Effect of hot water dip treatment on seedborne pathogens and germination of carrot seeds

Abstract

The effect of hot water treatment of carrot seeds on seedborne pathogens (Alternaria and Fusarium spp) and seed germination was studied Carrot seeds (no fungicide) were dipped in water at 50C or 52C for 10 20 or 30 min and plated on potato dextrose agar to assess pathogen growth Treated seeds were sown in cell trays to assess germination in a glasshouse The weight of the germinated seedlings was also recorded All hot water treatments significantly (P<0001) reduced the number of seeds bearing pathogens compared with the control (tap water) Treatment at 50C for 30 min and 52C for 10 and 30 min gave almost complete kill of seedborne pathogens For Alternaria treatment at 52C gave fewer seeds with pathogens than treatment at 50C (P<0001) whereas for Fusarium 50C gave fewer seeds with pathogens than 52C (P<0001) Treatment time did not affect the proportion of seeds bearing Fusarium but longer treatments reduced the numbers with Alternaria Treated seeds were more likely to germinate than control seeds (treated4364; control23; P<0001) There were only marginal differences in germination between treatment times at 50C treatment time did not affect germination whereas at 52C longer treatment reduced germination All hot water dip treatments (except 52C for 30 min) gave increased seedling weights over the control