In a cross-pollinated crop like maize, there is ample genetic variability and diversity as exemplified by the existent of more than 300 races of maize. As a consequence, therefore, biodiversity should not pose any concerns now and in the long range until and unless we dramatically change our system of exploiting existing maize germplasm. This is particularly true in hybrid development efforts where breeder may choose germplasm which has hybrid oriented features and exhibits cross-bred performance with only a few specific germplasm types. As a consequence of selecting more appropriate germplasm for hybrid work, it is thus understandable that only a small proportion of total germplasm will be used for hybrid development efforts. Once this happens, narrowing down of germplasm will occur as better surviving inbreds will be recycled to create new generation of lines. As this process goes on, one will realize after several decades that most good lines have some common lines in their parentage. Therefore, inbred recycling using pedigree Ibreeding will help to further narrow down the germplasm base of the maize inbreds. To prevent narrowing down of germplasm, it is thus important that breeders must use in totality more number of heterotic patterns and the responsibility can be shared among the breeders. An alternative approach will be to have more number of populations within each heterotic group. Other ideas include 1 building up strong inbred base germplasm originating from diverse germplasm sources. One can also i think of diversifying inbred recycling strategies by selecting partners that are exotic and have resulted from other germplasm sources. It is also advisable that new inbreds should be identified from recurrent selection programs on continuous basis to keep the germplasm base of the inbreds quite diversified. Consequently, using several of these approaches alone and in combination with each other will greatly aid to keep germplasm base quite broad and diverse. Hybrid diversity in the farmers' fields is also quite important, and this problem can be easily tackled by growing more hybrids and by consciously controlling widespread use of a single hybrid over wide areas.

English

0208|AGRIS 0201|AL-Maize Program|R01PROCE

Juan Carlos Mendieta

CIMMYT Staff Publications Collection