Abstract

Stem rust (Puccinia graminis f.sp.tritici) of wheat (Triticum aestivum) has caused wheat yield losses in Kenya for years and the trend shows the situation has worsened. The objective of the research was to identify elite genotypes for adult plant and seedling stage resistance. Adult plant resistance study was done under natural conditions in three locations. Scoring was done following the modified Cobbs scale. Seedling stage resistance was done in the greenhouse and scored following the Stakmans scale. Genotype KSL 144, 71, 50, 31 44, 115 were identified as having seedling stage resistance. Area Under Disease Progress Curve (AUDPC) and Final Disease Severity (FDS) when used for adult plant revealed KSL 142, 71, 144, 50, 31, 44, 115, 146, 69 and 76 as having resistance. The variance (S_i) and Coefficient of Variation (CV_i) was calculated from the FDS and yield values, which distinguished stable genotypes. The stable genotypes for disease severity were KSL 69 (8.8%), 161 (14.9%), 54 (12.4%), 156 (18.24%). The relationship between yield and AUDPC was strong and negative, r=-0. 943 same as yield and FDS relationship r= -0.84. Variation for yield performance was recorded KSL 137 (2.63t/ha), KSL 31 (2.52 t/ha) showing high performance. The thousand kernel weight values were not significant for the three location at (P<0.05). The advanced genotypes that consistently performed better should be released as varieties or used in improving local varieties in the Kenyan wheat stem rust breeding programme or potentially in the Eastern Africa region.

Key words: Ug99, disease severity, Area Under Disease Progress Curve (AUDPC), resistance.