Effect of fumigation on germination and vigour in chickpea and green gram during prolonged storage

Infestation of legume crop seeds with pulse beetle Callosobrnchus spp. (Coleoptera: Bruchidae) results in deterioration of seed quality during storage. Fumigation is carried out to control infestation of this bruchid in seed stores and as a quarantine precaution directed against the international spread of pests. A study was conducted to evaluate the effect of fumigation with phosphine and methyl bromide on chickpea (Cicer arietinum L.) and EDCT mixture on green gram (Vigna radiata L.) seed germination and vigour during a storage period of 3.5 years in chickpea and 6.5 years in green gram. The storage conditions varied from ambient to -20°C temperature and 12 to 6% seed moisture content. The effect of moisture, temperature, fumigant as well as storage period on seed germination and vigour was significant. Decline in germination and vigour was observed in response to fumigation at high seed moisture content and temperature in both crops. Phosphine was found to be more deleterious to seed quality than methyl bromide in chickpea. The effect was relatively delayed in green gram. Results suggest that great care is necessary in the choice of fumigant in combination with the storage environment before fumigating seeds meant for germplasm conservation.