Toppur Seethapaty Sadasivan obtained DSc (1955) from University of London, UK and specialized in the area of physiological plant pathology. He was Professor of Botany and Director, Centre for Advanced Studies in Botany at the University of Madras (1944-73) and also Consultant to CSIR on Plant-based Laboratories.

Academic and Research Achievements: Using model host-parasite systems, Sadasivan’s group specialized in studying physiology and biochemistry of the diseased plant and, in particular, demonstrated ionic imbalance and loss of permeability of toxin invaded plant tissues. The toxin production by Fusarium vasinfectum is controlled by zinc, in which the fungus does not produce fusaric acid and in higher concentrations of zinc the production of fusaric acid is inhibited. It is considered that the zinc factor is important not only for production of toxin in vivo but also in situ. Studies were also made to understand the essentiality of zinc for the production of the enzyme pectin methylesterase in vitro and polygalcturansase. Besides, an optimal amount of zinc was necessary for the maximum production of fusaric acid. There was a correlation between pectinolytic enzyme properties of the pathogen and severity of the disease development. One of the three long range problems was rhizosphere microflora and soil borne diseases. The concept of fungistatsis was studied in detail. Fungal spores could not germinate when introduced intro fresh fertile soils due to fungistasis but readily germinated when seedling roots grew in their vicinity. Fungistasis has been demonstrated in the top 12-15 inches of soil. The root exudates assumed importance in the understanding of pathogenesis and toxin production in the rhizosphere and rhixoplane by root infecting microbes. The points that emerge from the studies on rhizosphere microflora are : a) the influence of metals on the flora in the rhizosphere and rhizoplane, b) formation of toxins / antibiotics by the pathogens, c) the identification of rhizosphere exudates and formation of metalochelates and d) in vivo changes brought about by metals in substrates that aid pathogenesis.

Other Contributions: Professor Sadasivan established the School of Physiological Plant Pathology at University of Madras. He served as Editor of the Journal of the Indian Botanical Society and was also on the Editorial Board of Phytopathology Zeitschrift, Berlin. He was Member of the INSA Council (1958-59, 1962-64, 1971-73). He was Vice-President, International Botanical Congress (1959, 1964, 1969 and 1975), Vice-President, First International Plant Pathology Congress, London (1966) and Chairman, Governing Body of Birbal Sahni Institute of Paleobotany, Lucknow and was Birbal Sahni Professor (1977-80).

Awards and Honours: Sadasivan won many awards, notably: SS Bhatnagar Prize (1960); Birbal Sahni Medal of Indian Botanical Society (1962); the Jubliee Medal of Birbal Sahni Institute of Palaeobotany (1971); Sunder Lal Hora Medal of INSA (1973); Padma Bhushan (1974); and Birbal Sahni Birth Centenary Medal (1999). He was elected Fellow of the Indian Botanical Society (President 1963-64), Indian Phytopathological Society (President 1964), Indian Academy of Sciences, Bangalore and Deutsches Akademie der Naturforschung, Leopoldina, Germany; President, Botany Section, Indian Science Congress (1958).

The Indian National Science Academy has instituted ‘Professor TS Sadasivan Lecture Award’ in his honour.