Incidence of seed-borne fungi on Lupinus mutabilis depending on a plant morphotype, sowing date and plant density

Seeds of the Andean lupine are characterised by high nutritional value, and the plant could become an important crop in the production of food and forage. This legume continues to attract growing interest around the world. A field experiment was carried out in in Lower Silesia, Poland, in 2011-2012. Two Andean lupine morphotypes (indeterminate and determinate) were analysed. Andean lupine was grown in treatments characterised by different sowing dates and plant density per m2. Seed yield, macronutrient content, protein content and health were evaluated at harvest. Seed yield was determined by the interaction of all experimental factors. The indeterminate form produced a significantly higher yield than the determinate form, regardless of the sowing date. The factors had little influence on the mineral content of seeds and total protein content. Andean lupine seeds were colonised mostly by saprotrophic fungi of the genera Alternaria, Cladosporium, Epicoccum and Rhizopus and pathogenic fungi of the genera Botrytis, Colletotrichum and Fusarium. Delayed sowing contributed to seed colonisation by fungi of the genus Colletotrichum. The determinate form was more susceptible to infection than the indeterminate form. Molecular analysis showed that the Colletotrichum isolates found in the study belong to the Colletotrichum acutatum species complex. The pathogen causing lupine anthracnose, isolated from the seeds of Andean lupine in the present study, was identified as Colletotrichum lupini (within C. acutatum complex) in a molecular analysis, and its DNA sequence was compared with those of the isolates deposited in the GenBank.