Latin America is the center of domestication and diversity of maize, the second most cultivated crop worldwide. In this region, maize landraces are fundamental for food security, livelihoods, and culture. Nevertheless, genetic erosion (i.e., the loss of genetic diversity and variation in a crop) threatens the continued cultivation and in situ conservation of landrace diversity that is crucial to climate change adaptation and diverse uses of maize. We provide an overview of maize diversity in Latin America before discussing factors associated with persistence of large in situ maize diversity, causes for maize landrace abandonment by farmers, and strategies to enhance the cultivation of landraces. Among other factors, maize diversity is linked with: (1) small-holder farming, (2) the production of traditional food products, (3) traditional cropping systems, (4) cultivation in marginal areas, and (5) retention of control over the production system by the farmers. On the other hand, genetic erosion is associated with substitution of landraces with hybrid varieties or cash crops, and partial (off-farm labor) or complete migration to urban areas. Continued cultivation, and therefore on-farm conservation of genetic diversity held in maize landraces, can be encouraged by creating or strengthening market opportunities that make the cultivation of landraces and open pollinated varieties (OPVs) more profitable for farmers, supporting breeding programs that prioritize improvement of landraces and their special traits, and increasing the access to quality germplasm of landraces and landrace-derived OPVs.

The effects of two differentpozolepreparation processes, traditional (TP) and industrial (IP), on quality variables, chemical composition, and pasting properties of processed grain of nine maize landraces were evaluated. Nixtamalization and steeping time in TP (~15 h) allowed more water absorption resulting in higher moisture content as well as softer debranned nixtamal relative to the debranned nixtamal produced by IP (52 min). Steeping in TP and bleaching in IP increased the pasting temperature, peak viscosity, and time to peak viscosity of maize starch. Flowering time was shorter in IP (120 min) and was significantly affected by the hardness of debranned nixtamal and bleached precooked grains. Total dry matter loss was higher in IP (>10.5%) than in TP (<5.0%), mainly due to the complete elimination of pedicel and pericarp by the Ca(OH)₂+ NaOH solution during cooking. Soft grains, with low test weight, a high proportion of floury endosperm, and high peak viscosity, are required to obtain higher yield of bleached precooked grains and soft flowered grains in both processes.

The aim of this work was to identify maize (Zea mays L.) genotypes with stability on grain yield and potential for the masa and tortilla industry, by evaluating the effect of the genotype by environment interaction of eight genotypes grown in eight environments in the subtropics of Mexico. During the spring-summer seasons of 2015 and 2016 we evaluated maize genotypes with added value: three high-oil hybrids (H-327 AO, H-388 O, H-389 O), a quality protein maize hybrid (H-390 C), a yellow normal endosperm hybrid (H- 387 A), and commercial hybrids as control (H-377, H-383 C, DK2027Y). By means of sites regression model, the high-oil hybrid H-389 O was identified as one of the higher grain yield (12.07 t ha-1), more stable, with good grain quality and soft tortillas, both fresh and stored. In 2015 higher precipitation increased the accumulation of starch, grain density and hardness. Carotenoids content of H-387 A (12.11 μg g-1 maize) was higher than yellow control (2.72 μg g-1); therefore, it could have nutraceutical potential. The H-390 C hybrid did not highlight for its lysine and tryptophan content. Although the rest of genotypes were not stable on grain yield, they had grains with suitable characteristics for processing and for producing acceptable tortilla yield (1.5 kg kg-1 maize). El objetivo de este trabajo fue identificar maíces (Zea mays L.) con estabilidad en el rendimiento de grano y potencial para la industria de la masa y la tortilla, mediante la evaluación de la interacción genotipo ambiente de ocho genotipos cultivados en ocho ambientes del subtrópico de México. Durante los ciclos PV-2015 y 2016 se evaluaron maíces con valor agregado: tres de alto contenido de aceite (H-327 AO, H-388 O, H-389 O), uno de alta calidad proteínica (H-390 C), un amarillo normal (H-387 A) y tres testigos comerciales (H-377, H-383 C, DK2027Y). Mediante el modelo de regresión de sitios se identificó al híbrido H-389 O como uno de los materiales de mayor rendimiento (12.07 t ha-1) y más estable, con buena calidad de grano y producción de tortillas suaves, tanto frescas como almacenadas. En 2015 una mayor precipitación incrementó la acumulación de almidón, la densidad y la dureza del grano. El genotipo H-387 A sobresalió por su alto contenido de carotenoides (12.11 μg g-1 maíz) respecto al testigo amarillo (2.72 μg g-1), lo que le confiere propiedades nutracéuticas. El hibrido H-390 C no destacó por su contenido de lisina y triptófano. Aunque poco estables en rendimiento, el resto de los genotipos presentaron características de grano aptas para el procesamiento y rendimiento aceptable de tortillas (1.5 kg kg-1 de maíz).