Evaluation of groundnut (Arachis hypogaea L.) germplasm for resistance to leaf diseases and related cytoplasmic factors, testa colour and cup leaf

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Date
2008-02-28
Authors
Pretorius, Alana Elmarie
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University of the Free State
Abstract
English: Early leaf spot (ELS) caused by Cercospora arachidicola, late leaf spot (LLS) caused by Cercosporidium personatum, web blotch (WB) caused by Phoma arachidicola and rust caused by Puccinia arachidis, are serious diseases of groundnut in South Africa. The aims of this study were to evaluate ARC-GCI germplasm for resistance to the important foliar diseases such as ELS, LLS, WB, and rust and to ascertain if cytoplasmic factors influence the pattern of inheritance of resistance to ELS, LLS, and WB, testa colour and mutations such as the one responsible for cupleaf phenotypes. Twenty-one reciprocal crosses were made to study the cytoplasmic factors but the F1 progenies gave no evidence of cytoplasmic factors directly responsible for any of the above-mentioned traits. During 2003/04, 138 ARC-GCI germplasm entries were evaluated for resistance to ELS, LLS, WB and rust at Potchefstroom (North West Province; Highveld), Burgershall (Mpumalanga Province), Brits (North West Province), Vaalharts (Northern Cape Province) and Cedara (Kwazulu Natal Province). No fungicides were used to control the foliar diseases. In trials at Vaalharts, Cedara, and Burgershall entries 1, 10-13, 18-21, 23, 30, 52 and 56-58 were resistant to two of the three (LLS, WB, and rust) foliar diseases and entries 18, 19 and 20 (best) to LLS, WB and rust. At Brits, Elite (E) and ICRISAT (I) short/medium growth entries 8I and 7E, were resistant to LLS and WB and the long growth entries 1E and 3E were resistant to WB, LLS and rust. In micro-plots at Potchefstroom entries 6, 9, 10 and 13-15 were resistant to LLS and WB and in the brick plots 1-3, 6 and 7 to ELS and LLS. Entries with resistance to ELS, LLS, WB, and rust as well as other favourable traits, such as a high yield and oleic acid percentage, from the 2003/04 trials were included in the 2004/05 trials for further assessment. All the entries were evaluated for resistance to ELS, LLS, WB and rust, were graded and grouped by using the Canonical Variate Analysis (CVA). From the results on the five locality trials (2004/05) medium growth entries 1, 3, 7, 10, 14, 15, 20-22, 26, 27, 30, 32 and 33 were resistant to three or four of the foliar diseases, gave good yields and choice grade kernels. The CVA identified separate groups, containing entries 3, 20, 21 and 32, with resistance to two or more foliar diseases and with high yield. No choice grade entries were reported for unsound blemished and soiled (UBS) kernels with an UBS>13%. In the Elite short/medium trials at Brits (2004/05) entries 3 and 8 were resistant to rust, 1, 2, 4, 7, 11-13, 15, 17, 19-22, 24 and 25 gave choice grade kernels, and 10, 13 and 12 the highest yield. Entries 1-6, and 8-15 (Elite long) were resistant to LLS, 1-15 to WB, and 1, 4 and 15 to rust, 4, 10 and 12 gave choice grade kernels and 4, 1 and 10 the highest yields. ICRISAT (long) entries 5 and 7 gave choice grade kernels, and 1, 6 and 3 the highest yields. The CVA identified the groups containing medium growth entries 10, 12, 13, 22 and 23, Elite long 1, 4, 10 and 15 and ICRISAT long 5, 8 and 9 as groups with resistance to two or more foliar diseases (ELS, LLS, WB, and rust) and good yield. Twenty-three medium and 11 long growth entries in the Elite trials at Vaalharts (an extra trial planted where fungicides were used to control foliar diseases) gave choice grade kernels and good yields. In this study, some ARC-GCI germplasm entries were resistant to ELS, LLS, WB, and rust, but climatic factors influenced the severity of infection. Foliar diseases lowered the quality and grade of the kernels and resulted in lower yields. CVA simplifies the evaluation and grouping of new germplasm entries and will save valuable research resources.
Afrikaans: Vroeë blaarvlek, (VBV), veroorsaak deur Cercospora arachidicola, laat blaarvlek (LBV) deur Cercosporidium personatum, spatselvlek (Phoma) deur Phoma arachidicola en roes deur Puccinia arachidis, is ernstige grondboonsiektes in Suid Afrika. Die doelwitte van hierdie studie was om LNR-IGG kiemplasma vir weerstand teen VBV, LBV, Phoma en roes te evalueer en om vas te stel of sitoplasmiese faktore betrokke is by die oorerwing van weerstand, saadhuid kleur en mutasies, soos die een wat die “cup leaf” fenotipe veroorsaak. Tydens hierdie studie is 21 resiproke kruise gemaak om die sitoplasmiese faktore te bestudeer. Geen bewyse dat sitoplasmiese faktore direk verantwoordelik is vir enige van die bogemelde eienskappe is in die F1 nageslagte gevind nie. Gedurende 2003/04 is 138 LNR-IGG kiemplasma inskrywings vir weerstand teen VBV, LBV, Phoma en roes by Potchefstroom (Noordwes Provinsie, Hoëveld), Burgershall (Mpumalanga Provinsie), Brits (Noordwes Provinsie), Vaalharts (Noord Kaap Provinsie) and Cedara (Kwazulu Natal Provinsie) in SA geëvalueer. Geen swamdoders is gebruik om die blaarsiektes te beheer nie. In proewe by Vaalharts, Cedara en Burgershall het inskrywings 1, 10-13, 18-21, 23, 30, 52 en 56-58 weerstand teen twee van die drie (LBV, Phoma, en roes) blaarsiektes en 18, 19 en 20 (beste) teen LBV, Phoma en roes getoon. By Brits was die Elite (E) en ICRISAT (I) kort/medium groeiseisoen inskrywings 8I en 7E, die mees weerstandbiedend teen LBV en Phoma en die lang groeiers 1E en 3E, teen Phoma, LBV en roes. Inskrywings 6, 9, 10 en 13-15 het weerstand teen LBV en Phoma in mikroplot proewe en in steenplot proewe het die inskrywings 1-3, 6 en 7 weerstand teen VBV en LBV getoon. Die beste inskrywings met betrekking tot weerstand teen VBV, LBV, Phoma en roes, goeie opbrengs en ‘n hoë oleiensuur persentasie uit die 2003/04 proewe was in die 2004/05 proewe ingesluit vir verdere evaluasie. Al die inskrywings is vir weerstand 163 teen die blaarsiektes geëvalueer, gegradeer en die Liniêre Diskriminant Analise (LDA) is op hulle gedoen. Resultate op die vyf lokaliteite het getoon dat kort/medium groeiseisoen inskrywings 1, 3, 7, 10, 14, 15, 20-22, 26, 27, 30, 32 en 33, weerstand teen drie van die vier blaarsiektes (VBV, LBV, Phoma en roes) getoon het en goeie opbrengs en keurgraad pitte gelewer het. Met behulp van die LDA is afsonderlike groepe met goeie weerstand teen twee of meer van die blaarsiektes, asook ‘n goeie opbrengs, waarin inskrywings 3, 20, 21 en 32 geval het, geïdentifiseer. Geen keurgraad inskrywings is vir siek, gevlek en vuilgesmeerde pitte (SGV)>13% gerapporteer nie. In die Elite kort/medium proewe op Brits was inskrywings 3 en 8 weerstandbiedend teen roes. Inskrywings 1, 2, 4, 7, 11-13, 15, 17, 19-22, 24 en 25 het keurgraad pitte en 10, 13 en 12 die hoogste opbrengste gelewer. Inskrywings 1-6 en 8-15 (Elite lank) het weerstand getoon teen LBV, 1-15 teen Phoma en 1, 4, en 15 teen roes. Inskrywings 4, 10, en 12 het keurgraad pitte gelewer en 4, 1 en 10 die hoogste opbrengste. ICRISAT (lank) inskrywings 5 en 7 het keurgraad pitte gelewer en 1, 6 en 3 die beste opbrengste. LDA het afsonderlike groepe met medium groeier inskrywings 10, 12, 13, 22, and 23, Elite lank 1, 4, 10, en 15 en ICRISAT lank 5, 8, and 9 met goeie weerstand teen twee of meer van die blaarsiektes en ‘n goeie opbrengs, geïdentifiseer. Drie en twintig medium en 11 lang groeiers in die Elite proewe by Vaalharts (‘n ekstra proef waarin swamdoders gespuit is) het keurgraad pitte en goeie opbrengste gelewer. Tydens die studie was sommige LNR-IGG kiemplasma inskrywings weerstandbiedend teen VBV, LBV, Phoma en roes, maar klimaatsfaktore het die graad van infeksies beïnvloed. Blaarsiektes verlaag dan ook die kwaliteit van die pitte en die opbrengs. LDA sal evaluasie en plasing van nuwe kiemplasma inskrywings vergemaklik en vir die navorser tyd en geld bespaar.
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Keywords
Dissertation (M.Sc.Agric. (Plant Sciences (Plant Breeding))--University of the Free State, 2006, Peanuts -- Disease and pest resistance, Leaves -- Diseases and pests, Arachis hypogaea, Germplasm, Groundnut, Early leaf spot, Late leaf spot, Web blotch, Rust, Climate, Grading, Resistance
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