Abstract
Net form net blotch, caused by Pyrenophora teres f. teres, is a major constraint to barley production worldwide, including in Kazakhstan, where information on resistance sources remains limited. This study aimed to evaluate the resistance of 106 spring barley accessions from different breeding programs in Kazakhstan at both seedling and adult plant stages. Seedling resistance was assessed under greenhouse conditions using two predominant pathogen races (100 and 500), while field resistance was evaluated under artificial infection using disease severity and area under the disease progress curve (AUDPC). A greater virulence of race 500 compared to race 100 was observed, with fewer accessions showing resistance at the seedling stage. A strong positive correlation between disease severity and AUDPC (r = 0.885) was observed. Differences between seedling and adult plant responses suggest the involvement of both race-specific and quantitative resistance mechanisms. This study provides the first systematic evaluation of resistance to predominant P. teres f. teres races in Kazakh barley germplasm.