engleski

Genetic Correlations Between Photosynthetic and Yield Performance in Maize Are Different Under Two Heat Scenarios During Flowering

Chlorophyll fluorescence (ChlF) parameters are reliable early stress indicators in crops, but their relations with yield are still not clear. The aims of this study are to examinegenetic correlations between photosynthetic performance of JIP-test during floweringand grain yield (GY) in maize grown under two heat scenarios in the field environmentsapplying quantitative genetic analysis, and to compare efficiencies of indirect selectionfor GY through ChlF parameters and genomic selection for GY. The testcrossesof 221 intermated recombinant inbred lines (IRILs) of the IBMSyn4population wereevaluated in six environments at two geographically distinctive locations in 3 years.According to day/night temperatures and vapor pressure deficit (VPD), the two locationsin Croatia and Turkey may be categorized to the mild heat and moderate heatscenarios, respectively. Mild heat scenario is characterized by daytime temperaturesoften exceeding 33◦C and night temperatures lower than 20◦C while in moderate heatscenario the daytime temperatures often exceeded 33◦C and night temperatures wereabove 20◦C. The most discernible differences among the scenarios were obtainedfor efficiency of electron transport beyond quinone A (QA) [ET/(TR-ET)], performanceindex on absorption basis (PIABS) and GY. Under the moderate heat scenario, therewere tight positive genetic correlations between ET/(TR-ET) and GY (0.73), as well asbetween PIABSand GY (0.59). Associations between the traits were noticeably weakerunder the mild heat scenario. Analysis of quantitative trait loci (QTL) revealed severalcommon QTLs for photosynthetic and yield performance under the moderate heatscenario corroborating pleiotropy. Although the indirect selection with ChlF parametersis less efficient than direct selection, ET/(TR- ET) and PIABScould be efficient secondarybreeding traits for selection under moderate heat stress since they seem to begenetically correlated with GY in the stressed environments and not associated with yieldperformance under non- stressed conditions predicting GY during flowering. Indirectselection through PIABSwas also shown to be more efficient than genomic selectionin moderate heat scenario

flowering ; grain yield ; heat ; photosynthetic performance ; pleiotropy ; quantitative trait loci ; Zea mays

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