Plant characterization of genetically modified maize hybrids MON-89Ø34-3 × MON-88Ø17-3, MON-89Ø34-3 × MON-ØØ6Ø3-6, and MON-ØØ6Ø3-6: alternatives for maize production in Mexico.

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.

Fertirrigación con diferentes formas de nitrógeno en el cultivo de tomate en un suelo arcilloso / Tomato crop fertigation with different nitrogen form in clayed soil / Fertirrigação com diferentes formas de nitrogênio no cultivo de tomate em um solo argiloso

Se estudió el efecto de nitrógeno nítrico, amoniacal y ureico, suministrados en distintas etapas de desarrollo del cultivo de tomate, sobre el rendimiento y la calidad de fruto. El trabajo se realizó en campo bajo riego por goteo, en un suelo vertisol pélico y clima cálido y semiárido. Tres tratamientos de fertilización (T1, T2 y testigo) fueron distribuidos en un diseño de bloques completos al azar con tres repeticiones. T1 y T2 se fertilizaron con 250-50-190kg·ha-1 de N, P y K, respectivamente; en estos el N se suministró en diferentes proporciones de N-ureico, N-amoniacal y N-nítrico, en distintas etapas de desarrollo del cultivo; el T3 se aplicó como los productores del Valle de Culiacán, Sinaloa, México (450-118-413kg·ha-1 de N-P-K), con 75% del N como nitrato. La concentración de N-NO3 en el extracto celular de peciolos en los T1 y T2 fluctuó de 500 a 1360ppm, y en T3 fue de 300-1175ppm. Estos valores estuvieron relacionados con la dosis de N total suministrado pero no con la proporción de NH4/NO3 aplicada, y tampoco influyeron en la producción de fruto de exportación. La producción de fruto fue estadísticamente igual en las dosis de fertilización alta y moderada, con un ahorro del 75% de N-nítrico. En calidad poscosecha de frutos, la fertilización reducida y la aplicación de N-ureico y N-amoniacal en altas proporciones no afectó la firmeza, ºBrix ni la pérdida de peso de los frutos.

The effect of nitrogen form (urea, nitrate and ammonium) provided at various stages of development of the tomato crop on the yield and quality of fruit was studied. The work was conducted under field conditions in a pellustert soil, drip irrigation and a warm and semi-arid climate. Three fertilization treatments (T1, T2 and control) were arranged in a randomized complete-block design with three replicates. T1 and T2 were fertilized with 250-50-190kg·ha-1 N, P and K, respectively; which N was supplied in different ratios of ureic-N, ammonium-N and nitric-N along growing tomato plants; T3 was provided in a similar way as is generally employed by the tomato producers in the Culiacan Valley, Sinaloa, Mexico (450-118-413kg·ha-1 N-P-K), with 75% of N in nitrate form. The concentration of N-NO-3 in the petiole cell extract in T1 and T2 ranged from 500 to 1360ppm, and in the control it was 300-1175ppm. These values were related with the total N doses supplied but not with the ratio of NH4/NO3 provided, neither influenced on the total amount of exportation fruit. The fruit production was statistically similar in the high and moderated fertilizer doses with a fertilizer savings of 75% of nitrate N. With respect to the post-harvest quality in the tomato fruit, moderated fertilization associated with high application of ureic-N and ammonium-N did not affect the fruit firmness, ºBrix or the weight loss in the fruit.

Estudou-se o efeito do nitrogênio nítrico, amoniacal e uréico, subministrados em distintas etapas de desenvolvimento do cultivo de tomate, sobre o rendimento e a qualidade do fruto. O trabalho se realizou no campo sob irrigação por gotejamento, em um solo vertisol pélico e clima cálido e semi-árido. Três tratamentos de fertilização (T1, T2 e testemunho) foram distribuídos em um desenho de blocos completos aleatório com três repetições. T1 e T2 se fertilizaram com 250-50-190kg•ha-1 de N, P e K, respectivamente; em estes o N se subministrou em diferentes proporções de N-uréico, N-amoniacal e N-nítrico, em distintas etapas de desenvolvimento do cultivo; o T3 se aplicou como os produtores do Vale de Culiacán, Sinaloa, México (450-118-413kg•ha-1 de N-P-K), com 75% do N como nitrato. A concentração de N-NO3 no extrato celular de pecíolos nos T1 e T2 flutuou de 500 a 1360ppm, e em T3 foi de 300-1175ppm. Estes valores estiveram relacionados com a dose de N total subministrado, mas não com a proporção de NH4/NO3 aplicada, e tampouco influíram na produção do fruto de exportação. A produção do fruto foi estatisticamente igual nas doses de fertilização alta e moderada, poupando 75% de N-nítrico. Em qualidade pos-colheita de frutos, a fertilização reduzida e a aplicação de N-uréico e N-amoniacal em altas proporções não afetou a firmeza, oBrix nem a perda de peso dos frutos.