PARTIAL RESISTANCE OF WHEAT (TRITICUM AESTIVUM) TO LEAF RUST (PUCCINIA TRITICINA) IN EGYPT. A. EVALUATION OF SEVEN EGYPTIAN WHEAT CULTIVARS FOR PARTIAL RESISTANCE AGAINST LEAF RUST, UNDER FIELD CONDITIONS

Abstract

Leaf rust is the most prevalent and widespread disease of wheat in Egypt and worldwide. The major obstacle in the control of such disease is the loss of host genetic resistance, as the pathogen evolves into new pathotypes. Therefore, this study was carried out to characterize partial resistance (PR), as a more durable form of resistance in seven locally produced wheat cultivars. From the tested cultivars only four cvs., Giza 168, Sakha 94, Sakha 95 and sids-12 proved to have an adequate level of PR, compared to the highly susceptible cvs., Bids-1, Gemmeiza-7 and Giza 139. Rust incidence as a final rust severity (FRS%), rate of disease increase (r-value) and area under disease progress curve (AUDPC), were found to be lower in magnitude in PR cultivars than in the highly susceptible ones under the same field conditions in the two years in concern (2010 and 2011). Partially resistant cultivars were characterized by their high potential to slow down the incidence and development of leaf rust infection, under favorable field conditions, in contrast to the highly susceptible cultivars. Thus, partial resistance to leaf rust in wheat genotypes could be accurately measured, characterized, screened and selected equally well under field conditions by using the most convenient epidemiological parameters, FRS% , AUDPC and r- value