TITLE:
Yield Evaluation of a Wheat Line with Combined Resistance to Russian Wheat Aphid and Stem Rust Race “Ug99” in Kenya
AUTHORS:
F. O. Amulaka, J. N. Maling’a, R. S. Pathak, M. Cakir, R. M. S. Mulwa
KEYWORDS:
Rusian Wheat Aphid; Stem Rust “Ug99”; Gene Pyramiding; Combined Resistance
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.4 No.7,
July
17,
2013
ABSTRACT: InKenya,
Russian wheat aphid (RWA) and stem rust race TTKS (“Ug99”) are the most devastating pests of wheat. Severe
infestations by RWA result in yield losses of up to 90% while epidemics of “Ug99”can cause up to 100% loss. The two
pests combined have seriously affected farmer incomes forcing them to rely
heavily on pesticides and increasing the cost of production. This study sought
to evaluate a wheat line that has been developed to be resistant to both RWA
and “Ug99”by pyramiding two
major resistance genes. Three varieties were used in this study: “Kwale”, a Kenyan high yielding
commercial variety but susceptible to both RWA and “Ug99”; “Cook”, an Australian variety
carrying stem rust resistance gene Sr36 conferring immunity to “Ug99”; and “KRWA9”, a
Kenyan line resistant to RWA but with poor agronomic attributes. The F1 of the double cross (DC F1) was obtained by crossing the F1 of “Kwale × Cook” and the F1 of “Kwale × KRWA9”.
The DC F1 population was subjected to sequential screening for both
RWA and “Ug99”resistance. The surviving DC F1 progenies were left to self
pollinate in the field to obtain the DC F2. The DC F2 progenies
were sequentially screened against RWA and “Ug99”to obtain a resistant population to both RWA and “Ug99”. The yield and yield components of
the new resistant line were compared with the three parents. Results showed
that the DC F2:3 had higher yields than the three parents based on
1000 kernel weight, weight of kernel per spike, and the actual yield in
tons/ha, indicating that the genes were successfully introgressed. It is
concluded that though races with virulence for Sr36 have been reported, the gene provides immunity to race “Ug99”and can be used as a component for “Ug99”resistance breeding together with
other Sr genes.