Inheritance of nitrogen use efficiency components in maize

[摘要] English: The general objectives of this research were to study the genetic variability for nitrogenuse efficiency components, to identify suitable inbred parental lines with out standingnitrogen efficiency characteristics, to calculate the inheritance of nitrogen use efficiency(NUE) components and to develop a strategy for the development of nitrogen efficientmaize hybrids.Four parental lines (AC8342, CML394, K64R and M162W) were individually crossed toeach tester (CML351, CML202 and CML216) in a Line x Tester fashion to produce FIhybrids seed. The FI hybrids were evaluated in two different environments each under twodifferent nitrogen levels. Six agronomic and yield characteristics and three nitrogen useefficiency components were measured. The data were analysed using the computerprogram' AGROBASE 2000'. Analyses such as Line x Tester, additive main effects andgenetic correlations were performed.In the combined ANOVA, significant differences between locations were found for allcharacters measured. The nitrogen levels differed significantly for PLHT and GNC. The FIhybrids differed significantly for PLHT, GY, SDW, SDN and GNC. Significantdifferences were also found among the FI hybrids for PLHT, GY, SDW, SDN, HI, GNCand SNC at Doompan. Similar significant differences were observed at Bethlehem exceptfor HI and SNC.Significant variability between FI hybrids was observed for yield efficiency, recoveryefficiency and physiological efficiency. There was a large' environmental differencebetween locations for the nitrogen use efficiency components. In the simple ANOVA,significant differences between FI hybrids were observed for yield efficiency, recoveryefficiency and physiological efficiency at Doompan. Significant differences were also .found between the FI hybrids for yield efficiency and recovery efficiency at Bethlehem.With a few exceptions in the Bethlehem trial, the selection indices of the F, hybrids forPLHT were less than one. The selection index for GY exceeds the value of one in threeand nine of the F, hybrids in the Doornpan and Bethlehem trials respectively. For SOWthree of the F, hybrids in the Doornpan trial had values above one and nine of the F,hybrids in the Bethlehem trial. The selection index values for SDN were lower than one inthe Doornpan trial. In the Bethlehem trial the values of three of the crosses were largerthan one. The selection indices for HI in both trials were relatively high.At Ooornpan the F, hybrids responded significantly different to the two N-Ievels forPLHT, GY, SDW, SDN, HI and GNC. Significant differences between the F, hybrids atthe low N-Ievel were found for all characters measured except for SNC. At the high N-levelthe F, hybrids differed significantly for PLHT, GY, SDW, SDN, HI and GNC. AtBethlehem, FI hybrids responded significantly different to the two N-levels for GY, SONand HI. Significant differences were found between the F, hybrids at both N-levels forPLHT, GY, SDW, SDN and GNC.At Doornpan significant differences existed between the F, hybrids for yield efficiency,recovery efficiency and physiological efficiency. At Bethlehem significant variability wasfound between the FI hybrids for all three nitrogen use efficiency components.The two N-Ievels had a significant effect on the GCA-values of the lines and testers forPLHT and SDN in the Doornpan trial. Significant variability was also found between theGCA-values for PLHT, GY and SDN at both N-levels. The GCA-values of the inbredlines in the Bethlehem trial responded differently to the two N-Ievels for GY and SON.Significant differences were found between the GCA-values of the inbred lines for PLHTat both N-Ievels and for GY only between the testers at the high N-Ievel.At Doornpan significant differences between the GCA-values of the lines were found onlyfor physiological efficiency and between the testers for yield efficiency and recoveryefficiency. At Bethlehem the GCA-values for testers differed significantly for yieldefficiency and recovery efficiency. No significant differences were found between. theGCA-values of the lines for nitrogen use efficiency components at Bethlehem.The FI hybrids responded differently with regard to their SCA-values for GY, SOW. HI,GNC and SNC in the Doornpan trial. Significant differences for SCA-values were foundfor PLHT, GY, SOW, SON and SNC at both N-Ievels. In the Bethlehem trial the two N-levelshad only an effect on the SCA-values of a few of the hybrids for SON and GNC.Significant differences were found between the SCA-values of the FI hybrids for PLHT,GY, SOW, SON and GNC at both the low and the high N-Ievels.The F I hybrids showed significant differences between the SCA-values for all threenitrogen use efficiency components in the Doornpan trial and only for yield efficiency andrecovery efficiency in the Bethlehem trial.The GCA:SCA ratios differed significantly at the two N-levels for PLHT in the Doornpantrial. With the exception of SON the additive variance components of SOW, GNC andSNC were higher at the high N-level. In the Bethlehem trial the GCA:SCA ratios forPLHT, SDW and GNC were higher at the high N-level. SOW had the largest GCA:SCAratios under both N-levels. The GCA:SCA ratios for recovery efficiency was larger thanthat of yield efficiency.In the Doornpan trial the narrow-sense heritabilities for PLHT and GNC were the largestunder the high N-level. The narrow-sense heritabilities for nitrogen use efficiencycomponents were very low. The narrow-sense heritabilities of PLHT, GY, SOW, GNCand SNC were much larger at the high N-Ievel at Bethlehem. Again the heritabilitiesobtained for nitrogen use efficiency components were very low.Significant phenotypic correlation coefficients were found between GY and PLHT at thehigh N-Ievel in the Doompan trial. Significant correlation coefficients were also foundbetween GY and SDN at both N-Ievels. In the Bethlehem trail significant correlationcoefficients existed between GY and PLHT and between GY and SON at both N-levels.GNC was significant but negatively correlated with GY at the high N-level.The genotypic correlation coefficients in the Doompan trial were significant between GY .and SDN and between GY and SNC at both N-Ievels. HI and GY were significantlycorrelated at the high N-Ievel. In the Bethlehem trial SDN was highly correlated with GYat both N-levels. GY was significantly correlated with PLHT at the high N-level,negatively correlated with SDW at the low N-Ievel and negatively correlated with GNC atthe high N-Ievel.In the Doompan trial GY at the low arid the high N-levels was significantly correlated withyield efficiency. It was also significantly correlated with recovery efficiency at the high N-level.In the Bethlehem trial GY was significantly correlated with the three nitrogen useefficiency components at the high N-level. Recovery efficiency was significantlycorrelated with GY at the low N-level.

[发布机构] University of the Free State