Genotype by environment interaction (GxE) as a measure of yield stability of Dutch potato varieties in Uganda
Byarugaba, Arinaitwe Abel
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Twenty one (21) Dutch potato varieties were introduced in Uganda during 2015-2016 seasons for national yield performance and adaptability studies so that most stable varieties could be identified for production. The effect of genotype (G), environment (E) and their interaction (G x E) on tuber yield was assessed to establish variety adaptation in different agro ecologies. Five sites were used in the study that included; Kalegyere (2450 m/asl), Kachwekano (2225m/asl), Rwebitaba (1531m/asl), Buginyanya (1887m/asl) and Zeu-DFI (1642m/asl). The varieties that yielded highest were; El-mundo (22 t ha-1), Sarpomira (22 t ha-1), Connect (21.7T/ha), Rudolph (21.4t ha-1), Arizona (20.3 t ha-1), Voyager (20 t ha-1), Faluka (19.9 t ha-1) and Sagitta (19.9 t ha-1). GxE analysis was done using Additive main effects and multiplicative interaction (AMMI) and results showed that GxE interaction accounted for 12.6% of the total variation, while genotypes and environments accounted for 5.7% and 59.7% of the total variation respectively. The AMMI bi-plots identified varieties Caruso, Derby, Voyager, Royal, Navigator, Manitou, Destiny, Musica and Markies to have the lowest (0.00033-0.6609) IPCA 1 score hence were most adapted. Varieties Rwagume, Sarpo Mira, Connect and Kachpot 1 were more adapted at Kalegyere site (-3.601 IPCA1 score) while Sarpo Mira, Connect, El-Mundo and Rudolph were adapted at Kachwekano site (-0.562 IPCA1 score). Varieties Arizona, Faluka, Panamera and Connect were adapted at Zeu (0.125 IPCA1 score). Varieties El-Mundo, Arizona, Rudolph and Connect were more adapted at Buginyanya ZARDI (0.498 IPCA1 score) while El-Mundo, Rudolph, Sagitta and Royal most adapted at Rwebitaba ZARDI (3.54 IPCA1 score). The most interactive genotype was Rwagume with interaction score of - 2.30516 while the least interactive genotype were Caruso and Taurus with IPCA 1 score of 0.00033 and 0.01086 respectively.