| dc.description.abstract | In the province of Vojvodina, biotic and abiotic factors were identified that may lead
to significant yield losses. Their prevalence was directly correlated with climatic changes.
There is a strong correlation between the causal agents of powdery mildew and leaf
rust, because the occurrence of one of the two pathogens prevents the other from
occurring as a major outbreak. The present chapter introduces the concept of the Uredo-
Teleuto Spore Coefficient (UTC). In Puccinia coronata, this coefficient shows the
rapidity of transition from the uredo to the teleuto stage under the influence of
temperature on reproductive organs of the pathogen. Based on the UTC values (0-1 ), five
U/T categories were established. The most genotypes (54, or 22.6%) had UTC=l, i.e. a
complete transition of P. corona/a from the uredo stage to the teleuto one. Climatic
changes have resulted in the dominance of pathogens that require higher temperatures for
their development or are better able to adapt to drought conditions (Septoria spp.,
Pyrenophora tritici-repentis, P. teres, Rhynchosporium secalis). At phenophase 29-30, a
correlation was found between the number of pycnides fonned and infection severity by
Septoria tritici in the first seven leaves. The correlation was complete in the variety
Simonida (r=0.93) and very high in the variety Pobeda (r=0.88). The main causal agents
of grain destruction in wheat are FHB and bunt, which may result in total yield losses.
Abiotic factors that may significantly reduce grain yields are temperature conditions
causing problems in the early stages of small grains development or stress at yield
formation. The development of cultivars resistant to parasitic fungi is a very important
measure of their control. Small grains cultivars for planting should be adapted and chosen
based on resistance to abiotic and biotic factors, while the breeding strategy should be
oriented towards developing genotypes adapted to stress factors. | sr |
