Advanced Search
Now showing items 1-10 of 108
Efecto diferencial dependiente de fosfato de la variabilidad de hongo micorrízico sobre indicadores biológicos y bioquímicos de calidad del suelo en cultivo in situ de yuca en Kenia
(Universidad de Chile, 2021)
de fertilización y es muy útil,
especialmente en ambientes tropicales, donde los niveles de fosfato son bajos. La
presencia del hongo también incrementa la productividad, lo que es muy
importante en cultivos de yuca (Manihot esculenta), ya que...
The rhizosphere is very important in plant health and growth. As an integrated ecosystem it hosts all sorts of microorganisms that participate in plant defense, ecosystem diversity enrichment, nutrient availability and plant growth promotion. The use of mycorrhizal fungi Rhizophagus irregularis in agroecology is an attractive strategy because the fungus makes phosphate more available to plants, and this potentially decreases the need to fertilize. This is very useful, especially in tropical environments where the levels of phosphate are low. The presence of mycorrhizal fungi greatly increases crop productivity. This is especially important in cassava (Manihot esculenta) because this crop feeds a great part of the human population, including regions with recurrent starvation episodes. Even though R. irregularis is a ubiquitous organism, its large and complex genomic variability could cause different effects in soil microbiome. Because mycorrhizal fungi also exhibit an impact on soil structure, it is possible that they will affect the organic matter availability to microorganisms in soils, affecting soil respiration rates or enzymatic activities of the soil microbial community. All these possible impacted factors by mycorrhizal presence are important soil quality indicators, whose monitoring is crucial to assure a healthy agroecosystem. It was hypothesized that the genetic variability between R. irregularis lines impacts soil quality indicators such as soil respiration, enzymatic activities, total organic carbon and microbial biomass, depending on the level of phosphate fertilization used, on in situ cassava crops in Kenya. In order to determine their impact, the effects of four highly variable R. irregularis strains on soil quality indicators where studied after their application in cassava crops in Kenia. The first aim was to evaluate the impact of the variability between strains on the microbial biomass (Cmic) and total organic carbon (COT) of the soil. The fumigation method with chloroform and analysis of elemental carbon was used. Results suggested that there is no significant influence on the COT and Cmic associated to the genetic variability of R. irregularis. This appears to be independent of the phosphate fertilization level. The second aim was to compare soil respiration after inoculation of the different strains. CO2 release was measured by incubation of soil in hermetic glass vials. Measurements indicated that phosphate levels influence CO2 release of genetically variable R. irregularis lines. However, phosphate level did not influence the differential effect within a single R. irregularis line. The third aim was to evaluate the effect of the inoculation of the different lines on enzymatic activities of β-glucosidase (BG), leucine-aminopeptidase (LA) and acid phosphatase (FAc). Enzymatic reaction rates were measured after the administration of labeled substrates to soil samples. Results obtained suggest that phosphate levels have differential effects on the enzymatic rates of BG in the different R. irregularis lines, but this difference was not significant within a single fungus line. No significant effects were found on enzymatic rates of LA and FAc, associated with genetic variability of R. irregularis. Similarly, phosphate fertilization did not influence these enzymes. This study provides insights of how biochemical soil quality indicators contribute to monitor mycorrhizal fungal inocula on agroecosystems, in order to take advantage of their ecosystemic services. In conclusion, it is necessary to expand our research defining phosphate levels for optimal performance of each R. irregularis genetic line under field conditions. Extensive and local monitoring is required to evaluate possible impacts on COT, as well as an improvement of monitoring techniques in terms of processing capacity. This is the first time that the enzymatic activities of BG, LA and FAc were monitored on a commercial cassava crop inoculated with R. irregularis in Kenya. The results reported here provide important comparative background for further studies...
The rhizosphere is very important in plant health and growth. As an integrated ecosystem it hosts all sorts of microorganisms that participate in plant defense, ecosystem diversity enrichment, nutrient availability and plant growth promotion. The use of mycorrhizal fungi Rhizophagus irregularis in agroecology is an attractive strategy because the fungus makes phosphate more available to plants, and this potentially decreases the need to fertilize. This is very useful, especially in tropical environments where the levels of phosphate are low. The presence of mycorrhizal fungi greatly increases crop productivity. This is especially important in cassava (Manihot esculenta) because this crop feeds a great part of the human population, including regions with recurrent starvation episodes. Even though R. irregularis is a ubiquitous organism, its large and complex genomic variability could cause different effects in soil microbiome. Because mycorrhizal fungi also exhibit an impact on soil structure, it is possible that they will affect the organic matter availability to microorganisms in soils, affecting soil respiration rates or enzymatic activities of the soil microbial community. All these possible impacted factors by mycorrhizal presence are important soil quality indicators, whose monitoring is crucial to assure a healthy agroecosystem. It was hypothesized that the genetic variability between R. irregularis lines impacts soil quality indicators such as soil respiration, enzymatic activities, total organic carbon and microbial biomass, depending on the level of phosphate fertilization used, on in situ cassava crops in Kenya. In order to determine their impact, the effects of four highly variable R. irregularis strains on soil quality indicators where studied after their application in cassava crops in Kenia. The first aim was to evaluate the impact of the variability between strains on the microbial biomass (Cmic) and total organic carbon (COT) of the soil. The fumigation method with chloroform and analysis of elemental carbon was used. Results suggested that there is no significant influence on the COT and Cmic associated to the genetic variability of R. irregularis. This appears to be independent of the phosphate fertilization level. The second aim was to compare soil respiration after inoculation of the different strains. CO2 release was measured by incubation of soil in hermetic glass vials. Measurements indicated that phosphate levels influence CO2 release of genetically variable R. irregularis lines. However, phosphate level did not influence the differential effect within a single R. irregularis line. The third aim was to evaluate the effect of the inoculation of the different lines on enzymatic activities of β-glucosidase (BG), leucine-aminopeptidase (LA) and acid phosphatase (FAc). Enzymatic reaction rates were measured after the administration of labeled substrates to soil samples. Results obtained suggest that phosphate levels have differential effects on the enzymatic rates of BG in the different R. irregularis lines, but this difference was not significant within a single fungus line. No significant effects were found on enzymatic rates of LA and FAc, associated with genetic variability of R. irregularis. Similarly, phosphate fertilization did not influence these enzymes. This study provides insights of how biochemical soil quality indicators contribute to monitor mycorrhizal fungal inocula on agroecosystems, in order to take advantage of their ecosystemic services. In conclusion, it is necessary to expand our research defining phosphate levels for optimal performance of each R. irregularis genetic line under field conditions. Extensive and local monitoring is required to evaluate possible impacts on COT, as well as an improvement of monitoring techniques in terms of processing capacity. This is the first time that the enzymatic activities of BG, LA and FAc were monitored on a commercial cassava crop inoculated with R. irregularis in Kenya. The results reported here provide important comparative background for further studies...
Tropical Bites : productos de cóctel congelados de Yuca y Plátano
(Universidad de Chile, 2014-10)
Plataforma visual interactiva de interpretación lingüística latinoamericana. El cuaderno del sur
(Universidad de Chile, 2014)
Voces amerindias en el español oral culto de Santiago de Chile
(Universidad de Chile, Facultad de Filosofía y Humanidades, 1976)
Afronegrismos en el léxico de la prensa de Santiago de Chile
(Universidad de Chile, 2005)