Prof. CHEMINING'WA GEORGE N

Recurrent outbreaks of Aflatoxin (AF) poisoning in maize continue to exacerbate the food security crisis in Sub-Saharan Africa. This study determined the distribution and contamination levels of Aspergillus spp. and Aflatoxin B1 (AFB1) in soil, maize and maize-based products. Maize grain samples (n=256), semi-processed grain (n=56), flour (n=52), hammer mill dust (n=11), and soil (n=117) were collected during the 2008 and 2009 growing seasons. Aspergillus spp. was isolated and AFB1 was determined by Enzyme-Linked Immunosorbent Assay (ELISA). Aspergillus flavus was frequently isolated in maize samples from the semi-arid regions. The frequency of A. flavus was higher in semi-processed grain than in whole grain and packed flour samples. AFB1 was not detected in samples from the humid regions. AFB1 was detected at levels exceeding the Kenyan legal limit of 10 μg/kg in 20% of the samples, at maximum of 136 μg/kg for semi-processed maize,77 μg/kg for whole grain and 41 μg/kg for flour sold in open bags. The high temperature and periodic drought prevalent in the semi-arid regions could explain the higher levels of A. flavus and AFB1 contamination in that climate. In addition, unfavourable drying and storage practices may aggravate the problem. Therefore, it is recommended that the careful monitoring of AF be continued.

The same row and this also out-yielded sole Rhizobium inoculation of beans (Phaseolus vulgaris L.) and intercropping patterns of maize and beans were evaluated for two seasons in a field study. Plant population of each crop in all planting patterns was 53,333 plants ha-1. Beans were either uninoculated or inoculated with Rhizobium. Planting patterns consisted of maize and beans intercropped in the same hill, maize and beans intercropped as. alternating plants in the same row, maize and beans intercropped in alternate rows, sole maize and sole beans. Increasing intimacy between the intercrop species and inoculation significantly increased biomass and leaf area indices of both maize and beans, and also the number of nodules per bean plant. Inoculation significantly increased yield of maize in all intercropping treatments. In the inoculated treatments, intercropping maize and beans in the same hill had significantly higher maize grain yield than intercropping in alternate hills in the same row and this, in turn, out-yielded sole maize cropping and intercropping in alternate rows whose yields were not significantly different. When beans were inoculated, similar results were obtained but in the second season no difference was observed between intercropping in the same hill and intercropping in alternate hills in the same row. Sole maize was also significantly superior to maize intercropped with beans in alternate rows. Beans intercropped with maize in the same hill out-yielded beans intercropped with maize in alternate hills in the same row and this also out-yielded sole beans. Beans intercropped with maize in alternate rows had the lowest yield. These results demonstrate the superiority of intercropping maize and beans in close proximity and Rhizobium inoculation both of which promoted nodulation by the bean plants. There is need to establish why beans intercropped with maize in the same hill out¬yielded sole beans.