stage considerably alleviated the effect of salinity stress in both intermediated salt tolerant cultivars (Gimiza11 and Gimiza 10) and with low effect in salt-sensitive cv. Giza 168, while resulted in an inhibition effect in salt-tolerant cv. Sakha 94.
4. Fresh and dry matter yield declined significantly in roots, shoots and spikes with increasing osmotic stress levels during the vegetative and crop yield stages, this reduction was observed even at the lowest concentration of osmotic stress of the two tested cultivars cv. Sakha 94 and cv. Giza 168. The rate of decline in these growth parameters was greater at high osmotic stress levels and in salt-sensitive cv. Giza 168 more than the salt-tolerant cv. Sakha 94. Also, it is worthy to mention that root was the most sensitive organ in the both tested cultivars.
5. Treatment of cv. Sakha 94 and cv. Giza 168 with either 20 or 200 µM of Zn increased significantly the fresh and dry matter of roots, shoots and spikes. Also, Ni treatment with 1 µM induced an increasing effect in growth yield of three organs of both tested cultivars. While treatment with 100 µM of Ni in cv. G.168 caused un-changed effect in the growth parameter or tended to be decreased in the three tested organs while an enhancement effect was observed in cv. Sakha 94 in the three tested organs.
6. Leaf area in the two tested wheat cultivars decreased with elevated osmotic stress levels. While Zn or Ni treatments mostly increased leaf area, this enhancement reached 2-folds, in some cases, in cv. Sakha 94. Moreover, a minor increasing effect was recorded in the leaf area of cv. Giza 168 with both concentrations of Zn and at higher concentration of Ni (100 µM) but no change with 1 µM of Ni.
7. Soluble sugars in roots and shoots of cv. Sakha 94 were significantly decreased as increasing osmotic stress levels. Soluble sugar in all organs of cv. Sakha 94 was accumulated at moderate and high levels of osmotic stress combined with 20 or 200 µM of Zn. While, increasing in osmotic stress levels showed an accumulation in roots, shoots and spikes of cv. Giza 168. Treatment cv. Giza 168 plant with Zn or Ni concentrations mostly led to an increasing effect in soluble sugars in roots, shoots and spikes.
8. There was an irregular increasing effect in total carbohydrates in roots of cv. Sakha 94, whereas in shoots a significant reduction was observed. A surprising accumulation in total carbohydrate contents was exhibited in spikes. Mineralization treatment resulted in a significant accumulation in total carbohydrates in roots, while there was no obvious effect in shoots. Moreover, Zn treatments induced a marked increase in total carbohydrate contents in spikes, while, there was a reduction effect with Ni concentrations.
9. Elevating OSL exhibited a significant inhibitory effect in the accumulation of total carbohydrates in roots, shoots and spikes of cv. Giza 168, while, Zn with either concentration (20 or 200 µM) provided no marked change in roots, while in shoots showed a marked increase especially at high osmotic stress levels that reached about 2-folds. Plants exposed to 1 or 100 µM Ni induced a significant increase in total carbohydrates in three tested organs of cv. Giza 168.
10. Treatment of wheat cultivar Sakha 94 with different osmotic stress levels brought a reduction in soluble protein content in roots, shoots and spikes. In wheat cultivar Giza 168, soluble protein content exhibited some activation in shoots, but in roots and spikes soluble protein contents became more or less unchanged or tended to increase slightly especially in spikes. Zn or Ni treatments induced mostly no marked effect in soluble protein in Sakha 94, while, in cv. Giza 168, soluble protein contents decreased mostly at Zn or Ni treatment in both organs roots and spikes, while in shoot organ there was an irregular pattern in soluble protein contents.
11. Treatment of cv. Sakha 94 with various osmotic stress levels indicated that total protein remained mostly unchanged in both roots and spikes, while, a smooth reduction was recorded in shoots. Actually, treatments cv. Sakha 94 with both tested concentrations of Zn or Ni exhibited no marked effect in the accumulation of total protein in roots, shoots and spikes.
12. Successive increase in OSL indicated that while an irregular trend in total protein was induced in both roots and shoots of cv. Giza 168, a huge accumulation was recorded in spikes organ. Total protein in roots and spikes of cv. Giza 168 went mostly in a similar trend with corresponding levels of osmotic stress with mineral treatments (Zn or Ni); while in shoots, an enhancement effect was recorded.
13. The production of proline in wheat cultivar Sakha 94 was decreased with increasing osmotic stress levels in roots and spikes, while there was a significant enhancement in proline content in shoots at high osmotic stress levels. Proline was markedly reduced in the three tested organs under Zn or Ni treatments.
14. In wheat cultivar Giza 168, proline content was decreased in the three tested organs as increasing osmotic stress levels. Treatment with 20 µM of Zn induced, in most cases, unchanged effect in proline content in roots and spikes, whereas in shoots a reduction trend was observed. While treatment with 200 µM of Zn resulted in a significant increase in proline content in shoots and spikes. Treatment of cv. Giza 168 with 1 or 100 µM of Ni induced unchanged effects or the values of proline content tended to be decreased in the three tested organs.
15. A significant increase was detected in Na+ content in both organs shoots and spikes in cv. Sakha 94 with successive increase in osmotic stress levels, while mineralization treatment induced a reduction in these organs. Also, sodium ion content in wheat cultivar Giza 168 was increased in roots and shoots as increasing osmotic stress levels, while in spike, a significant reduction was recorded. Whereas, mineral treatments with Zn or Ni induced a marked reduction in Na+ content in the three organs as compared with corresponding levels.
16. In cv. Sakha 94, a huge reduction was recorded in K+ content in root organ, while, there was an irregular trend in both shoots and spikes. Also, there was no marked change occurred in K+ content in the three organs of cv. Sakha 94 under mineralization treatment. Whereas, there was an increasing effect in K+ content in roots that exposed to 20 µM of Zn or 100 µM of Ni as compared with corresponding levels.
17. In cv. Giza 186, increasing in osmotic stress exhibited a significant reduction in K+ content in roots, shoots and spikes, while, K+ content was increased in roots, shoots and spikes exposed to 200 µM of Zn. Treatment with Ni application remained K+ content unchanged in roots and spikes, while induced a marked increase in shoots especially in plants exposed to 1 µM of Ni.
18. Zn ion content in cv. Sakha 94 was increased in spikes that reached 2-folds at -1.2 MPa osmotic stress level. Mineral treatments mostly stimulated the accumulation of Zn element in spikes with or without osmotic stress treatments. While in spikes of cv. Giza 168 that treated with -1.2 MPa accumulated high amount of Zn in relation to its control. Exogenous application with low or high concentrations of Zn or Ni exhibited a reduction in Zn content in spikes. Except from this trend, plants treated with 200 µM of Zn in both control and -1.2 MPa level exhibited increasing effect in relation to control.
19. A slight reduction in the accumulation of Ni ion content was recorded in spikes of cv. Sakha 94 that treated with -1.2 MPa osmotic stress level in relations to control. Mineral treatment with both low and high concentrations of Zn or Ni induced a significant reduction in the accumulation of Ni with control or salinization level (-1.2 MPa).
The opposite trend was occurred in cv. Giza 168 as an accumulation of Ni was exhibited at -1.2 MPa salinization level. There was a stimulation effect in the accumulation of Ni especially with control plants, however Ni content ran around the corresponding level in all Zn or Ni treatments.
20. Peroxidase activity and its staining in cv. Sakha 94 were increased at -0.6 MPa, while were decreased at -1.2 MPa OSL. Zn application with 20 µM concentration increased peroxidase activity of salt-stressed plant. Opposite to the previous trend, peroxidase activity was obviously decreased with 200 µM of Zn or with 1 µM of Ni, while its activity was pronounced at 100 µM of Ni treatment. In cv. Giza 168, the enzyme activity and its staining were markedly decreased with elevating osmotic stress levels, while, Zn or Ni application with both low and high concentrations enhanced peroxidase activity.
21. In cv. Sakha 94, there are 3 isoforms bands of esterase (EST1, EST3, and EST4) under osmotic stress levels, while, mineral applications with 20 and 200 µM of Zn exhibited a lowering effect in esterase activity (EST1 and EST4) at all OSL, while EST3 was markedly increased at -0.9 MPa OSL plus 20 µM of Zn. Additionally, it was increased at -0.6, -0.9 and -1.2 MPa OSL plus 200 µM of Zn.
It was interesting to say that at Ni treatment with either 1 or 100 µM, EST5 isoform was appeared with the other isoforms (EST1, EST3, and EST4). Bands of EST1 and EST3, were prominently decreased as elevating osmotic stress levels as compared with corresponding OSL, while EST4 and EST5 bands were increased at all osmotic stress levels.
22. In cv. Giza 168, there are 4 isoforms of esterase enzyme under OSL treatments (EST1, EST3, EST4 and EST5). There was a surprising appearance of new isoform band EST2 with other isoforms (EST1, EST3 and EST4); while EST5 was dis-appeared at all osmotic stress levels with low and high concentrations of Zn. There was an enhancement effect in intensity of EST1 and EST3 as compared with corresponding level, however EST4 was decreased.
There was a huge intensity in staining in EST1, EST2 and EST3 isoforms as compared with corresponding level and absolute control under application with 1 or 100 µM of Ni. This observation was run with a reduction in the activity of EST4 and return appearance of EST5.
23. Anthocyanin pigments in cv. Sakha 94 were unchanged from -0.3 to -0.9 MPa OSL, after that a significant reduction was recorded at high OSL level, while, in cv. Giza 168 anthocyanin was decreased with successive increase in osmotic stress levels. In wheat cultivar Sakha 94, there was a significant increase in anthocyanin pigment especially at high osmotic stress levels under both mineral treatments. In wheat cultivar Giza 168, a smooth increase was documented in anthocyanin pigment at high osmotic stress levels in both concentrations of Zn and Ni.
24. Ascorbic acid was increased in cv. Sakha 94, while in cv. Giza 168 tended to decrease at all levels of osmotic stress. ASA content becomes more or less unchanged at all concentration of Zn. While a significant increase was observed in ascorbic acid at - 1.2 MPa with 1 µM of Ni and at -0.6 and -0.9 MPa OSL with 100 µM of Ni. In wheat cultivar Giza 168, ascorbic acid was significantly elevated at all osmotic stress levels with both concentration of Zn and Ni.
Finally, the outcomes of this study provided us with the concept that growth parameters, physiological insights, antioxidant compounds and enzymes induced by salt stress were good criteria for selecting salt-tolerant wheat cultivar and try to improve this tolerance through micronutrients applications such as Zn or Ni.