Physiological Determinants of Maize Grain Yield: Heritability and Correlation Analysis in a Dent x Flint-Caribbean RILs Familiy.

The understanding of physiological traits related to maize grain yield provides a useful framework for assisting molecular studies aimed to crop breeding. The objectives of this research were (i) to perform a detailed phenotyping of 23 traits related to phenology, light capture, biomass production and partitioning, numerical components of plant grain yield (PGY) and N metabolism, and (ii) to establish their correlation and heritability (h²). A population of 193 recombinant inbred lines (RILs) and its parental inbreds (B100 and LP2) were grown in the field during two seasons (Exp1: 2009-2010; Exp2: 2011-2012) in a completely randomized block design with two replicates. Five (Exp1) or seven (Exp2) plants were tagged in each plot at V₃, and measurements were performed on these plants until maturity. Significant genotypic (G), year (Y) and G×Y interactions effects (P<0.01) were detected for all measured traits, except for (i) maximum leaf area, plant biomass reproductive efficiency (BRE), and biomass partitioning to the ear during the critical period (BPEcp) that had no significant Y effect, and (ii) N uptake at maturity (PNuptake) that had no G effect. Heritability values were (i) high (h²>0.70) for thermal times to anthesis and silking, BRE, BPEcp and kernel weight; (ii) intermediate (0.70>h²>0.4) for kernel number (KNP), harvest index (HI), NHI, plant and ear growth rates and N use efficiency (NUE), and (iii) low (h²<0.40) for PGY, biomass at maturity (BIOpm) and PNuptake. Biplot analysis showed that first principal component explained up to 42% of the total variance and accounted for variations in PGY, highly associated with plant and ear growth rates, BIOpm, KNP and PNuptake. The second principal component accounted for variations (21%) in NUE, highly associated with HI, NHI and BRE. The phenotyping presented in this population is important because it is a starting point for further genetic studies based on molecular markers associations.