Yield stability of maize hybrids evaluated in multi-environment trials in Yunnan, China

Stable performance of maize (Zea mays L.) hybrids in multi-environment trials (MET) is important. The objectives of this investigation were (i) to evaluate grain yield stability of 13 Chinese hybrids tested across 10 locations in 2002 and 2003 via GGE biplot analysis and Kang's yield-stability statistic (YSi) and (ii) to identify nonrepresentative and/or nondiscriminating locations. Within years, cultivars and cultivar-by-location (C x L) interactions were significant. Heterogeneity caused by environmental index did not contribute appreciably to C x L interactions. The YSi identified, among the top five hybrids, LD10, Hai He, and YR1 as common between years. The GGE biplot analysis ranked hybrids with above-average yield across years as Hai He > LD10 > YR1 > Tun004 and for stability of performance as LD10, Hai He, Tun004, and YR1. The GGE biplots revealed that Hai He had the highest yield in seven and LD10 in 10 environments. Three different locations were identified in 2002 and 2003 as the least discriminating. Three common locations in 2002 and 2003 were the least representative of test locations. GGE biplot and YSi identified QC3, XHD892ck, and R313 as the least desirable hybrids. The YSi indicated ZZY6 and SB21-3 to be the most unstable hybrids between years. The only hybrid showing stable performance across locations was Tun004 in 2002. Overall, YSi versus GGE distance correlation (r) = -0.92**. YSi should be useful in selecting superior hybrids in the absence of GGEbiplot software. This information should help streamline the maize testing program in Yunnan.