Genetic Gains for Yield and Virus Disease Resistance of Cassava Varieties Developed Over the Last Eight Decades in Uganda
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Date
2021
Journal Title
Journal ISSN
Volume Title
Publisher
Frontiers in Plant Science
Abstract
Achieving food security for an ever-increasing human population requires faster
development of improved varieties. To this end, assessment of genetic gain for key traits
is important to inform breeding processes. Despite the improvements made to increase
production and productivity of cassava in Uganda at research level, there has been
limited effort to quantify associated genetic gains. Accordingly, a study was conducted in
Uganda to assess whether or not genetic improvement was evident in selected cassava
traits using cassava varieties that were released from 1940 to 2019. Thirty-two varieties
developed during this period, were evaluated simultaneously in three major cassava
production zones; central (Namulonge), eastern (Serere), and northern (Loro). Best
linear unbiased predictors (BLUPs) of the genotypic value for each clone were obtained
across environments and regressed on order of release year to estimate annual genetic
gains. We observed that genetic trends were mostly quadratic. On average, cassava
mosaic disease (CMD) resistance increased by 1.9% per year, while annual genetic
improvements in harvest index (0.0%) and fresh root yield (5 kg per ha or 0.03% per
ha) were non-substantial. For cassava brown streak disease (CBSD) resistance breeding
which was only initiated in 2003, average annual genetic gains for CBSD foliar and CBSD
root necrosis resistances were 2.3% and 1.5%, respectively. It’s evident that cassava
breeding has largely focused on protecting yield against diseases. This underpins the
need for simultaneous improvement of cassava for disease resistance and high yield for
the crop to meet its current and futuristic demands for food and industry.
Description
Keywords
Cassava breeding, Cassava brown streak disease, Cassava mosaic disease, Yield related traits, Genetic progress
Citation
Manze F, Rubaihayo P, Ozimati A, Gibson P, Esuma W, Bua A, Alicai T, Omongo C and Kawuki RS (2021) Genetic Gains for Yield and Virus Disease Resistance of Cassava Varieties Developed Over the Last Eight Decades in Uganda. Front. Plant Sci. 12:651992. doi: 10.3389/fpls.2021.651992