Mexico, the center of origin of maize (Zea mays L.), has taken actions to preserve the identity and diversity of maize landraces and wild relatives. Historically, spatial isolation has been used in seed production to maintain seed purity. Spatial isolation can also be a key component for a strategy to minimize pollen-mediated gene flow in Mexico between transgenic maize and sexually compatible plants of maize conventional hybrids, landraces, and wild relatives. The objective of this research was to generate field maize-to-maize outcrossing data to help guide coexistence discussions in Mexico. In this study, outcrossing rates were determined and modeled from eight locations in six northern states, which represent the most economically important areas for the cultivation of hybrid maize in Mexico. At each site, pollen source plots were planted with a yellow-kernel maize hybrid and surrounded by plots with a white-kernel conventional maize hybrid (pollen recipient) of the same maturity. Outcrossing rates were then quantified by assessing the number of yellow kernels harvested from white-kernel hybrid plots. The highest outcrossing values were observed near the pollen source (12.9% at 1 m distance). The outcrossing levels declined sharply to 4.6, 2.7, 1.4, 1.0, 0.9, 0.5, and 0.5% as the distance from the pollen source increased to 2, 4, 8, 12, 16, 20, and 25 m, respectively. At distances beyond 20 m outcrossing values at all locations were below 1%. These trends are consistent with studies conducted in other world regions. The results suggest that coexistence measures that have been implemented in other geographies, such as spatial isolation, would be successful in Mexico to minimize transgenic maize pollen flow to conventional maize hybrids, landraces and wild relatives.

In country, non-target arthropod (NTA) field evaluations are required to comply with the regulatory process for cultivation of genetically modified (GM) maize in Mexico. Two sets of field trials, Experimental Phase and Pilot Phase, were conducted to identify any potential harm of insect-protected and glyphosate-tolerant maize (MON-89Ø34-3 × MON-88Ø17-3 and MON-89Ø34-3 × MON-ØØ6Ø3-6) and glyphosatetolerant maize (MON-ØØ6Ø3-6) to local NTAs compared to conventional maize. NTA abundance data were collected at 32 sites, providing high geographic and environmental diversity within maize production areas from four ecological regions (ecoregions) in northern Mexico. The most abundant herbivorous taxa collected included field crickets, corn flea beetles, rootworm beetles, cornsilk flies, aphids, leafhoppers, plant bugs and thrips while the most abundant beneficial taxa captured were soil mites, spiders, predatory ground beetles, rove beetles, springtails (Collembola), predatory earwigs, ladybird beetles, syrphid flies, tachinid flies, minute pirate bugs, parasitic wasps and lacewings.Across the taxa analysed, no statistically significant differences in abundance were detected between GM maize and the conventional maize control for 69 of the 74 comparisons (93.2%) indicating that the single or stacked insect-protected and herbicide-tolerant GM traits generally exert no marked adverse effects on the arthropod populations compared with conventional maize. The distribution of taxa observed in this study provides evidence that irrespective of variations in overall biodiversity of a given ecoregion, important herbivore, predatory and parasitic arthropod taxa within the commercial maize agroecosystem are highly similar indicating that relevant data generated in one ecoregion can be transportable for the risk assessment of the same or similar GM crop in another ecoregion.This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Environmental risk assessment (ERA) of genetically modified (GM) crops is a process to evaluate whether the biotechnology trait(s) in a GM crop may result in increased pest potential or harm to the environment. In this analysis, two GM insect-resistant (IR) herbicide-tolerant maize hybrids (MON-89Ø34-3 × MON-88Ø17-3 and MON-89Ø34-3 × MON-ØØ6Ø3-6) and one herbicide-tolerant GM hybrid (MON-ØØ6Ø3-6) were compared with conventional maize hybrids of similar genetic backgrounds. Two sets of studies, Experimental Phase and Pilot Phase, were conducted across five ecological regions (ecoregions) in Mexico during 2009–2013, and data were subject to meta-analysis. Results from the Experimental Phase studies, which were used for ERA, indicated that the three GM hybrids were not different from conventional maize for early stand count, days-to-silking, days-to-anthesis, root lodging, stalk lodging, or final stand count. Statistically significant differences were observed for seedling vigor, ear height, plant height, grain moisture, and grain yield, particularly in the IR hybrids; however, none of these phenotypic differences are expected to contribute to a biological or ecological change that would result in an increased pest potential or ecological risk when cultivating these GM hybrids. Overall, results from the Experimental Phase studies are consistent with those from other world regions, confirming that there are no additional risks compared to conventional maize. Results from Pilot Phase studies indicated that, compared to conventional maize hybrids, no differences were detected for the agronomic and phenotypic characteristics measured on the three GM maize hybrids, with the exception of grain moisture and grain yield in the IR hybrids. Since MON-89Ø34-3 × MON-88Ø17-3 and MON-89Ø34-3 × MON-ØØ6Ø3-6 confer resistance to target insect pests, they are an alternative for farmers in Mexico to protect the crop from insect damage. Additionally, the herbicide tolerance conferred by all three GM hybrids enables more cost-effective weed management.Electronic supplementary materialThe online version of this article (doi:10.1007/s11248-016-9991-z) contains supplementary material, which is available to authorized users.

Pecans are cultivated extensively in the Yaqui Valley, Sonora. These soils often have problems of salinity and high concentrations of exchangeable sodium, which cause a decline in pecan productivity. At the end of the season of irrigation with water from the system of reservoirs on the Yaqui River, groundwater is generally used from May to August. This can result in salt accumulation in the soil when water is of poor quality. Gypsum has been used as an amendment to rehabilitate soil by improving its physical and chemical properties. The main objective of this study was to investigate the effect of gypsum application to a saline soil of a pecan orchard in the Yaqui Valley. Rehabilitation was carried out for two consecutive years. In the first year a dose of 5 and 10 Mg ha‑1 was applied, while in the second year 2 Mg ha‑1 of gypsum was used. Two ridge washings were done after each aplication. The physico-chemical analyses of the soil were conducted following NOM-021-RECNAT-2000 during three years prior to and after the applications of amedment. Once the amendement was applied, the values of electrical conductivity decreased from 12.41 to 6.29 dS m-1, percentage of exchangeable sodium from 12.48 to 5.57 and sodium adsorption ratio from 10.54 to 4.88 at the depth of 0-30 cm. The use of agricultural gypsum and washing in a saline soil of the pecan orchard improved soil chemical properties using 5 and 10 Mg ha-1.

El nogal pecanero (Carya illinoinensis Koch) es una especie hortofrutícola de rentabilidad alta, por lo que en México ha aumentado el área dedicada a este frutal. Dentro de los métodos nuevos utilizados para mejorar cultivos está la incorporación de organismos seleccionados por sus beneficios en el metabolismo vegetal, aplicados al sistema de la planta receptora como productos biológicos. Entre estos productos biológicos están los microorganismos promotores del crecimiento vegetal. Con la hipótesis de que al menos uno de estos productos biológicos favorecería el cultivo y rendimiento del nogal, el objetivo de este estudio fue analizar el efecto de la aplicación de microorganismos promotores de crecimiento para mejorar la productividad y calidad del nogal pecanero. La aplicación se realizó durante tres ciclos de 2017 a 2019; se utilizaron Bacillus subtilis, Bacillus cereus, Pseudomona fluorescens y Trichoderma harzianum, en una concentración de 108 UFC mL-1 m-2. El diseño fue en bloques al azar, con dos tratamientos; y se utilizó ANDEVA para la comparación de datos. Un conteo microbiológico en suelo se realizó y se evaluaron el rendimiento y la calidad del nogal. El conteo microbiológico dio como resultado de 105 a 107 poblaciones en el suelo inoculado. Los tratamientos mostraron diferencias significativas (p≤0.05) e incrementaron la productividad del nogal un 27.7% al utilizar el consorcio microbiano en el ciclo 2019, y además una calidad mejor se obtuvo en la nuez durante los tres ciclos consecutivos.