Wheat Information Service
Number 69: 13- 17(1989)

Wheat breeding for resistance to Fusarium diseases, especially to Fusarium graminearum Schw.

Slobodan Tomasovic

Faculty of Agricultural Scinces, University of Zagreb, Institute for Breeding and Production of Field Crops - ZAGREB Marulicev trg 5/I, Yugoslavia

Summary

Over 130 wheat sources of resistance were tested under conditions of artificial infection and chosen 7 genotypes were mutually crossed by using the scheme of partial diallel. Sources of resistance markedly differed in level of resistance, which ranged from 0, 65 to 3, 89 (rating scale 0 - 5). Improving the level of resistance was obtained in F₁ generation as well as in F₁ x F₁ crosses, in the several combinations, in comparison with their parental components. Additive gene effect (i.e. minor gene effects) and partial dominance were noticed. The highest level of resistance was found in F₁ generation and in F₁ x F₁ crosses of combinations involving genotypes Bizel and Poncheau.

Introduction

The genus Fusarium belongs to the order Moniliales and class Fungi imperfecti (Deuteromyceteae). The principal pathogen that causes wheat scab is Fusarium graminearum Schw. (the perfect stage is Gibberella zeae /Schw./Petch.). The pathogen that causes head blight and shrivelling of kernels, causes also rot on secondary roots, develops in the soil as facultative parasite, and usually lives saprophytically on debris. It is permanently present in the soil and thus greatly makes the study of inheritance of resistance difficult if the work is carried out under field conditions.

Attack of Fusarium graminearum Schw. in wheat has been known in Yugoslavia, long time ago (Milatovic 1960; Perisic 1963; Kostic and Smiljakovic 1966; Jovicevic 1969) During recent years this disease has been frequently occurred in Yugoslav agricultural practice, especially affecting heads of susceptible varieties. Disease attack is more expressed when high temperatures are accompanied with high air humidity during heading and flowering time. Since 1975 attack of Fusarium graminearum Schw. is increasing in our country.

Severe outbreaks of this disease is the consequence of narrow crop rotation of the two main crops (corn-wheat), which are the most common hosts for Fusarium graminearum Schw. Some times also happens that wheat comes after wheat. Increase of the mineral fertilisation, and especially discordance of nitrogen to other components favour the disease occurrence. The quantity of N fertilizer usually applied nowdays is as high as 200 kg per hectar of pure nitrogen. Yield reductions of wheat, caused by Fusarium graminearum Schw. forced us to improve investigations on this disease. So, in the year 1978 we started with wheat breeding program of resistance to Fusarium graminearum Schw. in Institute for Breeding and Production of Field Crops in Zagreb.

The program of incorporating wheat resistance to Fusarium spp., especially to Fusarium graminearum Schw. is very complex, because the pathogen itself is a facultative organism to which mecha nism of breeding and model of inheritance is also complex. Influence of the environmental conditions in expression of the genetic resistance is rather high.

The objective of our investigations is to determine the reaction of the wheat sources of resistance to fusarium head scab under conditions in Yugoslavia, with the purpose to use the best sources in our breeding program.

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