SCREENING OF IRON TOXICITY IN RICE GENOTYPES ON THE BASIS OF MORPHOLOGICAL, PHYSIOLOGICAL AND BIOCHEMICAL ANALYSIS

Fifty one varieties of upland and lowland rice were tested for their tolerance to different levels of iron (0, 50 mM, 100 mM and 200 mM) in nutrient solution at pH 6.8. Seeds were grown in the nutrient culture with different concentrations of iron under controlled environmental conditions. LC50 value was calculated after exposure to iron. Different physiological parameters such as germination percentage, root & shoot growth, shoot and root tolerant index and leaf bronzing symptoms were taken into consideration to screen the tolerant, medium tolerant and susceptible genotypes. Further, the selected high tolerant and susceptible varieties were taken further experiment at lower concentration of iron (0, 10, 20 and 40 mM) to study the physiological and biochemical analysis. Total chlorophyll, proline, total phenol, total protein and total carbohydrate content showed variation in both tolerant and susceptible ones. The oxidative enzymes also showed variation among the tolerant and non-tolerant genotypes. The tolerant, medium tolerant and susceptible to iron were classified on the basis of relative root and shoot growth and biochemical analysis. Based on observations, it is concludes that out of 51 varieties, 16 varieties are tolerant (> 200mM Fe), 11 varieties are medium tolerant(< 200 mM Fe) and 24 varieties are susceptible (< 100 mM) to selected iron concentration. This study can be employed for quick screening of rice varieties for Fe tolerance for breeding programme.