Field-Based Assessment of Partial Resistance to Yellow Rust in Wheat Germplasm

Abstract

Durable resistance based on partial resistance is an important and effective way to combat the problem of yellow rust (Puccinia striiformis West. tritici). Field-based assessment of partial resistance is crucial in developing countries for the breeders, dealing with hundreds of lines at a time. The present experiment was carried out during 2005-2006 to reveal variability for field based-partial resistance to yellow rust among 20 wheat breeding lines grown at Nuclear Institute for Food and Agriculture, Peshawar, along with ‘Morocco' as susceptible check. Partial resistance was assessed through the infection type, final rust severity (FRS), area under rust progress curve (AURPC), infection rate (IR) and co-efficient of infection (CI). Cluster analysis of the 20 wheat lines revealed two main groups/clusters along Morocco as a separate cluster. Based on overall parameters, these lines were grouped into two clusters. Nine lines were grouped in one cluster, while remaining 11 lines were clustered in another group. Similarly, cluster analysis based on partial resistance parameters also resulted in two groups for the tested lines along with Morocco as a separate line. The first cluster included the lines considered as moderately slow yellow rusting lines while those of later group were marked as better slow rusting lines. Strong association was found between co-efficient of infection (CI) with both FRS and AURPC, while it was too weaker with IR. The present study revealed that the lines were having enough diversity regarding slow rusting behavior and yellow rust resistance, ranging from immunity to partial resistant lines. Similarly, CI, FRS and AURPC are suggested to be useful for assessment of partial resistance to yellow rust. Key words: Wheat, yellow rust, partial resistance, field-based assessment. doi:10.3329/jard.v6i1.1663 J Agric Rural Dev 6(1&2), 99-106, June 2008