ABSTRACT
The aim of maize improvement research is to produce a continuing stream of improved genotypes that are highly efficient in their use of soil fertility, water, and light in spite of the biotic and abiotic stresses that can harm the crop. Indigenous tropical maize germplasm is inherently inefficient because of its tall stature, abundant foliage, large tassels, and, its relatively low harvest index. Common rust can be found in subtropical maize-growing environments and in the relatively cooler environments in the tropical mid-altitudes and highlands. The recurrent breeding methodology and artificial infestations are being used by several maize research programs to improve levels of host plant resistance to important maize pests. Despite the existence of genetic resistance, progress in breeding for host plant resistance to economically important insects has been slower than breeding for disease resistance. The challenge for breeders has been to develop early maturing varieties that combine high yield potential with disease and insect resistance.
