Stratification of SADC regional pearl millet testing sites based on grain yield performance of lines

Sequential retrospective (SeqRet) pattern analysis was used to stratify pearl millet [Pennisetum glaucum] testing sites according to their similarity of line-yield differentiation using grain yield data from 90 multi-environment trials (METs) conducted in the Southern African Development Community (SADC) region. The METs, conducted across 25 sites over 9 years were split into two sets: Set 1 (1989/90-1992/93) included introductory genetic materials, and Set 2 (1994/95-1998/99) included advanced genetic materials. Site stratification analysis from Set 1 and Set 2 partitioned the testing sites into six and five groups with R2-values of 76 and 79%, respectively. Analysis of the cumulative dataset (1989/90-1998/99) clustered the 25 sites into six groups with R2=76% and captured the major patterns of site similarities in Set 1 and Set 2. Based on our experience from running multi-year METs in the SADC region, the cumulative dataset was more informative in judging the relevance of site-stratification results. SeqRet pattern analysis, exploiting available highly imbalanced historical MET data, provided an objective basis for stratifying the test-sites to facilitate selection of a few representative test-sites for future testing of lines. The results from cumulative dataset suggest that future line testing could be restricted to a few sites picked from within each of the identified site-groups

Stratification of sorghum hybrid testing sites in southern Africa based on grain yield

Sequential retrospective (SeqRet) pattern analysis technique was applied to classify sorghum hybrid testing sites in accordance with their similarity for yield differentiation among genotypes. Historical grain yield data from 150 multi-environment trials (METs) conducted at 23 sites in the Southern Africa Development Community (SADC) region during 1987/1988-1992/1993 was used. The sites were clustered into six major environment groups in the SADC region with a model fit of R2=68%. Analysis of these 6 years' data together with additional data from 1999/2000 stratified the 23 sites in the same six major groups (R2=69%), the additional five sites in 1999/2000 classified with appropriate site groups. These results suggest that future sorghum hybrid testing could be cost-effectively conducted in a few representative sites selected from within each of the six identified site groups

Stratification of SADC regional sorghum testing sites based on grain yield of varieties

We applied sequential retrospective (SeqRet) pattern analysis to stratify sorghum variety testing sites according to their similarity for yield discrimination among genotypes using historical grain yield data from 147 multi-environment trials (METs). The trials were conducted at 38 sites in 10 countries of the Southern African Development Community (SADC) region during 1987/1988–1992/1993 and 1999/2000. The analysis for the 6 years 1987/1988–1992/1993, covering 34 sites, clustered these sites into 6 major groups with a model fit of R2 = 0.75.With additional data from the year 1999/2000, the SeqRet pattern analysis delivered a very similar clustering of the 34 sites, with the additional four sites in 1999/2000 properly classified with appropriate site groups (R2 = 0.74). The results suggest that future sorghum variety testing could be restricted to a few representative sites selected from within each of the six identified site-groups

Child Health and Relatives’ Employment in South Africa: The Gendered Effect Beyond Parents

This chapter assesses how children’s serious illness or disability affects the labour market participation of all adults living in a household. The chapter goes beyond the usual father–mother analyses and accounts for the context of developing countries characterised by an extended family structure. It uses the National Income Dynamics Study panel data and utilises fixed-effects logistic regressions and linear regressions for analysis. The results show that a child’s illness or disability significantly increases the employment odds of fathers while reducing those of mothers. These effects are even stronger among married parents. Non-parent males are more likely to work, while no significant effect is found on non-parent females. Child illness is associated, although not significantly, with the wider difference in the proportion of males and females working at the household level. This shows that there is an urgent need for policymakers to be concerned about families with ill or disabled children and to reduce the employment gender gap and make progress towards the fifth Sustainable Development Goal