Variability and inbreeding in semiexotic maize populations

Area of Science:

• Plant Breeding
• Genetics
• Agronomy

Background:

• Semiexotic maize populations were developed using CIMMYT germplasm resistant to corn stunt complex.
• Recurrent selection is a key strategy for improving quantitative traits in crop breeding.

Purpose of the Study:

• Evaluate the effectiveness of two cycles of half-sib recurrent selection in three semiexotic maize populations.
• Assess genetic parameters and identify promising families for future breeding efforts.

Main Methods:

• Half-sib family selection was conducted over two cycles.
• Evaluations included agronomic traits (ear yield, plant/ear height), ear and grain weight, tassel characteristics, and corn stunt complex resistance.
• Additive genetic variance, heritability, and inbreeding depression were estimated.

Main Results:

• Ear yield increased significantly across populations, reaching 83-86% of the hybrid check by cycle II.
• Heritability estimates were moderate to high, indicating substantial additive genetic variance.
• Inbreeding depression ranged from 39.1% to 45.3% in S1 families, highlighting the impact of inbreeding.

Conclusions:

• Two cycles of recurrent selection effectively improved yield and other desirable traits in semiexotic maize populations.
• The study identified populations with significant genetic gains and potential for further development.
• Results support the utility of recurrent selection for enhancing maize germplasm with resistance to diseases.