Genetic trends for yield and key agronomic traits in pre-commercial and commercial maize varieties between 2008 and 2020 in Uganda

Godfrey Asea; Daniel Bomet Kwemoi; Clay Sneller; Charles L Kasozi; Biswanath Das; Lennin Musundire; Dan Makumbi; Yoseph Beyene; Boddupalli M Prasanna

doi:10.3389/fpls.2023.1020667

Genetic trends for yield and key agronomic traits in pre-commercial and commercial maize varieties between 2008 and 2020 in Uganda

Front Plant Sci. 2023 Mar 10:14:1020667. doi: 10.3389/fpls.2023.1020667. eCollection 2023.

Authors

Godfrey Asea¹, Daniel Bomet Kwemoi¹, Clay Sneller², Charles L Kasozi¹, Biswanath Das³, Lennin Musundire³, Dan Makumbi³, Yoseph Beyene³, Boddupalli M Prasanna³

Affiliations

¹ National Crops Resources Research Institute, National Agricultural Research Organization, Kampala, Uganda.
² Department of Horticulture and Crop Science, The Ohio State University, Wooster, OH, United States.
³ Global Maize Program, International Maize and Wheat Improvement Center (CIMMYT), Nairobi, Kenya.

Abstract

Estimating genetic gains is vital to optimize breeding programs for increased efficiency. Genetic gains should translate into productivity gains if returns to investments in breeding and impact are to be realized. The objective of this study was to estimate genetic gain for grain yield and key agronomic traits in pre-commercial and commercial maize varieties from public and private breeding programs tested in (i) national performance trials (NPT), (ii) era trial and, (iii) compare the trends with the national average. The study used (i) historical NPT data on 419 improved maize varieties evaluated in 23 trials at 6-8 locations each between 2008 and 2020, and (ii) data from an era trial of 54 maize hybrids released between 1999 and 2020. The NPT data was first analyzed using a mixed model and resulting estimate for each entry was regressed onto its first year of testing. Analysis was done over all entries, only entries from National Agricultural Research Organization (NARO), International Maize and Wheat Improvement Center (CIMMYT), or private seed companies. Estimated genetic gain was 2.25% or 81 kg ha^-1 year^-1 from the NPT analysis. A comparison of genetic trends by source indicated that CIMMYT entries had a gain of 1.98% year^-1 or 106 kg ha^-1 year^-1. In contrast, NARO and private sector maize entries recorded genetic gains of 1.30% year^-1 (59 kg ha^-1 year^-1) and 1.71% year^-1 (79 kg ha^-1 year^-1), respectively. Varieties from NARO and private sector showed comparable mean yields of 4.56 t ha^-1 and 4.62 t ha^-1, respectively, while hybrids from CIMMYT had a mean of 5.37 t ha^-1. Era analysis indicated significant genetic gain of 1.69% year^-1 or 55 kg ha^-1 year^-1, while a significant national productivity gain of 1.48% year^-1 (37 kg ha^-1 year^-1) was obtained. The study, thus, demonstrated the importance of public-private partnerships in development and delivery of new genetics to farmers in Uganda.

Keywords: genetic gains; maize breeding; maize yields and agronomic traits; productivity gains; regression analysis.

Grants and funding

The maize breeding program in Uganda has been supported by USAID, Rockefeller Foundation and AGRA. The contribution of partnership support from CIMMYT-led initiatives, namely Africa Maize Stress (AMS), Drought Tolerant Maize for Africa (DTMA), Water Efficient Maize for Africa (WEMA), Stress Tolerant Maize for Africa (STMA), Accelerating Genetic Gains for Maize and Wheat Improvement (AGG), and Excellence in Breeding (EiB) is greatly acknowledged. This research was supported by grants from the Bill and Melinda Gates Foundation (BMGF) through the Drought Tolerant Maize for Africa (DTMA, OPPGD1390), Stress Tolerant Maize for Africa (STMA, OPP1134248), Accelerating Genetic Gains for Maize and Wheat Improvement (AGG, INV003439) and CGIAR Excellence in Breeding Platform (EiB, INV-008091). The Alliance for a Green Revolution in Africa (AGRA), Grant No. PASS011; USAID IARC Food security and Crisis Mitigation program, Grant EEM-G-00-04-0013-000; The Rockefeller Foundation Project2006 FS 008. The contribution of the maize working group in Uganda and the technical support of Julius P. Sserumaga, Micheal H. Otim, Majid Walusimbi, Moses Ebellu, Solomon Kaboyo, Annet Nakayima, and Jane Alupo is acknowledged. We also acknowledge the contribution of Denis Kyetere, George Bigirwa, Joseph Kikafunda and Justus Imanywoha (late), who laid the foundation for systematic maize breeding efforts in Uganda.