Under greenhouese condition,4-5 leaf-stage wheat seedlings of seven cultivars,including 5 representative slow-rusters,one susceptible check and one vertical resistant check,were inoculated separately with four isolates of wheat yellow rust each belonging to different race.By histological observations,it was found that early from the third day after inoculation,there occurred the phenomena of cell necrosis in the infected sites of all the slow-ruster-isolate combinations,while no cell necrosis occurred in the susceptible check,Yianda 1817.The area of the mycelial colony and the amount of sporulation in the slow-rusters were found to be smaller and lower than that in the susceptible check.
The possibility of evaluating the slow-rusting resistance of cultivars by histological method was discussed.