Showing items related by title, author, creator and subject.

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  Sand Dune Rehabilitation in Thal, Pakistan

  Anwar Khan, C. M. (Society for Range Management, 1968-09-01)

  Rangeland improvement in Thal, Pakistan through reseeding was started in 1962. These operations were impressively successful on heavy soil valley flats but loose sand dunes defied all efforts of sowings. These dunes have been successfully rehabilitated through planting tufts of Cenchrus ciliaris (dhaman) and Elyonurus hirsutus (karera). On better sites, grasses seeded in flats are spreading naturally to the dunes. Under "Thal Technique of Planting Trees" more than 100,000 fodder trees have been transplanted successfully since July 1964 in earthen tubes (baked) without watering. Experiments to determine effects of exposure and different competition levels on height growth of Zizyphus jujuba (ber) are presented. Southeastern (leeward) exposures have been found to be significantly (highly) better than tops and northwesterly (windward) exposures. The minimum plant competition level gave significantly (highly) more height growth than the other three levels./El mejoramiento de los pastizales en Thal, Pakistán por medio de la siembra, fue iniciado en 1962. Se obtuvo un éxito impresionante en las siembras hechas en valles planos con suelos pesados, pero en las dunas de arena suelta todos los esfuerzos por sembrar resultaron fallidos. Sin embargo, dichas dunas han sido rehabilitadas exitosamente por medio del transplante de macollos de Cenchrus ciliaris y Elyonurus hirsutus. Los zacates sembrados en los valles están invadiendo en forma natural las dunas. Los pastizales de verano en Thal tienen zacates verdes disponibles por seis meses únicamente; a excepción de Elysine flagellitera en general durante su dormancia dichos zacates no mantienen un alto valor nutritivo. Tradicionalmente durante el invierno la principal fuente de alimento es el ramoneo. Los árboles de ramoneo se presentan como fuente esencial de abastecimiento de forraje durante todo el año, su aumento estable por medio de técnicas de plantación es entonces un problema mayor en el área. Una técnica conocida como "técnica Thal para plantar árboles" ha probado tener mucho éxito en ciertas especies de árboles bajo situaciones específicas. La técnica incluye la construcción de tubos de arcilla cocidos, con una longitud de 30 cm (1 pie) y con un diámetro de 11.25 cm (4.5 pulgadas). Las especies deseadas son plantadas en los tubos en invernaderos para que posteriormente cuando tengan sus raíces y follaje adecuadamente desarrollados sean transplantados en el campo. El propósito del tubo es proporcionar a la planta un medio en el cual pueda sobrevivir hasta que pueda tomar ventaja de la humedad existente en la arena de las dunas, siendo entonces el tiempo de plantación el factor mas determinante. Se encontró que el transplante no se deberá intentar hasta que haya humedad adecuada en 30 cm (1 pie) en el estrato superficial del suelo. Las plantaciones de Prosopis spicigera han sido las de mas éxito, otras especies fueron susceptibles a la destrucción por insectos. Las plantaciones de exposición sureste fueron significativamente mejores que los realizados en exposición noroeste y en la cima de las dunas. Una mínima competencia con las plantas dio un crecimiento en altura significativamente mayor.
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  Canadian bluejoint response to heavy grazing

  Collins, W. B.; Becker, E. F.; Collins, A. B. (Society for Range Management, 2001-05-01)

  A disclimax stand of Canadian bluejoint (Calamagrostis canadensis (Michx.) Beauv.) was heavily grazed by cattle and horses for 4 years to weaken the grass's competition with hardwoods important as browse and cover to wildlife. Stocking at 0.084 ha AUM(-1) resulted in uniform utilization of bluejoint and maintenance of early phenology through the growing season. Etiolated bluejoint declined about 90%, but grass production increased 10 to 15%, as fireweed (Epilobium angustifolium L.), a principal herbaceous component of the stand, decreased in response to trampling. Rhizomes of heavily grazed bluejoint had lower total nonstructural carbohydrates (TNC) (p = 0.0127), lower weight (g cm(-1) length) (p = 0.05), and reduced biomass (g cm(-3) of soil) (p = 0.05). Shoots of grazed bluejoint maintained higher nitrogen (p = 0.0001) and higher digestibility (IVDMD) (p = 0.0017) than bluejoint that was never grazed. This enabled heavily grazed bluejoint to retain good forage quality through the entire growing season, as opposed to ungrazed bluejoint, which became poor forage at the time of flowering during early July. Following one season of rest, rhizome TNC, shoot nitrogen, and IVDMD returned to levels of never grazed bluejoint. Seedhead production, seed production, seed weights, and seed viability of rested bluejoint were about the same as in ungrazed stands. On wet sites, heavy grazing does not adequately reduce the vigor of this grass.
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  Genomic Characterization of the Cacao Swollen Shoot Virus Complex and other Theobroma Cacao-Infecting Badnaviruses

  Brown, Judith K.; Chingandu, Nomatter; Brown, Judith K.; Xiong, Zhongguo; Cotty, Peter J.; Pryor, Barry M.; Orbach, Marc J. (The University of Arizona., 2016)

  The cacao swollen shoot disease of Theobroma cacao L. (cacao) is caused by Cacao swollen shoot virus (CSSV; genus, Badnavirus, family, Caulimoviridae). The virus is endemic to West Africa, where it poses a serious threat to cocoa production. Despite efforts to control CSSV spread by replacement of infected trees with tolerant cultivars and mealybug vector management, the disease is widespread in West Africa. In Trinidad, leaf mosaic and vein-banding symptoms have been observed in cacao plants in the field since the 1940s, and recently at the International Cocoa Genebank (ICGT), a custodian of cacao germplasm resources. The strains A and B of the suspect Cacao Trinidad virus (CTV) caused the symptoms, and were thought to be related to CSSV, however, viral causality was not demonstrated, until now. To develop molecular detection methods for CSSV in infected plants, polymerase chain reaction (PCR) amplification of eight regions of the CSSV genome was implemented. The PCR results showed variable amplification frequencies of 19 - 42% at each region, for 124 isolates collected in Cote d'Ivoire and Ghana. Pairwise nucleotide (nt) analyses of the eight regions showed 66-99% shared identities, indicating that CSSV isolates exhibit extensive variability with respect to primer design. The results provided preliminary evidence for the existence of a CSSV complex consisting of four divergent species. The full length genome of 14 CSSV isolates from cacao determined using the Illumina HiSeq platform showed 70-99% shared nt identities. The pairwise nt identities placed CSSV sequences into a group of four distinct species, one of which represented a previously undescribed species. Moreover, the full-length genomes grouped phylogenetically with other badnaviruses and revealed two CSSV subclades with three types of genome arrangements; four, five or six open reading frames (ORFs). Predicted functional protein domains were conserved on each ORF. Two distinct, full-length genome sequences were determined using the Illumina HiSeq platform, from DNA isolated from cacao leaves exhibiting distinct symptoms in Trinidad. The sequences were validated by PCR-amplification and sequencing of overlapping viral genome fragments. Pairwise nt analysis indicated that each genome shared 52-62% nt identities with CSSV and other badnaviruses, suggesting that the two are distinct species. Phylogenetic analysis indicated that the two sequences are not strains of the same virus, as supposed, but they represent two previously undescribed species in the genus, Badnavirus, and they have been named Cacao mild mosaic virus (CaMMV) and Cacao yellow-vein-banding virus (CYVBV). Despite sharing the same host and causing similar symptoms in cacao, CSSV, CaMMV, and CYVBV are phylogenetically-distinct species. The discovery of a CSSV species complex and the identification of three new cacao-infecting badnavirus species will support the development of molecular detection tools using the partial and complete genome sequences determined in this study. The ability to develop validated molecular tools for the detection of CSSV and related viruses, CaMMV and CYVBV, in cacao will aid quarantine efforts and safe movement of germplasm from the ICGT in Trinidad to cacao-growing countries, worldwide. Also, molecular diagnostics tools are expected to be useful in efforts underway to develop CSSV-resistant planting material for countries in West Africa, which are currently experiencing continued or new disease outbreaks.