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Article Index
B. Grain micronutrient assessment in elite hybrids & varieties
D. Grain micronutrient assessment in Landraces/Farmers’ Varieties
G. Association mapping for grain iron and zinc
H. Identification of SNPs for genotyping of sorghum association mapping panel
SNPs identified for the candidate genes associated with iron and zinc accumulation in grains
I. SNP genotyping of sorghum association mapping panel
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1.    To profile sorghum cultivars and germplasm accessions for grain micronutrients and identify suitable donors.

2.    To develop improved sorghum cultivars with high grain iron and zinc density through conventional breeding.

3.    To identify SNP-trait associations for high grain iron and zinc contents in sorghum through candidate gene-based association mapping.

4.    To incorporate high zinc and iron content in sorghum with improved grain quality and elite background.

5.    To evaluate newly developed high zinc and iron promising genotypes under multi-location trials.

6.    To study the effect of external application of Iron and Zinc fertilizers through soil and foliar applications on grain micronutrient content.

7.    To evaluate nutritional quality of food products prepared from high yielding Rabi sorghum varieties, and standardization. 

ICAR-Indian Institute of Millets Research (IIMR), Hyderabad

PI: Dr. Hariprasanna K

CoPI: Drs. Rajendra Kumar R. Venkateswarlu

ICAR-IIMR, Hyderabad

A. Standardization of grain iron and zinc assessment

Standardization of micronutrient estimation is essential for accurate assessment of grain iron and zinc in breeding material. Sample preparation becomes very important when concentration is very low, and possibility of contamination is high as in case of iron. Approved methods of estimation recommend grinding of the grain sample into flour prior to digestion. Composition of grinding surface and handling errors can largely influence the results. Three methods of sorghum grain sample preparation viz., grinding using cyclone sample mill, hand pounding in mortar-pestle, and house-hold blender were adopted. One gram of sample was digested using nitric acid in a Microwave Digester and the concentration of iron and zinc was quantified using Atomic Absorption Spectrometer. Three independent grindings and three samples from each grinding were used for analysis. Grinding the sample using house-hold blender gave significantly higher value (p < 0.05) of 76.70±13.85 ppm for iron compared to grinding in mortar-pestle (26.99±2.32 ppm) and cyclone sample mill (25.41±1.7 ppm). There was no significant difference (p > 0.05) between grinding by mortar-pestle and cyclone sample mill. Also, there was no influence of grinding method on zinc content (p > 0.05).

To overcome problem of sample contamination during preparation, digestion of whole grains was tried and compared with cyclone sample mill ground flour. Two types of sorghum samples – white grain and red grain type were used for the study along with flour of both samples. There was no significant difference (p > 0.05) between whole grain (20.99±0.78 ppm Fe and 19.29±0.72 ppm Zn) and flour (20.19±0.43 ppm Fe and 19.56±0.43 ppm Zn) in case of white sorghum. In case of red sorghum, the whole grain analysis gave higher values for both iron and zinc compared to the flour. From the results, it was concluded that whole grain samples can be digested directly without grinding them in to flour. By the use of whole grains time-consuming step of sample grinding and potential contamination in the process can be avoided without influencing the final results.

In order to verify the accuracy of grain iron and zinc content estimation by the Flame AAS, a sample of biofortified pearl millet variety Dhanashakti with known values was analysed at IIMR. Both uncleaned and cleaned samples were used for grain iron and zinc estimation. For cleaning, 10 g of grain was mixed with 40 ml of water, swirled and filtered. Sample was oven dried at 45 °C. The grain was ground using UDY cyclone mill and moisture content was determined following hot air oven drying at 105 °C overnight. One gram sample was used for digestion with 50 dilution factor. The results obtained matched the reported values for grain iron and zinc thereby validating the method followed at IIMR.



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