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Increased nutrient withdrawal by rapidly expanding intensive cropping systems, in combination with imbalanced fertilization, is leading to potassium (K) depletion from agricultural soils in Asia. There is an urgent need to better understand the soil K-supplying capacity and K-use efficiency of crops to address this issue. Maize is increasingly being grown in rice-based systems in South Asia, particularly in Bangladesh and North East India. The high nutrient extraction, especially K, however, causes concerns for the sustainability of maize production systems in the region. The present study was designed to estimate, through a plant-based method, the magnitude, and variation in K-supplying capacity of a range of soils from the maize-growing areas and the K-use efficiency of maize in Bangladesh. Eighteen diverse soils were collected from several upazillas (or sub-districts) under 11 agro-ecological zones to examine their K-supplying capacity from the soil reserves and from K fertilization (100 mg K kg−1 soil) for successive seven maize crops grown up to V10–V12 in pots inside a net house. A validation field experiment was conducted with five levels of K (0, 40, 80, 120 and 160 kg ha−1) and two fertilizer recommendations based on “Nutrient Expert for Maize-NEM” and “Maize Crop Manager-MCM” decision support tools (DSSs) in 12 farmers’ fields in Rangpur, Rajshahi and Comilla districts in Bangladesh. Grain yield and yield attributes of maize responded significantly (p < 0.001) to K fertilizer, with grain yield increase from 18 to 79% over control in all locations. Total K uptake by plants not receiving K fertilizer, considered as potential K-supplying capacity of the soil in the pot experiment, followed the order: Modhukhali > Mithapukur > Rangpur Sadar > Dinajpur Sadar > Jhinaidah Sadar > Gangachara > Binerpota > Tarash > Gopalpur > Daudkandi > Paba > Modhupur > Nawabganj Sadar > Shibganj > Birganj > Godagari > Barura > Durgapur. Likewise, in the validation field experiment, the K-supplying capacity of soils was 83.5, 60.5 and 57.2 kg ha−1 in Rangpur, Rajshahi, and Comilla, respectively. Further, the order of K-supplying capacity for three sites was similar to the results from pot study confirming the applicability of results to other soils and maize-growing areas in Bangladesh and similar soils and areas across South Asia. Based on the results from pot and field experiments, we conclude that the site-specific K management using the fertilizer DSSs can be the better and more efficient K management strategy for maize. View Full-Text
Soil analysis Potassium Maize Site Specific K Management Soil K Supply Maize Yield Response to K Maize Crop Manager Nutrient Expert for Maize POTASSIUM SOIL FERTILITY MAIZE YIELD FACTORS CIENCIAS AGROPECUARIAS Y BIOTECNOLOGÍA
Cape gooseberry (Physalis peruviana L.) is a plant with a high nutrient content and various medicinal properties, it has a high economic potential, which makes it an alternative production. Currently, there is not enough experience on this crop in Mexico, for this reason the present study was performed to evaluate the response of young plants to different ratios of NO3 to NH4+ in protected conditions and in a hydroponic system. The experiment was carried out using a completely randomized design with three ratios of NO3 to NH4+(100:0, 75:25 and 50:50) and four replications. Plant height, main stem diameter and SPAD readings, at 1, 10, 17 and 27 days after transplanting (DAT), leaf area and fresh weight at 21 and 30 (DAT) were measured. The research showed that there were statistical differences in plant height and stem diameter as result of treatments effect. It was also concluded that the nitrogen preferably nutrition form for this crop is nitric, however, it was observed that the crop can also absorb ammonia nitrogen without affecting growth variables when the ratio is 50:50.
La uchuva (Physalis peruviana L.) es una planta con un alto contenido nutrimental y diversas propiedades medicinales, además de un alto potencial económico, lo que la hace una alternativa de producción. Actualmente, en México no existen experiencias ni suficiente información de este cultivo; por tal razón el presente trabajo se realizó para evaluar la respuesta de plantas jóvenes a diferentes formas de nitrógeno en condiciones protegidas y sistema hidropónico. Se utilizó la solución nutritiva Steiner (1984) con tres relaciones NO3:NH4+(100:0, 75:25 y 50:50) y cuatro repeticiones. Se midió la altura de planta, diámetro del tallo principal y lecturas SPAD; a los 1, 10, 17 y 27 días después de trasplante (DDT); área foliar y peso fresco a los 21 y 30 DDT. Se presentaron diferencias estadísticas en altura de planta y diámetro de tallo como efecto de los tratamientos evaluados. Se concluye que la forma nitrogenada de preferencia para el cultivo es la nítrica, sin embargo, el cultivo puede también absorber nitrógeno amoniacal sin afectar las variables de crecimiento, cuando está presente en una relación de 50:50, con respecto al nitrógeno nítrico.
HUMBERTO LOMELI PAYAN (2009)
The expert concept is applied to "the skilful, wise, understood, practical and competent person in some thing, science or art". As such, the veterinarians can be needed by the authorities to issue reports or opinions related with domestic animals, contributing with their knowledge to the clarification of facts. Taking intervention in civil, mercantile and penal litigations, as technicians personnel in those matters involving animals, food supply of animal origin, in the sanitary aspect of animal housing and/or the storage of their products, etc. In this order of ideas, it is important that to practice the role of a veterinary expert, besides having the scientific and legal knowledge required for the practice of the specialty, to clearly identify the functions and methodologies most adapted to the procedure to realize; initiating from the scheme report of presentation, up to the knowledge of the minimal but indispensable requirements to achieve their goals with justice and impartiality.
El concepto de perito se aplica a "la persona hábil, sabia, entendida, práctica, competente en alguna cosa, ciencia o arte". Como tales, los veterinarios pueden ser requeridos por las autoridades para emitir informes o dictámenes en relación con los animales domésticos, contribuyendo con sus conocimientos al esclarecimiento de los hechos. Teniendo intervención en litigios de orden civil, mercantil y penal, en calidad de técnicos en aquellos asuntos en que involucran animales, en abastecimiento de alimentos de origen animal, en el aspecto sanitario de alojamiento de animales, en el almacenaje de sus productos, etc. En este orden de ideas, es importante para ejercer la función de perito veterinario, además de los conocimientos científicos y legales requeridos para la práctica de la especialidad, tener claro cuales son las funciones y metodologías más adecuadas al procedimiento a realizar; partiendo desde el esquema de presentación del informe, hasta el conocimiento de los requisitos mínimos indispensables para desempeñarse con justicia e imparcialidad.
The characteristics of the soil in the Peninsula of Yucatán confer unique organoleptic properties to the habanero pepper (Capsicum chinense Jacq.), and thus this entity possesses the denomination of origin of the species, making these chilis the most coveted, nationally and internationally. However, the extreme microtopographic variation distinguishing the Peninsula complicates the transfer of technologies and the successful establishment of agricultural practices. Maya farmers of the region identify the brown soils as preferable for the cultivation of this chili, although there is some controversy among the farmers regarding the best yields when the quality of the water used for irrigation is poor. No studies of the effect of soil type on this plant have been carried out. This work evaluated the impact of three types of soil of the Peninsula (red, brown, and black) on growth, fruit production, and nutrient content in soils and plants, during different phenological stages. The results indicate that the red and brown soils were the best for the growth and production of the fruit. In the black soil, it was possible to observe greater retention and accumulation of sodium applied in the water used for irrigation and in the macronutrients N, P, K, which may have led to a negative effect in the development of the fruit in these plants. Moreover, the plants growing in red and brown soils seem to make a more efficient use of the nutrients, presenting higher values of N, P, and K in their tissues in the flowering-fructification stage. These results are particularly useful in the realization of agricultural plans with a lower consumption of fertilizers, which allows an increase in yield, particularly if we take into account the enormous problems of saline intrusion worldwide and in this region.
CAPSICUM CHINENSE FRUIT PRODUCTION LEPTOSOL SOILS NUTRIENT PHENOLOGICAL STAGE SALINITY SODIUM RETENTION BIOLOGÍA Y QUÍMICA CIENCIAS DE LA VIDA BIOLOGÍA MOLECULAR BIOLOGÍA MOLECULAR DE PLANTAS BIOLOGÍA MOLECULAR DE PLANTAS
Winter season maize (Zea mays L.) has emerged a new crop in many parts of South and South east Asia, where the crop has to face low temperature regimes (<5°C) for few weeks during vegetative growth stage. The objective of this study was to identify the morphological and physiological traits associated with cold stress tolerance during vegetative growth period, when maximum dry matter is accumulated and floral primodia are formed. A total of 80 cultivars, including hybrids and open pollinated varieties (OPVs) from International Maize and Wheat Improvement Center (CIMMYT) and Indian maize program were evaluated in replicated trials at Indian Agricultural Research Institute (IARI), New Delhi and at Regional Research Station, Haryana Agriculture University, Karnal, India during the winter season, where critical period of vegetative growth and floral primodia developmental stage was exposed to <10°C temperature. Data on various growth and developmental traits and key physiological traits were recorded during the low temperature regime. Except ears per plant and physiological maturity, the cold stress significantly affected all the growth and developmental traits and also physiological traits studied. However, significant genotypic variability was observed for most of the traits studied. Genotypes with relatively high leaf appearance and extension rate, less cold injury symptoms and cell membrane damage showed good level of cold tolerance in terms of reproductive behavior and eventually grain yield under cold stress. These secondary traits could be used in selection index along with days to anthesis, anthesis-silking interval (ASI) and grain yield for selection and improvement of tropical maize for low temperature adaptation.
Dagne Wegary Gissa (2015)
Quality protein maize (QPM) cultivars contain higher levels of lysine and tryptophan as compared to non-QPM counterparts, and can minimize the risk of protein malnutrition among communities increasingly dependent on maize as their food staple. This study was undertaken to assess the performances of QPM hybrids, and estimate heterosis and combining ability effects of highland QPM inbred lines for grain yield, agronomic and protein quality traits. Hybrids of 20 inbred lines and two testers, and the parental lines were evaluated across three locations in Ethiopia. Significant variations were observed among the parents and the hybrids for almost all measured traits that allows the selection of preferred inbred lines and hybrids. Several hybrids showed desirable heterosis for most studied traits. Mean squares attributable to general (GCA) and specific (SCA) combining ability effects were significant for most traits. However, the contributions of GCA sum of squares to the variation among the hybrids were larger than SCA sum of squares, suggesting that the traits were conditioned mainly by additive gene effects. Inbred lines L12, L17, L19, and L20 had desirable GCA effects for grain yield, whereas L12 and L13 were the best general combiners for protein quality traits. Hybrids L17 x 142-1eQ and L20 x 142-1-eQ showed most desirable perse performances and SCA effects for grain yield. Based on grain yield SCA effects, most inbred lines used in the study were grouped into distinctive heterotic patterns. This study indicated the possibility of developing highland QPM germplasm with acceptable grain yield, agronomic and protein quality traits.
Yunbi Xu (2017)
Waterlogging has increasingly become one of the major constraints to maize productivity in some maize production zones because it causes serious yield loss. Bulked segregant RNA-seq (BSR-seq) has been widely applied to profile candidate genes and map associated Single Nucleotide Polymorphism (SNP) markers in many species. In this study, 10 waterlogging sensitive and eight tolerant inbred lines were selected from 60 maize inbred lines with waterlogging response determined and preselected by the International Maize and Wheat Improvement Center (CIMMYT) from over 400 tropical maize inbred lines. BSR-seq was performed to identify differentially expressed genes and SNPs associated with waterlogging tolerance. Upon waterlogging stress, 354 and 1094 genes were differentially expressed in the tolerant and sensitive pools, respectively, compared to untreated controls. When tolerant and sensitive pools were compared, 593 genes were differentially expressed under untreated and 431 genes under waterlogged conditions, of which 122 genes overlapped. To validate the BSR-seq results, the expression levels of six genes were determined by qRT-PCR. The qRT-PCR results were consistent with BSR-seq results. Comparison of allelic polymorphism in mRNA sequences between tolerant and sensitive pools revealed 165 (normal condition) and 128 (waterlogged condition) high-probability SNPs. We found 18 overlapping SNPs with genomic positions mapped. Eighteen SNPs were contained in 18 genes, and eight and nine of 18 genes were responsive to waterlogging stress in tolerant and sensitive lines, respectively. Six alleles of the 18 originated from tolerant pool were significantly up-regulated under waterlogging, but not those from sensitive pool. Importantly, one allele (GRMZM2G055704) of the six genes was mapped between umc1619 and umc1948 on chromosome 1 where a QTL associated with waterlogging tolerance was identified in a previous research, strongly indicating that GRMZM2G055704 is a candidate gene responsive to waterlogging. Our research contributes to the knowledge of the molecular mechanism for waterlogging tolerance in maize.
To introduce new genetic diversity into the bread wheat gene pool from its progenitor, Aegilops tauschii (Coss.) Schmalh, 33 primary synthetic hexaploid wheat genotypes (SYN) were crossed to 20 spring bread wheat (BW) cultivars at the International Wheat and Maize Improvement Center. Modified single seed descent was used to develop 97 populations with 50 individuals per population using first back-cross, biparental, and three-way crosses. Individuals from each cross were selected for short stature, early heading, flowering and maturity, minimal lodging, and free threshing. Yield trials were conducted under irrigated, drought, and heat-stress conditions from 2011 to 2014 in Ciudad Obregon, Mexico. Genomic estimated breeding values (GEBVs) of parents and synthetic derived lines (SDLs) were estimated using a genomic best linear unbiased prediction (GBLUP) model with markers in each trial. In each environment, there were SDLs that had higher GEBVs than their recurrent BW parent for yield. The GEBVs of BW parents for yield ranged from -0.32 in heat to 1.40 in irrigated trials. The range of the SYN parent GEBVs for yield was from -2.69 in the irrigated to 0.26 in the heat trials and were mostly negative across environments. The contribution of the SYN parents to improved grain yield of the SDLs was highest under heat stress, with an average GEBV for the top 10% of the SDLs of 0.55 while the weighted average GEBV of their corresponding recurrent BW parents was 0.26. Using the pedigree-based model, the accuracy of genomic prediction for yield was 0.42, 0.43, and 0.49 in the drought, heat and irrigated trials, respectively, while for the marker-based model these values were 0.43, 0.44, and 0.55. The SYN parents introduced novel diversity into the wheat gene pool. Higher GEBVs of progenies were due to introgression and retention of some positive alleles from SYN parents.
In vivo haploid induction in high frequency followed by efficient identification of haploids are important components of deriving completely homozygous doubled haploid (DH) lines in maize. Several genetic marker systems were proposed and/or used for identification of in vivo maternal haploids in maize, such as R1-nj (Navajo), high oil, red root and transgenic markers. In this study, we propose a new method of haploid/diploid identification based on natural differences in seedling traits of haploids and diploids, which can be used in any induction cross independently of the genetic marker systems. Using confirmed haploids and diploids from five different populations, the study established that haploid and diploid seedlings exhibit significant differences for seedling traits, particularly radicle length (RL), coleoptile length (CL), and number of lateral seminal roots (NLSR). In six populations that exhibited complete inhibition of the commonly used R1-nj (Navajo) marker, we could effectively differentiate haploids from diploids by visual inspection of the seedling traits. In the haploid seed fraction identified based on R1-nj marker in ten populations, false positives were reduced several-fold by early identification of haploids at seedling stage using the seedling traits. We propose that seedling traits may be integrated at the haploid identification stage, especially in populations that are not amenable to use of genetic markers, and for improving the efficiency of DH line production by reducing the false positives.
Maize (Zea mays L.) yield in sub-Saharan Africa (SSA) is low because of both abiotic and biotic constraints, and limited availability or use of improved seed in some areas. This study was conducted (i) to estimate combining ability and heterosis among seven stress-tolerant populations, and (ii) to assess diversity among the populations and the relationship between diversity and heterosis. Twenty-one hybrids developed from diallel crosses of seven populations, parents, and two checks were evaluated in 10 optimal and 11 stressed environments (drought, low N, and random stress) in Kenya, Ethiopia, Uganda, and Zimbabwe for 2 yr. Analysis II of Gardner and Eberhart showed that variety and heterosis were significant for grain yield (GY) under optimal and managed stress, and across environments. Heterosis accounted for most of the variation for GY among populations under optimal conditions (67%) and drought stress (53%), which suggested the importance of dominance in inheritance of GY under these conditions. Genetic distance (GD) among populations ranged from 0.328 to 0.477 (mean = 0.404). The correlation between GD and heterosis was low (r = 0.14-0.40) in all environments. The simple sequence repeat (SSR) marker-based and GY-based clustering of parental populations showed similar patterns, with three populations distinct from the rest, suggesting significant differentiation of allelic variation in these three populations. The SSR-based diversity and phenotypic analysis results should be useful in defining breeding strategies and maintaining heterotic patterns among these populations.