Antioxidative responses of Calendula officinolis under salinity conditions. Plant Physiol. ... 27: 327-342. 40. Bekheta, M. A. and H. M. S. El â Bassiouny (2005).
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INCREASING SUNFLOWER SALT TOLERANCE USING NICOTINAMIDE AND α – TOCOPHEROL M.Sh. Sadak1, M.M. Rady2, N.M. Badr3, M.S. Gaballah3 1
Botany Department, National Research Centre Botany Department, Faculty of Agricultural El-Fayoum University 3 Water Relations and Field Irrigation Department, National Research centre (EGYPT) 2
ABSTRACT Reducing the spread of salinization and increasing the salt tolerance of high yielding crops are key global issues. In this regard an experimental design was laid out during two successive seasons of 2008 and 2009 at three different sites of soil salinity levels (1.56, 4.68, and 7.83 dS/m) at the experimental farm of faculty of Agriculture, Fayum University, Egypt. The experiment was conducted to determine how can priming seeds in αtocopherol or nicotinamide mitigate the negative effects of salinity on sunflower growth and yield. The experiment was designed using randomized complete block design on three different salinity levels,using two sunflower cultivars (hysun336 and Euroflor),two treatments (25or50 mg/l α-tocopherol) or (2.5 or 5mg/l nicotinamide) and three replications. The results revealed soil salinity significantly reduced plant height ,root size/plant, number of leaves/plant, area of leaves/plant ,shoot dry weight/plant, total chlorophyll ,total carotenoids and total pigments. Also soil salinity decreased yield and yield attributes, although the use of α-tocopherol and nicotinamide improved plant growth and yield. The maximum yield was attained by Hysun336 cultivar and 5mg/l nicotinamide treatment. Key words: sunflower, salinity, α-tocopherol, nicotinamide, growth, yield, IAA, carbohydrates, protein and oil 1. INTRODUCTION As a result of human activities of last decades, soil salinity had become a serious problem in both agricultural and natural ecosystems. About 20% of the cultivated area and nearly half of all irrigated lands in the world are affected by salinity. Salinity is one of the major abiotic stresses in arid and semiarid regions that (1) substantially reduce plant growth and average yield of major crops by more than 50%. These losses are of (2) great concern for most countries, like Egypt the economy of which rely mainly on agriculture. High salt concentration in the soil solution is bound to create high osmotic pressure in the root zone and reduce availability of water and nutrients to plants. Such conditions are known to affect plant physiological activities that determine (3) crop yield. Osmotic stresses, ion imbalances and the direct toxic effects of ions on the metabolic processes are (4) the most important and widely studied physiological impairments caused by salt stress. Salt stress also, induces (5) oxidative damage to plant cells catalyzed by reactive oxygen species (ROS). The level of ROS are regulated by their rates of generation, their rate of reaction with target substances such as proteins, lipids and/or nucleic acids, their potential rate of degradation and their rate of scavenging / buffering by enzymatic and/or non enzymatic (6) antioxidants. ROS, which produced as a result of salt stress, leads to chlorophyll degradation, photo damage (7) and lipid peroxidation. Out of various compounds exploited to alleviate the plant stress, vitamins from which nicotinamide and αtocopherol. Vitamins are required in trace amounts to maintain normal growth and proper development of all organisms; these compounds act as coenzyme systems and thus take essential part in the regulation of metabolism. α-Tocopherol (vitamin E) is lipophilic antioxidants synthesized by all plants. α-tocopherol protects lipid membranes from oxidative stress because they deactivate singlet oxygen, reduce superoxide radicals, and (7) terminate lipid peroxidation by reducing fatty acyl peroxy radicals. α-Tocopherols interact with the polyunsaturated acyl groups of lipids, stabilize membranes and scavenge & quench various reactive oxygen species (ROS) (8) and lipid soluble by products of oxidative stress. Nicotinamide (Vit. B) is a well-characterized constituent of the pyridine dinucleotide coenzymes NADH & (9) NADPH, which are involved in many enzymatic oxidations - reductions reactions in living cells. In addition, nicotinamide is a stress –associated compound that induces and regulate secondary metabolic accumulation (10) and/or the manifestation of defense metabolism in plants. Nicotinamide might be a link between various types (9) of stress which leads to an increased frequency of DNA strand breaks, and plant defensive gene transcription. Sunflower (Helianthus annuus L.) is an important oil seed crop worldwide, and it is an important crop in (11) Mediterranean areas where salinity is an increasing problem. Sunflower is moderately sensitive to soil salinity; the promotion of sunflower could be successful to increase the domestic production provided proper cultivars are (12) available which are suitable to different soil and climatic conditions. This work was designed to study the possibility of both vitamins, α-tocopherol or nicotinamide to alleviate the drastic effect of salt stress and increase sunflower salttolerance. The effect of soaking seeds in different
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concentrations of α-tocopherol or nicotinamide on growth, photosynthetic pigments, indole acetic acid contents, carbohydrates, protein, yield and protein and oil yield of the yielded seeds were investigated. 2. MATERIALS AND METHODS Experimental Design: A field experiment was conducted at the experimental farm of Faculty of agriculture, Fayoum University, Fayoum, Egypt during two successive seasons (2008 and 2009),at different sites with soil salinity levels (1.56,4.68 and 7.83 dS/m), the physical and chemical analysis was recorded in Table (1). Soil analysis was (13&14) carried out according to Black et al and Jackson. At soil preparation fertilizers supplemented with full dose 200 kg/fed of calcium superphosphate (15.5% P2O5), 200 kg/fed ammonium nitrate (33.5% N) and 50 Kg/fed potassium sulphate (48% K2O) were incorporated into the top 15 cm of the soil. Normal agricultural practices common in the area were followed. Seeds of sunflower were obtained from Agricultural Research Centre, Egypt. Two cultivars were chosen namely Hysun 336 and Euroflor. Soaking seeds for 12 hrs in different concentrations of nicotinamide (0.0, 2.5 and 5 mg/l) and (0.0,25 and 50 mg/l) α-tocopherol.. The seeds of two cultivars were sown in split split plot design and treatments were triplicated in rows of 4-meter long, 0.60-meter apart and 6 ridges with total area (14.4 m2). Hill spacing was 10 cm within the row. Seeds were sown at 3-5 seeds in each hill in the first week of April in both seasons. The site of each experiment was the main plot, vitamins as subplot and concentrations of α-tocopherol or nicotiamide as sub sub plot. Normal Irrigation water was used immediately after sowing, then every one week interval according to agronomic practices in the district. Thinning was carried out at 15 days after sowing to secure two plants per hill on both sides of the ridge. Table 1. Soil physical and chemical characteristics of the three sites used before planting
Properties Sand%, coarse Fine Silt% Clay% Soil texture pH (1:2.5) EC (ds/m) Organic matter% CaCO3 Total N% P K Fe Mn Zn Cu
Site 1 (1000 mg/l) Site 2 (3000 mg/l) Mechanical analysis 3.15 3.75 63.85 65.25 19.75 20.25 13.25 10.75 Sand loamy Sand loamy Chemical analysis 7.36 7.64 1.56 4.68 1.42 1.38 9.34 8.56 0.09 0.07 Available nutrients (mg/Kg soil)8.36 5.16 7.02 201.24 198.1 7.03 5.94 1.52 1.04 0.88 0.79 0.67 0.59
Site 3 (5000 mg/l) 2.85 47.15 20.50 29.50 Sand clay loamy 7.81 7.83 1.25 8.05 0.06 8.36 181.15 5.37 0.98 0.76 0.63
Plant sampling: Three plant samples/plot were harvested 50 days after sowing for determination of the growth criteria 2 2 (Plant height (cm), root size (cm ), number of leaves / plant, total leaves area / plant (cm ) as well as dry weight of leaves and shoot / plant (g). At harvest samples were collected for determination of yield components as: head diameter (cm), seeds weight / head (g), 100 seeds weight (g) and seeds weight / fed.( ton). Chemical analysis: Estimation of total chlorophylls and total carotenoids of vegetative samples were carried out according (15) (16) to. IAA contents as μg/100g fresh weight was determined as. Determination of total carbohydrates of the two (17) cultivars of sunflower were carried out according to. (18) Also, total protein % of the yielded seeds was determined according to. Total oil of the yielded seeds (19) /fed (Kg) were estimated by the method of. Statistical analysis: (20) The obtained data was statistically analyzed on complete randomized design according to. Means were compared by least significant difference (LSD) at 5% levels of probability.
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3. RESULTS Growth parameters: Table (2) illustrates the effect of α-tocopherol and nicotinamide on growth parameters of both sunflower cultivars (Hysun 336 and Euroflor) under three salinity levels. Data show that, increasing salinity levels resulted in significant gradual reductions of growth parameters (plant height, root size/plant, leaves number & leaves area/plant and dry weight of shoot/plant) except root size / plant at 4.68ds/m was non significant. Results also show that, priming of sunflower seeds by soaking seeds in the mentioned concentrations of αtocopherol or nicotinamide improved growth under salinity stress conditions. It was noticed that growth characters for both sunflower cultivars Hysun 336 and Euroflor were increased with increasing concentration of both αtocopherol and nicotiamide. The maximum of increases were obtained by using 5.0 mg/l nicotinamide and 50 mg/l α – tocopherol respectively, in the two cultivars at the three salinity levels. Table 2. Effect of α-Tocopherol and nicotinamide on morphological criteria of sunflower cultivars (Hysun 336 and Euroflor) under different levels of soil salinity Treatment
α-Tocopherol
Nicotinamide
α-Tocopherol
Material (mg/l)
α-Tocopherol Nicotinamide
7.83
Nicotinamide
4.68
1.56
Salinity ds/m
Plant height (cm)
LSD at 5%
Root size/plant (cm3)
Number of leaves /plant
Area of leaves /plant (dm2)
Dry weight of shoot (g)
Hysun 336
Euroflor
Hysun 336
Euroflor
Hysun 336
Euroflor
Hysun 336
Euroflor
Hysun 336
Euroflor
0.0
84.30
80.30
294.60
284.60
16.00
14.30
6.40
5.73
26.54
23.05
25
87.30
83.00
306.60
294.00
16.60
15.00
7.50
6.76
32.35
28.18
50
93.00
87.60
330.00
315.30
18.60
16.60
9.30
8.30
41.75
36.11
2.5
90.00
85.30
319.00
304.66
17.30
15.60
8.60
7.83
37.86
33.13
5.0
95.60
91.30
334.30
322.00
19.60
16.60
10.80
9.16
48.43
39.85
0.0
71.66
66.30
254.30
251.00
13.60
12.30
4.80
4.33
18.33
15.87
25
76.60
71.60
261.60
258.60
14.30
13.00
6.46
5.86
26.09
22.54
50
85.30
81.30
310.60
289.30
15.60
14.60
7.06
6.63
29.52
26.56
2.5
80.30
76.00
287.00
275.30
15.00
13.60
6.76
6.16
27.07
23.82
5.0
85.30
80.60
318.60
294.00
16.00
15.60
8.00
7.83
33.32
31.58
0.0
61.30
58.00
221.60
214.30
12.00
11.30
3.60
3.40
12.79
11.59
25
65.60
60.30
231.30
223.60
13.00
12.00
4.56
4.23
16.89
14.98
50
72.00
64.30
254.00
232.30
14.00
12.60
5.60
4.43
21.59
18.78
2.5
68.00
61.30
242.60
228.00
13.30
12.60
5.33
5.06
12.88
17.92
5.0
71.60
65.60
263.00
239.00
14.30
13.60
6.46
6.16
24.89
22.67
3.78
43.38
1.30
0.55
2.16
Changes in photosynthetic pigments: Data in Table (2) clearly show that, increasing salinity levels from 1.56 to 4.68 to 7.83 dS/m resulted in a reduction of total chlorophyll, carotenoids and total pigments of the two tested cultivars. Maximum reduction was obtained at 7.83 ds/m salt. An average reduction of 43.33 % and 38.51 % in total chlorophyll, 24.53 % and 29.00% in total carotenoids and 28.86 % and 30.92 % in total pigments contents were observed for Hysun 336 and Euroflor cultivars respectively as compared with plants grown at 1.56 dS/m salinity. It is clear that, Hysun 336 cultivar had more contents of photosynthetic pigments than Euroflor. Soaking sunflower seeds with α-tocopherol or nicotinamide with different concentrations significantly increased total chlorophyll, total carotenoids while in total pigments the increases were non significant compared with the corresponding salinity levels (Table 3). Data also show that, nicotinamide was more effective than αtocopherol in ameliorating salinity stress effects. High concentrations of both vitamins were more effective than low concentration the most pronounced treatment ( 5 mg/l nicotinamide) (Table 3).
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Table 3. Effect of α - Tocopherol and nicotinamide on some chemical contents of sunflower cultivars (Hysun 336 and Euroflor) under different levels of soil salinity Euroflor) under different levels of soil salinity. Treatment
α-Tocopherol
Nicotinamide
α-Tocopherol
Material (mg/l)
α-Tocopherol Nicotinamide
7.83
Nicotinamide
4.68
1.56
Salinity ds/m
Total chlorophyll
LSD at 5%
Total carotenoids
Total pigment
mg/g fresh weight
Total Indole
Total carbohydrates
Total Protein %
μg/g fresh weight
Hysun 336
Euroflor
Hysun 336
Euroflor
Hysun 336
Euroflor
Hysun 336
Euroflor
Hysun 336
Euroflor
Hysun 336
Euroflor
0.0
0.240
0.200
0.803
0.793
1.043
0.993
43.930
41.930
14.8
13.96
10.44
10.35
25
0.286
0.230
0.886
0.863
1.172
1.093
47.530
45.930
16.1
15.03
10.46
10.40
50
0.303
0.246
0.940
0.896
1.243
1.142
48.100
46.000
16.5
15.43
11.42
11.35
2.5
0.263
0.213
0.890
0.873
1.153
1.086
46.830
44.900
16.0
14.90
10.92
10.73
5.0
0.296
0.236
0.920
0.883
1.216
1.119
47.160
45.400
16.0
14.96
11.19
11.04
0.0
0.196
0.173
0.730
0.643
0.926
0.816
38.700
35.930
12.1
12.00
10.06
9.75
25
0.230
0.196
0.803
0.690
1.033
0.886
42.100
39.130
14.2
13.53
10.06
9.73
50
0.253
0.210
0.766
0.703
1.019
0.913
42.460
39.730
14.7
13.83
10.92
10.54
2.5
0.236
0.200
0.773
0.666
1.009
0.866
41.760
38.730
14.2
13.43
10.50
10.11
5.0
0.256
0.213
0.790
0.703
1.046
0.916
42.400
39.200
14.5
13.80
10.79
10.37
0.0
0.136
0.123
0.606
0.563
0.742
0.686
32.830
30.930
11.0
10.70
9.77
9.33
25
0.153
0.136
0.656
0.593
0.809
0.729
35.700
33.830
12.6
12.00
9.81
9.38
50
0.160
0.150
0.666
0.620
0.826
0.770
36.330
34.260
13.0
12.46
10.56
10.08
2.5
0.156
0.143
0.623
0.583
0.779
0.726
35.200
33.400
12.7
12.13
10.21
9.69
5.0
0.163
0.150
0.680
0.590
0.843
0.740
35.930
34.000
12.9
12.36
10.46
9.94
0.05
0.01
0.36
2.82
1.05
0.91
Changes in total indole contents: Results of the present work (Table 3) showed that increasing salinity levels up to 7.83 dS/m caused marked significant decreases in total IAA in the two tested sunflower cultivars of plants sowed at 4.68and 7.83 ds/m salinity levels as compared with the plants at 1.56 dS/m salinity level. Treatments of sunflower cultivars with different concentrations of α-tocopherol or nicotinamide significantly increased total indole acetic acid contents compared to low salinity level. Changes in total carbohydrates and total proteins percentages: Changes of total carbohydrates and total proteins percentages of the two cultivars of sunflower Hysun 336 and Euroflor are presented in Table (3). Data show that increasing salinity levels from 1.56 to 7.83 dS/m salinity levels caused gradual reduction in total carbohydrates and total protein percentages of shoots of the two tested cultivars. The percentage of reduction changed from 18.24 , 14.04 for carbohydrates and 3.64, 5.79 for protein at 4.68 dS/m to 21.62, 23.35 for carbohydrates and 6.42, 9.86 at 7.83 dS/m for protein for Hysun 336 and Euroflor cultivars respectively. It is clear from results in Table (3) that Hysun 336 cultivar had more carbohydrate percentages than Euroflor. Concerning the effect of soaking both sunflower seeds in α-tocopherol or nicotinamide, data show that neither α-tocopherol nor nicotinamide increased total carbohydrate and total protein percentages as compared to low salinity level. Yield and yield components: Table (4) illustrates the effect of soaking two sunflower seeds cultivars in different concentrations of αtocopherol or nicotinamide under different salinity levels on yield and yield components. Data reveal that increasing salinity levels resulted in reduction of yield components (head diameter (cm), seeds weight (g)/head, 100 seeds weight (g) and seeds weight (ton)/feddan). The percentage of decrease of 100 seeds wt (g) reached 29.41, 31.37 for Hysun 336 and 29.9, 38.52 for Euroflor cultivar at EC 4.68 and 7.83 dS/m salinity level compared to plants sown at 1.56 dS/m. Also, it was 16.85%, 62.92% for Hysun 336 and 26.51%, 87.95% for Euroflor for seeds weight/fed (ton). Concerning soaking sunflower seeds in α-tocopherol or nicotinamide, data clearly show that different concentrations of both used vitamins increased yield components of the two tested cultivars as compared with the corresponding salinity levels. It is noticed that sunflower cultivar Hysun 336 showed more pronounced increase in yield components than Euroflor cultivar. Data also show that the increases in different yield parameters were
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increased in value with increasing the concentrations of the used vitamins. High concentration of α-tocopherol (50 mg/l) or nicotinamide (5 mg/l) were more effective than low concentrations in the two sunflower cultivars, under different salinity levels. Changes in protein% and oil yield: Regarding to protein% and oil yield/fed for the yielded seeds, data in Table (4) show tha protein% and oil yield/fed decreased with increasing salinity levels from EC 1.56 to 4.68 to 7.83 ds/m for both tested sunflower cultivars. Table 4. Effect of α -tocopherol or nicotinamide on yield parameters of sunflower cultivars (Hysun 336 and Euroflor) under salinity stress under salinity stress. head diameter (cm) Cultivar
seeds wt/head (g)
100 seeds wt (g)
seeds wt /feddan (ton)
protein %
oil yield / feddan (kg)
Salinity (ds/m) Materials (mg/l) Hysun 336 Euroflor Hysun 336 Euroflor Hysun 336 Euroflor Hysun 336 Euroflor Hysun 336 Euroflor Hysun 336 Euroflor Nicotinamide α-Tocopherol
1.56
0
15.27
14.23
35.10
32.77
5.10
4.88
0.89
0.83
14.10
13.90
188.67
177.33
16.60
15.37
38.16
35.33
5.46
5.23
0.96
0.89
14.70
14.50
197.00
185.00
17.97
16.67
41.33
38.30
6.06
5.65
1.04
0.96
15.23
14.93
206.00
193.33
17.27
16.03
39.70
36.90
6.03
5.86
1.00
0.93
15.00
14.73
200.00
188.67
18.17
17.10
41.80
39.33
6.61
6.34
1.06
0.99
15.70
15.40
212.00
201.33
13.03
11.00
29.30
24.23
4.17
4.02
0.74
0.61
13.83
13.50
162.67
146.67
25
14.13
12.00
31.80
26.37
4.68
4.50
0.80
0.66
14.37
14.00
170.00
152.67
50
15.40
13.37
34.63
29.40
5.51
5.08
0.87
0.74
14.73
14.43
178.33
161.00
2.5
14.83
12.67
33.37
27.80
5.12
5.01
0.84
0.70
14.53
14.23
174.00
156.67
5
15.83
13.83
35.63
30.40
5.73
5.52
0.90
0.77
15.13
14.83
185.33
167.33
7.33
4.67
12.90
10.00
3.50
3.00
0.33
0.10
13.13
12.70
131.33
126.00
25
8.27
6.03
17.30
12.67
3.75
3.51
0.44
0.32
13.50
13.13
141.00
131.67
50
9.50
7.23
19.93
15.17
3.96
3.82
0.50
0.39
13.83
13.50
149.33
140.00
2.5
8.97
6.80
18.80
14.30
3.83
3.59
0.47
0.36
13.67
13.40
143.67
134.67
5
10.20
8.03
21.40
16.87
4.09
3.98
0.54
0.42
14.17
13.80
156.33
145.67
25.0 50.0 2.5 5.0
Nicotinamide α-Tocopherol
4.68
0
Nicotinamide α-Tocopherol
7.83
0
LSD at 5%
0.5496
1.141
0.1151
0.00514
0.4213
9.279
Soaking sunflower seeds in different concentrations of α-tocopherol or nicotinamide under different salinity levels increased protein% and oil yield / fed (ton) as compared with the corresponding salinity levels for both tested cultivars. Maximum increases in oil% and oil yield/fed were noticed at 5 mg/l nicotinamide soaked yielded seeds for all salinity levels. The percent of increase in protein% were 11.35 and 10.79 at 1.56 ds/m salinity level, 9.39 and 9.85 at 4.68 ds/m salinity level and 7.92 and 8.66 at 7.83 ds/m salinity level for Hysun 336 and Euroflor cultivars respectively. Meanwhile they were 12.37% & 13.53% , 13.93%, 14.09 and 19.04% 15.61% for Hysun 336 and Euroflor cultivars at 1.56, 4.68 and 7.83 ds/m salinity levels respectively. 4. DISSCUSSION Obtained data showed that salinity caused a decrease in all growth criteria. Our results are in agreement (21) (22) (23) (24) with those obtained by Khattab , El-Beltagi et al., , El-Khallal et al., and Athar et al. (25) In this connection, Neumann (1995) stated that, salinity can rapidly inhibit root growth and hence the capacity for water uptake. The retarded growth of salt stressed plants may result from the accumulation of toxic (26) ions, impaired uptake of essential nutrients and/or damage in cellular organelles. The reduction in plant growth of saline stressed plants may be attributed to the reduction of indole acetic acid content which was induced by (27) salinity consequently led to reduction on cell division and/or cell expansion. The reduction in leaf area of sunflower plant under salinity stress can be considered as avoidance mechanisms, which minimizes water loss when stomata closed. It is known that reduction in leaf area in salt stressed plants can be explained by a (28 and 29) decrease in leaf turgor, changes in cell wall properties and a decreased in photosynthetic rate. Moreover, the decrease in dry weight of shoots by increasing salinity levels could be ascribed to the decrease in photosynthetic output as indicated by the significant decrease in chlorophylls and total carbohydrates in saline
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(28)
stressed plants .Other authors concluded that, the reduction of dry weight may be due to a turgor limitation or (30) cell wall hardening by limited extension growth. Application of α-tocopherol or/and nicotinamide in the present study improved growth in the two cultivars of (31) (32) sunflower plants. Similar results were obtained by Zhang et al and El – Bassiouny et al using α-tocopherol, (31) (27) El – Bassiouny et al and Hassanein et al using nicotinamide. α-Tocopherol or nicotinamide may act as growth stimulants which can play a role in mitigating the adverse effect of salt on metabolic activities relevant to growth through increasing IAA content .These were further corroborated by the significantly higher levels of (33) carbohydrates observed generally in the test plants vitamins treated. With regard to photosynthetic pigments, obtained data show that salinity stress induced decrease in total chlorophyll, carotenoids and total pigments .These results are in accordance agreements with those obtained by (21) (34) (35) Khattab on canola, Desingh & Kanagaraj on cotton, Dolatabadian & Saleh Jouneghani on bean and El – (35) Khallal et al ., on maize plant. The effect of salinity stress on the photosynthetic pigments may be due to the effect of salinity on the activities of photosynthetic enzymes and this may be a secondary effect mediated by the (36) (34) reduced CO2 partial pressure in the leaves caused by stomatal closure . Also, Desingh & Kanagaraj presume that salinity stress might affect the biochemistry of photosynthesis by causing disorientation of the lamellar system of chloroplasts and loss of chloroplast integrity leading to a decrease in the activities of photosystems. Application of α-tocopherol or nicotinamide could alleviate the inhibitory effect of salinity .These results are (32) (27) in agreement with those obtained by El – Bassiouny et al., on faba bean and Hassanein et al., on maize. αTocopherol or nicotinamide may interfere with the protection of chloroplast and their membrane against salt (27) (37) toxicity and the maintaining their integrity, or vitamins protect chloroplast from oxidative damage. Also, (38) nicotinamide has a role in activation of enzymes that regulate photosynthetic carbon reduction. Increasing salinity levels caused gradual decreases in total IAA contents these results are in agreement (39) (40) (27) with those obtained by Wanget al., Bekheta and El – Bassiouny and Hassanein et al., on different plant species. The reduction in IAA contents under salinity stress might severely inhibit the biosynthesis of auxins (IAA) (39) and/or increase their degradation or transformation into inactive form. Application of α-tocopherol or nicotinamide increased IAA contents .These obtained results are in harmony with those obtained by El(41) (27) Bassiouny and Hassenein et al., .The increase in IAA contents in shoot tissues treated with α-tocopherol or nicotinamide concurrent with the increase in the growth rate .The data suggests that the role of the endogenous (42) hormones in stimulation of the cell division and/or cell enlargement and subsequently growth. (23) Also,salinity stress decreased total carbohydrates and protein contents as obtained by El - Khallal et al., (27) and Hassanein et al., . The reduction in total carbohydrates of salt stressed sunflower plant concomitantly with arrested growth rate and reduction in the leaf photosynthetic pigments led to the conclusion that salinity may inhibit photosynthetic activity and/or increased partial utilization of carbohydrates into other metabolic (43) (44) pathways. Brugnoli & Lauteri ) who reported that the reduction of total carbohydrates under salinity stress is probably due to higher sensitivity of photosystem II, decrease of CO2 in intercellular spaces of stomata, reduction in photochemical quantum efficiency of CO2 uptake, low level of O2 evolution and low level of 3 – phosphoglycerate, which led to the reduction in carbon allocation to new leaves and furthermore to potential photosynthetic capacity resulted in reduction of photon yield of CO2 assimilation and consequently minimize starch synthesis under salinity stress. The reduction in protein content may be attributed to the decrease in protein synthesis and/or the increase in its degradation. These results were in harmony with those obtained by (45) (21) (46) Azooz, on sorghum and Khattab, on canola. Moreover, Bassouny et al., proved that the degradation of protein under salinity conditions was suppressed by the accumulation of total amino – N and proline concurrently with the increase in protease activity. α-Tocopherol or nicotinamide application generally stimulated the accumulation of total carbohydrates and protein contents in salt affected sunflower plant .This is either via increasing endogenous levels of phytohormones such as indole acetic acid Moreover, accumulation of carbohydrate play a key role in alleviating salinity stress (47) either via osmotic adjustment or by conferring desiccation resistance to plant cells. Reduction in all yield parameters, protein% and oil yield of the two tested sunflower plants. Obtained (12) (23) (27) results are aided by Khatoon et al., , El - Khallal et al., and Hassanein et al., on different plant species. Reduction in seed yield of stressed plant might be attributed to the rapid reduction in leaf photosynthetic pigments and assimilates. 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