This presentation is describe by the following abstract,

Maria Andrade¹, Wolfgang Grüneberg², Robert Mwanga³, Federico Diaz², Charles Wasonga³, Godwill Makunde¹, Raul Eyzaguirre², Edward Carey⁴

International Potato Center (CIP), ¹Maputo, Mozambique; ²Lima, Peru; ³Kampala, Uganda; ⁴Kumasi, Ghana

Performance of breeding programs can be tracked both with respect to changes in traits under selection during a given period of time and with regard to release, adoption and impact of lines and varieties.  Predicting and estimating genetic gains for traits is the heart of plant breeding resource allocation, and approaches taken vary with traits and circumstances. This paper presents approaches we are taking to predict and measure genetic gains for key attributes in breeding programs at the sweetpotato support platforms in Mozambique, Uganda and Ghana, and at CIP headquarters in Peru.

Key attributes for which we wish to track genetic gains include yield – particularly through accelerated variety release and exploitation of heterosis – in each country and surrounding sub-region, sweetpotato virus disease (SPVD) resistance and beta-carotene in Uganda, drought tolerance, beta-carotene, iron and zinc in Mozambique, and reduced sweetness, perishability and increased beta-carotene in Ghana.  In 2009, variance component estimates and expected genetic gains for most key attributes evaluated to help guide breeding priorities; yield, SPVD resistance, drought adaptation, beta-carotene, and sweetness exhibited large genetic variation, whereas iron and zinc appeared to exhibit significant but low genetic variation, especially relative to genotype by environment interactions. However, SPVD resistance was recognized to be a tricky trait, due to its genotype by environment interactions, challenges of phenotyping, and mode of inheritance.

In 2014, consideration was given to genetic advance at support platforms through a) comparison of means of selected clones with those of parents and parental populations (either grown in the same trials or compared retrospectively), b) comparison of means in sets of variety release trials and demonstration trials including new and old varieties, or c) comparison of means of selected clones to those of standard checks in populations undergoing selection over years.  In each case where estimates were made, yield increases were high (most convincingly in the case of heterosis increments), gains for dry matter and reduced sugar content were also high, gains for beta-carotene content were very high, whereas gains for iron and zinc were low. Gains in frequency of SPVD resistance, drought tolerance, and reduced perishability remain to be addressed. In preparation for demonstration trials, names and key attributes of released and predominant varieties over the past two decades, have been documented across countries and regions with major sweetpotato production. 

We will continue to refine approaches for tracking progress in our breeding programs in the coming years. More emphasis will be given on the use of demonstration trials comparing newly-released and older varieties over years as well as the use of data from national variety release trials to monitor genetic gains in released varieties over time, and disaggregate genetic gains from cultural practices. We will also continue to monitor observed genetic gains and genetic variability in breeding populations, in particular partially inbred and mutually heterotic populations to aggressively improve specific attributes, including SPVD, micronutrient mineral content, earliness, quality attributes and reduced perishability.