COMPARATIVE STUDIES ON THE IRON AND ZINC CONTENTS ESTIMATION USING ATOMIC ABSORPTION SPECTROPHOTOMETER AND GRAIN STAINING TECHNIQUES (PRUSSIAN BLUE AND DTZ) IN MAIZE GERMPLASMS

Malnutrition arising from dietary deficiency of critically important mineral micronutrients such as iron (Fe) and zinc (Zn) is a serious problem affecting nearly half of the world's population. Screening for micronutrients rich breeding lines includes the estimation of grain micronutrient contents in the seed samples using atomic absorption spectrophotometer (AAS). Though the protocol produces precise results, it is usually costly and time consuming. The nutritionist started searching for newer methods like staining the particular plant tissue with dyes so the initial screening of among vast germplasm lines becomes easier. A set of four hundred and thirty genotypes were used in this experiment wherein the reliability and the cost effectiveness of the use of the staining method in place of the estimation using AAS was investigated. The intensity of the color developed was directly proportional to the amount of iron and zinc in the grains and were scored as 1, 2, 3, 4, and 5. The genotype UBC 7 has got the maximum level of iron (65.43 mg kg-1) with about 64 lines is found to contain higher levels of iron. The genotype UMI 421 had the maximum level of zinc (60.15 mg kg-1) along with ten lines showing richer zinc levels. The genotypes namely UMI 1069, UMI 630, UMI 473, UMI 327, and UMI 382 are found to be having considerably higher levels of iron and zinc in the kernels. These lines may be used for the introgression of the traits concerning micronutrient enhancement into the popular elite cultivars. When compared to the estimation with AAS, the staining methods with Prussian Blue and Dithizone (DTZ: 1,5-diphenyl thiocarbazone) are found be very cost effective and precise in identifying and categorizing the lines as micronutrient rich/deficit. The varying color intensities serve as a reliable selection criterion for grain micronutrient contents in maize and other cereal crops. These protocols, could, therefore, be effectively used as the initial screening methodology and so the genotypes might be identified for higher grain micronutrient contents among huge population in a short period of time.