Resumen

CASTRO-NAVA, Sergio; REYES-MENDEZ, César A.  y  HUERTA, Alfredo J.. Genetic diversity of leaf area traits in maize landraces native to Tamaulipas under high temperatures. Rev. fitotec. mex [online]. 2014, vol.37, n.3, pp.217-223. ISSN 0187-7380.

The Mexican state of Tamaulipas has a wide variety of maize (Zea mays L.) landraces not well studied and with high potential for genetic improvement. The aim of the study was to determine genetic variability for traits related to leaf area and efficiency for grain production in maize landraces from Tamaulipas grown under high temperature conditions. Twenty four maize landraces, two commercial materials ('H-437' and 'VS-536') and two improved advanced generations of hybrids were evaluated in two contrasting locations from Tamaulipas (Río Bravo in the North and Güémez in the Central part). The first location had optimum temperature and soil moisture, while in the second location high temperatures were ensured through late planting. Nine agronomic traits, leaf area and grain production efficiency were registered. The analysis of variance showed the presence of wide genetic diversity among the landraces for all the studied traits. Out of the 24 maize landraces, 79 % were superior for grain yield, ear leaf area, total leaf area and efficiency for grain production in relation to commercial breeding materials. These landraces might be potential donors of genes to enhance tolerance to high temperature. The genotype with the highest grain yield under high temperature conditions (> 35 °C) was C-3004 (71.4 g/plant). The efficiency for grain production had a significant and negative association with leaf area index (-0.59**), total leaf area (-0.59**), ear leaf area (-0.43*) and total leaf number (-0.51**), thus indicating the need of selection for physiological efficiency by choosing optimum leaf area index for high temperature conditions.

Palabras llave : Zea mays; ear leaf area; genetic variance; heritability; leaf number.