Abstract

Background and aim:
Sunflower is one of the most important oil seed crops. It is affected by several fungal pathogens. Most of these pathogens infect the seeds which becomes an efficient vehicle to disperse seedborne pathogens over long distances with consequent crop losses. The objective of this study was to identify seedborne myco-pathogens in sunflower seeds.

Methodology:
Sixty-five sunflower accessions were sourced from USDA, United States and IAR, Samaru, Nigeria. The seeds were surface sterilized and plated on streptomycin-modified Potato Dextrose Agar. The resultant colonies were identified, percent contamination of each accession by myco-pathogens and the percent seed germination were determined. The identity of some selected myco-pathogens was further confirmed through molecular means using ITS1 and ITS4.

Results:
Twelve myco-pathogens were isolated from the seeds and identified as Aspergillus niger, Alternaria tenuissima, Fusarium proliferatum, Alternaria alternata, Colletotrichum gloeosporiodes, Fusarium fujikuroi, Fusarium chlamydosporum, Fusarium verticillioides, Fusarium equiseti, Fusarium incarnatum, Rhizopus stolonifer, and Aspergillus flavus. The most frequent fungal contaminant was Alternaria tenuissima, followed by Alternaria alternata and the least occurring was Fusarium fujukuroi all belonging to 4 classes of fungi namely, Sordariomycetes, Dothideomycetes, Euromycetes and Mucoromycetes. Out of the 65 tested seed samples, 82.5% were found to be contaminated with multiple seedborne fungi, while 17.5% of the seed had no fungal contamination. 44% out of the 82.5% were contaminated with more than one fungus and 38.5% were contaminated with a single fungus. Samsun2 and Samsun3 had a 100% germination rate followed by Russian giant, CMS HA and HSP399 with 77% germination percentage.

Conclusion:
The effect of myco-pathogen contamination in sunflower seeds germination varies among the different accessions.

Key words: Accessions, Fungal classes, Contamination, Germination, Sunflower, Oil-seeds, Seedborne pathogens