Incidence of Bipolaris sorokiniana in seeds and transmission to barley plants

Abstract

The yeld potential of barley is reduced mainly because of diseases such as spot blotch caused by Bipoloaris sorokiniana which is seed transmitted. The objectives of the work were to study the correlation among different levels of seed infection and its transmission to barley plants under field and greenhouse conditions, and determine the capacity of seed-transmission of the fungus. Barley seeds cv ‘BR 2’ naturally infected with the levels of 2.7; 7.5; 12.5; 16.5; 31.0 and 55.5% of the fungus were sown in the field, with four replications. The evaluation of disease seedling showing simptoms of helminthosporiosis and its percentage in relation to the seed emergence, were made seven days after emergence. In greenhouse, seeds were sown in plastic trays containing with aproximatelly 13 kg of soil previously sterelized. Four hundred seeds of each tretament (infection level) were planted and covered with 3 cm of soil (3 cm depth). The importance of the infected seeds as a source of primary inoculum was demonstred. It was observed that on the field the transmission of the pathogen was more efficient when the seed infection level was 55%. On the other hand, in greenhouse there was correlation only between seed infection and roots. In conclusion, there was no correlation among the seed infection levels of B. sorokinianaand their incidence in the field, and seed infection levels of 55% reduce  seedling emergence both, in the field or in greenhouse.