2016-03-17T00:48:46+05:302016-03-17T00:48:34+05:302016-03-17T00:48:46+05:30Acrobat PDFMaker 11 for Worduuid:373964fc-a3ce-4fc1-9f9e-06d815bf5b2duuid:6b699dd8-a00d-4c77-bdbe-60ca11cfb2218xmlMitigation of drought stress on Fenugreek plant by foliar application of trehaloseMena GergesAdobe PDF Library 11.0D:20160313132325<egyptian hak>
International Journal of ChemTech Research CODEN (USA): IJCRGG ISSN: 0974-4290 Vol.9, No.02 pp 147-155, 2016
Mitigation of drought stress on Fenugreek plant by foliar application of trehalose Mervat Sh Sadak Botany Department; Division of Agricultural and Biology, National Research Centre, Cairo, Egypt Abstract: The present work aimed to study the alleviation effect of foliar treatment of different concentrations of trehalose at different water holding capacities (WHCs) on growth, photosynthetic pigments, seed yield quantity and quality in fever of nutritional value and antioxidant activities. In addition to raise the efficiency of Fenugreek plants to resist water stress to reduce the amount of irrigation water. So, this experiment was carried out at the green house of National Research Centre on Fenugreek plant. Three concentrations of trehalose were foliar sprayed (Tre0, Tre1 and Tre2). Plants were irrigated with different WHC 100% and 60%. Data showed that, irrigation of Fenugreek plants with lower WHC 60% resulted in decreases in all growth parameters, photosynthetic pigments, yield components, carbohydrate% and protein%. Meanwhile phenolic and flavonoids contents increased by drought stress. Antioxidant activity at 50 and 100µg/l showed significant increases in response to drought stress. On the other hand, treatment Fenugreek plant with different concentrations of trehalose led to increases in growth parameters, photosynthetic pigments, yield components, carbohydrate, protein, total phenolic, flavonoids contents, and antioxidant activity of the yielded seeds either in non stressed and drought stressed plants relative to corresponding controls. Generally, 500 µM Tre was the most pronounced and effective treatment in alleviating the deleterious effect of drought stress on Fenugreek plants. Key words: Antioxidant activity, Fenugreek, flavonoids, phenolics, protein, trehalose. Introduction Fenugreek (Trigonella foenum graecum) is an annual herb that belongs to the family Leguminosae widely grown in Egypt and Middle Eastern countries. Due to its strong flavor and its aroma, fenugreek is one of such plants whose leaves and seeds are widely consumed as a spice in food preparations, and as an ingredient in traditional medicine. It is rich source of calcium, iron, â-carotene and other vitamins1. Both leaves and seeds should be included in normal diet of family, especially diet of growing kids, pregnant ladies, puberty reaching girls and elder members of family because they have haematinic (i.e. blood formation) value2. The seeds of fenugreek contain lysine and L-tryptophan rich proteins, mucilaginous fiber and other rare chemical constituents such as saponins, coumarin, fenugreekine, nicotinic acid, sapogenins, phytic acid, scopoletin and trigonelline which are thought to account for many of its presumed therapeutic effects, may inhibit cholesterol absorption and to help lower sugar levels3. Drought is the most important limiting factor for crop production and it is becoming an increasingly severe problem in many regions of the world4. Despite, water is one of abundant compounds in earth and 2/3 of earth surface is covered by water, but water shortage is limitative to produce agriculture products in the world. Drought is one of the major physical parameter of an environment, which determines the success or failure of plants establishmentDrought is one of the major physical parameter of an environment, which determines the success or failure of plants establishmentDrought is one of the major physical parameter of an environment, which determines the success or failure of plants establishmentDrought is one of the major physical parameter of an environment, which determines the success or failure of plants establishmentDrought is one of the major physical parameter of an environment, which determines the success or failure of plants establishmentDrought is one of the major physical parameter of an environment, which determines the success or failure of plants establishmentDrought is one of the major physical parameter of an environment, which determines the success or failure of plants establishmentDrought is one of the major physical parameter of an environment, which determines the success or failure of plants establishmentDrought is one of the major physical parameter of an environment, which determines the success or failure of plants establishmentDrought is one of the major physical parameter of an environment, which determines the success or failure of plants establishmentDrought is one of the major physical parameter of an environment, which determines the success or failure of plants establishmentDrought is one of the major physical parameter of an environment, which determines the success or failure of plants establishmentDrought is one of the major physical parameter of an environment, which determines the success or failure of plants establishmentOver the last few decades, several techniques have been proposed to improve plant performance in drought environments. These include foliar treatment with osmoprotectants compounds as proline, glycinebetaine or trehalose11. Trehalose (Tre), is a non-reducing disaccharide of glucose, which plays an important role as a stress protectant in some plants12,13&14. In addition to being an energy source, the unique physicochemical properties of Tre efficiently stabilize dehydrated enzymes, proteins, and lipid membranes, as well as protect biological structures from damage during desiccation15. Tre has the added advantage of being a signaling and antioxidant molecule and acts as an elicitor of genes involved in detoxification and stress response16. However, Tre production in most plants is not sufficient to ameliorate stress-induced adverse effects. On the other hand, external Tre application increases the internal level of this osmolyte and has been suggested as an alternative approach to induce stress tolerance11&17. Exogenous Tre alleviates the adverse effects of various abiotic stresses including drought in maize14, heat and water deficit in wheat18&19. Therefore, this study was conducted to investigate the effects of exogenous applications of trehalose on various growth parameters, photosynthetic pigments, yield and yield attributes and some nutritional constituents of the yielded seeds of Fenugreek plants grown under drought stress. Materials and Methods Experimental Conditions,:Plant Materials, Growth and Treatment Conditions: Seeds of Fenugreek (Trigonella foenum graecum) cv. Giza 30 were obtained from Agriculture Research Centre, Ministry of Agriculture and Land Reclamation, Egypt. Seeds were grown in Pots (diameter 30 cm) at two successive seasons (2012/2013 and 2013/2014), filled with clay and sand soil with the ratio of 2:1. Treatments of WHC were started after 45 days from sowing. Irrigation treatments were given to plants with different levels of water holding capacity (WHC) 100%, and 60%. Trehalose concentrations (0, 250 or 500 µM) were sprayed after 30 and 37 days of sowing. Fertilization with super phosphate (5 g / pot), potassium sulfate (2.5 g / pot) and urea (6 g / pot) were used. Experimental Design, Growth and Yield & Yield components:. The pot experiment was conducted in the greenhouse of Botany Department, National Research Center. Experimental design was complete randomized blocks. Samples were taken after 60 days after sowing to analyze crop performed in terms of growth parameters, RWC% and photosynthetic pigment (chlorophyll a, chlorophyll b and carotenoids). Each treatment was replicated four times and each replicate had three plants. Three healthy plants were left in each pot to determine number of pods/ plant, number of seeds/pod weight of seeds/ plant, and seed index were determined. Air dried seeds were ground into a fine powder and kept in desiccators for chemical analysis. Chemical Analysis: Photosynthetic pigments (chlorophyll a, chlorophyll b and carotenoids) of fresh leaves were determined20. For seed chemical analysis, seeds were powdered to determine carbohydrates, proteins, phenolic and flavonoids cntents. Protein contents were determined by microkjeldahl method21. Total carbohydrates were determined calorimetrically according to the method22. Total phenol content was measured23. Total flavonoid contents were measured by the aluminum chloride colorimetric assay24. The free radical scavenging activity was determined25using the 1.1-diphenyl-2-picrylhydrazil (DPPH) reagent. Statistical Analysis: The data were statistically analyzed on complete randomized design system according26. Combined analysis of the two growing seasons was carried out. Means were compared by using least significant difference (LSD) at 5% levels of probability. Result Changes in growth parameters: Drought stress (60% WHC) caused significant decreases in Fenugreek plant growth parameters (shoot length, branches and leaves number/ plant, fresh & dry weight of shoot/plant, RWC of shoot) Meanwhile, increased significantly root length, fresh and dry weights of root/plant) relative to control plants (D0T0) (Table 1). On the other hand, Trehalose treatments proved to be effective in enhancing shoot height, root length, fresh and dry weights of shoot and root under unstressed and drought stressed plants (Table 1). It was noted that Tre2 was more effective than Tre1 treatment at unstressed and drought stressed as caused significant increases in dry weight of shoot by 38.32% and 62.5% respectively, compared to 15.89% & 47.22% at Tre1. It was interesting to observe a considerable increment in root length of trehalose-treated plants more than the control and the drought-stressed plants. Fresh and dry mass of roots also increased in response to trehalose treatment under stress and un-stress conditions (Table 1). Table 1. Effect of Trehalose at 250 µM (Tre1) and 500 µM (Tre2) on growth parameters of Fenugreek plants irrigated with 100%WHC (WHC0) or 60%WHC (WHC1). The presented results are means of the measurements taken at two successive seasons.
Drought
Trehalose conc (µM)
Shoot length (cm)
Leaves no/plant
Fresh wt/plant (g)
Dry wt (g)
RWC%
Root length (cm)
Root fresh wt (g)
Root dry wt (g)
WHC0
Tre0
24.00
14.00
6.3
1.07
83.02
15.00
1.59
0.37
Tre1
27.00
16.00
8.26
1.24
84.99
19.00
2.30
0.38
Tre2
32.00
18.33
9.92
1.48
85.08
21.30
2.50
0.39
WHC1
Tre0
16.00
10.67
4.05
0.72
82.22
18.00
2.27
0.47
Tre1
21.33
12.00
6.39
1.06
83.41
21.33
3.40
0.58
Tre2
24.33
13.00
7.36
1.17
84.10
22.33
3.40
0.59
LSD at 5%
1.25
0.64
0.79
0.07
0.86
1.25
0.45
0.03
Changes in photosynthetic pigments: Chlorophyll (Chl. a, b), total chlorophylls, carotenoids and total pigments contents of Fenugreek leaves were significantly decreased by drought stress (60%WHC) as compared with control plants (Table 2). The percentages of decreases were 14.33%, 6.29%, 12.03%, 14.06% and 12.29% in chlorophyll a, chlorophyll b, chloro a+b, carotenoids and total pigments, respectively. Different concentrations of trehalose foliar treatment to Fenugreek plant significantly increased photosynthetic pigments (chlorophyll a, chlorophyll b, total chlorophylls, carotenoids and total pigments) as compared to untreated plants in normal irrigated and drought stressed plants. Data clearly show the gradual increases of photosynthetic pigments with increasing trehalose concentrations. Table2. Effect of Trehalose at 250 µM (Tre1) and 500 µM (Tre2) on photosynthetic pigments (mg/g FW) of Fenugreek plants irrigated with 100%WHC (WHC0) or 60%WHC (WHC1). The presented results are means of the measurements taken at two successive seasons.
Drought
Trehalose conc (µM)
Chlo a
Chlo b
Chl a+b
Car
Total pig
WHC0
Tre0
1.186
0.477
1.663
0.249
1.912
Tre1
1.66
0.608
2.268
0.295
2.563
Tre2
1.693
0.701
2.394
0.312
2.706
WHC1
Tre0
1.016
0.447
1.463
0.214
1.677
Tre1
1.383
0.54
1.923
0.358
2.281
Tre2
1.557
0.672
2.229
0.436
2.665
LSD at 5%
1.245
0.067
0.112
0.052
0.342
Yield and Yield Components: Data in Table 3 show that, at harvest, pods number/plant seeds number/pod, seeds weight/plant and seed index of Fenugreek plant significantly affected by drought stress. Drought stress induced significant decreases in all the previous parameters of yield and its components as compared with control treatment. For instance, the reduction in seed weight/plant and seed index reached to 37.79%, 14.90%, respectively as compared with normal irrigated plants. On the other hand, foliar treatment of Fenugreek plant with different concentration of trehalose (250 and 500 µM) under normal conditions and drought stressed conditions caused significant increases in all parameters of yield components as compared to the corresponding control plants, the most prominence concentration was 500µM. Table 3. Effect of Trehalose at 250 µM (Tre1) and 500 µM (Tre2) on yield parameters of Fenugreek plants irrigated with 100%WHC (WHC0) or 60%WHC (WHC1). The presented results are means of the measurements taken at two successive seasons.
Treatment
Pods
Seeds no/pod
Seeds wt/plant
Seed index
WHC
Trehalose conc (µM)
no/plant
100%
Tre0
7.67
6.33
2.985
5.154
Tre1
8.33
7.00
3.735
5.827
Tre2
9.00
8.33
4.542
6.431
60%
Tre0
5.33
4.67
1.857
4.386
Tre1
6.33
5.33
2.687
5.021
Tre2
8.67
6.67
3.383
5.674
LSD at 5%
0.225
0.245
0.145
0.177
Biochemical constituents of the yielded Fenugreek seeds: Carbohydrate Contents: Data in Table 4 demonstrate that, WHC at 60% led to marked decrease in total carbohydrates of the yielded seeds compared to plants grown under 100% of field capacity. Foliar trehalose treatment on Fenugreek plant under different WHC (100% and 60% WHC) led to marked increases in total carbohydrates when compared with the corresponding controls especially at 100% WHC. Protein Contents: Table (4) show that, the decrease of WHC (60%) of soil led to marked decreases in protein content of yielded seeds compared to plants grown under 100% WHC. The results showed the stimulatory effects of trehalose treatment especially at 500 µM under normal or under different levels of water stress on protein contents compared to untreated plants. Antioxidant Substances of the Yielded Seed and its Activity: Data in Table (4) show the variation in antioxidant substances of the yielded seeds of Fenugreek plant in response to spraying with different concentrations of trehalose and subjected to different levels of WHC. WHC decreases at 60% caused marked significant increases in both total phenolic contents and flavenoids content as compared with those of the corresponding controls. Spraying Fenugreek plants with different concentrations of trehalose increased significantly total phenolic contents and flavenoids content as compared with the corresponding control plants. Regarding to antioxidant activity as WHC decreased from 100% to 60% caused significant increases at all treatments. Foliar treatment with trehalose at different concentrations caused significant increases in antioxidant activities at 50 & 100 µg/l of the yielded seeds of Fenugreek plant grown under 100% and 60% WHC as compared with the corresponding untreated controls. Table 2. Effect of Trehalose at 250 µM (Tre1) and 500 µM (Tre2) on carbohydrate%, protein%, Flavonoids and phenolic contents and antioxidant activities% at 50&100 µg/l of Fenugreek plants irrigated with 100%WHC (WHC0) or 60%WHC (WHC1). The presented results are means of the measurements taken at two successive seasons.
Drought
Trehalose conc
Carbohydrate%
Protein%
Flavonoids mg/g DW
DPPH% (µg/l)
Phenolics
50
100
WHC0
Tre0
41.64
23.35
1.504
24.80
40.80
47.60
Tre1
42.75
25.77
2.517
36.80
49.20
65.00
Tre2
43.25
26.34
3.080
39.35
51.82
76.56
WHC1
Tre0
40.18
20.92
2.239
27.67
44.89
79.32
Tre1
41.14
22.76
3.154
38.77
52.00
92.62
Tre2
42.32
23.24
4.430
41.39
57.45
124.34
LSD at 5%
1.021
0.574
0.245
2.411
3.489
2.985
Discussion Water is one of the major factors limiting crop production, affecting not only agricultural output but also food security. Consequently, developing drought tolerant plants/crops is a major research goal for both plant scientists and farmers. Trehalose as an osmoprotectant maintains cellular osmotic balance It protects biological structures from damage at desiccation28. Previous studies proved Tre as efficient protectant against drought stress or under water deficit conditions14&29. Our results of drought stress are in harmony with11which stated that both fresh and dry weights of shoots of canola decreased with increasing drought stress and these reductions may be due to the metabolic disorders induced by stress and generation of ROS. Also, the decrease in shoot height in response to drought might be due to decrease in cell elongation, cell turgor, cell volume and eventually cell growth30. In addition, drought affects plant–water relations, reduces water contents of shoot, causes osmotic stress, inhibits cell expansion and cell division as well as growth of plants as a whole31. Also, the effect of drought in reduced plant height (Table 1) might be due to the adaptation of Fenugreek plants to cope with drought stress. With the initial effects of drought stress, Fenugreek plants started to divert the assimilates from stem and utilized them for increased root growth in order to increase the water absorption. Regarding to trehalose effect, Tre application alleviated the adverse effects of drought stress of Fenugreek plant by improving their growth and physiological attributes. However, water content or growth reduction was restored by exogenous Tre supplementation under drought stress as evidenced by improved shoot RWC and fresh weight and dry weight of plant. Similar findings were documented previously by Tre addition with abiotic stress 13,14&32. Trehalose reduced the inhibitory effects of drought on growth may be through improving the water status of the plant tissues, since the relative water content of the shoot increased (Table 2). Also, trehalose treatment on maize plants improves water retention and plant tolerance through osmoregulation and stomatal closing at stress33. Chlorophyll (Chl. a, b), chlorophyll a+b, carotenoids and total pigments content of Fenugreek leaves were significantly decreased by drought stress (Table 2). Numerous studies reported that inhibition of photosynthesis were attributed by damages to photosynthetic pigments due to oxidation of pigments, impaired pigment biosynthesis34,35&36. One visible symptom of water stress in leaves is a concomitant loss of chlorophyllchlorophyllchlorophyllchlorophyllchlorophyllchlorophyllchlorophyllchlorophyllchlorophyllchlorophyllchlorophyllIt is worthy to mention that water availability to plant in different growth stages affect on plant yield and biochemical constituents of the plant and the yielded seeds. Table 3&4 indicates that drought stress significantly decreased yield and yield attributes of Fenugreek plant accompanied with significant decreases in biochemical constituents and nutritional values of the yielded seeds (Carbohydrates, proteins) relative to control plants. The reduction in yield of quinoa plant is mainly due to the reduction in growth parameters (Table 1) and photosynthetic pigments (Table 2). Carbohydrate changes are of particular importance because of their direct relationship with such physiological processes as photosynthesis, translocation, and respiration. Water stress decreased the pigments concentration in leaves which results in inhibition of photosynthetic activity, in turn it leads to less accumulation of carbohydrates in mature leaves and consequently may decrease the rate of transport of carbohydrates from leaves to the developing seeds40. The decreases in seed chemical composition might be due to the reason that low water supply during the plant life affects many enzymes whose activity is reduced under water stress conditions and leading to changes in metabolic activities that result in altered translocation of assimilates to seeds. Moreover, it was mentioned that the main cellular components susceptible to damage by free radicals are lipids (peroxidation of unsaturated fatty acids in membranes), proteins (denaturation), carbohydrates and nucleic acids42. Regarding to the promotive effect of trehalose foliar treatments on yield and yield components and chemical composition of the yielded seeds. In recent decades exogenous protectant such as osmoprotectant (proline, glycinebetaine, trehalose, etc) have been found effective in mitigating the stress induced damage in plant43&44. Trehalose can serve as a carbohydrate storage molecule as well as a transport sugar, similar to the function of sucrose45. It can also stabilize proteins and membranes of plants when exposed to stress by replacing hydrogen bonding through polar residues, preventing protein denaturation and fusion of membranes46. Moreover, trehalose acts as a source of carbon and energy and a protector against stresses. In the present study, data revealed that drought stress increased the amount of flavonoids and total phenols. Flavonoids are one of the largest classes of plant phenolics performing different functions in plant system, including pigmentation and defense47. Intriguingly, the conditions leading to inactivation of antioxidant enzymes can also upregulate flavonoids biosynthesis, suggesting that flavonoids constitute a secondary ROS-scavenging system in plants exposed to prolonged stress47. Coinciding with the results obtained in the present study, it was recorded48 that water stress enhanced the accumulation of flavonoids in Plantago ovata plants. Similarly, drought increased the concentration of total phenols in the leaves of five tomato cultivars49. It is well known that many phenolics are stress-induced metabolites that accumulate in plant tissues after different abiotic and biotic stress stimuli. These metabolites may participate in reactive oxygen species (ROS) scavenging mainly through the antioxidative enzymes utilizing polyphenols as co-substrates50. Application of Tre markedly increased total phenols and flavonoids contents. Generally, Tre treatment appeared to be effective treatment in counteracting the negative effects of water stress on total phenols and flavonoids contents. Hence, Tre has been proposed to be a signaling molecule which induce plants to speed up their rate of ROS production that sends signal to activate non-enzymatic antioxidants for ROS scavenging in order to counteract stress-associated oxidative stress. Beside, phenolic the non-photosynthetic pigments investigated in the present study may contribute to the antioxidant activity of wheat plants51. In the present study, seed antioxidant activities in methanolic extract of Fenugreek seeds was positively related to seed phenolics and flavonoids contents Table 4. The strong positive correlation between total phenolics and antioxidant activity as observed in the present study had already been observed in cereals52 and soybeanand soybeanand soybeanand soybeanand soybeanReferences
1. Sharma RD, Sarkar A, Hazra DK. Phytother. Res.,1996, 10:332.
2. Ody P. New York: Dorling Kindersley., 1993, 47: 164.
3. Bukhari SB, Bhanger MI, Memon S. Antioxidative activity of extracts from fenugreek seeds (Trigonella foenum-graecum). Pak. J. Environ. Chem., 2008, 9:78-83.
4. Passioura JB. The drought environment: physical, biological and agricultural perspectives. J. Exp. Bot,. 2007, 58(2), 113-117.
5. Gamze O, Mehmet DK, Mehmet A. Effects of salt and drought stresses on germination and seedling growth of pea (Pisum sativum L.). Turk. J. Agric., 2005, 29, 237-242.
6. Khajeh HM, Powell AA, Bingham IJ. The interaction between salinity stress and seed Vigor during germination of soybean seed. Seed Sci. Technol, 2003, 1, 715-725.
7. Jensen H, Mogensen VP. Yield and nutrient contents of spring wheat subjected to water stress at various growth stages. Acta. Agric. Seandinar, 1984, 34: 527–533.
8. Farooq M, Wahid A, Kobayashi N, Fujita D, Basra SMA. Plant drought stress, effects, mechanisms and management. Agron. Sustain. Dev., 2009, 29: 185–212
9. Lawlor DW, Cornic G. Photosynthetic carbon assimilation and associated metabolism in relation to water deficits in higher plants. Plant Cell Environ., 2002, 25: 275–294.
10. Khan AH, Mujtaba SM, Khanzada B. Response of growth, water relation and solute accumulation in wheat genotypes under water deficit. Pakistan J. Bot., 1999, 31: 461–468.
11. Dawood Mona G, Sadak Mervat Sh. Physiological Role of Glycinebetaine in Alleviating the Deleterious Effects of Drought Stress on Canola Plants (Brassica napus L.) Middle East Journal of Agriculture Research,, 2014, 3(4): 943-954.
12. Garcia AB, Engler JDA, Iyer S, Gerats T, Montagu MV, Caplan AB. Effects of osmoprotectants upon NaCl stress in rice. Plant Physiol, 1997, 115:159–169.
13. Duman F, Aksoy A, Aydin Z, Temizgul R. Effects of exogenous glycinebetaine and trehalose on cadmium accumulation and biological responses of an aquatic plant (Lemna gibba L). Water Air Soil Pollut, 2010, 217:545–556.
14. Ali Q, Ashraf M. Induction of drought tolerance in maize (Zea mays L.) due to exogenous application of trehalose: growth, photosynthesis, water relations and oxidative defense mechanism. J Agron Crop Sci., 2011, 197:258–271.
15. Fernandez O, Béthencourt L, Quero A, Sangwan RS, Clément C. Trehalose and plant stress responses: friend or foe? Trends Plant Sci., 2010, 15:409–417.
16. Bae H, Herman E, Bailey B, Bae HJ, Sicher R. Exogenous trehalose alters Arabidopsis transcripts involved in cell wall modification, abiotic stress, nitrogen metabolism, and plant defense. Physiol Plant, 2005, 125:114–126.
17. Chen Th, Murata N. Enhancement of tolerance of abiotic stress by metabolic engineering of betaines and other compatible solutes. Curr Opin Plant Biol., 2002, 5:250–257.
18. Luo Y, Li F, Wang GP, Yang XH, Wang. Exogenously-supplied trehalose protects thylakoid membranes of winter wheat from heat induced damage. Biol Plant, 2010, 54:495–501.
19. Ma C, Wang Z, Kong B, Lin T. Exogenous trehalose differentially modulate antioxidant defense system in wheat callus during water deficit and subsequent recovery. Plant Growth Regul., 2013, 70:275–285
20. Moran R. Formula for determination of chlorophyllous pigments extracted with N.N. dimethylformamide. Plant Physiol., 1982, 69: 1371-1381.
21. A.O.A.C. Official methods of analysis. 20th edition. Association of Official Analytical Chemists, Arlington, Virginia, U.S.A., 1990, No 984.
22. Dubois M, Guilles KA, Hamilton JK, Rebers PA, Smith F. Colorimetric method for determination of sugars and related substances. Anal. Chem., 1956, 28: 350-356.
23. Danil AD, George CM. Peach seed dormancy in relation to endogenous inhibitors and applied growth substances. J. Amer. Soc. Hort. Sci., 1972, 17: 621-624.
25. Brand-Williams W, Cuvelier ME, Berset C. Use of a free radical method to evaluate antioxidant activity. Lebensmittel Wissenschaften und Technologi, 1995, 28: 25-30.
26. Snedecor GW, Cochran WG. Statistical Methods 7th ed., the Iowa State Univ., Press. Ames, IA. 1980.
27. Garg AK, Kim JK, Owens TG, Ranwala AP, Choi YD, Kochian LV, Wu RJ. Trehalose accumulation in rice plants confers high tolerance levels to different abiotic stresses. Proc Natl Acad Sci., 2002, 99: 15898–15903.
28. Alam MD, Nahar MK, Hasanuzzaman M, Fujita M. Trehalose-induced drought stress tolerance: A comparative study among different Brassica species, POJ., 2014, 7(4):271-283.
29. Banon SJ, Ochoa J, Franco JA, Alarcon JJ, Sanchez-Blanco MJ. Hardening of oleander seedlings by deficit irrigation and low air humidity. Environ. Exp. Bot., 2006, 56: 36-43.
30. Alam MM, Hasanuzzaman M, Nahar K, Fujita M. Exogenous salicylic acid ameliorates short-term drought stress in mustard (Brassica juncea L.) seedlings by up-regulating the antioxidant defense and glyoxalase system. Aust J. Crop Sci., 2013, 7:1053–1063.
31. Theerakulpisut P, Gunnula W. Exogenous sorbitol and trehalose salt stress damage in salt-sensitive but not salt-tolerant rice seedlings. Asian J Crop Sci.,2012, 4:165-170.
32. Zeid, IM. Effect of arginine and urea on polyamines content and growth of bean under salinity stress. Acta Physiol. Plant, 2009, 31: 65-70.
33. Gonzàlez JA, Gallardo M, Hilai M, Rosa M, Prado FE. Physiological responses of quinoa (Chenopodium quinoa Willd.) to drought and waterlogging stresses: dry matter partitioning., Botanical Studies, 2009, 50: 35-42.
34. Anjum SA, Xie X, Farooq M, Wang L, Xue L, Shahbaz M, Salhab J. Effect of exogenous methyl jasmonate on growth, gas exchange and chlorophyll contents of soybean subjected to drought. Afr. J. Biotech,.2011, 10: 9640-9646.
35. Pandey HC, Baig MJ, Bhatt RK. Effect of moisture stress on chlorophyll accumulation and nitrate reductase activity at vegetative and flowering stage in Avena species. Agric Sci Res. J., 2012, 2: 111–118.
36. Din J, Kans SU, Ali J, Gurmani AR. Physiological and agronomic response of canola varieties to drought stress. The J. of Animal and Plant Sci., 2011, 21: 78-82.
37. Theerakulpisut P, Gunnula W. Alleviation of adverse effects of salt stress on rice seedlings by exogenous trehalose., Asian J. Crop Sci., 2013, 5(4): 405-415.
38. Abdelgawad ZA, Hathout TA, El-Khallal SM, Said EM, Al-Mokadem AZ. Accumulation of trehalose mediates salt adaptation in rice seedlings., American-Eurasian J. Agric. & Environ. Sci., 2014, 14 (12): 1450-1463.
39. Anjum F, Yaseen M, Rasul R, Wahid A, Anjum S. Water stress in barley. I. Effect on chemical composition and chlorophyll content. Pakistan J. Agric. Sci., 2013, 40: 45-49.
40. Ali Q, Ashraf M, Anwar F. Seed composition and seed oil antioxidant activity of maize under water stress. J. Am. Oil Chem. Soc., 2010, 87:1179-1187.
41. Ali A, Alqurainy F. Activities of antioxidants in plants under environmental stress. In: MotohashiN (ed.), The lutein-prevention and treatment for diseases. Trans-world Research Network, India 2006, 187- 256.
42. Hoque MA, Okurna E, Banu MNA, Nakaamura Y, Shimoishi Y, Murata Y. Exogenous pproline mitigates the detrimental effects of salt stress more than exogenous betaine by increasing antioxidant enzyme activities. J. Plant Physiol., 2007, 164:553-561.
43. Hasanuzzaman M, Nahar K, Fujita M. Plant response to salt stress and role of exogenous protectants to mitigate salt – induced damages. In: Ecophysiology and responses of plants under salt stress, Ahmed, P., M.M. Azooz and M. N. V. Prasad (Eds.). 2013, Chapter 2, Springer, New York, USA., ISBN-13: 9781461447467, pp: 25-87.
44. Muller J, Wiernken A, Aschbacher R. Trehalose metabolism in sugar sensing and plant development. Plant Sci., 1999, 147: 37-47.
45. Iturriaga G, Suarez R, Nova-Franco B. Trehalose metabolism: rom osmoprotection to signaling. Int. J. Mol. Sci., 2009, 10:3793-3810.
46. Harborne JB, Williams CA. Advances in flavonoid research since 1992. Phytochemistry, 2000, 55: 481-504.
47. Haghighi Z, karimi N, Modarresi M, Mollayi S. Enhancement of compatible solute and secondary metabolites production in Plantago ovata Forsk by salinity stress. Journal of Medicinal Plants Research, 2012, 6: 3495- 3500.
48. Ianovici N. Histoanatomical and ecophysiological studies on some halophytes from Romania - Plantago schwarzenbergiana, Annals of West University of TimiÅŸoara, Biology, 2011, 14: 53-64.
49. Sgherri C, Cosi E, Navari-Izzo F. Phenols and antioxidative status of Raphanus sativus grown in copper excess. Physiol Plant, 2003, 118: 21-28.
50. Aldesuquy H, Ghanem H. Exogenous Salicylic Acid and Trehalose Ameliorate Short Term Drought Stress in Wheat Cultivars by Up-regulating Membrane Characteristics and Antioxidant Defense System., J Horticulture 2015, 2:2 http://dx.doi.org/10.4172/2376-0354.1000139
51. Dykes L, Rooney LW. Phenolic compounds in cereal grains and their health benefits. Cereal Foods World, 2007, 52, 105–111.
52. Kumar, V.; Rani, A.; Dixit, A.K.; Bhatnagar, D.; Chauhan, G.S. 2009. Relative changes in tocopherols, isoflavones, total phenolic content, and antioxidative activity in soybean seeds at different reproductive stages. J. Agric. Food Chem., 2009, 57, 2705–2710.
53. Ali, Q.; Ashraf, M.; Anwar, F. 2009. Physicochemical attributes of seed oil from drought stressed sunflower (Helianthus annuus L.) plants. Grasas Y Aceites, 2009, 60, 475–481.
54. Ali, Q., F. Anwar, M. Ashraf, N. Saari and R. Perveen . 2013, Ameliorating Effects of Exogenously Applied Proline on Seed Composition, Seed Oil Quality and Oil Antioxidant Activity of Maize (Zea mays L.) under Drought Stress., Int. J. Mol. Sci., 2013, 14, 818-835.