Timea Hajnal-Jafari

Effects of plant growth promoting rhizobacteria on maize in greenhouse and field trial

L.) is an important crop in temperate and semi-arid regions and one of the three major food staple crops for the world’s population. In Serbia, maize is grown on about 1 200 000 ha of soils per year and results of yield testing on numerous locations show its high genetic potential (Jockovic et al., 2010). Beside the genetic potential, achieving higher yields also require appropriate application of agro-technical measures, espe-cially fertilization. After nitrogen (N), phosphorus (P) is the most limiting nutrient for crop yields, and is essential for maize growth and development (Wu et al., 2005). In order to increase the natural fertility of soils and develop new approaches to reduce the need for chemical ferti-lizers and pesticides the rhizosphere microorganisms *Corresponding author. E-mail: mirjana@polj.uns.ac.rs. Tel/Fax: +381 21 4853 426. especially some rhizobacteria called plant growth promo-ting rhizobacteria (PGPR) are recognized as an important factor in sustainable agricultural production (Mrkovacki and Bjelic, 2011). PGPR may be important for plant nutrition by increa-sing N and P uptake by plants, and playing a significant role in the biofertilization of crops (Cakmakci et al., 2005). Maize stimulates different N

Microbial Activity in Forest Soil Under Beech, Spruce, Douglas Fir and Fir

Summary The aim of this research was to investigate the microbial activity in forest soil from different sites under deciduous and coniferous trees in Serbia. One site on Stara planina was under beech trees (Fagus sp.) while another under mixture of spruce (Picea sp.) and Douglas fir (Pseudotsuga sp.). The site on Kopaonik was under mixture of beech (Fagus sp.) and spruce (Picea sp.) trees. The site on Tara was dominantly under fir (Abies sp.), beech (Fagus sp.) and spruce (Picea sp.). The total number of bacteria, the number of actinobacteria, fungi and microorganisms involved in N and C cycles were determined using standard method of agar plates. The activities of dehydrogenase and ß-glucosidase enzymes were measured by spectrophotometric methods. The microbial activity was affected by tree species and sampling time. The highest dehydrogenase activity, total number of bacteria, number of actinobacteria, aminoheterotrophs, amylolytic and cellulolytic microorganisms were determined in soil under beech trees. The highest total number of fungi and number of pectinolytic microorganisms were determined in soil under spruce and Douglas fir trees. The correlation analyses proved the existence of statistically significant interdependency among investigated parameters.

Nematophagous Activity of Duddingtonia Flagrans MUCL 9827 Against Sheep Gastrointestinal Nematodes

Summary Gastro-intestinal nematodes (GIN) of sheep are one of major constraints in grazing production systems worldwide. Control is commonly achieved using anthelmintics, but global occurrence of anthelmintic resistance to different drugs and the emergence of multi-resistant GIN species seriously limit the efficiency of their use. Therefore, integrated parasite management is widely recommended, with nematophagous fungi as one of control tools. Duddingtonia flagrans is one of the most used species, with various effect of different isolates. In previously performed coproculture assay, we showed low efficacy of D. flagrans MUCL 9827 against infective larvae (L3) of sheep GIN. The aim of current experiment was to reevaluate its nematophagous potential, using the medium where direct interaction between the fungus and L3 could be observed. Nematophagous activity was tested on 2% water agar with addition of chloramphenicol on three series of plates seeded with 500 and 1000 chlamidospores and agar blocks with 7 days old mycelium. At Days 0 and 5, 500 L3 of sheep GIN were added to test the trapping activity. The cultures, including control plates with only L3, were incubated at 25°C for 10 days, followed by evaluation of their number and reduction percentage. Nematophagous activity of D. flagrans MUCL 9827 against L3 was clearly demonstrated. However, the overall efficacy was poor since trapping was observed only in one out of nine plates containing fungal material. Potential reasons for such poor performance of the isolate of fungal species, otherwise known as successful in trapping animal parasitic nematodes, are discussed.