GENOTYPIC VARIATION FOR BRITTLE-SNAP SUSCEPTIBILITY IN MAIZE (ZEA MAYS L.): PHENOTYPING OF STALK BREAKAGE AND RELATED TRAITS IN A RILS POPULATION

RODRIGUEZ, J.G.; KUSSROW, N.; PIRCHI, I.L.; CIRILO, A.G.; CERRI, A.M.; OTEGUI, M.E.

Bento Goncalves

Congreso; VI International Crop Science Congress; 2012

International Crop Science Society

Winds stronger than 45 m s-' are known to cause severe brittle-snap of maize (Zea mays L.), with stalks breaking near the uppermost ear node, particularly in crops undergoing active stem elongation immediately before anthesis. Early studies on this trait focused on genotypic variation among commercial hybrids and the effect of management practices. They concluded that the best strategy is to plant hybrids less prone to breakage, but breeding against this constrait is limited by the lack of accurate methods for simulating brittle-snap. The aim of this work was to study the genotypic variation in maize susceptibility to stalk breakage. Primarily, for providing robust data for QTL analysis, and additionally for evaluating its relationship with several morphometric traits. These traits were plant height to the uppermost ear and to the uppermost collar, estimated stem volume at ear and uppermost collar heights, and stalk diameter at ground level. We phenotyped mentioned traits for a collection of 180 recombinant inbred lines (RILs) derived from two contrasting parental inbreds (B100: American semident; LP2: Argentine flint). Inbreds were sown in the field at three different sowing dates (14, 18 and 23 Nov, 2011) for avoiding the confounded effect of their variation in time to anthesis (surveyed during 2009-2010). The experimental layout was a completely randomized block design with two replicates. Stand density was 7 plants m-2, and plots had 10.5 m2. A severe wind storm (winds > 45 m s-') took place on 23-Jan-2012. It was immediately before anthesis of the experiment, which spanned between 24-Jan and 7-Feb. Stalk breakage ranged between 0 (28% of inbreds) and >50% damage (1.1% of inbreds, with maximum of 55.6%), it was not normally distributed