Value of secondary traits in selecting for drought tolerance in tropical maize
Edmeades, G.O.
Value of secondary traits in selecting for drought tolerance in tropical maize - Mexico, DF (Mexico) CIMMYT : 1997 - Printed
The use of adaptive traits which are secondary to the primary trait, grain yield, when improving drought tolerance is often advocated, even though their relationships to yield and their contribution to increased yield under water deficits are poorly quantified. Secondary traits should be (i) genetically variable and genetically associated with grain yield in the target environment; (ii) highly heritable; (iii) easy to measure; (iv) observed at or before flowering; and (v) provide an estimate of yield potential well before final harvest. The value of secondary traits can be established by correlation analysis, by comparison of near-isogenic lines, or by divergent selection for the trait of interest. Secondary traits examined thus far at CIMMYT include anthesis-silking interval (ASI), leaf and stem elongation rate under drought versus well-watered conditions (RLE), canopy temperature (CT), leaf rolling and erectness scores (LRS; LES), leaf chlorophyll concentration (CHL), staygreen score (LDS), tassel size (TS), leaf osmotic concentration (OSM) and lodging (LOD). Relationships between yield and yield components (weight kernel-1, kernels ear -1, ears plant -1 (WPK, KPE, EPP)) have also been determined. Correlations between some of these traits and grain yield under drought are: large (0.5-0.9)for EPP, KPE, PH, TS, and ASI; low (0.1-0.4)for WPK, CT, LDS, CHL and OSM; and <0.1 for LOD, LRS, RLE, LES and TBN. Divergent selection (4% selection intensity in each direction) showed that realized heritability and adaptive value of ASI and EPP were high (not higher than yield alone, however), while those for LDS and CT were low. LES, TS and OSM had little effect on yield, though LES and TS were highly heritable and OSM moderately so. Results suggest that selecting for a combination of these traits in addition to yield should result in faster improvements in yield and yield stability under drought compared with selection for yield alone, and possibly at no cost to yield under well-watered conditions.
English
968-6923-93-4
Drought resistance
Drought stress
Selection
Tropical zones
Zea mays
Plant breeding
CIMMYT
633.153 / EDM
Value of secondary traits in selecting for drought tolerance in tropical maize - Mexico, DF (Mexico) CIMMYT : 1997 - Printed
The use of adaptive traits which are secondary to the primary trait, grain yield, when improving drought tolerance is often advocated, even though their relationships to yield and their contribution to increased yield under water deficits are poorly quantified. Secondary traits should be (i) genetically variable and genetically associated with grain yield in the target environment; (ii) highly heritable; (iii) easy to measure; (iv) observed at or before flowering; and (v) provide an estimate of yield potential well before final harvest. The value of secondary traits can be established by correlation analysis, by comparison of near-isogenic lines, or by divergent selection for the trait of interest. Secondary traits examined thus far at CIMMYT include anthesis-silking interval (ASI), leaf and stem elongation rate under drought versus well-watered conditions (RLE), canopy temperature (CT), leaf rolling and erectness scores (LRS; LES), leaf chlorophyll concentration (CHL), staygreen score (LDS), tassel size (TS), leaf osmotic concentration (OSM) and lodging (LOD). Relationships between yield and yield components (weight kernel-1, kernels ear -1, ears plant -1 (WPK, KPE, EPP)) have also been determined. Correlations between some of these traits and grain yield under drought are: large (0.5-0.9)for EPP, KPE, PH, TS, and ASI; low (0.1-0.4)for WPK, CT, LDS, CHL and OSM; and <0.1 for LOD, LRS, RLE, LES and TBN. Divergent selection (4% selection intensity in each direction) showed that realized heritability and adaptive value of ASI and EPP were high (not higher than yield alone, however), while those for LDS and CT were low. LES, TS and OSM had little effect on yield, though LES and TS were highly heritable and OSM moderately so. Results suggest that selecting for a combination of these traits in addition to yield should result in faster improvements in yield and yield stability under drought compared with selection for yield alone, and possibly at no cost to yield under well-watered conditions.
English
968-6923-93-4
Drought resistance
Drought stress
Selection
Tropical zones
Zea mays
Plant breeding
CIMMYT
633.153 / EDM