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Search Results: 1 - 10 of 5890 matches for " Idupulapati Rao "
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Estrategias de enraizamiento de genotipos Brachiaria en suelos ácidos y de baja fertilidad en Colombia
Ricaurte,Jaumer; Rao,Idupulapati M; Menjivar F.,Juan Carlos;
Acta Agronómica , 2007,
Abstract: in a typic haplustox soil in the ?altillanura? of the eastern plains (llanos orientales) of colombia shoot biomass production was evaluated, during 41 months in 6 brachiaria genotypes with variable resistance to high al levels. with two nutrient levels. moderate and highly al-resistant brachiaria genotypes maintained high shoot biomass production in early months of establishment, declined to medium values until 21 months. root biomass and root length production of brachiaria genotypes, as well as native savanna grasses, was greater during rainy season, with a high root production in the first 5 cm of the soil. savanna species and the genotypes b. decumbens ciat 606 (high al+3 resistant) produced finer roots and less root biomass than native savanna species. the dry season induced a proportional increase in deeper root length and biomass production compared with rainy season in both moderately and highly al-resistant brachiaria genotypes as well as in native savanna species.
Differences in root distribution, nutrient acquisition and nutrient utilization by tropical forage species grown in degraded hillside soil conditions1
Gómez-Carabalí,Arnulfo; Idupulapati Madhusudana,Rao; Ricaute,Jaumer;
Acta Agronómica , 2010,
Abstract: low nutrient availability, especially phosphorus (p) and nitrogen (n) supply is the major limitation to forage production in acid infertile soils of the tropics. a field study was conducted at the farm ?la esperanza? located in mondomo, department of cauca, in the coffee growing zone of colombia. the main objective was to determine differences in root distribution, nutrient (n, p, k, ca, mg and s) acquisition and nutrient utilization of one c4 forage grass (brachiaria dictyoneura) and two c3 forage legumes (arachis pintoi and centrosema macrocarpum) grown under two fertilization levels, cultivated either in monoculture or in association and harvested at four different ages.there were no significant differences in root biomass among the grass and legumes and their combinations. the native vegetation had the lowest root biomass; while the introduced grass (b. dictyoneura) had the highest root length density among all materials at all depths and ages and the native vegetation had the highest specific root length. as expected, nutrient uptake increased with age and with high fertilization in all species. centrosema macrocarpun had the highest n and ca uptake among all plant materials tested. uptake of p, k and mg was greater in the grass b. dictyoneura than in the other plant species and combination planting at all ages. on the other hand, the grass had the lowest ca uptake. the grass and its mixture with the legumes a. pintoi and c. macrocarpun had the highest s uptake. a highly significant (p<0.001)correlation was found between root length density (depths 0-10 and 10-20 cm) and n and p uptake. nutrient use efficiency (g of forage produced for g of nutrient uptake) increased with age until 38 weeks. at 55 weeks a sharp decline was observed in nutrient use efficiency. n, ca and p use efficiency values were higher with the grass than with the two legumes tested. k use efficiency was similar among the three species. for mg and s the grass had the highest values and the le
Differences in root distribution, nutrient acquisition and nutrient utilization by tropical forage species grown in degraded hillside soil conditions
Gómez Carabalí Arnulfo,Madhusudana Rao Idupulapati,Ricaute Jaumer
Acta Agronómica , 2010,
Abstract: Low nutrient availability, especially phosphorus (P) and nitrogen (N) supply is the major limitation to forage production in acid infertile soils of the tropics. A field study was conducted at the farm 'La Esperanza' located in Mondomo, Department of Cauca, in the coffee growing zone of Colombia. The main objective was to determine differences in root distribution, nutrient (N, P, K, Ca, Mg and S) acquisition and nutrient utilization of one C4 forage grass (Brachiaria dictyoneura) and two C3 forage legumes (Arachis pintoi and Centrosema macrocarpum) grown under two fertilization levels, cultivated either in monoculture or in association and harvested at four different ages.There were no significant differences in root biomass among the grass and legumes and their combinations. The native vegetation had the lowest root biomass; while the introduced grass (B. dictyoneura) had the highest root length density among all materials at all depths and ages and the native vegetation had the highest specific root length. As expected, nutrient uptake increased with age and with high fertilization in all species. Centrosema macrocarpun had the highest N and Ca uptake among all plant materials tested. Uptake of P, K and Mg was greater in the grass B. dictyoneura than in the other plant species and combination planting at all ages. On the other hand, the grass had the lowest Ca uptake. The grass and its mixture with the legumes A. pintoi and C. macrocarpun had the highest S uptake. A highly significant (p<0.001)correlation was found between root length density (depths 0-10 and 10-20 cm) and N and P uptake. Nutrient use efficiency (g of forage produced for g of nutrient uptake) increased with age until 38 weeks. At 55 weeks a sharp decline was observed in nutrient use efficiency. N, Ca and P use efficiency values were higher with the grass than with the two legumes tested. K use efficiency was similar among the three species. For Mg and S the grass had the highest values and the legume, A. pintoi the lowest.
Influence of fertilization, season, and forage species in presence of arbuscular mycorrhizae in a degraded Andisoil of Colombia
Gómez Carabalí Arnulfo,M. Rao Idupulapati,Otero Joel Tupac
Acta Agronómica , 2011,
Abstract: Para determinar la influencia de la fertilización, época, y especies forrajeras en la producción de micorrizas arbusculares se realizó un experimento con una graminea C4, (Brachiaria dictyoneura), dos leguminosas forrajeras C3 (Arachis pintoi y Centrosema macrocarpum) y la vegetación nativa; cultivadas en dos sistemas de siembra (monocultivo y asociación), dos niveles de fertilización (alto y bajo) y cuatro edades de cosecha. Se uso un dise o de parcelas sub-sub divididas, en el cual la parcela principal fue la especie, los niveles de fertilización como subparcelas y la edad de rebrote como la sub-sub parcela. El número de esporas de hongos micorrizicos en el suelo y el porcentaje de infección en las raices se incrementó con la edad y varió con la especie y la época del muestreo (seca o húmeda). Se encontraron diferencias en la capacidad para formar simbiosis micorrízica entre las especies de gramíneas y leguminosas bajo condiciones de campo.
Variabilidad espacial y diaria del contenido de humedad en el suelo en tres sistemas agroforestales
Rivera Pe?a,Mariela; Amézquita Collazos,Edgar; Rao,Idupulapati; Menjivar Flores,Juan Carlos;
Acta Agronómica , 2009,
Abstract: the objective of this study was to determine the level of soil spatial variability in an area consisting of the land uses: quesungual slash and mulch agroforestry system with less than two years (qsmas<2), slash-and-burn traditional system (sb) and secondary forest (sf). soil samples were taken in three parallel transects of 102 m in length, separated 9 meters. the profile was sampled in the depths from 0 to 5 cm, 5 to 10 cm, 10 to 20 cm and 20 to 40 cm in 6 points (09, 11 am and 05) during 9 days. coefficient of variation for soil properties varied for bulk density (0.76 and 15.1%), organic carbon (30.4 and 54.3%), volumetric moisture (9.5 and 23.5%), sand (12.8 and 22.5%) and clay (14.0 and 29.2%). the geo-statistical analysis showed that the random component of the spatial dependence was predominant over the nugget effect. the functions of semivariograms, structured for each variable were used to generate maps of interpolated contours at a fine scale. the moran (i) autocorrelation indicated that sampling ranges less than 9 m would be adequate to detect spatial structure of the volumetric moisture variable.
Influence of fertilization, season, and forage species in presence of arbuscular mycorrhizae in a degraded Andisoil of Colombia
Gómez-Carabalí,Arnulfo; M. Rao,Idupulapati; Otero,J. Tupac;
Acta Agronómica , 2011,
Abstract: in the colombian coffee zone much of the land has infertile soils with an ongoing accelerated degradation. as vegetation has changed from forest to transitory base (cassava cropping) and overgrazed pastures, ground cover has decreased resulting in increasing runoff. these changes have contributed to severe erosion, decline in soil fertility, productivity, soil structure, and water quality as well as loss of biodiversity. a field study was conducted at the farm "la esperanza" (mondomo, department of cauca, colombia, south-america). the main objective was to determine the influence of fertilization, season and forage species in arbuscular mycorrhyzae in a degraded andisol. one c4 forage grass (brachiaria dictyoneura) and two c3 forage legumes (arachis pintoi and centrosema macrocarpum) and native vegetation grown under two fertilization levels, cultivated either in monoculture or in association and harvested at four different ages were evaluated. the numbers of mycorrizal spores in the soil and percentage of root infection of arbuscular mycorrhiza increased with age and varied with the species and season. we founded differences among forage grass and legume species under field conditions to form symbiosis with mycorrhizal fungi. knowledge on these interspecific differences could contribute to developing better adapted forage systems to contribute recuperating the degraded soils of the andean hillsides of latin america.
Desarrollo y distribución de raíces bajo estrés por sequía en fríjol común (Phaseolus vulgaris L.) en un sistema de tubos con suelo
Polanía,Joséé A.; Rao,Idupulapati M.; Beebe,Steve; García,Ramiro;
Agronomía Colombiana , 2009,
Abstract: phenotypic differences in root development and distribution of 16 common bean genotypes grown under drought stress were analyzed. we developed a method using transparent plastic tubes (inserted in pvc tubes), filled with a soil-sand mix (2:1, weight: weight), to capture differences in root growth under greenhouse conditions. ten days after emergence, two water supply treatments were imposed: 80% of field capacity (without stress) and withholding of water (to induce drought stress). total leaf chlorophyll content and transpiration rate were measured during the trial. at harvest (32 days after planting), leaf area, shoot biomass, leaf and stem total nonstructural carbohydrates content (tnc) were determined. the soil in the tubes was divided into five layers from the top to the bottom of the tube (0-5, 5-10, 10-20, 20-30 and 30-45 cm). roots were washed from each soil layer to determine their length, diameter and dry biomass. a randomized complete block design was used with three replications. the method was suitable for determining phenotypic differences in total root length, specific root length and root distribution by soil depth. three lines (bat 477, sea 5 and ser 16) were superior in their root development under drought stress.
Identification of aluminum resistant Andean common bean (Phaseolus vulgaris L.) genotypes
Blair, Matthew W.;López-Marín, Hernán D.;Rao, Idupulapati M.;
Brazilian Journal of Plant Physiology , 2009, DOI: 10.1590/S1677-04202009000400005
Abstract: aluminum (al) toxicity is the principal abiotic constraint in acid soils of the tropics. common bean, meanwhile, is for the most part very sensitive to this stress although certain genotypes within the species show some level of resistance, justifying screening of germplasm from both the andean and mesoamerican genepools to identify better performing sources. the objective of this study was to evaluate 36 genotypes of common bean under hydroponic conditions to identify root morphological traits that could be associated with al resistance. a total of five root traits (elongation rate of the primary root, total root length, root biomass, average root diameter and specific root length) were measured using a simple nutrient solution with or without al (20 μm) over a 48 hour growth period with the experiments conducted in five replicates. we found that genotypes from the andean gene pool were more resistant to al than mesoamerican genotypes under these conditions, based on a smaller decrease in the elongation rate of the primary root, total root length, specific root length and a lesser increase in root diameter in the presence of al in nutrient solution. these root traits but not root biomass can serve as selection criteria to distinguish between al-resistant and al-sensitive genotypes.
Atributos morfológicos y fisiológicos de genotipos de Brachiaria en un suelo con bajo fósforo disponible y alta saturación de aluminio
Mejía Kerguelen Sergio,Rao Idupulapati,Ramírez Hernando,Louw-Gaume Annabé
Acta Agronómica , 2009,
Abstract: Se evaluaron en invernadero en un suelo de Matazul, Meta, Colombia durante 6 semanas, 2 genotipos de Brachiaria (uno mejor adaptado a bajo P, B. decumbens y otro menos adaptado, B. ruziziensis) y 8 progenies del cruzamiento entre ellos ( mejores adaptados: H-7, H-40, H-28, H-58; menos adaptados: H-190, H-94, H-82, H-179). Los genotipos mejor adaptados presentaron mayor biomasa aérea, explicada por mayor área foliar, mayor absorción de P en el tallo y mayor volumen de raíz. Las características morfológicas de las raíces, principalmente longitud, peso seco y contenido de P, permiteron mejor adaptación a bajo P disponible en el suelo. El periodo de evaluación fue suficiente para observar diferencias entre progenies.
Variabilidad espacial y diaria del contenido de humedad en el suelo en tres sistemas agroforestales
Rivera Pe?a Mariela,Amézquita Collazos Edgar,Rao Idupulapati,Menjivar Flores Juan Carlos
Acta Agronómica , 2009,
Abstract: En seis puntos de tres transectos (102 m) paralelos (9 m) en tres sistemas de uso del terreno (Quesungual menor de dos a os, SAQ<2, Tradicional de Tala y Quema, TQ y Bosque Secundario, BS) se tomaron muestras de suelo a cuatro profundidades (0-5 cm, 5-10 cm, 10-20 cm y 20 a 40 cm) y tres horas (09, 11 y 15) durante 9 días. Se modeló el análisis estructural de la variación de los parámetros humedad volumétrica, densidad aparente, carbono orgánico, arena y arcilla. El coeficiente de variación de los parámetros evaluados presentó rangos para densidad aparente (0.76 y 15.1%), carbono orgánico (30.4 y 54.3%), humedad volumétrica (9.5 y 23.5%), arena (12.8 y 22.5%) y arcilla (14.0 y 29.2%). En los análisis geoestadísticos el componente al azar de la dependencia espacial predominó sobre el efecto pepita (nugget). Con las funciones de los semivariogramas estructurados para cada variable se generaron mapas de contorno interpolados a escala fina los cuales mostraron heterogeneidad en las propiedades evaluadas. La autocorrelación de Morán (I) indicó que rangos de muestreo menores a 9 m podrían ser adecuados para detectar la estructura espacial de la variable humedad volumétrica.
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