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

Vlatko Galic; Mario Franic; Antun Jambrovic; Tatjana Ledencan; Andrija Brkic; Zvonimir Zdunic; Domagoj Simic

doi:10.3389/fpls.2019.00566

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

Front Plant Sci. 2019 Apr 30:10:566. doi: 10.3389/fpls.2019.00566. eCollection 2019.

Authors

Vlatko Galic¹, Mario Franic¹, Antun Jambrovic^{1

2}, Tatjana Ledencan¹, Andrija Brkic¹, Zvonimir Zdunic^{1

2}, Domagoj Simic^{1

2}

Affiliations

¹ Department of Maize Breeding and Genetics, Agricultural Institute Osijek, Osijek, Croatia.
² Centre of Excellence for Biodiversity and Molecular Plant Breeding, Zagreb, Croatia.

Abstract

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 examine genetic correlations between photosynthetic performance of JIP-test during flowering and grain yield (GY) in maize grown under two heat scenarios in the field environments applying quantitative genetic analysis, and to compare efficiencies of indirect selection for GY through ChlF parameters and genomic selection for GY. The testcrosses of 221 intermated recombinant inbred lines (IRILs) of the IBM Syn4 population were evaluated in six environments at two geographically distinctive locations in 3 years. According to day/night temperatures and vapor pressure deficit (VPD), the two locations in Croatia and Turkey may be categorized to the mild heat and moderate heat scenarios, respectively. Mild heat scenario is characterized by daytime temperatures often exceeding 33°C and night temperatures lower than 20°C while in moderate heat scenario the daytime temperatures often exceeded 33°C and night temperatures were above 20°C. The most discernible differences among the scenarios were obtained for efficiency of electron transport beyond quinone A (Q_A) [ET/(TR-ET)], performance index on absorption basis (PI_ABS) and GY. Under the moderate heat scenario, there were tight positive genetic correlations between ET/(TR-ET) and GY (0.73), as well as between PI_ABS and GY (0.59). Associations between the traits were noticeably weaker under the mild heat scenario. Analysis of quantitative trait loci (QTL) revealed several common QTLs for photosynthetic and yield performance under the moderate heat scenario corroborating pleiotropy. Although the indirect selection with ChlF parameters is less efficient than direct selection, ET/(TR-ET) and PI_ABS could be efficient secondary breeding traits for selection under moderate heat stress since they seem to be genetically correlated with GY in the stressed environments and not associated with yield performance under non-stressed conditions predicting GY during flowering. Indirect selection through PI_ABS was also shown to be more efficient than genomic selection in moderate heat scenario.

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