Research Article Efficiency on the Use of Radiation and Corn Yield under Three Densities of Sowing A. Morales-Ruiz, 1 J. M. Loeza-Corte, 1,2 E. Díaz-López, 1 E. J. Morales-Rosales, 3 O. Franco-Mora, 3 M. D. Mariezcurrena-Berasaín, 3 and G. Estrada-Campuzano 3 1 Ingenier´ ıa en Agricultura Sustentable y Protegida, Universidad Tecnol´ ogica de Tehuac´ an, Prolongaci´ on de la 1 sur No. 1101 San Pablo Tepetzingo, 75859 Tehuac´ an, PUE, Mexico 2 Ingenier´ ıa en Agroindustrias, Universidad de la Ca˜ nada, Carretera Teotitl´ an, San Antonio km 1.7, Paraje Titlacuatitla, 68540 Teotitl´ an de Flores Mag´ on, OAX, Mexico 3 Centro de Investigaci´ on y Estudios Avanzados en Fitomejoramiento, Universidad Aut´ onoma del Estado de M´ exico, Campus Universitario El Cerrillo Piedras Blancas, 50200 Toluca, MEX, Mexico Correspondence should be addressed to A. Morales-Ruiz; alejandro.morales@uttehuacan.edu.mx Received 9 November 2015; Revised 8 February 2016; Accepted 10 February 2016 Academic Editor: Silvia Imhof Copyright © 2016 A. Morales-Ruiz et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Aiming to evaluate sowing densities and efciency of radiation use, six corn genotypes, three from open pollination (“Amarillo Almoloya,” “Cacahuacintle,” and “Jiquipilco”) and three hybrids (“Z-60,” “Condor,” and “H-50”), were sown at densities of 6.9, 7.8, and 8.9 plants m −2 , under a split plot design, within a factorial arrangement of treatments during three years (2008, 2009, and 2010). Evaluated variables were yield, harvest index, biomass production, attenuation coefcient, and radiation use efciency. Results indicate that 2008 was the best year because yield, biomass, and radiation use efciency were 1132.6, 3505 gm −2 , and 0.79 g MJ −1 , respectively. “Jiquipilco” was the genotype that exhibited the best adaptability to climatic conditions of the zone; thus, it is recommended to be grown on the studied zone. 1. Introduction Te maize (Zea mays L.) is of family Gramineae domesticated by indigenous cultures in Mesoamerica region, particularly in the Tehuacan-Cuicatlan Valley in Mexico [1]. It is considered a staple crop on human diet because it supplies carbohydrates needed to obtain metabolic energy. It is also used to grow huitlacoche gall that is used for human consumption [2, 3]. Among environmental factors that afect yield signif- cantly, we may cite solar radiation that interacts with water absorption, nutrients, and temperature [4], infuencing the photosynthesis process, which, in turn, determines biomass accumulation on crops; this has been corroborated by [5] who mentioned that solar radiation is a key to determine the plant growth factor. Factors that afect this process are solar light interception and utilization, through crop canopy structure, to transform light in photo assimilates and to transfer carbohydrates to demanding organs [6]. For corn production, dry matter accumulation is one of the more important yield components and this, in turn, is the result of interception and use of the incident solar radiation on the foliage structure of the crop during the growing cycle [7]. To increase grain yield on corn, it is important to increase the amount of intercepted radiation that depends on the variety, sowing density, sowing date, and stage of develop- ment [8]. To reach high levels of intercepted radiation, the development of a high leaf area index since early growth stages [9] is needed. An optimum leaf area index (LAI) is the one that allows the maximum dry biomass production, and this is reached when lower canopy leaves maintain a positive balance of carbon; this means when the crop absorbs the whole photosynthetically active radiation (PAR) [10]. Photosynthetically active radiation (PAR) intercepted by the crop is transformed in biomass; thus, the lineal relationship among these variables represents radiation use efciency (RUE) that is expressed in g of dry matter (DM) per MJ −1 Hindawi Publishing Corporation International Journal of Agronomy Volume 2016, Article ID 6959708, 5 pages http://dx.doi.org/10.1155/2016/6959708