The influence of the testa, damage and seed dressing on the emergence of groundnut (Arachis hypogea)

The effects of damaging the testa and the application of seed dressings were examined in field trials on several short-and long-season cultivars of groundnut (Arachis hypogea) with differently-pigmented testas at Samaru, Nigeria, in 1967. There was a high correlation between the number of seedlings which emerged in these trials and the resistance or susceptibility of the seed to invasion by the fungus Aspergillus flavus, as assessed by laboratory tests. When the testa was undamaged the emergence of white (susceptible) seed was only 50% while that of coloured (resistant) seed was between 95 and 98%. Damage to the testa by scratching greatly decreased emergence. The application of seed dressing increased the emergence of susceptible seed and also restored the emergence of scratched seeds to the level of undamaged seeds. The effect of the complete removal of the testa was not counteracted by seed dressing; naked seeds, with and without dressing, gave c. 10% emergence. The importance of pigment in the testa, the condition of the seed and the effects of seed dressing are discussed.