Resumo

CORONA-MENDOZA, Esmeralda; MARTINEZ-RUEDA, Carlos Gustavo  e  ESTRADA-CAMPUZANO, Gaspar. Determinants of grain weight in native cultivars and hybrids of maize. Rev. Mex. Cienc. Agríc [online]. 2012, vol.3, n.8, pp.1479-1494. ISSN 2007-0934.

The objective of this work was to study the physiological parameters that explain variations in individual grain weight among native cultivars and hybrids and analyze the genetic advance in grain yield of highland maize. There were evaluated two native cultivars (Ixtlahuaca and Jiquipilco), two ancient hybrid (H-30 and H-32) and two modern (Z-60 and H-40), in four contrasting environments, varying planting date (OD: optimal 2/4/09 and LD: late 30/04/09) and production systems (AS: ancient 5 plants m^-2, 80N-40P-00K and MS: modern 8 plants m^-2, 180N-90P-60K), in 2009 in Toluca, Mexico. There were significant differences between genotypes and environments for maximum grain weight (MGW), grain yield (GY) and its maj or components, without GxA interaction effects. Variations in the MGW were mainly explained by changes in the grain filling rate (GFR). In the OD, native cultivars showed higher MGW and maximum water content in the grain (MWCG) due to increased RGF. The potential capacity ofdemand (PCD) was higher in modern hybrids, and was directly related (R²= 0.89, p< 0.01) with a higher GY. The modern hybrids in the four environments had higher GY, exceeding in average the native cultivars at 2.27 t ha^-1 and to ancient hybrids in 1.59 t ha^-1. These results indicate that genetic progress achieved with modern hybrids from Highlands is based on a more stable GN and MGW.

Palavras-chave : Zea mays L.; grain filling rate; maximum grain weight; water content in grain.