Increased occurrence of saprophytic fungi and leaf reddening on small grains during 2007

Abstract

Severe occurrence of saprophytic fungi on wheat, barley and triticale ears was registered in Serbia, during the 2007 growing season. This had not strong influence on early maturing winter wheat variety Prima, since the average number of ears colonized by saprophytic fungi was 3.75 per m2. In the field trial of 21 fungicides for seed treatment (wheat variety Dragana), there was a high positive correlation between number of ears colonized by saprophytic fungi and kernel number (r= 0.86) as well as number of ears colonized by saprophytic fungi and kernel weight (r= 0.87). Furthermore, there was a complete positive correlation between kernel weight and kernel number (r= 0.95). Percentage of seed fraction lt 2.2 mm was 41.4-47.3% and 1000 kernel weight (g) was 16.9-18.2, depending on seed category, variety and location. In the samples of seeds from three locations, the major saprophytic fungi were species of the genus Alternaria, Aspergillus, Penicillium and Rhizopus. The most dominant saprophytic fungi on the glumes of empty and thin ears were species of the genus Alternaria and Cladosporium while fungi of the genus Fusarium, Alternaria, Cladosporium, Cochliobolus and Penicillium were the most common on kernels from those ears. By the end of April, reddening of leaves of wheat varieties appeared most frequently in the area of Banat. The explanations of this appearance and its cause were different. However, changes the leaf, ligule and stem colour due to abiotic or biotic factors.

Tokom 2007. godine u Srbiji je došlo je do jače pojave saprofitnih gljiva na klasovima pšenice, ječma i tritikalea. Kod rane sorte Prima ova pojava nije imala značajnijeg uticaja na prinos, jer je prosečan broj saprofitnih klasova bio 3,75 po m2. Kod sorte Dragana u ogledu sa 21 varijantom fungicida za tretiranje semena, između broja saprofitnih klasova i broja zrna ustanovljena je vrlo jaka pozitivna korelacija (r=0,86), kao i između broja saprofitnih klasova i mase zrna (r=0,87). Između mase zrna i broja zrna ustanovljena je potpuna korelacija (r=0,95). U zavisnosti od proizvodne kategorije, sorte i lokaliteta, udeo frakcije semena lt 2,2 mm, kretao se 41,4-47,3%, a masa 1000 takvih zrna bila je 16,9-18,2 grama. Saprofitne gljive iz rodova Alternaria, Aspergillus, Penicillium i Rhizopus bile su dominante na uzorcima semena koje potiče iz tri doradna centra. Na plevama i plevicama praznih i šturih klasova u polju dominantne su bile gljive iz rodova Alternaria i Cladosporium, a na semenu koje potiče iz tih klasova Fusarium, Alternaria, Cladosporium, Cochliobolus i Penicillium. Crvenilo pšenice javilo se krajem aprila, a najizraženije je bilo na području Banata. Tumačenja ove pojave i uzroka njenog nastanka su različita. Međutim, bez obzira koji je faktor prevalentan, u osnovi promene boje liske, lisnog rukavca i stabla pšenice leži stres koji je biljka doživela usled delovanja abiotičkih ili biotičkih faktora.