Standardization of X-Ray Radiography Methodology for the Detection of Hidden Infestation in Cereals*

A comprehensive study was carried on standardization of X-ray radiography methodology for the detection of hidden insect infestation in cereals from November 2009 - March 2010 at the National Bureau of Plant Genetic Resourses – Regional Station (NBPGR RS), Hyderabad. A compact and standard X-ray machine, Faxitron model 43855A was used in the experiments. Studies revealed that the controllable input electrical parameters of the xray machine viz., voltage, current and exposure period required for the detection of hidden insect infestation varied widely for different cereal seed materials. High voltage and current were required for dense seed materials to ensure adequate penetration of radiation compared to light seed materials. Good image contrast was obtained when the exposure period was between 20 - 25 seconds with all combinations of rest of the electrical parameters for variety of cereals. The standardized X-ray input values viz., voltage, current and exposure period for paddy seed were 15 kV, 12 mA and 25 seconds respectively and resulted in good imagery revealing the gross internal contents of the seed facilitating the detection of hidden infestation and the damage caused by Angoumois grain moth, Sitotroga cereallela. Standardized voltage, current and exposure period for wheat, sorghum and maize seeds infested with Lesser grain borer, Rhizopertha dominica were found to be 15 KV, 12 mA for 25 seconds; 20 KV, 6 mA, for 25 seconds; and 25 KV, 8 mA for 20 seconds respectively. Usage of adhesive tapes was found highly helpful to locate and pick out the infested seed from the healthy ones. Experimental results also proved that the germination percentage at different combinations of input values varied only from 90–100% for paddy, wheat, sorghum and 80–100% for maize indicating negligible or no impact of these soft X-rays on the viability of seeds.