Genotype x Environment Interactions andYield Stability of Orange Fleshed SweetpotatoVarieties Grown in EthiopiaEngida Tsegaye, Mihertu Cherinet, Asfaw Kifle, , DanielMekonen & Tesfaye TadesseA Paper Presented to ISTRC Symposium: TropicalRoots and Tubers in a Changing Climate. A CriticalOpportunity for the World.2 -66 Nov 2009 Lima, Peru
INTRODUCTIONEthiopia is located in Eastern Africa►Area- 1,100,000 Km 2►Estimated population- over 79 000,000 MillionThe principal root and tuber crops grown in Ethiopia are:– Enset (Ensete ventricosum)-– Potato (Solanum(tuberosum)– Sweetpotato (Ipomoea(batatas Lam.)– Taro (Colocasia(esculenta Schott.)– Cassava (Manihot(esculanta)– Yam (Dioscorea(spp.)– Ethiopian dinich’ (Coleus edulis) &– Tannia (Xanthsoma(spp.).Among root and tuber crops, sweet potato is the third important rootcrop next to Enset and Potato at national level
and second to Enset in Southern Ethiopia■ In 2008Area covered by sweet potato : 33,070 haTotal Production – 262,853.8 tAverage national yield- 8 t/ha■■■■Vitamin A deficiency (VAD) and food insecurity are the majorpublic issues in Ethiopia.to control VAD food diversification programs represent one ofthe possible strategiesSix OFSP varieties have been released in Ethiopia.particularly, for southern part of the countrytheir root yield performance varies across differentenvironments
there is no information on GXE interactions and storage root yieldstability of released as well as promising sweet potato varieties s inEthiopia.Hence this study was undertaken as part GXE Regional OFSPVariety Trial in East and Central Africa In collaboration with VITAAV Specific ObjectiveTo identify stable and adapted orange fleshed sweet potatovarieties for major sweet potato growing areas of Ethiopia.
Materials and MethodsTreatments: Fourteen sweet potato varieties introduced from CIPalong with one standard checkLocations: Awassa, Gofa, Bako and Chanomile Duration: Two consecutive years (2007 & 2008)Design: RCB replicated three timesPlot size: 3X3mSpacing: 60cmX30cmData: On yield, yield components, dry matter, beta carotene content ,insect pest & disease incidence
RESULTS AND DISCUSSION There were significant differences among the clones forboth marketable and total root yields.►significant variation in the geneticyield potential among the tastedclones Genotype by location (GXE) interaction was also highlysignificant►differential variatal response forstorage root yield across locations
Table 1. Combined analysis of variance for storage rootyields (t/ha) of 15 OFSP clones evaluated at fourlocations in 2007 & 2008SourceYearLocationYLDegree offreedom133Mean squareMarketable yield Total yield24.24** 49.63**114.30** 50.26**4.42** 12.28**R(LY)160.59*0.94**Genotype( G)1418.08**23.15**YG141.65**1.73**LG422.08**3.02**YLG421.41**1.45**Error2240.29**0.42**CV(%)15.916.40*,** significant at 5% and 1% probability level, respectively.
Table 3 Mean storage root yields and estimates of stability for total rootyields of 15 OFSP clones evaluated at four locations s during2007& 2008GenotypesUkereweK 118Ejumula199062.1Naspot 1K135K566632ResistoGweriPipiZambeziCarrot CMayaiSpkoo4TIS-8250MeanS.EMean yield (t.ha -1 )18.9711.8918.4835.9624.7110.8820.6421.555.1311.1817.8711.8017.5013.5428.9317.933.91Regressioncoefficient (b)1.330.771.041.000.770.718.104.22.1680.881.080.911.391.151.99Stability parametersDeviations fromlinearity(S 2 d)-3.3221.32**26.29**151.59**6.4913.74*48.43**204.78**-2.1017.66*29.88**11.07*12.99*43.38**23.94**Coefficient ofdetermination(r 2 )0.970.500.600.220.690.540.550.000.850.600.600.690.830.550.86
Table 4 Dry matters, Beta-carotene content and other parameters of 15OFSP clones evaluated at Awassa in 2007& 2008GenotypesDry mattercontent in %Totalcarotenoidµ/gramBeta-caroteneµg/gRoot fleshcolorVirusdiseasescore(1-9)A. blightdisease score(1-5)Ukerewe22.214.171.124Pale yellow30.8K 11828.727.221.7Pale orange30.0Ejumula32.5135.1112.6Orange30.0199062.120.726.121Pale orange40.3Naspot 126.96.36.199Cream20.0K13529.325.718.9P-0range30.3K56663223.7126.8115.4D. orange42.0Resisto20.2238.3196.1D. orange41.7Gweri32.823.517.6Pale orange20.8Pipi34.35.3-cream20.0Zambezi27.968.859.3D. orange31.5Carrot C32.688.580.1D. orange30.0Mayai30.3134.5125.8D. orange20.3Spkoo431.829.422.9Pale orange20.0TIS-825020.04.22.8Pale yellow20.0
Acknowledgements CIP/VITAA /Harvest Plus – For funding & provision of germplasm For technical support Harvest Plus –For sponsoring to attend STRC symposium