I. Maize hybrid breeding for sub-tropical mega -environments: strategies, and recent progress - Hugo Cordova|.Emphasis was on the use of different breeding schemes and multilocational testing.|.The use of tropical and subtropical elite lines in hybrid combination could develop many promising hybrids.|.This includes QPM hybrids along the same principles.|.A new set of subtropical elite inbred parents will be released soon.|2. Role of exotic germplasm for hybrid maize breeding research -Shihuang Zhang|.Heterotic groups such as Lancaster and Reid have been used in China including Luda Red Cob.|.More than 50% of good inbred lines were extracted from hybrids -again using tropical - subtropical materials.|.Emphasis was on the reduction of photoperiod sensitivity and success has been achieved.|3. The Evolution of Hope : A hierachical open -ended breeding system- L.W. Kannenberg|.HOPE = hierachical open-ended breeding system that is used to broaden genetic base and to reduce genetic erosion.|.There are several breeding schemes used sequentially. For example, mass selection, half-sib and full -sib are used with RRS ,at different levels of improvement of the gene pools.|.Such breeding system successfully diversified germplasm as evidenced by the increased polymorphism in HOPE populations.|.There is still a need to develop a "NEW HOPE" meaning that modification of breeding strategy and methodology are necessary to simplify the development of diverse populations.|4. Evolution of inbred line developmental methodologies --D.N. Chaudhary|.In plant breeding it is necessary to make use of 3 main resources -genetic resources, science|and art, and investment.|.Emphasis should be on population improvement, inbred based heterotic populations and stress breeding in the development of hybrids.|.Both abiotic and biotic tolerance should be included.|.Recent trends towards 2-parent hybrids require that programs should emphasize more on seed production strategies, productivity of inbred and hybrid seeds.|5. Breeding maize hybrids in commercial environment -Kishen Narayan|.There may be a small difference in public and private breeding program. On private side, more clearcut objectives should be made on what type of hybrids are needed and for what location.|.Under Indian situation, doublecross and 3-waycross hybrids are preferred.|.Emphasis was on the seed yield of hybrids.|6. Performance and potential of CIMMYT's maize germplasm in Asian region -G. Srinivasan|.Presentation of CIMMYT trials -IPTTs, EVTs, CHTs was made.|.From this long time effort in collaborate testing with NARS, CIMMYT has gained|tremendous information and experience on how to develop populations, lines and hybrids suitable for different environments.|7. Recombinant inbred lines in tropical maize improvement -J ames L. Brewbaker|.Attempt has been made to collect inbred lines from different groups but only about 200|inbreds from 40 institutes were made available-|.These inbreds were tested in order to characterize for hybrid development. He suggested that somebody should act as a coordinator in assembling all inbreds from all over the world and systematically test and characterize them for the purpose of exchanges.|.His strategies in improvement include the use of molecular mapping technology such as SSRs|(single- sequence repeats) and RFLPs.|.He showed that QTLs are not all polygenic -there are major genes and minor genes involved.|8. DNA Fingerprinting and the seed business in Thailand -Apichart Vanavichit|.Since hybrid seed industry in Thailand has grown tremendously and more and more use of hybrid (80% at present), there are fake, not true-to-type, hybrids in the market.|.The DNA Fingerprinting technique has been set up jointly between KU and the National Center for Genetic Engineering and Biotechnology (BIOTEC) in order to help certifying the inbreds and hybrids.|9. Utilization and study on male sterility in maize -Zhou Hongsheng.|.Dr. Zhou described the study of genetic male sterility and cytoplesmic male sterility including restorer genes -Rfl and Rf2. He studied at the molecular level the CMS of maize and found that the mechanism of S-CMS and C-CMS were more complicated than that of T -CMS from US.|10. Transgenic maize confers resistance to Asiatic corn borer -E. Fernandez.|.Transgenic maize expressing Bt. gene (Cry I a (b)) was developed using maize variety|MON8l0.|.It was quite clear that resistance to borer of transgenic plants was much better than that of the non-transgenic ones. Only the question of when it could be released to be used by farmers, depends on the Biosafety Committee to decide.

English

0208|AGRIS 0201|AL-Maize Program|R01PROCE

Juan Carlos Mendieta

CIMMYT Publications Collection