THE EFFECTS OF YELLOW MOULD AND AFLATOXIN CONTAMINATION ON SEED GERMINATION, VIGOUR AND YIELD OF GROUNDNUT (Arachis hypogaea L.)
ABSTRACT
Groundnut (Arachis hypogaea L.) is an important oilseed and one of the world’s major food legume crop. Aflatoxin contamination remains a significant problem in Africa and Asia and has enormous economic consequences on product losses, health and trade. Studies were carried out to ascertain the effects of seed infection and growth of Aspergillus flavus (yellow mould), on the germination, vigour and yield of groundnut and the relationship and subsequent susceptibility of the progeny to aflatoxin contamination in the harvested produce. Seven genotypes of groundnuts (ICGV 91317, GAF 1665, GAF 1723, NkATIE SARI, Manipinta, ICGV-IS 08837 and Chinese), differing in seed coat colour and thickness, were artificially inoculated, with a spore suspension of A. flavus by shaking the seed samples in the suspension for a period. A Completely Randomized Design (CRD) was used for the laboratory experiment. Germination percentage was significant (p<0.05) among the genotypes with ICGV 91317 (inoculated) recording the highest germination percentage of 89%, whilst Manipinta (inoculated) recorded the lowest germination percentage of 61%. GAF 1665 was also observed to have the highest seedling vigour with, 79% and 78% for both the inoculated and control respectively. A field evaluation was also carried out using RCBD with three (3) replications to estimate effects of A. flavus inoculation on the yield and the aflatoxin build up in the harvested seeds. The results indicated a significant (p<0.05) difference in pod and kernel yield with NkATIE SARI (control) recording the highest pod weight of 3505.0 kg/ha and kernel weight of 1916.7 kg/ha. There was significant (p<0.05) differences in the aflatoxin content, with GAF 1665 (inoculated) and Chinese (inoculated) recording the highest levels of 0.8 ppb, whiles Manipinta recorded the lowest aflatoxin content of 0.1 ppb as the recommended levels of A. flavus infection of harvested seeds before storage is 0.25%. These observations can be explained by genetic and environmental responses of the various genotypes to A. flavus infection.