Int.J.Curr.Microbiol.App.Sci (2019) 8(1): 37-44 37 Original Research Article https://doi.org/10.20546/ijcmas.2019.801.005 Correlation among Morphological, Biochemical and Physiological Responses under Iron Toxic Conditions in Rice M. Amaranatha Reddy*, Rose Mary Francies, P.S. Abida and P. Suresh Kumar Department of Plant Breeding and Genetics, College of Horticulture, Kerala Agricultural University, Thrissur, Kerala 680 656, India *Corresponding author ABSTRACT Introduction Iron toxicity in soil is reported to be a widespread problem to affect more than 50% of lowland rice in Sri Lanka, Vietnam, Malaysia, India (especially in Kerala, Orissa, West Bengal and Andaman Islands), Indonesia, Philippines, Brazil, Columbia and Madagascar (Shimizu et al., 2005). Iron toxicity prevalent in the rice growing tracts of the state, further compounds the problem of low rice production. Yield reduction may range from 10 to 90% depending on soil, variety and growth stage of the appearance of symptoms (Sahrawat, 2004). Iron toxicity is characterized by the appearance of small brown spots on the lower leaves starting from the tips. Later the whole leaf turns brown, purple, yellow or orange. Growth and tillering are depressed and the root system is coarse, scanty and dark brown. Great inter-varietal differences in iron toxicity tolerance in rice have been reported (Mohanty and Panda, 1991). Therefore, exploiting the varietal tolerance to iron toxicity is accepted as the most cost-effective and practical means for increasing rice production under iron toxic soils (Shimizu, 2009).Iron toxicity tolerance is a complex character and is influenced by International Journal of Current Microbiology and Applied Sciences ISSN: 2319-7706 Volume 8 Number 01 (2019) Journal homepage: http://www.ijcmas.com F 2 Population obtained from F 1 cross between Tulasi (Most tolerant genotype) and CUL- 8709 (Most susceptible genotype). 300F 2 plants and their parents were screened at 800 ppm of Fe. Phenotyping screening of F 2 plants under iron toxic levels indicated that leaf bronzing is associated with growth reduction due to Fe 2+ toxicity in this F 2 population confirms the usefulness of leaf bronzing index as criterion for differentiating between genotypes susceptible and tolerance to iron toxicity. This typical symptom of Fe toxicity, showed a strong negative correlation with shoot length, root length, total number of roots, number of fresh roots, shoot weight and root weight. Iron reversibly adsorbed on root surface was positively correlated with iron content in the root and observed in plants with lower leaf bronzing symptoms indicated that physiological mechanisms like Fe exclusion from roots and root tissue tolerance at higher Fe content in roots are predominant in Fe toxicity tolerance. Keywords Correlation, Iron toxic conditions, Rice Accepted: 04 December 2018 Available Online: 10 January 2019 Article Info