Genetic variation in a maize population of RILs: II- Heritability study of the eco-physiological determinants of kernel weight.

PIEDRA, C.V; BENDER, R.R.; D'ANDREA, K.E.; CERRI, A.M.; CIRILO, A.G.; OTEGUI, M.E.

Bento Goncalves

Congreso; VI International Crop Science Congress; 2012

International Crop Science Society

In maize (Zea mays L.), final kernel weight (KW) is determined by the rate (KGR) and the duration (KFD) of grain filling. The genetic control of these traits is currently unknown. The aim of this work was to study the genotypic variation in final KW and its physiological determinants, KGR and KFD during the active grain-filling period. We phenotyped these traits for a collection of 180 recombinant inbred lines (RILs) derived from two contrasting parental inbreds (B100: American semident; LP2: Argentine flint). The collection, both parentals and a tester line were grown under irrigation during two seasons (Exp.1: 2009-2010, Exp.2: 2011-2012). The experimental layout was always a completely randomized block design with two replicates. At the start of silking, a total of eight plants were tag in each plot. Silking date was registered for each tagged plant. Apical ears of these plants were collected on 18, 23, 28, 33, 38, 43, 48 and 53 days after silking, and 15 grains were sampled from each ear at the position 10 from the bottommost spikelet. Grains were oven dried and weighed for the determination of KW. Significant genotypic variation (p280 mg). For tested environments, grain yield was strongly associated with kernel number and to a less extent with KW. Therefore, inbreds with highest KW were not among those that reached highest grain yields. Nevertheless, we identified some inbreds that combined high kernel numbers and high KW (i.e., within the uppermost quartile of grain yield). The selection of these inbreds would allow for the improvement of both grain yield components simultaneously, avoiding the apparent trade-off between them. The observed phenotypic variation in this mapping population will be used for the detection of candidate QTLs that control final KW.