Heterosis in maize is the result on differences in water status
Material type:
TextPublication details: 2009Description: p. 35Summary: While heterosis confers stress tolerance in maize the physiological mechanisms underlying remains elusive. A set of 16 inbreeds of tropical maize (Zea mays L.) from La Posta Population and the derived single crosses using a common tester were grown in the field. Three different water regimes were assayed: fully irrigation and two levels of water stress imposed by stop irrigation before anthesis, with an averaged ratio between total water input (rainfall plus irrigation) and reference evapotranspiration of 1.5, 1.0 and 0.5, respectively. Total plant biomass was measured about two weeks after flowering and further grain yield and its agronomical components were assessed at maturity. Plant water status was evaluated by instantaneous and time-integrated measurements. The first consisted in periodical measurements of leaf stomatal conductance and leaf temperature from just prior water treatments were imposed, until middle grain filling. Integrated traits included total mineral (ash) accumulated in the whole leaves of plants harvested during grain filling as well as the enrichment in stable isotope 18O (18O) in the dry matter of the same leaves as well as in mature kernels. Within each growing conditions hybrids showed a better water status, differences being already evident under the fully watered trials. Therefore, for a given water regime, lines exhibit poorer water status than hybrids. Taken the 6 trials together the water status within each trail related almost linearly with the total biomass accumulated during grain filling. The traits best fitting biomass were ash content and Ä18O of leaves and grains (R2 = 0.82, 0.91 and 0.92, respectively). However when the water status traits were correlated with grain yield (R2 = 0.92, 0.90 and 0.76) as well as with total number of kernels per plant (R2 = 0.86, 0.87 and 0.75), the relationship moved to non linear with a threshold where any improvement in water regime increase strongly grain yield and kernel number. Results suggest that differences in biomass as well as in grain yield between lines and hybrids are basically the consequence of differences in water regime.
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|---|---|---|---|---|---|---|---|---|
| Conference proceedings | CIMMYT Knowledge Center: John Woolston Library | CIMMYT Staff Publications Collection | CIS-5770 (Browse shelf(Opens below)) | Available |
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Abstract only
While heterosis confers stress tolerance in maize the physiological mechanisms underlying remains elusive. A set of 16 inbreeds of tropical maize (Zea mays L.) from La Posta Population and the derived single crosses using a common tester were grown in the field. Three different water regimes were assayed: fully irrigation and two levels of water stress imposed by stop irrigation before anthesis, with an averaged ratio between total water input (rainfall plus irrigation) and reference evapotranspiration of 1.5, 1.0 and 0.5, respectively. Total plant biomass was measured about two weeks after flowering and further grain yield and its agronomical components were assessed at maturity. Plant water status was evaluated by instantaneous and time-integrated measurements. The first consisted in periodical measurements of leaf stomatal conductance and leaf temperature from just prior water treatments were imposed, until middle grain filling. Integrated traits included total mineral (ash) accumulated in the whole leaves of plants harvested during grain filling as well as the enrichment in stable isotope 18O (18O) in the dry matter of the same leaves as well as in mature kernels. Within each growing conditions hybrids showed a better water status, differences being already evident under the fully watered trials. Therefore, for a given water regime, lines exhibit poorer water status than hybrids. Taken the 6 trials together the water status within each trail related almost linearly with the total biomass accumulated during grain filling. The traits best fitting biomass were ash content and Ä18O of leaves and grains (R2 = 0.82, 0.91 and 0.92, respectively). However when the water status traits were correlated with grain yield (R2 = 0.92, 0.90 and 0.76) as well as with total number of kernels per plant (R2 = 0.86, 0.87 and 0.75), the relationship moved to non linear with a threshold where any improvement in water regime increase strongly grain yield and kernel number. Results suggest that differences in biomass as well as in grain yield between lines and hybrids are basically the consequence of differences in water regime.
English
Lucia Segura
CIMMYT Staff Publications Collection