Evaluation of Kenyan wheat (Triticum aestivum L.) cultivars for rust resistance, yield and yield components

Stem rust (Puccinia graminis f. sp. tritici) is an important fungal disease of wheat (Triticum aestivum) due to its ability to cause severe yield losses on susceptible cultivars grown under conducive conditions. The objective of this study was to evaluate 81 Kenyan wheat cultivars for yield, agronomic traits and resistance to rust. A 3-season field experiment was conducted in a 9 × 9 partially balanced lattice design at KALRO, Njoro (0˚ 20’S and 35˚ 56’E) under stem rust (Sr) and yellow rust (Yr) pressure. The results from this study showed that effects due to season, cultivar and cultivar × season interaction were significant (p≤0.001) for number of kernels spike-1, Area Under Disease Progress Curve for stem rust (AUDPC_SR), Area Under Disease Progress Curve for yellow rust (AUDPC_YR), yield, 1000-kernel weight (TKW), biomass and days to heading. Principal component analysis showed AUDPC was the most effective disease parameter for determining rust resistance and biplot analysis identified cultivars K. Fahari, K. Kingbird, K. Songbird and K. Pelican with desirable traits for yield, TKW, biomass and kernels spike -1. Stem rust contributed to the highest in reduction of yield and TKW accounting for 12.87% and 21.95% variation, respectively while Yr contributed the most to biomass reduction accounting for 25.65% variation. From this study, cultivars Bounty, Lenana, and K. Leopard which produced high yield, low AUDPC_SR and AUDPC_YR values ranging from 3.5- 32.2 and 15.6-80.4, respectively can be used as valuable genetic stocks for improvement of rust resistance in wheat cultivars in Kenya