ABSTRACT Physical mutagenesis with 60Co is a technique used in plant breeding to induce desired phenotypic characteristics. This research objective was to evaluate physical and physiological quality and protein content of jalapeño pepper (Capsicum annuum L.) seeds from plants that were selected as tolerant to water stress, these plants were derived from seeds irradiated with 60Co at 100 Gy dose (T1P2 and T1P5 both from tolerant plants to water stress). Control seeds were significantly superior to the mutants in the variable standard germination (90.66%), standard germination with accelerated aging (57.3%), normal seedlings (95.6%), 1000 seeds weight (6.349 g), hectoliter weight (51.97 kg hL-1) and radicle dry weight (18 mg). Mutant seeds were significantly superior to control seeds in seed length and width (4.356 mm in T1P2 and 4.256 mm in T1P5 for length; 3.544 mm in T1P2 and 3.632 mm in T1P5 for width). In seed thickness tests, germinated seeds aerial part fresh and dry weight, radicle fresh weight, the two mutants seed types and the control were significantly equal. In seed storage proteins content, T1P2 treatment had a higher globulins concentration. In the prolamin fraction, the two mutant seed types were superior to control. T1P5 treatment seeds had the highest glutelins concentration. Mutant seeds showed different characteristics as compared to control in physical, physiological and plantlet parts weight components.

ABSTRACT In recent years, benefits of silicon in plants grown under stress conditions have been reported. The objective of the research was to evaluate the response at a physiological and biochemical level of millet (Panicum miliaceum L.) to fertilization with Si under controlled stress conditions during vegetative stage, drought, salinity and the control (without stress). After stress, shoot and root length, DM content, peroxidase (POD) and catalase (CAT) activity, proline, H2O2 and Si content, seed yield and germination percentage were measured. Drought and salinity significantly decreased shoot (24%, 21%) and root (30% in drought) development, weight (36%, 29%) and seed number (30%, 21%) per plant. Application of Si significantly increased seed number (289) and seed weight (1.20 g) in the control plants, increased seed weight (0.83 g) in plants under drought and germination percentage (99%) in plants under salinity. Silicon increased 2.1 times POD activity in drought, 1.4 times in salinity and control plants; CAT activity increased 10.6 times in salinity and 1.7 times in control plants. Silicon decreased 10 times proline levels in plants under drought; in salinity and control, proline content increased 1.3 times with Si and H2O2 levels decreased in these treatments. The Si content in plants fertilized with Si under drought, salinity and control was 6%, 3.54% and 5.45% respectively. In conclusion, Si can improve plant stress tolerance by stimulating POD and CAT activity, and regulating proline levels, allowing it to improve the production and physiological seed.

Abstract It is an annual crop of temperate and semi-warm environments with clay and sandy soils. There are wild populations in Mexico that in pre-Columbian times allowed the selection of plants with larger fruit that did not disperse the seed. Domesticated varieties, compared to wild ones, have larger seeds, more compact inflorescence, closed calyces, longer flower, apical dominance, uniformity in flowering and ripening periods. Chia contains between 9 and 23% protein, 26-41% carbohydrates and 30 to 33% oil, 40% dietary fiber and calcium and a high antioxidant content. It has acquired great importance because it is considered a functional food. There is consensus on the importance of the study and conservation of plant genetic resources. The objective of this research was to characterize the morphological diversity of 31 chia genotypes based on the variations identified between wild and domesticated populations. It was observed that the presence of anthocyanins is characteristic of wild plants, as well as the presence of open calyx, which is related to the dispersal of the seeds; these were smaller and darker, and their calyces were short and opened when ripe. The size of the seed and the weight of a thousand seeds are highly correlated with the yield per plant. Domesticated plants presented closed calyx, without anthocyanin coloration, reduction of pubescence in most of the plant, larger inflorescence, greater number of florets, greater seed weight, higher yield. Domesticated, semi-domesticated and wild populations were characterized and grouped. The wild ones have an open calyx. The semi-domesticated ones are similar to the cultivated ones but have an open calyx. The domesticated ones had apical dominance, greater size of spike and closed calyx.

Resumen Es un cultivo anual de ambientes templados y semicálidos con suelos arcillosos y arenosos. Existen poblaciones silvestres en México que en tiempos precolombinos permitieron seleccionar plantas con fruto más grande que no dispersara la semilla. Las variedades domesticadas, comparadas con las silvestres, tienen semillas de mayor tamaño, inflorescencia más compacta, cálices cerrados, flor más larga, dominancia apical, uniformidad en los periodos de floración y maduración. La chía contiene entre 9 y 23% de proteína, 26-41% de carbohidratos y de 30 a 33% de aceite, 40% de fibra dietética y calcio y un alto contenido de antioxidantes. Ha adquirido gran importancia porque se considera un alimento funcional. Existe consenso sobre la importancia del estudio y conservación de los recursos fitogenéticos. El objetivo de esta investigación fue caracterizar la diversidad morfológica de 31 genotipos de chía con base en las variaciones identificadas entre poblaciones silvestres y domesticadas. Se observó que la presencia de antocianinas es característica de plantas silvestres, así como la presencia de cáliz abierto, que está relacionado con la dispersión de las semillas; estas fueron más pequeñas y oscuras y sus cálices fueron cortos y se abrieron al madurar. El tamaño de la semilla y el peso de mil semillas están altamente correlacionado con el rendimiento por planta. Las plantas domesticadas presentaron cáliz cerrado, sin coloración por antocianinas, reducción de la pubescencia en la mayor parte de la planta, inflorescencia más grande, mayor número de floretes, mayor peso de semilla, mayor rendimiento. Se caracterizaron y agruparon poblaciones domesticadas, semidomesticadas y silvestres. Las silvestres presentan cáliz abierto. Las semidomesticadas son semejantes a las cultivadas pero presentan cáliz abierto. Las domesticadas tuvieron dominancia apical, mayor tamaño de espiga y cáliz cerrado.

Resumo: A quitosana é um biopolímero obtido a partir da desacetilação da quitina, tem múltiplas aplicações na agricultura como antifúngico, condicionador de solo, indutor de mecanismos de defesa, revestimento pós-colheita de frutos, folhas e sementes, entre outros. O objetivo desta pesquisa foi avaliar o efeito de revestimentos de quitosana misturados com fungicida (ditiocarbamato) na germinação e velocidade de germinação de sementes de feijão e milho armazenadas e determinar a capacidade de retenção do fungicida nas sementes revestidas sob diferentes tempos de embebição. Dois tratamentos de revestimento usando quitosana nas concentrações de 0,1 e 0,5% de quitosana em agua, dois tratamentos de revestimento usando quitosana nas concentrações de 0,1 e 0,5% de quitosana suplementados com fungicida 0,5% e um revestimento usando apenas 0,5% de fungicida em água foram aplicados como recobrimento em sementes de feijão e milho; e como controle foram utilizadas sementes embebidas em água destilada; após os tratamentos, a porcentagem de germinação e a velocidade de germinação foram determinadas, também a liberação de fungicida foi determinada em 0, 1, 2 e 6 h de embebição, e o efeito do tempo de armazenamento na germinação e na velocidade de germinação foi determinado a 30, 60, 90, 120, 150 e 180 dias de armazenamento a 4 °C e 45% de umidade relativa. O efeito da liberação do fungicida foi determinado pela inibição da germinação de conídios de Fusarium oxysporum. Não houve efeitos negativos dos revestimentos na germinação da semente após o armazenamento. O tratamento que proporcionou maior retenção do agente fungicida e liberou-o gradativamente foi a concentração de 0,5% de quitosana misturada ao fungicida. O recobrimento de sementes com quitosana misturadas com fungicida não causam mudanças negativas na germinação das sementes ou na taxa de germinação.

Abstract: Chitosan is a biopolymer obtained from deacetylation of chitin; it has multiple applications in agriculture as an antifungal, soil conditioner, inducer of defense mechanisms, fruits postharvest coating, leaves and seeds, among others. The objective in this research was to evaluate the effect of chitosan coatings mixed with fungicide (dithiocarbamate) on the germination and germination speed of bean and maize seeds in storage and to determine the retention capacity of the fungicide in the coated seeds under different times of imbibition. Two coating treatments at concentrations of 0.1 and 0.5% chitosan in water, two coatings treatments at 0.1 and 0.5% chitosan supplemented with 0.5% fungicide and a coating without chitosan using only 0.5% fungicide in water were used in bean and maize seed; and as control seeds imbibed in distilled water were used; after treatments, germination percentage and germination speed were determined, also fungicide release were determined at 0, 1, 2 and 6 h of imbibition, and the effect of storage time on germination and germination speed was determined at 30, 60, 90, 120, 150 and 180 days of storage at 4 °C and 45% relative humidity. The fungicide release effect was determined by inhibiting Fusarium oxysporum conidia germination. There were no negative effects of coatings on seed germination after storage. The treatment that provided both greater retention of the fungicidal agent and released it gradually, was 0.5% chitosan mixed with fungicide concentration. Chitosan coating seeds mixed with fungicide do not cause negative changes in seed germination or germination rate.

ABSTRACT The soil microbial communities involved in the biogeochemical cycles of plant nutrients are negatively affected by unfavorable agricultural practices. In three tillage systems (traditional tillage, TT; traditional tillage with residue incorporation, TTI; and conservation tillage, CT) with three crop rotations (cereal-cereal, C-C; legume-cereal, L-C; and cereal-legume, C-L) at three soil depths (0-5, 5-15, and 15-30 cm), the effects on the populations of bacteria, actinomycetes, and fungi over a period of six crop cycles (3 yr) were evaluated. The tillage system, crop rotation, and depth affected the concentration of microbes in the soil. Under TT/C-C (regional control), they decreased by 7.5%; in contrast, under CT/L-C and TTI/L-C, they increased by 144% and 76%, respectively. Regardless of the tillage system, rotation with legumes, especially when the legume was cultivated in the spring-summer cycle (C-L), caused significant increases in microbial populations. At the end of 3 yr, under CT and TTI the populations of actinomycetes increased, while the fungal population remained stable and the bacterial populations fluctuated in the different crop cycles. In all treatments, the concentration of microorganisms decreased with soil depth. Local practices represent a risk to the diversity of soil microbiota, and it is imperative that farmers adopt conservation practices to achieve sustainability.

ABSTRACT Drought is one of the most limiting factors in agricultural production worldwide. The aim of this work was to evaluate the per se response to drought stress of three maize (Zea mays L.) semi-inbred lines (CHIH, COAH, and ARZM) during the anthesis and grain filling stages. These semi-inbred lines (BC1S1) are S1 offspring of crosses between drought-tolerant maize and a high-yield line bred by the Centro Internacional de Mejoramiento de Maíz y Trigo (CIMMYT). Materials were evaluated during a 15-d controlled drought and post-drought irrigation reestablishment period. The photosynthetic rate decreased by 50% in CHIH during drought and it recovered after stress was removed. Proline levels increased 2.3 times in COAH during stress and nonsignificant increases were observed in ARZM or CHIH. However, glycine betaine accumulated at 1061-1133 ng mg-1 fresh weight (FW) before stress, but decreased to 879-1000 ng mg-1 FW during drought stress. The trehalose concentration increased 1.8 times in ARZM (5.60 ng mg-1 FW) under drought stress and remained at similar levels in CHIH (6.48 ng mg-1 FW) and COAH (8.63 ng mg-1 FW) before and during drought stress. In contrast, trehalose-6-phosphate decreased 33% to 38% under drought stress in all three BC1S1 entries and recovered its initial levels after irrigation. Grain biomass loss under drought stress was 54% for ARZM, 48.2% for COAH, and only 26.5% for CHIH. These results showed that CHIH, COAH, and ARZM are drought-tolerant and suggest that osmoprotectant accumulation might play a key role in their physiological performance and grain biomass trait.

Mexico is the center of origin, domestication and diversity of maize. This cereal is the main constituent of the Mexican diet, especially for low-income families. In this research, 10 maize accessions derived from a large landrace collection, with the 'INIFAP-QPM' accession and a 'regional landrace' as controls, were studied to identify the accessions with the best biochemical and physiological characteristics showing good adaptation to 'El Bajío' (regional center in Mexico) conditions. The accessions were statistically superior to the two controls in the germination and accelerated aging tests. In the assessment of variable plumule length, variability was observed among the accessions, but the controls showed the lowest values. Protein contents in different fractions (albumins, globulins, prolamins and glutelins) showed variability as did oil and fiber contents. The 'HRH2015' accession showed high contents of albumins and globulins and low contents of prolamins and glutelins. The 'regional landrace' accession exhibited the highest contents of glutelins and prolamins but the lowests content of globulins and albumins. The total percentage of proteins showed variability among the accessions, but the values were within those reported in the literature. The 'RQ2015' accession presented the highest oil content (5.25%). The electrophoretic patterns of prolamins were obtained, and some differences were observed between them. The 'regional landrace' presented the lowest protein content, which was significantly different from those of the other evaluated accessions. This research demonstrates biochemical, germination and vigor variability among the studied maize accessions.

México es el centro de origen, domesticación y diversidad del maíz. Este cereal ocupa el primer lugar como constituyente de la dieta de los mexicanos, sobre todo de las familias de bajos recursos. En esta investigación se estudiaron 10 accesiones de maíz derivadas de una colecta amplia de Criollos y como testigos INIFAP-QPM y un criollo de la región, con el objetivo de identificar las accesiones con mejores características bioquímicas y fisiológicas con buena adaptación a las condiciones de El Bajío. Las accesiones fueron estadísticamente superiores a los dos testigos en las pruebas de germinación y envejecimiento acelerado; en la variable longitud de plúmula se observó variabilidad entre las accesiones, pero los testigos siguieron mostrando los valores más bajos. El contenido de proteína en sus diferentes fracciones (albúminas, globulinas, prolaminas y glutelinas) mostró variabilidad, así como el contenido de aceite y fibra. Se encontró una accesión (HRH2015) con alto contenido de albúminas y globulinas y bajo contenido de prolaminas y glutelinas; el 'genotipo criollo' presentó el mayor contenido de glutelinas y prolaminas pero el menor en globulinas y albúminas. El porcentaje total de proteínas presentó variabilidad entre las accesiones, pero los valores están dentro de los reportados en la literatura. El genotipo 'RQ2015' presentó el más alto contenido de aceite (5,25%). Se obtuvieron los patrones electroforéticos de las prolaminas y se observaron algunas diferencias entre ellas. El criollo de la región, tomado como referencia, presentó el menor contenido de proteína estadísticamente diferente al resto de las accesiones evaluadas. Esta investigación demuestra la variabilidad existente a nivel bioquímico, germinación y vigor entre las accesiones de maíz estudiadas.

Abstract Chia is a very valuable resource since it is the main source of unsaturated fatty acids, mainly α-linolenic, in addition to protein and fiber. In this investigation, seven collections were made in seven locations for study and comparison. Seed size were measured, thousand seed weight, volumetric weight, color, germination percentage and oil extraction for chromatography analysis. The collection of cultivated chia from Guanajuato showed greater variability in seed size and that of Roque la minor. The wild collections had the smallest seed size. The cultivated one of Guanajuato has the greater weight in seed and the wild ones the minor, the latter did not germinate, but the domesticated ones did. There were no differences in volumetric weight; however, there were differences in chromatograms (HPLC) and in physical characteristics and color variation in domesticated ones, including white seeds. This prospective research shows that the variability present in wild and cultivated chia can be used for plant breeding.

Resumen La chía es un recurso muy valioso ya que es la principal fuente de ácidos grasos insaturados, principalmente α-linolénico, además de proteína y fibra. En esta investigación se realizaron siete colectas en siete localidades para su estudio y comparación. Se midió tamaño de semilla, peso de mil semillas, peso volumétrico, color, porcentaje de germinación y extracción de aceite para análisis en cromatografía. La colecta de chía cultivada de Guanajuato presentó mayor variabilidad en tamaño de semilla y la de Roque la menor. Las colectas silvestres tuvieron el menor tamaño de semilla. La cultivada de Guanajuato tiene el peso mayor en semilla y las silvestres el menor, estas últimas no germinaron, pero sí lo hicieron las domesticadas. No hubo diferencias en peso volumétrico; sin embargo, si hubo diferencias en los cromatogramas (HPLC) y en las características físicas y variación de color en las domesticadas, incluidas semillas de color blanco. Esta investigación prospectiva muestra que la variabilidad presente en la chía silvestre y cultivada puede ser aprovechada para el fitomejoramiento.

Abstract The pre-treatment of the seeds allows to improve their behavior in the field, through an increase in germination, vigor and lengthen the shelf life. In this investigation the effect of the pretreatment with potassium nitrate (3%) plus gibberellins (GA3) (0.06%) in two periods: 6 and 12 h on the seed of five races of maize, including an experimental hybrid (Roque B16) was quantified. The objective of this research was to undergo osmoaconditioning to these races of maize and then to accelerated aging and quantify their effect on the percentage of germination. The Roque B16 hybrid showed no difference in germination percentage and maintained a good germination percentage after 60 days of storage. The Elotes Occidentales (purple pigment) race exhibits a similar behavior between the control and the treated seed at 7 and 30 days of storage, at 60 days it indicated a significant fall. Elotes Occidentales (red pigment) showed a significant decrease at 7, 30 and 60 days of storage with the 12 h treatment. The Palomero race showed a significant decrease in germination at seven days with the 12 h treatment, Amarillo Roque evidenced a significant decrease at 7 and 60 days of storage with the 12 h osmoaconditioning, the Pozolero race revealed a significant decrease at 7 and 30 days of storage with 12 h and at 60 days with both periods of treatment (6 and 12 h). The Amarillo and hybrid varieties were statistically equal with a higher germination percentage during storage. Purple and Pozolero were very affected by the storage at three months. Rojo was also affected, but to a lesser extent than the previous two.

Resumen El pretratamiento de las semillas permite mejorar su comportamiento en campo, mediante un incremento en la germinación, el vigor y alargar la vida de almacén. En esta investigación se cuantificó el efecto del pretratamiento con nitrato de potasio (3%) más giberelinas (GA3) (0.06%) en dos periodos: 6 y 12 h sobre la semilla de cinco razas de maíz, incluido un híbrido experimental (Roque B16). El objetivo de esta investigación fue someter a osmoacondicionamiento a estas razas de maíz y luego a envejecimiento acelerado y cuantificar su efecto sobre el porcentaje de germinación. El híbrido Roque B16 no mostró diferencias en porcentaje de germinación y mantuvo un buen porcentaje de germinación a los 60 días de almacenamiento. La raza Elotes Occidentales (pigmento morado) expone un comportamiento similar entre el testigo y la semilla tratada a los 7 y 30 días de almacenamiento, a los 60 días señaló una caída significativa. Elotes Occidentales (pigmento rojo) mostró una baja significativa a los 7, 30 y 60 días de almacenamiento con el tratamiento de 12 h. La raza Palomero manifestó una disminución significativa en germinación a los siete días con el tratamiento de 12 h, Amarillo Roque evidenció una baja significativa a los 7 y 60 días de almacenamiento con el osmoacondicionamiento de 12 h, la raza Pozolero reveló una disminución significativa a los 7 y 30 días de almacenamiento con 12 h y a los 60 días con ambos periodos de tratamiento (6 y 12 h). Las variedades Amarillo e híbrido fueron estadísticamente iguales con un mayor porcentaje de germinación durante el almacenamiento. Morado y Pozolero fueron muy afectadas por el almacenamiento a tres meses. El Rojo también fue afectado, pero en menor cuantía que los dos anteriores.

Abstract The inhibitory potential of three strains of actinobacteria (B21, B22 and B37) against phytopathogens: Rhizoctonia solani, Phytophthora capsici and Fusarium oxysporum was evaluated in vitro using the technique of aperados culture, where at 72 h after confrontation the percentage of radial growth inhibition (PICR) by actinobacteria was evaluated. The results showed a variable PICR between 67.54 and 93.84% depending on the pathogen. Strain B22 was the one that showed an average PICR of 98.73% for the three phytopathogens. In the in vivo scrutiny, the chili plants inoculated with the actinobacteria showed higher plant height and greater dry weight of the fruits with respect to the control, which suggests that actinobacteria promote the growth of chili plants.

Resumen El potencial inhibitorio de tres cepas de actinobacterias (B21, B22 y B37) contra los fitopatógenos: Rhizoctonia solani, Phytophthora capsici y Fusarium oxysporum fue evaluado in vitro mediante la técnica de cultivos aperados, donde a las 72 h después de la confrontación se evaluó el porcentaje de inhibición del crecimiento radial (PICR) por las actinobacterias. Los resultados mostraron un PICR variable entre 67.54 y 93.84% dependiendo del patógeno. La cepa B22 fue la que mostro un PICR promedio de 98.73% para los tres fitopatógenos. En el escrutinio in vivo, las plantas de chile inoculadas con las actinobacterias mostraron mayor altura de la planta y mayor peso seco de los frutos con respecto al testigo, lo que sugiere que las actinobacterias promueven el crecimiento de plantas de chile.

ABSTRACT In Guanajuato, Mexico, water deficits have dramatically increased in recent years due to over-exploitation of this resource. The objective was to identify high yielding wheat (Triticum spp.) varieties under two irrigation regimes. The experiments were planted at Celaya, Guanajuato, for two consecutive (2013-2014 and 2015-2016) growing seasons (GS). Eleven commercial varieties and nine experimental lines were evaluated under 3 or 4 irrigation regimes; split-plot design with 4 replicates was considered; data on yield performance and its components were measured. There were significant differences between GS and number of irrigation regimes (p ≤ 0.01) for most evaluated traits. ANOVA showed significant differences for all traits in the study, except for the 1000-grains weight. Growing seasons affected yield, grains number m-2 and biomass, mainly; on last cropping season, grain yield was higher (1.8 t ha-1) than first one; strong gluten genotypes were more stable, as compared with the soft gluten genotypes. Some experimental varieties exceeded commercial varieties, which means success in wheat breeding. Genotypes Experimental Line D and control ‘Bárcenas F2002’ under 3 irrigations regime treatment showed the highest grain yield (7.7 and 7.0 t ha-1, respectively). On 4 irrigations regime, the best yielding genotypes were experimental lines D, and H, with 6.5 and 6.1 t ha-1, respectively. Based on regression deviations the most stable and predictable wheat genotypes were strong gluten genotypes.

Summary Maize (Zea mays L.) hybrids of yellow kernels and high oil content possess characteristics that might have a great impact on the agricultural, livestock and industrial sectors in Mexico due to their high energy value. With the ultimate goal of developing in the short term highly productive hybrids with these characteristics, the aim of this study was to determine the genetic effects involved in grain yield, oil content and agronomic characteristics in direct and reciprocal crosses of doubled haploid lines (DHL) with yellow kernel and high oil content. Eight DHL derived from two subtropical populations were used: five of them were derived from the Northwest Yellow Population (NYP) and three from the Bajío Yellow Population (BYP). Both populations were developed by recurrent selection schemes to increase oil content. Direct and reciprocal crosses were formed in Celaya, Guanajuato in the 2013 Spring-Summer (S-S) season and were evaluated in 2014 S-S in Celaya, Guanajuato and Tarímbaro, Michoacán. During the field evaluation days to male (DMF) and female (DFF) flowering, plant (PH) and ear (EH) height, grain yield (GY) and oil grain content (OC) were registered. Highly significant differences (P ≤ 0.01) were observed for genotypes and environments in all the studied traits. General combining ability (GCA) effects were highly significant (P ≤ 0.01) in most of the traits; the specific combining ability (SCA) effects were lower than those of GCA, except for PH and EH. Reciprocal effects (ER) were highly significant (P ≤ 0.01) for GY and OC. Maternal effects (EM) showed significant differences for OC. Parental lines PAN DH 142 and PAB DH 230 showed the highest GCA for GY and OC, and the highest values in specific hybrid combinations.

Resumen Los híbridos de maíz (Zea mays L.) de grano amarillo con alto contenido de aceite, por su alto valor energético, poseen características que pueden generar un gran impacto en el sector agropecuario e industrial de México. Con el propósito de desarrollar a corto plazo híbridos productivos con estas características, el objetivo de este estudio fue determinar los efectos genéticos involucrados en rendimiento de grano, contenido de aceite y características agronómicas en cruzas directas y recíprocas de líneas doble haploides (LDH) de maíz de grano amarillo con alto contenido de aceite. Se utilizaron ocho LDH derivadas de dos poblaciones subtropicales: cinco de la Población Amarilla del Noroeste (PAN) y tres de la Población Amarilla del Bajío (PAB). Ambas poblaciones fueron desarrolladas a través de esquemas de selección recurrente para incrementar el contenido de aceite. Las cruzas directas y recíprocas se formaron en Celaya, Guanajuato en primavera-verano (P-V) 2013 y se evaluaron en P-V 2014 en Celaya, Guanajuato y Tarímbaro, Michoacán. Durante la evaluación en campo se registraron los días a floración masculina (DFM) y femenina (DFF), altura de planta (AP) y de mazorca (AM), rendimiento de grano (RG) y contenido de aceite en grano (CA). Se observaron diferencias altamente significativas (P ≤ 0.01) para los factores de variación genotipos y ambientes en todos los caracteres estudiados. Los efectos de aptitud combinatoria general (ACG) fueron altamente significativos (P ≤ 0.01) en la mayoría de las características; los efectos de aptitud combinatoria específica (ACE) fueron menores que los de ACG con excepción de AP y AM. Los efectos recíprocos (ER) fueron altamente significativos para RG y CA (P ≤ 0.01). Los efectos maternos (EM) mostraron diferencias significativas para CA. Las líneas parentales PAN DH 142 y PAB DH 230 mostraron la mayor ACG para RG y CA, y los valores más altos en sus combinaciones híbridas específicas.

SUMMARY Hybridization schemes based on doubled haploid lines (DHL) can be structured to develop productive high oil content (HOC) maize hybrids that impact the livestock and food industry in Mexico in the short term. The objective of this study was to determine, through direct and reciprocal crosses, genetic effects underlying grain yield, agronomic characteristics and oil content of nine HOC white kernel DHLs. Five DHL were derived from Northwest White Population (NWP) and four from Bajio White Population (BWP), which are heterotically opposite. The possible crosses were formed during the Spring-Summer 2013 in Celaya, Gto. and they were evaluated in Spring-Summer 2014 in Celaya, Gto. and Tarímbaro, Mich. Data on grain yield (GY), days to pollen shed (DPS), plant height (PH) and grain oil content (GOC) were recorded. Results showed highly significant differences (P ≤ 0.01) between localities (L) and genotypes (G) for all traits. The G × L interaction was highly significant (P ≤ 0.01) for GY and DPS. General and specific combining ability (GCA) and (SCA) effects were significant (P ≤ 0.01) for all the traits, and GCA predominated over SCA. Maternal effects showed statistical differences (P ≤ 0.01) for GY. For GCA effects, line PBN DH 10 presented large effects for GY, DPS and PH, and line PBB DH 178 presented the highest effects for GOC. In regard to SCA, combinations with high and significant effects were observed for all traits. The type of gene action of the evaluated traits was determined, and it was observed that DHLs with higher GCA participated in high SCA crosses. High oil content crosses were observed with grain yield above 12.2 t ha-1. The DHL derived from NWP and BWP maintained the heterotic pattern already established between both populations.

RESUMEN Para desarrollar híbridos de maíz (Zea mays L.) productivos con alto contenido de aceite (ACA), que impacten a corto plazo la industria pecuaria y alimenticia en México, se pueden estructurar esquemas de hibridación con líneas doble haploides (LDH). El objetivo del presente estudio fue determinar, mediante cruzas directas y recíprocas, los efectos genéticos presentes en rendimiento, características agronómicas y contenido de aceite en nueve LDH de grano blanco con ACA. Cinco LDH fueron derivadas de la Población Blanca del Noroeste (PBN) y cuatro de la Población Blanca del Bajío (PBB), que son heteróticamente contrastantes. Las cruzas posibles se formaron en primavera-verano 2013 en Celaya, Gto. y se evaluaron en primavera-verano 2014 en Celaya Gto. y Tarímbaro, Mich. Se registraron datos de rendimiento de grano (RG), días a floración masculina (DFM), altura de planta (AP) y contenido de aceite (CA). Los resultados mostraron diferencias altamente significativas (P ≤ 0.01) entre localidades (L) y genotipos (G) en todas las variables. La interacción G × L fue altamente significativa (P ≤ 0.01) para RG y DFM. Los efectos de aptitud combinatoria general (ACG) y especifica (ACE) fueron significativos (P ≤ 0.01) para todas las características, en las que predominó ACG sobre ACE. Los efectos maternos (EM) mostraron diferencias significativas (P ≤ 0.01) para RG. Para ACG la línea LDH PBN DH 10 tuvo efectos altos para RG, DFM y AP, y la línea PBB DH 178 tuvo los mayores efectos para contenido de aceite en el grano (CA). En relación con ACE se observaron combinaciones con efectos altos y significativos en todas las variables. Se determinó el tipo de acción génica de las variables evaluadas y se observó que las LDH con mayor ACG participaron en cruzas de alta ACE. Se observaron cruzamientos de alto contenido de aceite y RG superiores a 12.2 t ha-1. Las LDH derivadas de PBB y PBN mantuvieron el patrón heterótico establecido entre ambas poblaciones.

Abstract Seeds are an indispensable element in agricultural production and represent one of the means to improve crop yield and fertilization is essential for the production of high quality seeds. In the present work, the quality of the wheat seed was evaluated when the fertilizer-N is divided into different percentages. The varieties used were Gema C2004, Nana F2007 and Urbina S2007. The recommended N-P-K fertilization dose in the The Bajio region is 240-60-00. The fertilization-N divisions (FFN) were at planting, 45 days after sowing (dds) and 75 dds in the following percentages: 1) 00-00-00, 2) 100-00-00, 3) 00-100-00, 4) 50-50-00, 5) 00-50-50, 6) 70-30-00, 7) 30-70-00, 8) 00-30-70, 9) 00-70-30 and 10) 33-33-33. In the field the yield was evaluated, in the laboratory the physiological quality of the seed and in the greenhouse the vigor of the seedling in a sand bed. By fractionating the fertilizer-N at 30-70-00 and 33-33-33 the amount of m2 seeds increased, observing higher yields in wheat production compared to the recommended fertilization-N of 50-50-00 that currently used. The best emergency percentages were presented in the subdivisions 33-33-33, 30-70-00 and 70-30-00. Regarding vigor indexes IV-I and IV-II, the treatment that showed the highest values was 30-70-00. The FFN in which the best results were observed in the variables of yield, physiological seed quality and seedling vigor was 30-70-00.

Resumen Las semillas son un elemento indispensable en la producción agrícola y representan uno de los medios para mejorar el rendimiento en los cultivos y la fertilización es indispensable para la producción de semillas de alta calidad. En el presente trabajo se evaluó la calidad de la semilla de trigo cuando el fertilizante-N se fracciona en diferentes porcentajes. Las variedades utilizadas fueron Gema C2004, Nana F2007 y Urbina S2007. La dosis de fertilización N-P-K recomendada en la región de El Bajío es de 240-60-00. Los fraccionamientos de la fertilización-N (FFN) fueron a la siembra, 45 días después de la siembra (dds) y 75 dds en los siguientes porcentajes: 1) 00-00-00, 2) 100-00-00, 3) 00-100-00, 4) 50-50-00, 5) 00-50-50, 6) 70-30-00, 7) 30-70-00, 8) 00-30-70, 9) 00-70-30 y 10) 33-33-33. En campo se evaluó el rendimiento, en laboratorio la calidad fisiológica de semilla y en invernadero el vigor de plántula en cama de arena. Al fraccionar el fertilizante-N en 30-70-00 y 33-33-33 se incrementó la cantidad de semillas m2, observando mayores rendimientos en la producción de trigo en comparación con la fertilización-N recomendada de 50-50-00 que actualmente se utiliza. Los mejores porcentajes de emergencia se presentaron en los fraccionamientos 33-33-33, 30-70-00 y 70-30-00. Con relación a los índices de vigor IV-I y IV-II, el tratamiento que mostro los valores mayores fue 30-70-00. El FFN en el que se observaron los mejores resultados tanto en las variables de rendimiento, calidad fisiológica de semilla y vigor de plántula fue 30-70-00.

Abstract In this research, seeds of two maize races, with PEG or potassium nitrate plus gibberellic acid, were osmo-conditioned to estimate its effect on the variables: germination, weight and length of radicle and seedling, titratable acidity and electrophoretic pattern of proteins; they were soaked (hypoxia, “soak test”) and the response was quantified. The objective was to contribute to the characterization of the native maize of México that are sown under rainfed conditions. The Bofo and Elotes Occidentales maize showed the highest imbibition with KNO3 + gibberellic acid for 12 h. The germination percentage after soaking was higher with KNO3 + gibberellic acid for 6 h and was superior to the control. As for the length of radicle and plumule, the treatments exceeded the control in both counts. With Elotes Occidentales, after the soaking test, the treatments were superior to the control in plumule length. The osmoconditioned seed showed a tendency to have a longer plumule and radicle length and a higher percentage of germination when the seed was subsequently subjected to soaking. The electrophoretic patterns are very similar, indicating a great similarity at the biochemical level among the studied races; a finer fractionation is desirable in extracting proteins and more sensitive techniques for the detection of differences.

Resumen En la presente investigación se osmoacondicionaron semillas de dos razas de maíz, con PEG o con nitrato de potasio más ácido giberélico, para estimar su efecto en las variables: germinación, peso y longitud de radícula y plántula, acidez titulable y patrón electroforético de proteínas; se les sometió a remojo (hipoxia, “soak test”) y se cuantifico la respuesta. El objetivo fue contribuir a la caracterización de los maíces nativos de México que se siembran bajo condiciones de temporal. Los maíces Bofo y Elotes Occidentales mostraron la mayor imbibición con KNO3 + ácido giberélico durante 12 h. El porcentaje de germinación después del remojo, fue mayor con KNO3 + ácido giberélico durante 6 h y fue superior al testigo. En cuanto a la longitud de radícula y plúmula, los tratamientos superaron al testigo, en ambos conteos. Con Elotes Occidentales, luego de la prueba de remojo, los tratamientos resultaron superiores al testigo en longitud de plúmula. La semilla osmoacondicionada tuvo una tendencia a presentar mayor longitud de plúmula y radícula y mayor porcentaje de germinación cuando la semilla se sometió posteriormente a remojo. Los patrones electroforéticos son muy semejantes, lo que indica gran parecido a nivel bioquímico entre las razas estudiadas; es deseable un fraccionamiento más fino al extraer las proteínas y técnicas más sensibles para la detección de diferencias.