TY  - PRO
AU  - Shi-huang Zhang
AU  - De-quan Shi
AU  - Vasal,S.K.|Gonzalez Ceniceros,F.|XiongMing,F.
ED  - Centro Internacional de Mejoramiento de Maiz y Trigo (CIMMYT), Mexico, DF (Mexico)
ED  - 7, Proceedings of the Asian Regional Maize Workshop
TI  - The role of exotic germplasm for hybrid maize breeding research
PY  - 2000///
CY  - Los Baños, Laguna (Philippines)
PB  - PCARRD
KW  - Beijing
KW  - Germplasm
KW  - AGROVOC
KW  - Grain
KW  - Heterosis
KW  - Maize
KW  - Subtropical zone
KW  - Yields
KW  - Genotypes
KW  - Hybrids
KW  - Plant breeding
N2  - Germplasm is critical for assuring continuity of maize breeding activities in the corning century. Lack of germplasm resources is the bottleneck of hybrid maize breeding programs in China. We have introduced and will continue to introduce exotics to broaden the genetic base of hybrid maize breeding and try to enhance the heterosis level. Bi-parental mass selection for early silking is an effective method to improve the adaptation of tropical and subtropical populations to long-day conditions in temperate regions. The adaptability of maize genotypes is associated with photoperiod sensitivity . Four cycles of bi-parental mass selection carried out in Beijing reduced the photoperiod sensitivity in two subtropical populations successfully. The correlated responses of grain yield to selection were positive and significant when evaluated in long-days, but negative when evaluated under short-day condition. This contrast indicates that most of the yield increases were due to the effects of desensitizing germplasm to photoperiod under long-day conditions
ER  -