Abstract The use of biostimulants has been an agricultural strategy for increasing crop yields and quality. The objective of this work was to evaluate the effect of biostimulants on the yield and components of corn hybrids (Zea mays L.) in the High Valleys of the State of Mexico. The sowing was carried out during the spring summer 2017 cycle in three environments (Jocotitlán, Temascalcingo, Jilotepec). Eleven corn hybrids were evaluated (TSIRI PUMA; ATZIRI PUMA; TLAOLI PUMA; IXIM PUMA, H-50, #46#48; H-66; H-76; H-77; H-47AE and H-49AE). The foliar treatments with biostimulants were the following: B1= control; B2=Eurobor; B3= Euroligo; B4= Eurodual; B5= Euroalg. Evaluations included: grain yield, straw production, rows per cob, grains per row, grains per cob, volumetric weight, weight of 200 grains, and cob diameter. For all variables, a combined analysis of variance, a mean comparison test (Tukey) and a correlation analysis (Pearson) were performed. Between environments, hybrids and biostimulants there were significant differences. In Temascalcingo, higher grain yield was observed with 13.5 t ha-1. The hybrids had yields higher than those of studies reported in the literature, and the genotypes H-66, H-50 and H-76 stand out in the present study. Biostimulants increased grain yield from 7.9 to 11.4%, with respect to the control, and positively affected the agronomic components of the hybrids evaluated. Biostimulants are an alternative in complementary fertilization to increase production in the cultivation of corn.

Resumen El uso de bioestimulantes ha sido una estrategia agrícola para aumento del rendimiento y la calidad de los cultivos. El objetivo de este trabajo fue evaluar el efecto de bioestimulantes en el rendimiento y en los componentes de híbridos de maíz (Zea mays L.) en Valles Altos del Estado de México. La siembra se realizó durante el ciclo primavera verano 2017 en tres ambientes (Jocotitlán, Temascalcingo, Jilotepec). Se evaluaron once híbridos de maíz (TSIRI PUMA; ATZIRI PUMA; TLAOLI PUMA; IXIM PUMA, H-50, #46#48; H-66; H-76; H-77; H-47AE y H-49AE). Los tratamientos foliares con bioestimulantes fueron los siguientes: B1= testigo; B2= Eurobor; B3= Euroligo; B4= Eurodual; B5= Euroalg. Las evaluaciones incluyeron: rendimiento de grano, producción de paja, hileras por mazorca, granos por hilera, granos por mazorca, peso volumétrico, peso de 200 granos y diámetro de mazorca. Para todas las variables se realizó un análisis varianza combinado y se realizó una prueba de comparación de medias (Tukey) y análisis de correlación (Pearson). Entre los ambientes, híbridos y en los bioestimulantes hubo diferencias significativas. En Temascalcingo se observó mayor rendimiento de grano con 13.5 t ha-1. Los híbridos presentaron rendimientos superiores a estudios reportados en la literatura, y destacan los genotipos H-66, H-50 y H-76 en el presente estudio. Los bioestimulantes aumentaron el rendimiento de grano de 7.9 a 11.4%, respecto al testigo, y afectó positivamente los componentes agronómicos de los híbridos evaluados. Los bioestimulantes resultan una alternativa en la fertilización complementaria para incremento de producción en el cultivo de maíz.

Abstract Given the insufficiency in corn production, which translates into the import of up to 15 million tons of grain, it is urgent to increase the productivity of this crop, using more and better varieties. The objective of this work was to determine the agronomic characteristics of white hybrids in five different environments, the best response, as well as to define the effect of genotype × environment interaction on yield, and other characteristics evaluated for the High Valleys of Mexico (2 200 at 2 600 meters above sea level). In the spring-summer 2016 agricultural cycle, ten maize hybrids were evaluated in five locations using an experimental design of randomized complete blocks, with four repetitions. The analysis was factorial considering as factors the environments (5), the hybrids (10), as well as the environment × hybrid interaction. Eight agronomic variables were evaluated. Anovas and comparisons of Tukey means p= 0.05 were performed. Both factors presented differential responses and the variables evaluated were influenced by the effect of the environment. The hybrids with the highest average productivity were ATZIRI PUMA (12 t ha-1) and TSIRI PUMA (11.8 t ha-1) followed by the hybrids H-50, H-66 and H-70, which produced 11.5, 11.6 and 11.6 t ha-1 respectively. Considering that H-50 is one of the hybrids of greater commercial use in the High Valleys, the four referred hybrids of greater yield of white grain, could have perspectives of commercial use, in the environments managed in this study.

Resumen Dada la insuficiencia en producción de maíz, que se traduce en la importación de hasta 15 millones de toneladas de grano, urge elevar la productividad en este cultivo, utilizando más y mejores variedades. El objetivo de este trabajo fue determinar las características agronómicas de híbridos blancos en cinco ambientes diferentes, la respuesta mejor, así como definir el efecto de la interacción genotipo × ambiente sobre el rendimiento, y otras características evaluadas para los Valles Altos de México (2 200 a 2 600 msnm). En el ciclo agrícola primavera-verano 2016, se evaluaron diez híbridos de maíz en cinco localidades mediante un diseño experimental de bloques completos al azar, con cuatro repeticiones. El análisis fue factorial considerando como factores los ambientes (5), los híbridos (10), así como la interacción ambiente × híbridos. Se evaluaron ocho variables agronómicas. Se realizaron Anovas y comparaciones de medias Tukey p= 0.05. Ambos factores presentaron respuestas diferenciales y las variables evaluadas estuvieron influenciadas por el efecto del ambiente. Los híbridos de productividad media mayor fueron ATZIRI PUMA (12 t ha-1) y TSIRI PUMA (11.8 t ha-1) seguidos por los híbridos H-50, H-66 y H-70, que produjeron 11.5, 11.6 y 11.6 t ha-1 respectivamente. Considerando que H-50 es uno de los híbridos de mayor uso comercial en los Valles Altos, los cuatro híbridos referidos de mayor rendimiento de grano blanco, podrían tener perspectivas de uso comercial, en los ambientes manejados en este estudio.

O objetivo desse estudo foi investigar o emprego dos componentes da eficiência no uso de nitrogênio e das atividades das enzimas nitrato redutase e glutamina sintetase na seleção de genótipos de milho eficientes no uso de nitrogênio (N). Foram avaliados 10 genótipos de milho em estádio de V4 em condições de alto e baixo N. O experimento foi composto por um fatorial 2 x 10 (dois níveis de N e 10 genótipos de milho) em delineamento inteiramente casualizados com três repetições. Os seguintes caracteres foram avaliados: as eficiências na absorção (EAbN), na utilização (EUtN) e no uso de N (EUsN) e as atividades das enzimas glutamina sintetase (GS) e nitrato redutase (NR). Para os caracteres que o efeito de genótipos foi significativo (p<0,05) na análise de variância por nível de N, as médias foram comparadas por meio do teste t (p<0,05). Os ganhos indiretos na EUsN e em seus componentes com seleção sobre as atividades das enzimas NR e GS foram estimados em baixo N. Conclui-se que em alto N: a EAbN é eficiente para discriminar genótipos de milho eficientes no uso de nitrogênio; em baixo N: as EAbN e EUtN são eficientes para discriminar genótipos de milho eficientes no uso de nitrogênio, a atividade de NR não é um bom parâmetro fisiológico para discriminar genótipos de milho eficientes no uso de nitrogênio, e a seleção sobre atividade da enzima GS possibilita a seleção indireta de genótipos de milho eficientes no uso de nitrogênio.

The aim of this study was to investigate the employment of components of the nitrogen efficiency use (NUE), and of the activities of the nitrate reductase and glutamine synthetase enzymes in the selection of nitrogen use efficient maize genotypes of maize. Ten maize genotypes at V4 stage were evaluated under high and low N. The experiment consisted of a 2 x 10 factorial (two levels of N and ten maize genotypes), in a randomized complete block design with three replicates. The following traits were evaluated: N uptake efficiency (NUpE), N utilization efficiency (NUtE) and N use efficiency (NUE), and activities of the glutamine synthetase (GS) and nitrate reductase (NR) enzymes. For traits which the effect of genotype was significant (p<0.05) in the variance analysis for level of N, the mean were compared using the t test (p<0.05). The indirect gains in NUE and their components with selection over the activities of the enzymes NR and GS were estimated under low N. We conclude that: under high N, NupE is efficient to differentiate nitrogen use efficient maize genotypes; under low N, NupE and NUtE efficient to differentiate nitrogen use efficient maize genotypes, the activity of NR enzyme is not a good physiological parameter for differentiate nitrogen use efficient maize genotypes, and selection over activity of GS enzyme enables the indirect selection of nitrogen use efficient maize genotypes.