Genetic trends in the Kenya Highland Maize Breeding Program between 1999 and 2020.

Area of Science:

• Agricultural Science
• Plant Breeding
• Genetics

Background:

• Maize breeding programs require evaluation of genetic trends to optimize strategies.
• The Kenyan Highland Maize Breeding Program (KHMP) has a long history of developing adapted maize varieties.

Purpose of the Study:

• To establish and quantify genetic trends in the KHMP from 1999-2020.
• To assess the effectiveness of past breeding efforts and identify areas for improvement.

Main Methods:

• Analysis of a two-decade historical dataset from Preliminary Variety Trials (PVT) and Advanced Variety Trials (AVT).
• Mixed model analysis to compute genetic gains using best linear unbiased estimates.

Main Results:

• Significant positive genetic gain for grain yield (88 kg ha⁻¹ year⁻¹ in PVT, 26 kg ha⁻¹ year⁻¹ in AVT).
• Desirable genetic gain for reduced root lodging (-2.65% year⁻¹ in AVT).
• Improved resistance to Turcicum Leaf Blight (-1.19% in PVT, -0.27% in AVT) and Gray Leaf Spot (-0.81% in AVT).

Conclusions:

• The KHMP has made good progress in developing adapted maize hybrids for Kenya's highlands.
• Opportunities exist to further enhance genetic gains through introgression of favorable alleles and advanced breeding technologies like marker-assisted selection and genomic selection.