Dynamics of incidence and frequency of populations of Fusarium species on stored maize grain

Abstract

Production and providing of high quality maize grain are of primary importance for livestock production since maize is the main component of livestock feed. Contamination with fungi not only diminishes the quality of grain, but some fungi species can produce highly toxic compounds known as mycotoxins. Considering that maize is economically the most important grown plant in Serbia, content and intensity of frequency of these pathogen fungi species are investigated in maize stored in the storage facilities. Based on studies of the fungi incidence in stored maize intended for nutrition of livestock, it was established that during the period from February 2005 to March 2006, some fungi species were present successively (Fusarium spp., Penicillium spp.), other with interruptions of one (Nigrospora spp., Aspergillus spp., Acremonium spp., Alternaria spp), three (Mucor spp., Chaetomium spp., Rhizopus spp.) to four months (Cladosporium spp.), and also sporadically during three (Epicoccum spp., Rhizopus spp., Trichothecium spp.), two (Gliocladium spp.) or one month (Papulaspora spp., Phialophora spp.). Period June-October is the most critical for preservation of the quality of stored maize since the number of fungi species present (8−14 of total of 17 identified fungi genera) and their frequency during this period are the highest, especially of toxigenic species of Fusarium (43.5−62.5%) and Penicillium (10.0−33.5%) genera. Positive correlation (r = 0.5979**) between dynamics of incidence and frequency of isolated fungi species indicates that fungi with higher frequency of incidence remain longer on the grain during storage. F. verticillioides and F. subglutinans, of total of 6 identified Fusarium species were present on the grain during entire year and with the highest frequency (24.7% and 5.9%, respectively). During single year (2005) F. verticillioides was present in the highest percentage from February to October (22.0−39.5%), and F. subglutinans from April to October (8.0−12.5%), whereas the both species were isolated the least during winter period December-January (4.0−8.0% and 0.5−1.0%, respectively). F. graminearaum is the third toxigenic Fusarium species which from the mycotoxicological aspect can be important for period June-September when it is mostly present (5.0−11.0%). Incidence of other Fusarium species is sporadic (1.3% F. proliferatum, 1.0% F. sambucinum and 0.5% F. poae).

Proizvodnja i obezbeđivanje visokog kvaliteta zrna kukuruza su od primarnog značaja za stočarsku proizvodnju jer je kukuruz osnovna komponenta stočne hrane. Zaraza gljivama ne samo da smanjuje kvalitet zrna, već neke vrste gljiva mogu produkovati visoko toksična jedinjenja, poznata kao mikotoksini. S obzirom da je kukuruz ekonomski najvažnija gajena biljka u Srbiji, sadržaj i intenzitet učestalosti ovih patogenih vrsta gljiva se ispituje u kukuruzu u skladištu. Na osnovu proučavanja pojave gljiva na uskladištenom kukuruzu, koji je bio namenjen za ishranu životinja, utvrđeno je da su u periodu od februara 2005. do marta 2006. godine neke gljive prisutne sukcesivno (Fusarium spp., Penicillium spp.), druge diskontinuirano sa prekidom od jednog (Nigrospora spp., Aspergillus spp., Acremonium spp., Alternaria spp), tri (Mucor spp., Chaetomium spp., Rhizopus spp.) ili četiri meseca (Cladosporium spp.), a treće sporadično u toku tri (Epicoccum spp., Rhizopus spp., Trichothecium spp.), dva (Gliocladium spp.) ili jednog meseca (Papulaspora spp., Phialophora spp.). Period jun-oktobar je najkritičniji za očuvanje kvaliteta uskladištenog kukuruza jer je brojnost (prisutno 8−14 od ukupno 17 identifikovanih rodova gljiva) i frekvencija gljiva u tom periodu najveća, posebno toksigenih vrsta iz rodova Fusarium (43.5−62.5%) i Penicillium (10.0−33.5%). Pozitivna korelacija (r = 0.5979**) između dinamike pojave i frekvencije izolovanih vrsta gljiva ukazuje da se gljive sa većom frekvencijom pojave duže održavaju na zrnu kukuruza tokom skladištenja. F. verticillioides i F. subglutinans su od ukupno šest identifikovanih vrsta roda Fusarium prisutne na zrnu tokom cele godine i sa najvećom frekvencijom (24.7% i 5.9%). U toku jedne godine (2005) F. verticillioides je u najvećem procentu prisutna od februara do oktobra (22.0−39.5%), a F. subglutinans od aprila do oktobra (8.0−12.5%), dok su obe vrste najmanje izolovane u zimskom periodu decembar-januar (4.0−8.0% i 0.5−1.0%). F. graminearum je treća toksigena vrsta roda Fusarium koja sa mikotoksikološkog aspekta može biti značajna za period jun-septembar kada se javlja u najvećem procentu (5.0−11.0%). Pojava ostalih vrsta roda Fusarium je sporadična (1.3% F. proliferatum, 1.0% F. sambucinum and 0.5% F. poae).