Efectos De La Fertilización Nitrogenada Y Fosfatada Sobre Poblaciones De Micorrizas Asociadas Al Cultivo De Cacao

Cocoa is one of the most significant assets in the ecuadorian agricultural structure, which also provides a good source of income for thousands of farmworker families. However, fertilization research works in cocoa cultivation have been relatively scarce. Decades of global research have shown that mycorrhizal fungi determine the fertilization and conservation of agrosystems. Fertilization is considered to be among the cultural and agricultural practices affecting mycorrhizas, which diminishes or prevents the fungal colonization. The objectives of research works were the following: the characterization of mycorrhiza species associated with cocoa, to determine the effects of nitrogen and phosphate fertilization in plant population and to identify the critical dose affecting the fungus development. A factorial design was used (AxBxC), with two (2) application systems, four (4) doses of nitrogen fertilizer, and two (2) doses of phosphate fertilizer with three repetitions. The turkey’s test was used to evaluate means with confidence interval of 95%. The evaluated variables were: diameter and length of cocoa pods, number of cocoa pods per tree, index of cocoa beans and almond yield per hectare, as well as, mycorrhizal spore counting, percentage of mycorrhizal fungi colonization, visual density of endophyte, and characterization of mycorrhiza species. The results concluded that the application of 100 Kg/ha N + 70 kg/ha P in the system below the soil surface, achieved yield increments of 68% over the absolute witness. The same dose and application method, increased the number of spores per gram of soil, mycelium colonization and density of mycorrhizal endophyte in roots.

Selected Metals in Various Fractions of Soil and Fungi in a Swedish Forest

The patterns of uptake and distribution of Co, Ni, Cu, Zn, Cd, and Pb in the soil-mycelium-sporocarps compartments in various transfer steps are presented. I attempted to find out whether there is a difference between the uptake of metals from soil to fungi (mycelium/soil ratio) and transport within fungal thalli (sporocarps/mycelium ratio). The concentration of Cu, Zn, and Cd increased in the order bulk soil < soil-root interface (or rhizosphere) < fungal mycelium < fungal sporocarps. The concentration of Co, Ni, and Pb decreased in the order bulk soil (or rhizosphere) < fungal mycelium < soil-root interface < fungal sporocarps. The uptake of Cu, Zn, and Cd during the entire transfer process in natural conditions between soil and sporocarps occurred against a concentration gradient. Mycorrhizal fungi (mycelium and sporocarps) only absorbed Co, Ni, and Pb but did not accumulate these elements in their thalli. Metal accumulation within fungal mycelium biomass in the top forest soil layer (0–5 cm) may account for about 5% of the total amount of Co, 4% Ni, 7% Cu, 8% Zn, 24% Cd, and 3% Pb.

Septoria gladioli. [Descriptions of Fungi and Bacteria].

A description is provided for Septoria gladioli. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. DISEASE: Hard rot (ANON., 1984), leaf spot and black spot on corm scales. HOSTS: Acidanthera spp., Crocus angustifolius (syn. : C. susianus), Freesia refracta, Gladiolus byzantinus, G. communis, G. dubius, G. gandavensis, G. hybridus, G. illyricus, G. imbricatus, G. inarmensis, G. italicus, (syn. : G. segetum), G. neglectus, G. palustris (Iridaceae). [Type host - Gladiolus italicus (syn. : G. segetum).] GEOGRAPHICAL DISTRIBUTION: Africa: Algeria. Asia: Armenia, Republic of Georgia, India, Iran, Russia (Far East), Syria, Turkmenistan. Atlantic Islands: Canary Islands. Central America: Costa Rica. Europe: Albania, Belarus, Bulgaria, Cyprus, Czech Republic, Denmark, Eire, Estonia, France, Germany, Greece, Hungary, Italy, Hungary, Latvia, Netherlands, Poland, Portugal, Romania, Russia, Spain, Switzerland, UK, Ukraine. North America: Canada, USA. South America: Argentina. TRANSMISSION: Three different distribution paths are known for this fungus: old corm to new corm, or mother corm to daughter corm infection; infection of corms or cormlets from infected débris in the soil (mycelium infection); secondary spread by means of spores from plants, in plantings of cormlets and seedlings (STONE, 1958).