RESISTANCE OF SOME EGYPTIAN BARLEY GENOTYPES TO LEAF RUST CAUSED BY Puccinia hordei Otth.

Abstract

One hundred and twenty barley lines as well as three commercial cultivars belonging to the Egyptian breeding program ( A , B , D & E trials ) were tested for resistance to barley leaf rust (Puccinia hordei Otth.) at seedling stage and at adult stage in 2005/2006 season. Under green-house conditions, a total of 55 lines showed resistant response ( low infection type). These lines comprise 45.83 %, comparing with the check commercial varieties which were susceptible (high infection types). Of these lines, 20 were highly resistant. At adult stage, the evaluation was carried out at four locations differed in climatic conditions i.e. Sakha, Gemmeiza, Nubaria and Ismalyia. Rust Severity( RS ), Average Coefficient of Infection ( ACI ) and Relative Resistance Index ( RRI ) were calculated. Also ,the desirable / acceptable levels of relative resistance index ( RRI ) were estimated. The stability parameters using the regression coefficient of the performance of each genotype under different environments ( b ) and the mean square deviation from linear regression ( S 2 d ) were calculated. Most of the tested lines showed susceptible responses to leaf rust. The susceptibility to leaf rust of the tested lines was the least in Ismaylia. The line No. 29 was the best one for both resistance and stability to leaf rust disease at the four locations as it had the lowest value of ACI ( 5.00 ) and the highest value of RRI (8.38 ) , followed by lines No. 88, 28 and 12 where the ACI ranged between ( 12.50 -14.00 ) and the RRI ranged between ( 7.45 -7.26 ).These materials can be used as parents in barley breeding programs for developing new disease resistant cultivars.