01970naa a2200193 a 450000100080000000500110000800800410001910000140006024500630007426000090013752013650014670000150151170000160152670000170154270000140155970000150157370000160158877301720160416372412009-02-03       2008    bl uuuu     u00u1 u    #d1 aALVES, A.  aTraits related to drought tolerance mechanisms in cassava.  c2008  aContrasting cassava varieties were screened in semi-arid environments to characterise genotypes for drought tolerance traits. The following hypotheses were supported: 1) genotypes that accumulated substantial stem starch reserves may be more able to sustain meristems and other respiring organs during a prolonged stress; 2) genotypes that maintain deep fibrous root growth perform better in drought; 3) genotypes that maintain partiotioning to storage roots and have high harvest index yield better in drought; and 4) genotypes that are more effective in closing stomata are more able to maintain water status and retain leaves. Leaf conductance, leaf retention, leaf size, harvest index, ABA, sugars and starch accumulation in the leaves and stems were differentially affected in the cassava varieties and highly correlated to yield performance under water deficit. The different responses to water deficit for some parameters has helped us to better discriminate varieties as tolerant or susceptible to drought and to define the best traits for selecting in breeding programmes. Three segregating populations with a total of 370 individuals were produced. A genotypic parental screen has revealed 168 polymorphic SSRs in COL1734 x VEN77 and 147 in COL1468 x BRA255, from 307 SSRs screened. Genotyping and phenotyping of the mapping populations are underway.1 aSETTER, T.1 aFREGENE, M.1 aFERGUSON, M.1 aDUQUE, L.1 aMUTEGI, R.1 aMKAMILO, G.  tIn: CGIAR GENERATION CHALLENGE PROGRAMME ANNUAL RESEARCH MEETING, 2008, Bangkok, Thailand. Poster abstracts... Mexico, DF: Generation Challenge Programme, 2008. p. 53.