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The aims of this work were to discriminate among a group of variables of size and shape of wheat grains and embryos, some of direct measurement or primary variables (VP) and others derived from them or secondary variables (VS), those which were most adequate to describe these two characteristics, those equivalent or redundant, and to improve or propose new variables. Grains of a wide size range of two wheat cultivars, which visually differ in shape, were studied. The grains were produced in a three-year field experiment. The first axis (67.77% of the variance) obtained by Principal Component Analysis was associated with VP and VS of both grain and embryo size, while second axis (16.73% of the variance) was associated with VS of shape. Some variables, such as embryos Length and Form-density factor, presented mixed or unexpected associations. It is suggested a modified Form-density factor (Ffdm) which showed a low number of significant correlations with size VP. Also, it was possible to propose two new variables: one that evaluates the shape of grains (Desf AN) and the other, the relative embryo-grain size (Le/Lg). Both variables could differentiate between cultivars, were not affected by production year, and showed few significant correlations with VP. [ABSTRACT FROM AUTHOR]

This study was done with the aim to identify and quantify the incidence and prevalence of fungi in rainfed wheat seed in the high valleys of Mexico. The seed was collected during spring-summer 2009 and 2010 in 10 locations of Mexico, Puebla and Tlaxcala states. The incidence and frequency of each species was quantified by the Freezing Blotter method. Eleven reported pathogenic species were identified and reported: Curvularia sp., Fusarium avenaceum, F. culmorum, F. equiseti, F. graminearum, F. oxysporum, F. poae, F. verticillioides, Helminthosporium cynodontis, H. sativum and Microdochium nivale; the most common species was F. graminearum with 4 % and the highest species incidence was in Chapingo and Puebla in 2009 and Tlaxcala in 2010. [ABSTRACT FROM AUTHOR]

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Wheat (Triticum aestivum L.) yields of crops under no-tillage (NT) that have had broadcast phosphorus (P) applications do not differ from NT wheat crops that have had near-the-seed banded P applications. Although it is believed that an adequate colonization of roots by arbuscular mycorrhiza (AM) under NT could contibute to a better crop growth, the effect of P placement on the AM colonization of a wheat crop under NT is unknown. The objective of the study was to evaluate the influence of P fertilizer placement (banded or broadcast) on growth and the AM indigenous colonization of wheat under NT. The experiment was carried out in a soil with 13.9 mg kg-1 Bray-P and the treatments were: 0 (NP0), 25 (NP25) y 50 kg ha-1 (NP50), banded (inc) at planting or broadcast (vol) three months before planting. In addition, two treatments were included: one without fertilizer application (N0P0) and another with 150 kg of P ha-1 broadcast (NP150 vol). Aerial plant P concentration and biomass production, percentage of AM in roots, arbuscules content (A) and soil Bray-P availability was evaluated in tillering and stem elongation at two soil depths (0-10 and 10-20 cm). Phosphorus fertilization increased the soil P content (0-10 cm) and the plant P content. At the two soil depths, fertilization with 25 and 50 kg P ha-1 depressed AM and A as compared to the unfertilized treatments, mainly when the P was banded. Mycorrhizal colonization was negatively associated with the soil and plant P contents. We found a high (r²= 0.85, P< 0.05) relationship among AM and the soil P content (0-20 cm). The rate of AM colonization was slower in the 6-13 mg kg-1 soil P-Bray range. In situations with similar soil P contents, treatments with P inc produced a smaller AM colonization compared to the broadcast P treatments. This could explain the lack of grain yield response between different P placements in soils under NT with low P contents. [ABSTRACT FROM AUTHOR]

Wheat (Triticum aestivum L.) yields of crops under no-tillage (NT) that have had broadcast phosphorus (P) applications do not differ from NT wheat crops that have had near-the-seed banded P applications. Although it is believed that an adequate colonization of roots by arbuscular mycorrhiza (AM) under NT could contibute to a better crop growth, the effect of P placement on the AM colonization of a wheat crop under NT is unknown. The objective of the study was to evaluate the influence of P fertilizer placement (banded or broadcast) on growth and the AM indigenous colonization of wheat under NT. The experiment was carried out in a soil with 13.9 mg kg-1 Bray-P and the treatments were: 0 (NP0), 25 (NP25) y 50 kg ha-1 (NP50), banded (inc) at planting or broadcast (vol) three months before planting. In addition, two treatments were included: one without fertilizer application (N0P0) and another with 150 kg of P ha-1 broadcast (NP150 vol). Aerial plant P concentration and biomass production, percentage of AM in roots, arbuscules content (A) and soil Bray-P availability was evaluated in tillering and stem elongation at two soil depths (0-10 and 10-20 cm). Phosphorus fertilization increased the soil P content (0-10 cm) and the plant P content. At the two soil depths, fertilization with 25 and 50 kg P ha-1 depressed AM and A as compared to the unfertilized treatments, mainly when the P was banded. Mycorrhizal colonization was negatively associated with the soil and plant P contents. We found a high (r²= 0.85, P< 0.05) relationship among AM and the soil P content (0-20 cm). The rate of AM colonization was slower in the 6-13 mg kg-1 soil P-Bray range. In situations with similar soil P contents, treatments with P inc produced a smaller AM colonization compared to the broadcast P treatments. This could explain the lack of grain yield response between different P placements in soils under NT with low P contents. [ABSTRACT FROM AUTHOR]

Copyright of Universidad & Ciencia is the property of Universidad Juarez Autonoma de Tabasco and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The use of high N doses to enhance the expression of the yield potential in currently marketed wheat (Triticum aestivum L.) cultivars requires a careful and efficient fractionating of the total amount in order to minimize nutrient losses and improve nitrogen use efficiency (EUN). The effect of a range of annual N doses on the performance of high-yielding cv. Dollinco-INIA was studied in a Vilcún series soil of the Pachic Melanudans family (Andisol) in the Araucanía Region, Chile. The objective was to determine doses that optimize productivity and grain quality. Five annual N doses (0, 150, 200, 250 and 300 kg ha-1) as Nitromag (CAN 27), were evaluated in a randomized complete block design with three replicates, during two successive winter wheat cropping seasons, on a soil subjected to inten-sive rotation with annuals crops. A significant effect (P ≤ 0.01) of the N doses on grain production and quality was found. The optimal economic annual N dose (DOE) ranged between 239 and 253 kg ha-1. The estimates of EUN (kg of grain produced kg-1 N) were high (38.4 and 40.3). The results confirm that high N requirements need to be met for the new high-yielding wheat cultivar Dollinco-INA, in order to achieve its full yield potential. [ABSTRACT FROM AUTHOR]

A field experiment was carried out in order to select rhizobial strains inoculated to wheat {Triticum aestivum, L., var. Cuba-204). Several parameters of agricultural significance were assessed, such as: aerial dry weight, length of stems, grain yield, weight of 1 000 grains and nitrogen yield. As selection criterion of the best treatments, the statistically higher values compared to the fertilized control were considered. Four reference strains, belonging to several rhizobial genus and species were used, as well as ten native strains, belonging to Sinorhizobium that were isolated from roots of legumes (Melilotas and Medicago), adapted to Canadian livestock ecosystems in Alberta. One of the strains was isolated from legumes adapted to soils contaminated with hydrocarbons located in the same geographic zone. The strains grew YMA and re-suspended in YMB until they reached a CFU of 106 - 10Bcells/mL. Standard methods for the inoculation of cereals were used. A complete randomized block experimental design with 16 treatments and four replications within plots was used. A treatment was fertilized with 150 kg/ha (NH4NO3). Variance analysis was applied while differences between treatments were found through LSD (Fisher's test) (p<0,05). A dendrogram was built through the centroid method (Euclidian distance). It was concluded that a significant increase of values in all the variables was shown as compared to the absolute control. Several treatments, inoculated with reference or native strains showed values statistically higher than those of the fertilized control. Six rhizobial strains of highly promising use for the local agriculture were selected. Biofertilization of wheat with rhizobia is strongly recommended as an alternative of high ecological and economic value for the agriculture of Cuba. [ABSTRACT FROM AUTHOR]

Se efectuó un ensayo en invernadero con el objetivo de seleccionar cepas de rizobio inoculadas en trigo (Triticum aestivum, L., var. CDC Teal). Para ello se utilizaron 16 cepas nativas canadienses pertenecientes a Sinorhizobium medicae, así como 12 cepas comerciales. Los inóculos se confeccionaron en medio CLM y fueron agitados hasta alcanzar un título de 106-108 cél./mL. Se utilizaron los métodos estándar para la inoculación de cereales. Se construyó un dendrograma mediante el método de Ward (distancia euclidiana al cuadrado). Se evaluaron las variables: peso seco aéreo (PSA), peso seco raíz (PSR), longitud del tallo (LT), peso seco espigas (PSE) y número de hijos (NH). Se constató un incremento significativo en todas las variables en los tratamientos inoculados con las cepas nativas y las cepas comerciales de rizobio, comparados con el testigo absoluto. En peso seco aéreo, peso seco espigas y peso seco raíz, la mayor parte de los tratamientos no difirieron significativamente del control fertilizado. En longitud del tallo existieron 17 tratamientos superiores estadísticamente con respecto al control fertilizado. Se seleccionaron 10 cepas del total. Los tratamientos seleccionados en el dendrograma constituyeron el 31 % para las cepas nativas y el 42% para las comerciales. Se recomienda efectuar ensayos de campo con las cepas seleccionadas inoculadas en cereales de interés económico para Cuba. [ABSTRACT FROM AUTHOR]

Wheat nitrogen fertilization at planting or tillering allows the achievement of high yields, but it does not necessarily considerate grain quality. Under adequate water availability, complementary nitrogen fertilization at booting stage is a promissory strategy to increase grain quality. The aim of this work was to determinate the probability of water excess or stress during initial stages (sowing or tillering) or reproductive stages (booting) for wheat crop in the south of Buenos Aires province. Wheat Ceres model was utilized to determine average dates to emergence, late tillering and booting stages in Balcarce, Tres Arroyos and Puán. It was determined an annual soil water balance using a climatic series of 30 years (1971-2001), and it was estimated the probability of water stress or excess for these stages. Average date to emergence, late tillering and booting was the second decade of July, first and third decade of October, respectively. Water stress happened at some moment during the growing season in the 33, 68 and 70% of the years in Balcarce, Tres Arroyos and Puán, respectively. However, in Balcarce and Tres Arroyos water availability was adequate from sowing in the third decade of October for 97 and 74% of the years, respectively. At emergence stage, water excess greater than 10 mm was estimated in the 33, 35 and 12% of the years in Balcarce, Tres Arroyos and Puán, respectively. In Tres Arroyos and Puán, water stress for the first decade of October was estimated in the 23 and 50% of the years, respectively. For these counties, water stress in the third decade of October was estimated in the 17 and 50% of the years, respectively, but it was only 3% for Balcarce. These results would indicate that in Balcarce exist a high probability of achieve response for nitrogen fertilization at sowing, late tillering and booting, however nitrogen fertilization at sowing would not be an efficient practice to achieve high nitrogen use efficiency. In Puán, nitrogen fertilization at sowing would be the most efficiency strategy. In Tres Arroyos, nitrogen could be apply at sowing, late tillering and boot stage, although nitrogen fertilization at booting would have a lower probability of response than Balcarce. [ABSTRACT FROM AUTHOR]

The straw left in the wheat (Triticum aestivum L.) stubbles after harvest presents great difficulties to the following tillage or direct seeding operations. The objectives of this work were to determine the quantities of straw available in the wheat stubbles and to assess the quantities of straw that could be collected by balers from the swath left by the combine harvester. Measurements were taken during January and February of 2005 in 15 farms located in the provinces of Linares, Ñuble and Malleco. The main data collected included quantities of straw left by the harvester in the swath, the straw left standing, the harvester´s cutting width and height, wheat height, and straw moisture content. The results showed straw densities in the swath between 0.552 and 2.686 kg m-1, directly related to the harvester cutting width, which gave a range of 1.5 to 4.5 t ha-1, with a mean near 2.5 t ha-1, for a country total near one million tonnes. The quantities of straw left standing fluctuated between 1.6 and 5.1 t ha-1. The average total straw left in the field reached 6.4 t ha-1, for a country total of 2.7 million tonnes. Direct significant correlations were found between cutting width and straw in the swath, between cutting height and straw left standing, between wheat height and total straw, and between this total and wheat yield. [ABSTRACT FROM AUTHOR]

Se efectuó un ensayo de invernadero con el objetivo de seleccionar cepas de rizobios inoculadas en trigo (Triticum aestivum, L., var. CDC Teal), así como determinar las interrelaciones de dependencia entre algunas variables. Se utilizaron 30 cepas procedentes de leguminosas naturalizadas de Sancti Spíritus, Cuba, pertenecientes al género Bradyrhizobium sp., así como 12 cepas comerciales. Los inóculos se confeccionaron en medio CLM y fueron agitados hasta alcanzar un título de 106 -108 cél./mL. Se utilizaron métodos estándar para la inoculación de cereales. El diseño experimental fue de bloques al azar con 44 tratamientos y cuatro réplicas. Un -1 tratamiento se fertilizó con NH4NO3 (150 ppm N/kg-1 ). Se construyó un dendrograma mediante el método de Ward y se hallaron los coeficientes de regresión. Se constató un incremento significativo de los valores en todas las variables (excepto en el peso seco de las espigas) de los tratamientos inoculados, comparados con el testigo absoluto. Se seleccionaron 20 cepas como altamente promisorias sobre la base de los valores estadísticos alcanzados en las variables estudiadas. Los tratamientos seleccionados, cuyos valores fueron estadísticamente superiores a los del control absoluto, constituyeron el 47% en los inoculados con cepas nativas y el 50% en los inoculados con cepas comerciales; y existió una mayor dependencia estadística entre el PSR y las variables de mayor representatividad productiva en los tratamientos inoculados con cepas comerciales. [ABSTRACT FROM AUTHOR]

The effect of different levels of NaCl over seed water absorption, germination, growth and accumulation of total fresh and dry matter was studied in the first wheat seedling stages of Cuba-C-204 variety. Results showed that water uptake is only significatively affected at higher salt concentrations than 25 dS.m-1, showing its tolerance to salinity. Germination, its final percentage and growth indicators as well as accumulation of fresh and dry matter did not show significative damages at less salt concentrations than 25 dS.m-1. Regression analysis proved the regression coefficient was negative and highly significative, then showing that the higher the levels of salinity the lesser the growth. From such regression equations, the levels of electric conductivity that diminish growth and the accumulation of fresh and dry matter by 50 % were determined, observing a major sensitivity in the accumulation of fresh and dry matter and plant height related to root length. [ABSTRACT FROM AUTHOR]

The effect of preceding crop residue characteristics on N availability for wheat (Triticum aestivum L.) may mask the changes in soil capability to provide N due to management. Preceding crop effects should be taken into account to diagnose N fertility. The aims of this work were to evaluate i) wheat relative (to the maximum obtained in the corresponding experiment and year) yields (RR) and aboveground dry matter (MSR) and N accumulation (NR) in time after different preceding crops, and ii) the relationship between RR, MSR and NR variation and soil organic matter content changes. In two long term crop rotation experiments at Balcarce (on a complex of Typic Argiudoll and Petrocalcic Paleudoll) the variation of RR, MSR and NR along years under cropping with conventional tillage, was analyzed. The preceding crops were potato (Solanum tuberosum L.), soybean (Glycine max L. Merr.), wheat, sunflower (Helianthus annuus L.) and maize (Zea mays L.). All three variables showed a decrease along cropping years, but up to different levels according to which had been the preceding crop. Residue characteristics and/or the way they had been managed before wheat seeding made that RR, MSR and NR after soybean, potato and wheat were higher. On the other hand, wheat RR, MSR, NR after maize were the lowest. These effects were associated with the role of residues on N mineralization-immobilization cycle. In general, the variation in wheat RR, MSR and NR along cropping years was not associated with changes in soil organic matter due to soil management under cropping. The short term effect of preceding crop residues and of its management on N dynamics defined the amount and timing of the availability of N for wheat. This was independently of the effect of the rotation on the capability of the soil to mineralize N due to how the residues intervene on the cycle mineralization-immobilization. [ABSTRACT FROM AUTHOR]

In the last years, a more intensive cropping in the Pampa region, and particularly in the southeast of Buenos Aires province, has caused a decrease of soil sulphur (S) availability. The objective of this work was to evaluate the effect of S fertilization on wheat (Triricum aestivum L.) grain yield, grain protein and S concentration. Another objective was to evaluate some S diagnostic methodologies reported in the literature. Two experiments were carried out in the 2003 and 2004 growing seasons at Balcarce, Argentine (37° 45′ S; 58° 18′W, 130 m on sea level) on a soil with a longer agriculture history. One experiment was carried out under no-tillage (NT) and conventional tillage (CT) (Experiment A) and another experiment was carried out under NT (Experiment B). In the Experiment A treatments were tillage system (NT and CT) and nutrient combinations [T: control; nitrogen (N) + phosphorus (P); NPS]. Nutrients rates were 120 kg N ha-1 30 kg P ha-1 and 15 kg S ha-1. Tillage systems were assigned to the main plots and nutrient combination to the sub-plots. The experiment was carried out with three replications. In the Experiment B treatments were two N rates (70 and 130 kg ha-1) and two S rates (0 and 15 kg ha-1. The experiment was carried out with four replications. Both experiments were carried out under rainfed conditions and without P limitation. In the Experiment B and for both years, S addition increased grain yield (4.703 vs 5.328 kg ha-1 without and with S, respectively), whereas in the Experiment A, S addition increased grain yield (4.172 vs 4.748 kg ha-1, without and with S, respectively) only under NT in the 2004. Grain protein was not increased by S fertilization and N use efficiency was only slightly increased by S addition. Sulfur as sulfate (SO4=-S) concentration (0-20 cm soil depth) at sowing and grain total N/S ratio were not able to detect S deficiencies. However, the SO4=-S content (0-60 cm soil depth) at sowing would be a promissory methodology to detect S deficiencies. [ABSTRACT FROM AUTHOR]

Seven trials with spring bread wheat (Triticum aestivum L.) cultivar Domo-INIA were carried out during the 2001-2002 and 2002-2003 seasons, to evaluate the effect of diverse herbicides applied during grain ripening on yield and grain quality. A randomized complete block design with five treatments and four replications was used. The difference in the trials was the stage of maturity at the moment the herbicides were sprayed. The used herbicides were: 2,4-D, glyphosate, glyphosate + MCPA, and paraquat, plus a control treatment without herbicide. The evaluated parameters were: grain yield, hectoliter weight, 1,000 grain weight, seed germination (%), sedimentation index and wet gluten. The experiments were located in an Andisoil soil at the Santa Rosa Experimental Station (36°31′ S lat; 71°54′ W long), Quilamapu Research Center, Chillán, Chile belonging to the National Agriculture Research Institute. The results indicated that the herbicide 2,4-D can be applied when grains have a milky consistency, as well, results obtained in one season indicated that 2,4-D also could be applied when the grain has a watery consistency. From the stage of semihard grain and on, any of the herbicides used in these trials can be applied, without affecting grain yield and germination, as well as hectoliter weight, sedimentation value and gluten content. [ABSTRACT FROM AUTHOR]