Genetic Variation among Inbred Lines and Testcrosses of Maize for Early Growth Parameters and Their Relationship to Final Dry Matter Yield

Abstract

ABSTRACTReduced early growth of maize (Zea mays L.) might impair subsequent biomass accumulation, and, therefore, final whole‐plant dry matter yield (DMY). Quantitative genetic studies on biomass growth rates and their relation to final DMY in large germplasm sets have been hampered so far by a lack of suitable phenotyping techniques. In this study, we took advantage of a recently developed nondestructive phenotyping platform to (i) determine early biomass and growth rates in a broad set of 285 dent inbred lines and their testcrosses with two flint testers grown at three locations in 2008 and 2009, based on nondestructive measurements of biomass between the four‐ and eight‐leaf stage; (ii) estimate variance components and heritability for these traits; (iii) investigate the association of early growth with final DMY and other agronomic traits; and (iv) calculate correlations between line per se performance (LP) and general combining ability (GCA) for these traits. We observed significant genetic variance and high heritabilities for early growth traits, though masking variance components were larger than for agronomic traits. Early growth traits showed weak (GCA) to moderate (LP) correlations with final DMY. Correlations between LP and GCA were only moderate for early growth traits, most probably due to masking effects of the testers. Since correlations among early growth traits were tight, the simple visual scoring of early vigor is sufficient in selection of promising testcrosses.