Evaluation of some maize crosses and cultivars and their F1 hybrids infected with common smut disease was conducted under field conditions. Changes in sugars, phenols and total free-amino acids resulting from infection were also studied. S. C104 and Pioneer exhibited the highest resistance while Amricany Badry, T.W.C. 309 and Mogtamaa 45 were susceptible. Crosses of possible combinations between Pioneer (resistant)and Amricany (susceptible) were more resistant than other crosses. While cross between cvs. Sabeeny and Mogtamaa 45, were the most susceptible of all crosses.
The highest levels of total and non-reducing sugars were in the healthy stems followed by ears and leaves. Leaves and stems of cv. Pioneer and its hybrid with cv. Sabeeny had high levels of total and non-reducing sugars. Infected plants differed greatly in their contents to total and non-reducing sugars. Infected ears of most cultivars and F1 hybrids showed low contents of sugars compared with healthy ears.
Phenolic compounds were higher in infected than in uninfected leaves, stems and ears. Stems and ears of infected plants (particularly with the susceptible cultivars and their hybrids) contained higher levels of total free-amino acids than their healthy counterparts.