Physiological and biochemical changes in wheat cultivars under salt stress as affected by foliar boron application
Yıl 2020,
, 100 - 107, 29.06.2020
Ali Doğru
,
Şansel Bildiren
Öz
In this study, interactive effects of salt stress (150 mM NaCl) and foliar boron (H3BO3; 30 µM) application was studied in two wheat (Triticum aestivum L.) genotypes (Momtchil and Pamukova-97). Chlorophyll a and total chlorophyll content in Momtchil were not affected by salinity, foliar boron and salinity+foliar boron application while chlorophyll b content was increased by foliar boron and salinity+foliar boron application as compared to relative controls, probably due to higher total carotenoid and free proline level. In Pamukova-97, however, foliar boron and salinity+foliar boron application led to the reduced photosynthetic pigment content because of the absence of such a protective mechanism. Antioxidant enzymes of ascorbate-glutathione cycle and superoxide dismutase was not induced by all applications and both remarkable H2O2 accumulation and membrane damage was determined in the leaves of wheat cultivars, as demonstrated by higher MDA content in leaves. As a result, it may be concluded that expected ameliorative effect of foliar boron application did not occur in salt-affected wheat cultivars used in this study.
Kaynakça
- [1] Ruan C. J., da Silva J. A. T., Mopper S., Qin P., Lutts S., Halophyte improvement for a salinized world, Crit. Rev. Plant Sci., 29, 329-359, 2010.
- [2] Flowers T. J., Galal H. K., Bromham L., Evolution of halophytes: Mutiple origin of salt tolerance in land plants, Func. Plant Biol., 37, 604-612, 2010.
- [3] Qadir M., Tübeileh A., Akhtar J., Larbi A., Minhas P. S., Khan M. A., Productivity enhancement of salt-affected environments through crop diversification, Land Degrad. Dev., 19, 429-453, 2008.
- [4] Orcutt D. M., Nilsen E. T., The physiology of plants under stress: Soil and biotic factors, Wiley, Haboken, 2000.
- [5] Doğru A., Yılmaz Kaçar M., A preliminary study on salt tolerance of some barley genotypes, Sakarya Uni. J. Sci., 23, 755-762, 2019.
- [6] Barassi C. A., Ayrault G., Creus C. M., Sueldo R., Sobrero M. T., Seed inoculation with Azospirillum mitigates NaCl effects on lettuce, Sci. Hort., 109, 8-14, 2006.
- [7] Eraslan F., İnal A., Savaştürk O., Güneş A., Changes in antioxidative system and membrane damage of lettuce in response to salinity and boron toxicity, Sci. Hort., 114, 5-10, 2007.
- [8] Kaya C., Higgs D., Sakara E., Response of two leafy vegetables grown at high salinity to supplementary potassium and phosphorus during different growth stages, J. Plant Nutr., 25, 2663-2676, 2002.
- [9] Mohammadi P., Khoshgoftarmanesh A. H., The effectiveness of synthetic zinc (Zn)-amino chelates in supplying Zn and alleviating salt-induced damages on hydroponically grown lettuce, Sci. Hort., 172, 117-123, 2014.
- [10] Mota-Cadenas C., Alcaraz-Lopez C., Martinez-Ballesta M. C., Carvajal M., How salinity affects CO2 fixation by horticultural crops, HortSci., 45, 1798-1803, 2010.
- [11] Perez-Lopez U., Miranda-Apodaca J., Munoz-Rueda A., Mena-Petita A., Lettuce production and antioxidant capacity are differentially modified by salt stress and light intensity under ambient and elevated CO2, J. Plant Physiol., 170, 1517-1525, 2013.
- [12] Doğru A., Bitkilerde antioksidant sistemler ve tuz stresine verdikleri yanıtlar, Uluslararası Doğu Anadolu Fen Mühendislik ve Tasarım Dergisi, 1, 164-185, 2019.
- [13] Wei Z., Julkowska M. M., Laloe J. O., Hartman Y., de Boer G. J., Michelmore R. W., van Tienderen P. H., Testerink C., Schranz M. E., A mixed-model QTL analysis for salt tolerance in seedlings of crop-wild hybrids of lettuce, Mol. Breeding, 34, 1389-1400, 2014.
- [14] Ashraf M., Salt tolerance of cotton: Some new advances, Crit. Rev. Plant Sci., 21,1-30, 2002.
- [15] Ashraf M., Athar H. R., Harris P. J. C., Kwon T. R., Some prospective strategies for improving crop salt tolerance, Adv. Agron., 97, 45-110, 2008.
- [16] Khan A., Ahmad M. S. A., Athar R. E., Ashraf M., Interactive effect of foliarly applied ascorbic acid and salt stress on wheat (Triticum aestivum L.) at the seedling state, Pak. J. Bot., 38, 1407-1414, 2006.
- [17] Torun A., Dumuş E., Erdem H., Tolay İ., Cenkseven Ş., Gülüt K. Y., Torun B., Ayçiçeğinde tuz zararı üzerine bor uygulamalarının etkisinin belirlenmesi, Türk Tarım-Gıda Bilim ve Teknoloji Dergisi, 6, 1781-1788, 2018.
- [18] Tariq M., Mott C.J.B., The significance of boron in plany nutrition and environment-a review, J. Agron., 6, 1-10, 2007.
- [19] Greenwood N. N., Earnshow A., Chemistry of elements, John Wiley and Sons, Inc., 1984.
- [20] Warington K., The effect of boric acid and borax on the broad bean and certain other plants, Ann. Bot., 37, 629-672, 1923.
- [21] Emebiri L., Michael P., Moody D., Enhanced tolerance to boron toxicity in two-rowed barley by marker-assisted introgression of favorable alleles derived from Sahara 3771, Plant Soil, 314, 77-85, 2009.
- [22] Rehman S., Park T. I., Kim Y. J., Seo Y. W., Yung S J., Inverse relationship between boron toxicity tolerance and boron contents of barley seed and roots, J. Plant Nutr., 29, 1779-1789, 2006.
- [23] Reid R., Can we really increase yields by making crop plants tolerant to boron toxicity? Plant Sci., 178, 9-11, 2010.
- [24] Naz T., Akhtar J., Haq M. A., Saqib M., Iqbal M. M., Shahid M., Interaction of salinity and boron in wheat affects physiological attributes, growth and activity of antioxidant system, Pak. J. Agric. Sci., 55, 339-347, 2018.
- [25] Çavuşoğlu D., Tabur S., Tuz stresi altında çimlendirilen arpa tohumlarında borik asit uygulamasının sitogenetik etkisi, SDÜ Fen Bil. Enst. Dergisi, 19, 142-150, 2015.
- [26] Mittler R., Oxidative stress, antioxidants and stress tolerance, Trends Plant Sci., 7, 405-410, 2002.
- [27] Miller G., Shulaev V., Mittler R., Reactive oxygen signaling and abiotic stress, Physiol. Plant., 133, 481-489, 2008.
- [28] Dağlıoğlu Y., Türkiş S., Myriophyllum spicatum’un süperoksit dismutaz aktivitesi, lipid peroksidasyonu ve hidrojen peroksit seviyesi üzerine nano ve mikro bor partiküllerinin etkisi, BEÜ Fen Bilimleri Dergisi, 6, 62-70, 2017.
- [29] Dağlıoğlu Y., Yılmaz Öztürk B., The assessment of biological accumulation on exposure in boron particles of Desmodesmus multivariabilis, Biol. Div. Cons., 9, 204-209, 2016.
- [30] Dağlıoğlu Y., Yılmaz Öztürk B., A comparison of the acute toxicity and bioaccumulation of boron particles (nano and micro) in Chodatadesmus mucronulatus, Boron, 3, 157-165, 2018.
- [31] Lichtenthaler H. K., Chlorophylls and carotenoids: Pigments of photosynthetic biomembranes, Meth. Enzymol., 148, 350-382, 1987.
- [32] Ohkawa H., Ohishi N., Yagi Y., Assay of lipid peroxides in animal tissue by thiobarbituric acid reaction, Anal. Biochem., 95, 351-358, 1979.
- [33] Beyer W. F., Fridovich I., Assaying for superoxide dismutase activity: Some large consequences of minor changes in conditions, Anal. Biochem., 161, 559-566, 1987.
- [34] Wang S. Y., Jiao H., Faust M., Changes in ascorbate, glutathione and related enzyme activity during thidiazuron-induced bud break of apple, Plant Physiol., 82, 231-236, 1991.
- [35] Sgherri C. L. M., Loggini B., Puliga S., Navari-Izzo F., Antioxidant system in Sporobolus stapfianus: changes in response to desiccation and rehydration, Phytochem., 35, 561-565, 1994.
- [36] Sanchez-Romero C., Garcia-Gomes M. L., Pliego-Alfaro F., Heredis A., Peroxidase activities and isoenzyme profiles associated with development of avocado (Persea americana M.) leaves at different ontogenetic stages, J. Plant Growth Regul., 12, 95-100, 1993.
- [37] Karimi S., Tavallali V., Wirthensohn M., Boron amendments improves water relationsand performance of Pistachia vera under salt stress, Sci. Hort., 241, 252-259, 2018.
- [38] Abdel-Motagally F. M. F., El-Zohri M., Improvement of wheat yield grown under drought stress by boron foliar application at different growth stage, J. Saudi Soc. Agric. Sci., 17, 178-185, 2018.
- [39] Güneş A., Gezgin S., Kalınbacak K., Özcan H., Çakmak İ., Bor elementinin bitkiler için önemi, Boron, 2, 168-174, 2017.
- [40] Jiang Q., Roche D., Monaco T. A., Durham S. Gas exchange, chlorophyll fluorescence parameters and carbon isotope discrimination of 14 barley genetic lines in response to salinity, Field Crop Res., 96, 269-278, 2006.
- [41] Ghanati F., Mortia A., Yokota H., Induction of suberin and increase of lignin content by excess boron in tobacco cells, Soil Sci. J. Plant Nutr., 48, 357-364, 2002.
- [42] Reid R., Identification of boron transporter genes likely to be responsible for tolerance to boron toxicity in wheat and barley, Plant Cell Physiol., 48, 1673-1678, 2007.
- [43] Tewari A. K., Tripaty B. C., Acclimation of chlorophyll biosynthetic reactions to temperature stress in cucumber (Cucumis sativus L.), Planta, 208, 431-437, 1999.
- [44] Luna C. M., Gonzalez C. A., Trippi V. S., Oxidative damage caused by an excess of copper in oat leaves, Plant Cell Physiol., 35, 11-15, 1994.
- [45] Trebst A., Function of -carotene and tocopherol in photosystem II, Zeit. Nat., 58, 609-620, 2003.
- [46] Jain M., Mathur G., Koul S., Sarin N. B., Ameliorative effects of proline on salt stressed lipid peroxidation in cell lines of groundnut (Arachis hypogea L.). Plant Cell Rep., 20, 463-468, 2001.
- [47] Brown P. H., Bellaloui N., Wimmer M. A., Bassil E. S., Ruiz J., Hu, H., Pfeffer H., Dannel V., Romheld V., Boron in plant biology, Plant Biol., 4, 205-233, 2002.
- [48] Tavallali V., Karimi S., Espargham O., Boron enhances antioxidative defence in the leaves of salt-affected Pistacia vera seedlings, The Hort. J., 87, 55-62, 2018.
- [49] Sairam R. K., Srivastava G. C., Aharwal S., Meena R. C., Differences in antioxidant activity in response to salinity stress in tolerant and susceptible wheat genotypes, Biol. Plant., 49, 85-89, 2005.
- [50] Gratao P. L., Polle A., Lea P. J., Azevado R. A., Making the life heavy metal-stressed plants a little easier, Func. Plant Biol., 32, 481-494, 2005.
- [51] Karimi S., Rahemi M., Eshghi S., Maftoun M., Tavallali V., Effects of long-term salinity on growth and performance of two pistachio (Pistacia vera L.) rootstocks. Aust, J. Basic Appl. Sci., 3, 1630-1639, 2009.
- [52] Karimi S., Eshghi S., Hasan-Nezhadian S., Inducing salt tolerance in sweet corn by magnetic priming. Acta Agric, Slov., 109, 89-102, 2017.
- [53] Matysik J., Alia Bhalu B., Mohanty P., Molecular mechanisms of quenching of reactive oxygen species by proline under stress in plants, Curr. Sci., 82, 525–
532, 2002.
Tuz stresi altındaki buğday genotiplerinde foliar bor uygulamalarının neden olduğu fizyolojik ve biyokimyasal değişimler
Yıl 2020,
, 100 - 107, 29.06.2020
Ali Doğru
,
Şansel Bildiren
Öz
Bu çalışmada farklı iki buğday (Triticum aestivum L.) genotipinde (Momtchil ve Pamukova-97) tuz stresi (150 mM NaCl) ve foliar bor (H3BO3; 30 µM) uygulamalarının etkileşimleri incelenmiştir. Momtchil’de klorofil a ve toplam klorofil miktarı tuz stresi, foliar bor ve tuz+foliar bor uygulamalarından etkilenmemiş, klorofil b miktarı ise, muhtemelen yüksek toplam karotenoid ve serbest prolin miktarından dolayı, ilgili kontrollerle karşılaştırıldığında artış göstermiştir. Pamukova-97’de ise böyle koruyucu bir mekanizmanın bulunmaması nedeniyle foliar bor ve tuz+foliar bor uygulamaları fotosentetik pigment miktarının azalmasına yol açmıştır. Askorbat-glutatyon döngüsünün enzimleri ve süperoksit dismutaz aktivitesi tüm uygulamalar sonucunda indüklenmemiş ve buğday genotiplerinin yapraklarında hem belirgin derecede H2O2 birikimi hem de yüksek MDA miktarı ile gösterildiği gibi membran hasarı belirlenmiştir. Sonuç olarak, bu çalışmada kullanılan, tuz stresi altındaki buğday genotiplerinde foliar bor uygulamalarının beklenen iyileştirici etkisinin gözlenemediği söylenebilir.
Kaynakça
- [1] Ruan C. J., da Silva J. A. T., Mopper S., Qin P., Lutts S., Halophyte improvement for a salinized world, Crit. Rev. Plant Sci., 29, 329-359, 2010.
- [2] Flowers T. J., Galal H. K., Bromham L., Evolution of halophytes: Mutiple origin of salt tolerance in land plants, Func. Plant Biol., 37, 604-612, 2010.
- [3] Qadir M., Tübeileh A., Akhtar J., Larbi A., Minhas P. S., Khan M. A., Productivity enhancement of salt-affected environments through crop diversification, Land Degrad. Dev., 19, 429-453, 2008.
- [4] Orcutt D. M., Nilsen E. T., The physiology of plants under stress: Soil and biotic factors, Wiley, Haboken, 2000.
- [5] Doğru A., Yılmaz Kaçar M., A preliminary study on salt tolerance of some barley genotypes, Sakarya Uni. J. Sci., 23, 755-762, 2019.
- [6] Barassi C. A., Ayrault G., Creus C. M., Sueldo R., Sobrero M. T., Seed inoculation with Azospirillum mitigates NaCl effects on lettuce, Sci. Hort., 109, 8-14, 2006.
- [7] Eraslan F., İnal A., Savaştürk O., Güneş A., Changes in antioxidative system and membrane damage of lettuce in response to salinity and boron toxicity, Sci. Hort., 114, 5-10, 2007.
- [8] Kaya C., Higgs D., Sakara E., Response of two leafy vegetables grown at high salinity to supplementary potassium and phosphorus during different growth stages, J. Plant Nutr., 25, 2663-2676, 2002.
- [9] Mohammadi P., Khoshgoftarmanesh A. H., The effectiveness of synthetic zinc (Zn)-amino chelates in supplying Zn and alleviating salt-induced damages on hydroponically grown lettuce, Sci. Hort., 172, 117-123, 2014.
- [10] Mota-Cadenas C., Alcaraz-Lopez C., Martinez-Ballesta M. C., Carvajal M., How salinity affects CO2 fixation by horticultural crops, HortSci., 45, 1798-1803, 2010.
- [11] Perez-Lopez U., Miranda-Apodaca J., Munoz-Rueda A., Mena-Petita A., Lettuce production and antioxidant capacity are differentially modified by salt stress and light intensity under ambient and elevated CO2, J. Plant Physiol., 170, 1517-1525, 2013.
- [12] Doğru A., Bitkilerde antioksidant sistemler ve tuz stresine verdikleri yanıtlar, Uluslararası Doğu Anadolu Fen Mühendislik ve Tasarım Dergisi, 1, 164-185, 2019.
- [13] Wei Z., Julkowska M. M., Laloe J. O., Hartman Y., de Boer G. J., Michelmore R. W., van Tienderen P. H., Testerink C., Schranz M. E., A mixed-model QTL analysis for salt tolerance in seedlings of crop-wild hybrids of lettuce, Mol. Breeding, 34, 1389-1400, 2014.
- [14] Ashraf M., Salt tolerance of cotton: Some new advances, Crit. Rev. Plant Sci., 21,1-30, 2002.
- [15] Ashraf M., Athar H. R., Harris P. J. C., Kwon T. R., Some prospective strategies for improving crop salt tolerance, Adv. Agron., 97, 45-110, 2008.
- [16] Khan A., Ahmad M. S. A., Athar R. E., Ashraf M., Interactive effect of foliarly applied ascorbic acid and salt stress on wheat (Triticum aestivum L.) at the seedling state, Pak. J. Bot., 38, 1407-1414, 2006.
- [17] Torun A., Dumuş E., Erdem H., Tolay İ., Cenkseven Ş., Gülüt K. Y., Torun B., Ayçiçeğinde tuz zararı üzerine bor uygulamalarının etkisinin belirlenmesi, Türk Tarım-Gıda Bilim ve Teknoloji Dergisi, 6, 1781-1788, 2018.
- [18] Tariq M., Mott C.J.B., The significance of boron in plany nutrition and environment-a review, J. Agron., 6, 1-10, 2007.
- [19] Greenwood N. N., Earnshow A., Chemistry of elements, John Wiley and Sons, Inc., 1984.
- [20] Warington K., The effect of boric acid and borax on the broad bean and certain other plants, Ann. Bot., 37, 629-672, 1923.
- [21] Emebiri L., Michael P., Moody D., Enhanced tolerance to boron toxicity in two-rowed barley by marker-assisted introgression of favorable alleles derived from Sahara 3771, Plant Soil, 314, 77-85, 2009.
- [22] Rehman S., Park T. I., Kim Y. J., Seo Y. W., Yung S J., Inverse relationship between boron toxicity tolerance and boron contents of barley seed and roots, J. Plant Nutr., 29, 1779-1789, 2006.
- [23] Reid R., Can we really increase yields by making crop plants tolerant to boron toxicity? Plant Sci., 178, 9-11, 2010.
- [24] Naz T., Akhtar J., Haq M. A., Saqib M., Iqbal M. M., Shahid M., Interaction of salinity and boron in wheat affects physiological attributes, growth and activity of antioxidant system, Pak. J. Agric. Sci., 55, 339-347, 2018.
- [25] Çavuşoğlu D., Tabur S., Tuz stresi altında çimlendirilen arpa tohumlarında borik asit uygulamasının sitogenetik etkisi, SDÜ Fen Bil. Enst. Dergisi, 19, 142-150, 2015.
- [26] Mittler R., Oxidative stress, antioxidants and stress tolerance, Trends Plant Sci., 7, 405-410, 2002.
- [27] Miller G., Shulaev V., Mittler R., Reactive oxygen signaling and abiotic stress, Physiol. Plant., 133, 481-489, 2008.
- [28] Dağlıoğlu Y., Türkiş S., Myriophyllum spicatum’un süperoksit dismutaz aktivitesi, lipid peroksidasyonu ve hidrojen peroksit seviyesi üzerine nano ve mikro bor partiküllerinin etkisi, BEÜ Fen Bilimleri Dergisi, 6, 62-70, 2017.
- [29] Dağlıoğlu Y., Yılmaz Öztürk B., The assessment of biological accumulation on exposure in boron particles of Desmodesmus multivariabilis, Biol. Div. Cons., 9, 204-209, 2016.
- [30] Dağlıoğlu Y., Yılmaz Öztürk B., A comparison of the acute toxicity and bioaccumulation of boron particles (nano and micro) in Chodatadesmus mucronulatus, Boron, 3, 157-165, 2018.
- [31] Lichtenthaler H. K., Chlorophylls and carotenoids: Pigments of photosynthetic biomembranes, Meth. Enzymol., 148, 350-382, 1987.
- [32] Ohkawa H., Ohishi N., Yagi Y., Assay of lipid peroxides in animal tissue by thiobarbituric acid reaction, Anal. Biochem., 95, 351-358, 1979.
- [33] Beyer W. F., Fridovich I., Assaying for superoxide dismutase activity: Some large consequences of minor changes in conditions, Anal. Biochem., 161, 559-566, 1987.
- [34] Wang S. Y., Jiao H., Faust M., Changes in ascorbate, glutathione and related enzyme activity during thidiazuron-induced bud break of apple, Plant Physiol., 82, 231-236, 1991.
- [35] Sgherri C. L. M., Loggini B., Puliga S., Navari-Izzo F., Antioxidant system in Sporobolus stapfianus: changes in response to desiccation and rehydration, Phytochem., 35, 561-565, 1994.
- [36] Sanchez-Romero C., Garcia-Gomes M. L., Pliego-Alfaro F., Heredis A., Peroxidase activities and isoenzyme profiles associated with development of avocado (Persea americana M.) leaves at different ontogenetic stages, J. Plant Growth Regul., 12, 95-100, 1993.
- [37] Karimi S., Tavallali V., Wirthensohn M., Boron amendments improves water relationsand performance of Pistachia vera under salt stress, Sci. Hort., 241, 252-259, 2018.
- [38] Abdel-Motagally F. M. F., El-Zohri M., Improvement of wheat yield grown under drought stress by boron foliar application at different growth stage, J. Saudi Soc. Agric. Sci., 17, 178-185, 2018.
- [39] Güneş A., Gezgin S., Kalınbacak K., Özcan H., Çakmak İ., Bor elementinin bitkiler için önemi, Boron, 2, 168-174, 2017.
- [40] Jiang Q., Roche D., Monaco T. A., Durham S. Gas exchange, chlorophyll fluorescence parameters and carbon isotope discrimination of 14 barley genetic lines in response to salinity, Field Crop Res., 96, 269-278, 2006.
- [41] Ghanati F., Mortia A., Yokota H., Induction of suberin and increase of lignin content by excess boron in tobacco cells, Soil Sci. J. Plant Nutr., 48, 357-364, 2002.
- [42] Reid R., Identification of boron transporter genes likely to be responsible for tolerance to boron toxicity in wheat and barley, Plant Cell Physiol., 48, 1673-1678, 2007.
- [43] Tewari A. K., Tripaty B. C., Acclimation of chlorophyll biosynthetic reactions to temperature stress in cucumber (Cucumis sativus L.), Planta, 208, 431-437, 1999.
- [44] Luna C. M., Gonzalez C. A., Trippi V. S., Oxidative damage caused by an excess of copper in oat leaves, Plant Cell Physiol., 35, 11-15, 1994.
- [45] Trebst A., Function of -carotene and tocopherol in photosystem II, Zeit. Nat., 58, 609-620, 2003.
- [46] Jain M., Mathur G., Koul S., Sarin N. B., Ameliorative effects of proline on salt stressed lipid peroxidation in cell lines of groundnut (Arachis hypogea L.). Plant Cell Rep., 20, 463-468, 2001.
- [47] Brown P. H., Bellaloui N., Wimmer M. A., Bassil E. S., Ruiz J., Hu, H., Pfeffer H., Dannel V., Romheld V., Boron in plant biology, Plant Biol., 4, 205-233, 2002.
- [48] Tavallali V., Karimi S., Espargham O., Boron enhances antioxidative defence in the leaves of salt-affected Pistacia vera seedlings, The Hort. J., 87, 55-62, 2018.
- [49] Sairam R. K., Srivastava G. C., Aharwal S., Meena R. C., Differences in antioxidant activity in response to salinity stress in tolerant and susceptible wheat genotypes, Biol. Plant., 49, 85-89, 2005.
- [50] Gratao P. L., Polle A., Lea P. J., Azevado R. A., Making the life heavy metal-stressed plants a little easier, Func. Plant Biol., 32, 481-494, 2005.
- [51] Karimi S., Rahemi M., Eshghi S., Maftoun M., Tavallali V., Effects of long-term salinity on growth and performance of two pistachio (Pistacia vera L.) rootstocks. Aust, J. Basic Appl. Sci., 3, 1630-1639, 2009.
- [52] Karimi S., Eshghi S., Hasan-Nezhadian S., Inducing salt tolerance in sweet corn by magnetic priming. Acta Agric, Slov., 109, 89-102, 2017.
- [53] Matysik J., Alia Bhalu B., Mohanty P., Molecular mechanisms of quenching of reactive oxygen species by proline under stress in plants, Curr. Sci., 82, 525–
532, 2002.