Detection of pest-pathogen in forage legume seeds with X-Ray radiography

Abstract

During storage, seeds are attacked by a number of agents including insect pests, which cause damage by infestation and results in loss of germination and vigour. Different techniques are used to separate healthy and infested seeds, most of which are complicated and time consuming. Soft x-ray radiography, a quick non-destructive and accurate method, was applied to determine the infestation in present study. Seeds of eleven range and cultivated fodder legumes were exposed to x-rays and the photographs of the internal structure of irradiated seeds were taken. Healthy seeds were seen as shining white whereas infested seeds were dull brown or dark coloured. For comparison, the infestation in the seeds was observed visually with naked eyes and also studied by lacto-phenol test. The maximum infested seeds (19.7%) were observed in Lucerne (Medicago sativa) followed by 19.3 per cent in Berseem (Trifolium alexandrinum) var. Wardan while minimum 7.7 per cent was observed in Berseem (T. alexandrinum) var. JHB-146 and 9.7% in Neel (Indigofera astragalina). Pest infestation in other forage legumes was between 11.0 to 18.0 per cent. Lacto phenol test provided almost similar results but visual observation with naked eyes, could identify only about half of the infestation in comparison to those recorded with x-ray radiography.