Effects of water stress on phenolic content and antioxidant activity of African nightshades
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Abstract. Okello OP, Gweyi JPO, Nawiri Mp, Musila W. 2017. Effects of water stress on phenolic contents and antioxidant activity of African nightshades. Biofarmasi J Nat Prod Biochem 15: 74-90. This study aimed to map out the distribution of different African Nightshade species in Siaya and Kisii Counties of Kenya and determine the water stress effect on total antioxidant capacity and total phenolic content of two selected African nightshade, namely, giant nightshade (Solanum scabrum) and black nightshade (Solanum villosum). Before selecting the two varieties, the study involved field visits, mapping of nightshades present, and administering semi-structured questionnaires to farmers to determine the indigenous vegetables being grown, the nightshade species grown, and factors affecting their production. The experiments were conducted both in the field and in greenhouse conditions. Watering intervals were at 15 cbars, 50 cbars, and 85 cbars. Data on the number of secondary buds, leaf area, shoot height, and shoot and root dry weights were gathered. The total antioxidant capacity and the total phenolic content were recorded using the DPPH radical scavenging method and the Folin-Ciolcalteu method, respectively. The data collected were subjected to ANOVA. In both counties where production was 100% under small scale, Solanum scabrum was the main variety grown in Siaya County (36%), while in Kisii, the main variety was Solanum villosum (32%). There were significant differences (P?0.05) among treatments in leaf area, plant height, shoot biomass, number of secondary buds, leaf and root total phenolic content, and leaf and root antioxidant activity. At all stress levels, Solanum scabrum exhibited the tallest plant with a maximum height of 45.17cm at 15cbars. At the same time, Solanum villosum had the shortest plants at all stress levels, with the shortest one being recorded at 16.65 cm at 85 cbars. S. scabrum also had the highest root dry weight (7.78g), shoot dry weight (50.78g), and highest leaf area (304.45cm2). However, Solanum villosum had the highest number of secondary buds at all stress levels, with the highest being 24 at 15 cbars. Concerning phytochemicals, Solanum villosum had a higher concentration of both the total phenolics and antioxidant activity in the shoots (46.41g GAE/Kg DM total phenolic content and 52.68% total antioxidant activity). Meanwhile, Solanum scabrum had a higher concentration in the roots (25.06gGAE/Kg DM total phenolic content and 27.18% total antioxidant activity). Water stress causes a decline in all growth parameters but increases phytochemical accumulation in nightshade accessions grown. Therefore, it is suggested that for better yields, irrigation should be performed at every 15 cbars; however, for adequate phytochemical accumulation, the irrigation should be carried out at 50 cbars. Further research must explore and quantify other phytochemical components affected by different watering regimes.
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References
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Abukutsa-Onyango MO, Tushabomwe-Kazooba C, Mwai W, Onyango
GM, Macha ES. 2005. Diversity of African indigenous vegetables
with nutrition and economic potential in the Lake Victoria region. In:
Oniang’o R, Grum M, Obel-Lawson E. (eds.), Developing African
Leafy Vegetables for Improved Nutrition, Regional Workshop, 6-9
December, 2005. Bioversity International, 2007.
Abukutsa-Onyango MO. 2003. Unexploited potential of Indigenous
African Vegetables in Western Kenya. Maseno J Educ Arts Sci 4 (1):
103-122.
Aderolu AM. 2000. The effect of water stress at different growth stages on
yield and seed quality of cowpea varieties. B. Agric Project
University of Ilorin, Nigeria.
Akıncı S, Lösel DM. 2012. Plant Water-Stress Response Mechanisms,
Water Stress. Intech, Rijecka, Croatia.
Akter S, Ahmed M, Eun JB. 2010. Solvent effects on antioxidant
properties of persimmon (Diospyros kaki L. cv. Daebong) seeds. Intl
J Food Sci Technol 45: 2258-2264.
Alexieva V, Sergiev I, Mapelli S, Karanov E. 2001. The effect of drought
and ultraviolet radiation on growth and stress markers in pea and
wheat. Plant Cell Environ 24: 1337-1344.
Apel K, Hirt H. 2004. Reactive oxygen species: metabolism, oxidative
stress, and signal transduction. Ann Rev Plant Biol 55: 373-399.
Ayaz FA, Kadioglu A, Turgut R. 2000. Water stress effects on the content
of low molecular weight carbohydrates and phenolic acids in
Ctenanthe setosa (Rosc.) Eichler. Canadian J Plant Sci 80: 373-378
Bhatt RM, Rao NKS. 2005. Influence of pod load on response of okra to
water stress. Indian J Plant Physiol 10 (1): 54-59.
Blokhina O, Virolainen E, Fagerstedt KV. 2003. Antioxidants, oxidative
damage and oxygen deprivation stress: A review. Ann Bot 91: 179-
194.
Blum A, Shipler L, Golam G, Mayer J. 1989. Yield stability and canopy
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22: 289- 296.
Bowler C, Montagu M, Inze D. 1992. Superoxide dismutase and stress
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Bradford KJ, Hsiao TC. 1982. Physiological responses to moderate water
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Day AW, Legg BJ, French BK, Johnson AE, Lawlor DW, Jeffers WD.
1978. A drought experiment using mobile shelters: The effects of
drought on barley yield, water use and nutrient uptake. J Agric Sci
Camb 91: 599- 623.
Desclaux D, Huynh TT, Roumet P. 2000. Identification of Soybean
characteristics that indicate the timing of drought stress. Crop Sci 40
(3): 716-722.
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Two Common Bean Cultivars with Contrasting Growth Habits.
Amer-Eur J Agric Environ Sci 9 (5): 495-499.
Foyer CH, Descourvières P, Kunert K. 1994. Protection against oxygen
radicals: an important defense mechanism studied in transgenic
plants. Plant Cell Environ 17: 507- 523.
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tolerance and signaling. Physiol Plant 100: 241-254.
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A metabolic interface between stress perception and physiological
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water relationship of Medicago sativa (L.) cv. Gabès and Astragalus
gombiformis (Pom.) under water-limited conditions. Emir J Food
Agric 22 (1): 1-12
Gupta AS, Webb R P, Holaday AS, Allen D. 1993. Over expression of
SOD protects plants from oxidative stress. Induction of ascorbate
peroxidase in superoxide dismutase over expressing plants. Plant
Physiol 103: 1067-1073.
Hiler EA, Bavel CHM, Hossain MM, Jordan WR. 1972. Sensitivity of
Southern peas to water deficits at three growth stages. Agron J 64: 60-
64.
Imungi JK. 2002. The brighter side of phenolic compounds abundance in
African leafy vegetables. Nairobi, IPGRI Newsletter for sub-Saharan
Africa 17: 205- 210
Irungu C, Mburu J, Maundu P, Grum M, Hoescle-Zeledon I. 2007.
Analysis of Markets for African Leafy Vegetables within Nairobi and
its Environs and Implications for On-farm Conservation of
Biodiversity. A consultancy report for Global Facilitation Unit for
Underutilized Species, Rome, Italy.
Jaleel CA, Sankar B, Murali PV, Gomathinayagam M, Lakshmanan
GMA, Panneerselvam R. 2008. Water deficit stress effects on reactive
oxygen metabolism in Catharanthus roseus;impacts on ajmalicine
accumulation. Colloids Surf B: Biointerfaces 62: 105-111.
Kameli A. 1990. Metabolic Responses of Durum Wheat to Water Stress
and their Role in Drought Resistance. [Dissertation]. University of
Sheffield, U.K.
Kannan ND, Kulandaivelu G. 2011. Drought induced changes in
physiological, biochemical and phytochemical properties of Withania
somnifera Dun. J Med Plants Res 5 (16): 3929-3935.
Kimiywe J, Waudo J, Mbithe D. 2006. Reducing hidden hunger and
malnutrition through traditional foods. Nairobi, IPGRI Newsletter for
sub- Saharan Africa 21: 75-84.
Kirnak H, Kaya C, Higgs D, Tas I. 2003) Responses of drip irrigated bell
pepper to water stress and different nitrogen levels with or without
mulch cover. J Plant Nutr 26: 263-277.
Løvaas E. 1997. Antioxidative and metal-chelating effects of polyamines.
Adv Pharmacol 38: 119-149.
Lütje S, Böttger M, Döring O. 2000. Are plants stacked neutrophyles?
Comparison of pathogen induced oxidative burst in plants and
mammals. In: K Esser J, Kadereit W, Lütge U, Runge M (eds.). Prog
Bot 61: 187-222.
MalenÄić D, GaÅ¡ić O, Popović M, Boza P. 2000. Screening for antioxidant
properties of Salvia reflexa Hornem. Phytother Res 14: 546-548.
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Chem Pharmacol Res 1: 102-104.
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and Phaseolus acutifolius Gray. Plant Physiol 77: 113-117.
Maundu PM, Ngugi GW, Kabuye CH. 1999. Traditional Food plants of
Kenya. KENRIK, National Museums of Kenya, Nairobi.
Maundu PM, Njiro EI, Chweya JA, Imungi JK, Seme EN. 1999. The
Kenyan case study. In: Chweya JA, Eyzaguirre PB. (eds.). The
Biodiversity of Traditional Leafy Vegetables. IPGRI,Rome.
Menconi M Sgherri CL Pinzino, Navari-Izzo F. 1995. Activated oxygen
production and detoxification in wheat plants subjected to a water
deficit programme. J Exp Bot 46: 1123-1130.
Mittler R. 2002. Oxidative stress, antioxidants and stress tolerance. Trends
Plant Sci 7: 405-410.
Mustapha Y, Biwe E R, Salem A. 2014. Effects of moisture stress on the
growth parameters of soybean genotypes. Discourse J Agric Food Sci
2 (5): 142-148.
Muthomi J, Musyimi DM. 2009. Growth responses of African nightshade
(Solanum scabrum Mill) Seedlings to water deficit. ARPN J Agric
Biol Sci 4(5): 24-30
Mwaura SN, Muluvi SA, Mathenge MK. 2013. African Leafy Vegetables
and Household Wellbeing in Kenya: A Disaggregation by Gender.
The 4th International Conference of the African Association of
Agricultural Economists,Tunisia
Nielsen DC, Nelson NO. 1998. Black bean sensitivity to water stress at
various growth stages Crop Sci 38: 422-427.
Oh MM, Edward EC, Rajashakar CB. 2010. Regulated water deficit
improve phytochemical concentration in lettuce. Amer Soc Hort Sci
l135: 223-229.
Olembo, NK, Fedha SS, Ngaira ES. 1995. Medicinal and Agricultural
Plants of Ikolomani Division, Kakamega District, Kenya.
Development Partners, Kakamega, Kenya.
Otieno DJ, Omiti J, Nyanamba T, McCullough E. 2009. Market
participation by vegetable farmers in Kenya: A comparison of rural
and peri-urban areas. African J Agric Res Vol 4 (5): 451-460.
Rispail N, Moris P, Webb K J. 2005. Phenolic compounds- extraction and
analysis. In: Lotus japonicus Handbook. Márquez AJ, Stougaard J,
Udvardi MK, Parniske M, Spaink HP, Saalbach G, Webb KJ,
Chiurazzi M , Márquez AJ. (eds.). Springer, Dordrecht, The
Netherlands
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of Roots of Tephrosia Purpurea Linn. International Journal in
Pharmacy Sciences 2: 30-33.
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wheat genotypes tolerance to water stress. Biol Plant 41: 387-394.
Sairam RK, Kumutha D, Ezhilmathi K, Deshmukh PS, Srivastava GC.
2008. Physiology and biochemistry of waterlogging tolerance in
plants. Biol Plant 52: 401-412.
Sánchez-RodrÃguez E, Rubio-Wilhelmi M. 2010. Genotypic differences in
some physiological parameters symptomatic for oxidative stress
under moderate drought in tomato plants. J Plant Sci 178: 30-40.
Scandalios JG, Guan L, Polidoros AN. 1997. Catalases in plants: gene
structure, properties, regulation and expression. In: J G Scandalios
(Ed.). Oxidative stress and the molecular biology of antioxidant
defenses. Cold Spring Harbor Laboratory Press. New York.
Schippers RR. 2002. African indigenous vegetables, an overview of the
cultivated species. Chatham, UK. Natural Resources Institute /ACPEU Technical Centre for Agricultural and rural Cooperation.
Schreck R, Baeuerle PA. 1991. The role of oxygen radicals as second
messengers. Trends Cell Biol 1: 39-42.
Sgherri CL M, Navari-Izzo F. 1995. Sunflower seedlings subjected to
increasing water deficit stress: oxidative stress and defense
mechanisms. Physiol Plant 93: 25- 30.
Shao HB, Chu LY, Jaleel CA, Manivannan P, Panneerselvam R, Shao
MA. 2009. Understanding water deficit stress-induced changes in the
basic metabolism of higher plants - biotechnologically and
sustainably improving agriculture and the eco-environment in arid
regions of the globe. Crit Rev Biotechnol 29: 131-151.
Sharp RE. 1996. Regulation of plant growth responses to low soil water
potential. Hort Sci 31(1): 36-38.
Shenkut AA, Brick MA. 2003. Traits associated with dry edible bean
(Phaseolus vulgaris L.) productivity under diverse soil moisture
environments. Euphytica 133: 339-347.
Summerfield RJ, Huxley PA, Dart PJ, Hughes. 1976. Some effect of
environmental stress on seed of cowpea (Vigna unguiculata (L)
Walp). Prima Plant Soil 44: 527-546.
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249: 33-36.
Tan WX, Blake TJ. 1997. Gas exchange and water relations responses to
drought of fast and slow growing black spruce families. Canadian J
Bot 75: 1700-1706.
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Abukutsa-Onyango MO, Tushabomwe-Kazooba C, Mwai W, Onyango
GM, Macha ES. 2005. Diversity of African indigenous vegetables
with nutrition and economic potential in the Lake Victoria region. In:
Oniang’o R, Grum M, Obel-Lawson E. (eds.), Developing African
Leafy Vegetables for Improved Nutrition, Regional Workshop, 6-9
December, 2005. Bioversity International, 2007.
Abukutsa-Onyango MO. 2003. Unexploited potential of Indigenous
African Vegetables in Western Kenya. Maseno J Educ Arts Sci 4 (1):
103-122.
Aderolu AM. 2000. The effect of water stress at different growth stages on
yield and seed quality of cowpea varieties. B. Agric Project
University of Ilorin, Nigeria.
Akıncı S, Lösel DM. 2012. Plant Water-Stress Response Mechanisms,
Water Stress. Intech, Rijecka, Croatia.
Akter S, Ahmed M, Eun JB. 2010. Solvent effects on antioxidant
properties of persimmon (Diospyros kaki L. cv. Daebong) seeds. Intl
J Food Sci Technol 45: 2258-2264.
Alexieva V, Sergiev I, Mapelli S, Karanov E. 2001. The effect of drought
and ultraviolet radiation on growth and stress markers in pea and
wheat. Plant Cell Environ 24: 1337-1344.
Apel K, Hirt H. 2004. Reactive oxygen species: metabolism, oxidative
stress, and signal transduction. Ann Rev Plant Biol 55: 373-399.
Ayaz FA, Kadioglu A, Turgut R. 2000. Water stress effects on the content
of low molecular weight carbohydrates and phenolic acids in
Ctenanthe setosa (Rosc.) Eichler. Canadian J Plant Sci 80: 373-378
Bhatt RM, Rao NKS. 2005. Influence of pod load on response of okra to
water stress. Indian J Plant Physiol 10 (1): 54-59.
Blokhina O, Virolainen E, Fagerstedt KV. 2003. Antioxidants, oxidative
damage and oxygen deprivation stress: A review. Ann Bot 91: 179-
194.
Blum A, Shipler L, Golam G, Mayer J. 1989. Yield stability and canopy
temperature of wheat genotypes under drought stress. Field Crops Res
22: 289- 296.
Bowler C, Montagu M, Inze D. 1992. Superoxide dismutase and stress
tolerance. Ann Rev Plant Physiol 43: 83-116.
Bradford KJ, Hsiao TC. 1982. Physiological responses to moderate water
stress. In: Lange O, Nobel PS, Osmond CB, Zeigler H (eds.).
Physiological plant ecology II. Water relations and carbon
assimilation. Encyclop Plant Physiol 12B. ed. Springer, Berlin.
Cadenas SE. 1989. Biochemistry of oxygen toxicity. Ann Rev Biochem
58: 79-110.
Chartzoulakis K, Noitsakis B, Therios I. 1993. Photosynthesis, plant
growth and dry matter distribution in kiwifruit as influenced by water
deficits. Irrigation Sci 14: 1-5.
Chaudhuri UN, Kanemasu ET. 1982. Effect of water gradient on sorghum
growth, water relations and yield. Canadian J Plant Sci 62: 599-607.
Day AW, Legg BJ, French BK, Johnson AE, Lawlor DW, Jeffers WD.
1978. A drought experiment using mobile shelters: The effects of
drought on barley yield, water use and nutrient uptake. J Agric Sci
Camb 91: 599- 623.
Desclaux D, Huynh TT, Roumet P. 2000. Identification of Soybean
characteristics that indicate the timing of drought stress. Crop Sci 40
(3): 716-722.
Emam Y, Shekoofa A, Salehi F, Jalali AH. 2010. Water Stress Effects on
Two Common Bean Cultivars with Contrasting Growth Habits.
Amer-Eur J Agric Environ Sci 9 (5): 495-499.
Foyer CH, Descourvières P, Kunert K. 1994. Protection against oxygen
radicals: an important defense mechanism studied in transgenic
plants. Plant Cell Environ 17: 507- 523.
Foyer CH, Lopez-Delgado H, Dat JF, Scott IM. 1997. Hydrogen peroxideand glutathione-associated mechanisms of acclamatory stress
tolerance and signaling. Physiol Plant 100: 241-254.
Foyer CH, Noctor G. 2005. Redox homeostasis and antioxidant signaling:
A metabolic interface between stress perception and physiological
responses. Plant Cell 17: 1866-1875.
GoK. 1999. National poverty eradication plan 1999-2015. Government of
Kenya Printers, Nairobi.
GoK. 2004. Strategy for revitalizing Agriculture 2004-2014: Nairobi,
Ministry of Agriculture and the Ministry of Livestock and Fisheries
Development, Republic of Kenya, Nairobi.
Gorai M, Hachef A, Neffati M. 2010. Differential responses in growth and
water relationship of Medicago sativa (L.) cv. Gabès and Astragalus
gombiformis (Pom.) under water-limited conditions. Emir J Food
Agric 22 (1): 1-12
Gupta AS, Webb R P, Holaday AS, Allen D. 1993. Over expression of
SOD protects plants from oxidative stress. Induction of ascorbate
peroxidase in superoxide dismutase over expressing plants. Plant
Physiol 103: 1067-1073.
Hiler EA, Bavel CHM, Hossain MM, Jordan WR. 1972. Sensitivity of
Southern peas to water deficits at three growth stages. Agron J 64: 60-
64.
Imungi JK. 2002. The brighter side of phenolic compounds abundance in
African leafy vegetables. Nairobi, IPGRI Newsletter for sub-Saharan
Africa 17: 205- 210
Irungu C, Mburu J, Maundu P, Grum M, Hoescle-Zeledon I. 2007.
Analysis of Markets for African Leafy Vegetables within Nairobi and
its Environs and Implications for On-farm Conservation of
Biodiversity. A consultancy report for Global Facilitation Unit for
Underutilized Species, Rome, Italy.
Jaleel CA, Sankar B, Murali PV, Gomathinayagam M, Lakshmanan
GMA, Panneerselvam R. 2008. Water deficit stress effects on reactive
oxygen metabolism in Catharanthus roseus;impacts on ajmalicine
accumulation. Colloids Surf B: Biointerfaces 62: 105-111.
Kameli A. 1990. Metabolic Responses of Durum Wheat to Water Stress
and their Role in Drought Resistance. [Dissertation]. University of
Sheffield, U.K.
Kannan ND, Kulandaivelu G. 2011. Drought induced changes in
physiological, biochemical and phytochemical properties of Withania
somnifera Dun. J Med Plants Res 5 (16): 3929-3935.
Kimiywe J, Waudo J, Mbithe D. 2006. Reducing hidden hunger and
malnutrition through traditional foods. Nairobi, IPGRI Newsletter for
sub- Saharan Africa 21: 75-84.
Kirnak H, Kaya C, Higgs D, Tas I. 2003) Responses of drip irrigated bell
pepper to water stress and different nitrogen levels with or without
mulch cover. J Plant Nutr 26: 263-277.
Løvaas E. 1997. Antioxidative and metal-chelating effects of polyamines.
Adv Pharmacol 38: 119-149.
Lütje S, Böttger M, Döring O. 2000. Are plants stacked neutrophyles?
Comparison of pathogen induced oxidative burst in plants and
mammals. In: K Esser J, Kadereit W, Lütge U, Runge M (eds.). Prog
Bot 61: 187-222.
MalenÄić D, GaÅ¡ić O, Popović M, Boza P. 2000. Screening for antioxidant
properties of Salvia reflexa Hornem. Phytother Res 14: 546-548.
Mandal S, Yadav S, Yadav S, Nema RK. 2009. Antioxidants: A Review. J
Chem Pharmacol Res 1: 102-104.
Markhart HA. 1985. Comparative water relations of Phaseolus vulgaris L.
and Phaseolus acutifolius Gray. Plant Physiol 77: 113-117.
Maundu PM, Ngugi GW, Kabuye CH. 1999. Traditional Food plants of
Kenya. KENRIK, National Museums of Kenya, Nairobi.
Maundu PM, Njiro EI, Chweya JA, Imungi JK, Seme EN. 1999. The
Kenyan case study. In: Chweya JA, Eyzaguirre PB. (eds.). The
Biodiversity of Traditional Leafy Vegetables. IPGRI,Rome.
Menconi M Sgherri CL Pinzino, Navari-Izzo F. 1995. Activated oxygen
production and detoxification in wheat plants subjected to a water
deficit programme. J Exp Bot 46: 1123-1130.
Mittler R. 2002. Oxidative stress, antioxidants and stress tolerance. Trends
Plant Sci 7: 405-410.
Mustapha Y, Biwe E R, Salem A. 2014. Effects of moisture stress on the
growth parameters of soybean genotypes. Discourse J Agric Food Sci
2 (5): 142-148.
Muthomi J, Musyimi DM. 2009. Growth responses of African nightshade
(Solanum scabrum Mill) Seedlings to water deficit. ARPN J Agric
Biol Sci 4(5): 24-30
Mwaura SN, Muluvi SA, Mathenge MK. 2013. African Leafy Vegetables
and Household Wellbeing in Kenya: A Disaggregation by Gender.
The 4th International Conference of the African Association of
Agricultural Economists,Tunisia
Nielsen DC, Nelson NO. 1998. Black bean sensitivity to water stress at
various growth stages Crop Sci 38: 422-427.
Oh MM, Edward EC, Rajashakar CB. 2010. Regulated water deficit
improve phytochemical concentration in lettuce. Amer Soc Hort Sci
l135: 223-229.
Olembo, NK, Fedha SS, Ngaira ES. 1995. Medicinal and Agricultural
Plants of Ikolomani Division, Kakamega District, Kenya.
Development Partners, Kakamega, Kenya.
Otieno DJ, Omiti J, Nyanamba T, McCullough E. 2009. Market
participation by vegetable farmers in Kenya: A comparison of rural
and peri-urban areas. African J Agric Res Vol 4 (5): 451-460.
Rispail N, Moris P, Webb K J. 2005. Phenolic compounds- extraction and
analysis. In: Lotus japonicus Handbook. Márquez AJ, Stougaard J,
Udvardi MK, Parniske M, Spaink HP, Saalbach G, Webb KJ,
Chiurazzi M , Márquez AJ. (eds.). Springer, Dordrecht, The
Netherlands
Rumit S, Heena K, Rajal S, Naveen S. 2010. In vitro Antioxidant Activity
of Roots of Tephrosia Purpurea Linn. International Journal in
Pharmacy Sciences 2: 30-33.
Sairam R, Deshmukh P, Saxena D C. 1998. Role of antioxidant systems in
wheat genotypes tolerance to water stress. Biol Plant 41: 387-394.
Sairam RK, Kumutha D, Ezhilmathi K, Deshmukh PS, Srivastava GC.
2008. Physiology and biochemistry of waterlogging tolerance in
plants. Biol Plant 52: 401-412.
Sánchez-RodrÃguez E, Rubio-Wilhelmi M. 2010. Genotypic differences in
some physiological parameters symptomatic for oxidative stress
under moderate drought in tomato plants. J Plant Sci 178: 30-40.
Scandalios JG, Guan L, Polidoros AN. 1997. Catalases in plants: gene
structure, properties, regulation and expression. In: J G Scandalios
(Ed.). Oxidative stress and the molecular biology of antioxidant
defenses. Cold Spring Harbor Laboratory Press. New York.
Schippers RR. 2002. African indigenous vegetables, an overview of the
cultivated species. Chatham, UK. Natural Resources Institute /ACPEU Technical Centre for Agricultural and rural Cooperation.
Schreck R, Baeuerle PA. 1991. The role of oxygen radicals as second
messengers. Trends Cell Biol 1: 39-42.
Sgherri CL M, Navari-Izzo F. 1995. Sunflower seedlings subjected to
increasing water deficit stress: oxidative stress and defense
mechanisms. Physiol Plant 93: 25- 30.
Shao HB, Chu LY, Jaleel CA, Manivannan P, Panneerselvam R, Shao
MA. 2009. Understanding water deficit stress-induced changes in the
basic metabolism of higher plants - biotechnologically and
sustainably improving agriculture and the eco-environment in arid
regions of the globe. Crit Rev Biotechnol 29: 131-151.
Sharp RE. 1996. Regulation of plant growth responses to low soil water
potential. Hort Sci 31(1): 36-38.
Shenkut AA, Brick MA. 2003. Traits associated with dry edible bean
(Phaseolus vulgaris L.) productivity under diverse soil moisture
environments. Euphytica 133: 339-347.
Summerfield RJ, Huxley PA, Dart PJ, Hughes. 1976. Some effect of
environmental stress on seed of cowpea (Vigna unguiculata (L)
Walp). Prima Plant Soil 44: 527-546.
Tadolini B. 1988. Polyamine inhibition of lipid peroxidation. Biochem J
249: 33-36.
Tan WX, Blake TJ. 1997. Gas exchange and water relations responses to
drought of fast and slow growing black spruce families. Canadian J
Bot 75: 1700-1706.
Tanguilig VC, Yambao E B, O' Toole J C, De Datta S K. 1987. Water
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