Stripe Rust Resistant and High Yielding Winter Wheat Genotypes for Central Asia.

Stripe (yellow) rust, caused by Puccinia striiformis f. sp. tritici is the most important disease constraint to winter wheat (Triticum aestivum L.) production in Central Asia. Most of the widely grown commercial cultivars in the region are either susceptible or possess low levels of resistance to stripe rust. In susceptible wheat cultivars, grain yield reductions due to stripe rust could go up to 40%. To evaluate stripe rust resistance and agronomic performance of a set of recently developed advanced breeding lines by International Winter Wheat Improvement Program (IWWIP), replicated field trials were conducted in 2010 at two sites in Uzbekistan. A set of 23 lines, selected from the above mentioned trials for high levels of stripe rust resistance, high grain yield and acceptable agronomic traits, was evaluated at four sites in Uzbekistan in 2011.These lines were also tested in Azerbaijan, Kazakhstan, Kyrgyzstan, Tajikistan, and Turkmenistan. Results from 2010 and 2011 trials across sites in Uzbekistan revealed several stripe rust resistant lines that produced significantly higher grain yield than the local checks in both years. In the absence of the disease in 2011, several stripe rust resistant lines had yields either equal to or greater than the most widely grown cultivar in Uzbekistan. A few lines showed 0% stripe rust severity and 6 to 7 t/ha grain yield. A number of these stripe rust resistant lines also possess early maturity, high 1000-kernel weight, lodging resistance, acceptable plant height and other desirable agronomic traits. Such lines could be released as new cultivars or used in wheat improvement programs in Central Asia as improved sources of stripe rust resistance. A few lines are being considered as candidate cultivars in Uzbekistan. These findings underline the importance of international collaboration in developing superior winter wheat varieties with stripe rust resistance for Central Asia.