engleski

Several years of testing maize hybrids for resistance to Giberalla ear rot

Gibberella ear rot, caused by the Fusarium graminearum Schwabe Fungus (teleomorph Gibberella zeae (Scwein.) Petch), is a serious disease of corn (Zea mays) grown in Croatia and many other cool and humid areas worldwide. Because of lower grain quality of the infected ears and due to numerous mycotoxins produced by this pathogen, this disease should be considered seriously because it decreases food and feed safety. Two major mycotoxins are produced by Fusarium graminearum (deoxynivalenol and zear alenone). Breeding for resistance appears to be the most effective means of ear rot and mycotoxins control. A new technique of artificial ear rot infection with Fusarium graminearum into the silk channel was developed previously by Reid et al. (1996.) published in Tehcnical Bulletin 1996-5E Agriculture and Agri-Food Canada. This method was adopted in our breeding program from 1998. During a 3-year experimental period, 22 maize hybrids (FAO 300-600) were tested for resistance to Gibberella ear rot with the aim to analyze the inoculation technique in different years at location Rugvica near Zagreb without irrigation. A randomized complete block design was used with four replications. The F. graminearum inoculum was produced using modofied Bilay's liquid medium. Ten primary ears from center plants were infected 6 days after silk emergence by infecting 2ml of conidia suspension (5x106) spores/ml into the silk channel inside the husk cavity above the cob using a self-refilling syringe with the pistol handle SOCOREX 187, 2, 0502 (an 18 gauge Luer-lock stainless steel hypodermic). The inoculation needle was held at right angles to the silk channel. Infection severities and ranges for 2004, 2005 and 2006 were 3, 0 (1, 4-4, 6), 2, 8 (1, 8-4, 1) and 1, 9 (1, 2-3, 2) respectively. The most susceptible hybrids were from FAO 300, rated 2, 1. This indicates that hybrid resistance is to be compared within the same maturity group. In comparison with the checks, which proved to be resistant, considerably more susceptible were H-3, H-10 and H-16. Correlative association was found among hybrid resistance tested in different years, i.e. in different enviroments (r= 0, 66, 0, 61, 0, 84). Artificial ear inoculation with F. graminearum proved as a reliable method in our local conditions.

maize; Fusarium graminearum; silk channel inoculation; field trials

nije evidentirano