Proceedings of the XLV Italian Society of Agricultural Genetics - SIGA Annual Congress

Salsomaggiore Terme, Italy - 26/29 September, 2001

ISBN 88-900622-1-5

Poster Abstract

SCREENING OF SUBTERRANEAN CLOVER GENOTYPES UNDER ARTIFICIAL INOCULUM OF FUSARIUM SP.

PECETTI L.*, PIANO E.*, RICCIONI L.**, CARRONI A.M.***, PORTA-PUGLIA A.**

* Istituto Sperimentale per le Colture Foraggere, Viale Piacenza 29, 26900 Lodi

** Istituto Sperimentale per la Patologia Vegetale, Via G.C. Bertero 22, 00156 Roma

*** Istituto Sperimentale per le Colture Foraggere, Via Crespellani 4, 09121 Cagliari

Fusarium sp., genetic resources, root-rot, selection, Trifolium subterraneum L.

Breeding programmes of subterranean clover in southern Europe have traditionally set low priority on selection against major pathogens, also because of the lack of important disease outbreaks in this area. However, root-rot causing agents, such as Fusarium sp., are frequent on other crops and can also represent, therefore, a threat for the clover. Thus, in our breeding programme carried out in Sardinia, Italy, some attention was given to this disease. This study refers to 2 trials performed in consecutive years under artificial epiphytotic of Fusarium sp. The first trial included 45 genotypes, of which 37 were Sardinian lines under advanced breeding and 8 commercial varieties. To validate the variation observed in disease response, a subset of 27 genotypes were further evaluated in the second trial. In both trials, 3 pathogen treatments were applied, in addition to a control, uninoculated treatment, viz. F. avenaceum, F. oxysporum, and a mixture in equal amount of both fungi. One-month-old clover seedlings were scored in all treatments for top-growth vigour (1-9 scale), then excavated for scoring root-rot symptoms (1-5 scale), and finally weighed after drying. Analysis of variance tested differences between subspp. subterraneum and brachycalycinum of Trifolium subterraneum, among treatments, and among genotypes. On the common set of genotypes to both trials, a cluster analysis was applied using as original variables the average disease score across the 3 inoculated treatments in the 2 trials. Confirming previous evidence, F. avenaceum proved more pathogenic than F. oxysporum. The results suggested that high seedling vigour may play a role in limiting root-rot effects, and this may also contribute to the relative better tolerance of subsp. brachycalycinum over subsp. subterraneum to some extent here observed. Despite some inconsistency of response in the 2 trials both at the treatment and genotype level, some Sardinian genotypes were noted for a certain consistent level of tolerance, also with reference to the performance of commercial varieties. Among them were the lines ‘125 sub C’, ‘56 sub D’, ‘22 brachy G’, ’56 sub B’ (=Campeda), and ’19 brachy E’ (=Antas).