GENOTYPE X ENVIRONMENT INTERACTION STUDIES ON YIELDS OF SELECTED POTATO GENOTYPES IN UGANDA

High yielding potato (Solanum tuberosum) genotypes with good levels of resistance to late blight were identified at Kalengyere Research Station in southwestern Uganda. The yield stability of these genotypes, however, remains uncertain. For instance, the performance of these genotypes varied over 4 seasons of evaluation and when tested at Kachwekano site. Genotype x environment interaction study was therefore required to determine their adaptation in the different agroecologies where the genotypes would be grown. Five sites in Uganda at different elevations were selected for the study and these were Kalengyere (2450 masl), Bulegeni (1670 masl), Mbarara (1500 masl), Tororo (1250 masl) and Namulonge (1150 masl). The trials were conducted for three seasons: namely 2000 (A and B) and 2001 (C) being the first (A) and second (B) and third (C) seasons of the trials. Each location for a particular season was regarded as one environment. Genotypes 389484.20, 389685.2, 389698.12, 389584.22 and 389701.34 performed better than the other genotypes in all the five locations. The G x E analysis was done using Additive Main effects and Multiplicative Interaction (AMMI) and the biplot identified genotypes 389484.20, 391558.16, Victoria, 391558.5, 389584.22, Kisoro and 391558.13 as adapted to Bulegen C, Mbarara B, Namulonge B and C and Tororo A, B and C. Genotypes 391558.11, 389685.2 and 391558.1 were adapted to Kalengyere A. Namulonge B and C and Tororo A, B and C were identified as similar environments basing on their responses. Key Words: Adaptation, AMMI analysis, Phytophthora infestans, Solanum tuberosum, yield stability Résumé Les génotypes de patates à haut rendement (Solanum tuberosum) avec des bons niveaux de résistance à la brunissure tardive étaient identifiés à la station de recherche de Kalengyere en sud-ouest de l'Ouganda. La stabilité du rendement de ces génotypes, cependant, reste incertaine. Par exemple, la performance de ces génotypes a varié au delà de 4 saisons d'évaluation et au moment de l'épreuve au site de Kachwekano. L'étude d'intéraction génotype x environnement était ainsi donc nécessaire pour déterminer leur adaptation dans les différentes zones agro-écologiques où les génotypes seront germés. Cinq sites en Ouganda aux élévations différentes étaient séléctionnés pour l'étude notamment Kalengyere (2450 masl), Bulegeni (1670 masl), Mbarara (1500 masl), Tororo (1250 masl) et Namulonge (1150 masl). Les essais étaient conduits pour trois saisons : nommément 2000 (A et B) et 2001 (C) étant la première (A) et la seconde (B) et la troisième (C) saisons d'essais. Chaque emplacement pour une saison particulière était regardée comme un environnement. Les génotypes 389484,20 ; 389685,2 ; 389698,12 ; 389584,22 et 389701,34 ont eu une bonne performance que les autres génotypes dans tous les cinq emplacements. L'analyse de GxE était faite utilisant les principaux effets additifs et multiplicatifs d'intéraction (AMMI) et les génotypes double identifiés 389484,20 ; 391558,16 ; Victoria, 391558,5 ; 389584,22, Kisoro et 391558,13 comme adaptés à Bulegen C, Mbarara B, Namulonge B et C et Tororo A, B et C. Les génotypes 391558,11; 389685,2 et 391558,1 étaient adaptés à Kalengyere A. Namulonge B et C et Tororo A, B et C étaient identifiés comme des environnements similaires en se basant sur leurs réponses. Mots Clés: Adaptation, analyse AMMI, Phytophthora infestans, Solanum tuberosum, stabilité de rendement (Af Crop Sci J 2003 Vol 11 No 1 pp9-16

Genotype X environment interaction studies on yield of selected potato genotypes in Uganda

High yielding potato (Solanum tuberosum   ) genotypes with good levels of resistance to late blight were identified at Kalengyere Research Station in southwestern Uganda. The yield stability of these genotypes, however, remains uncertain. For instance, the performance of these genotypes varied over 4 seasons of evaluation and when tested at Kachwekano site. Genotype x environment interaction study was therefore required to determine their adaptation in the different agroecologies where the genotypes would be grown. Five sites in Uganda at different elevations were selected for the study and these were Kalengyere (2450 masl), Bulegeni (1670 masl), Mbarara (1500 masl), Tororo (1250 masl) and Namulonge (1150 masl). The trials were conducted for three seasons: namely 2000 (A and B) and 2001 (C) being the first (A) and second (B) and third (C) seasons of the trials. Each location for a particular season was regarded as one environment. Genotypes 389484.20, 389685.2, 389698.12, 389584.22 and 389701.34 performed better than the other genotypes in all the five locations. The G x E analysis was done using Additive Main effects and Multiplicative Interaction (AMMI) and the biplot identified genotypes 389484.20, 391558.16, Victoria, 391558.5, 389584.22, Kisoro and 391558.13 as adapted to Bulegen C, Mbarara B, Namulonge B and C and Tororo A, B and C. Genotypes 391558.11, 389685.2 and 391558.1 were adapted to Kalengyere A. Namulonge B and C and Tororo A, B and C were identified as similar environments basing on their responses

Agronomic performance of twelve elite potato genotypes in southwestern Uganda

Twelve potato genotypes including two checks were evaluated for yield and resistance to late blight. Weekly assessments of late blight severity were done using a 1-9 CIP scale and percentage leaf area affected. In 1998A all genotypes yielded better than the local checks (Kisoro and Victoria) except for 391558.16 that yielded lower than Victoria. In 1998B only 4 genotypes (389685.2, 389698.12, 389584.33 and 391557.1) performed better than the local checks, while in 1999A only 3 genotypes performed better than the local checks. Better yields were recorded in 1999B, which ranged from 15.2 to 44.7 Mt ha-1. The average yields for the genotypes in four seasons were 21.7, 16.7, 20.2 and 29.8 Mt ha-1, respectively. All genotypes showed higher levels of resistance to late blight than Victoria (28.8%), except 389484.20 in 1998B with AUDPC of 28.8%. Field evaluation at the two sites in 2000B generally showed a similar trend. The promising clones are undergoing multilocational trials in different parts of Uganda. Key Words: Genotype evaluation, late blight resistance, Kisoro, Victoria, Uganda> (African Crop Science Journal 2001 9(1): 17-24

Adaptability of Sift Potato Genotypes in Different Agro-Ecologies of Uganda

The effect of genotype by environment interaction (G x E) on fresh tuber yield of nine Standard International Field Trials (SIFT) potato (Solanum tuberosum L.) genotypes and Kisoro, a local variety, was studied in Uganda using additive main effects and multiplicative interaction (AMMI) model 3. Results indicated that the proportion of the environmental variation was much larger than the proportion due to genotypes and the proportion due to G x E interaction was also larger than the genotype main effects. Genotypes (G), environments (E) and the G x E interactions accounted for 8.43, 57.13 and 34.44% of the treatment sums of squares, respectively. AMMI and the biplot identified genotypes 384866.5, 381381.13, 389746.2, Kisoro and 386209.10 as adapted to four environments. Test genotypes 389746.2, Robijn and 381381.13 were the most stable and had higher yields (> 19 t ha-1) than all genotypes except Torridon, which was also very unstable and specifically adapted to one environment (Kalengyere 2B). Kalengyere 1B and Wanale 2A were identified as similar environments

Resistance to Late Blight and Yield of Population B3 Potato Selections in Uganda

Population B3 is the most advanced source of horizontal resistance available at the International Potato Centre (CIP). In this population, testing and selection for horizontal resistance to late blight, unlike those previously applied to population A clones, were simplified significantly (P<0.05) due to the absence of known R-genes. This study, conducted in southwestern and eastern Uganda, evaluated 20 selected potato genotypes in Population B3 for late blight resistance and tuber yield. Late blight severities on many of the Population B3 genotypes were lower than on most local cultivars, including the resistant cultivar, Rutuku. Population B3 genotypes performed better when sprayed with fungicide, Mancozeb, but the reduction in late blight severities due to spraying varied with genotype and location. Although spraying did not significantly (P>0.05) increase yields, almost all genotypes gave higher yields with than without spraying, with significant (P<0.05) differences among genotypes. Population B3 entries 389746.2, 383382.44, 393371.58, 392637.10, 391002.6, 393349.63, 393617.18, 391011.17, 391580.30, 393385.39, 393339.242, 393077.54, 393280.64 and 392657.8 performed well and could be considered for on-farm trials

Resistance to late blight and yield of population B3 potato selection in Uganda

No Abstract. African Crop Science Journal Vol. 13(2) 2005: 95-10

Adaptability of sift potato genotypes in different agro-ecologies of Uganda

No Abstract. African Crop Science Journal Vol. 13(2) 2005: 107-11