Pre-breeding sesame (Sesamum indicum L.) for improved yield, and oil quality and quantity in Ethiopia = Ukuzalanisa kwangaphambili i-Sesame (Sesamum indicum L.) ukuze kuvunwe u-oyela okuthuthukisiwe, oyikhwalithi nomningi e-Ethiopia.

Abstract

ABSTRACT

Pre-breeding Sesame (Sesamum indicum L.) for Improved Yield, and Oil Quality and Quantity in Ethiopia Sesame (Sesamum indicum L.; 2n = 2x = 26) is a multi-purpose industrial oilseed crop serving the food, feed, and cosmetic industries globally. Sesame is Ethiopia’s most valuable export crop after coffee (Coffea arabica L.), contributing to socio-economic development. However, the productivity of the crop is low (<0.6 ton ha-1) and stagnant in Ethiopia and other major sesame growing regions in sub- Saharan Africa due to a multitude of production constraints. The low yield of sesame is attributable to lack of high-yielding and well-adapted varieties, with less capsule shattering; resistant/tolerant to biotic and abiotic stresses; a lack of modern crop production technologies and well developed infrastructure. Sesame remains a largely under-researched and underutilized crop in Ethiopia despite its economic value in the local, regional and international trades. There is a need for a dedicated sesame genetic improvement programme to develop and deploy new improved varieties with farmer- and market-preferred traits. Therefore, the specific objectives of this study were: i) to document sesame production opportunities and constraints and farmer-and market-preferred varieties and traits in eastern and southwestern Ethiopia as a guide for breeding; ii) to determine the variance components, broad-sense heritability (h2b) and association of seed and oil yield-related traits in Ethiopian sesame germplasm for effective breeding; iii) to determine the extent of genetic variation among 100 diverse sesame germplasm collections of Ethiopia using phenotypic traits and simple sequence repeat (SSR) markers and select distinct and contrasting genotypes for breeding and iv) to determine the genetic diversity and relationships among Ethiopia’s sesame germplasm collections using seed oil content and fatty acid compositions and diagnostic SSR markers and select genetically unique and promising parental lines for breeding. Different but complementary research activities were conducted to attain the objectives. The first study was conducted using a participatory rural appraisal (PRA) involving 160 farmers in two selected sesame growing regions and four districts in Ethiopia. A considerable proportion of the respondent farmers (56.0%) reported cultivating sesame using seeds of unknown varieties often sourced from the informal seed sector. The most important constraints to sesame production in the study areas were lack of access to improved seeds (reported by 83.0% of respondents), low yield potential of the existing varieties (73.8%), diseases (69.4%), and low market price (68.8%). These constraints were attributed to the lack of a dedicated breeding programme, formal seed sector, strong extension services, and well-developed pre-and post-harvest infrastructures. The most important market-preferred traits of sesame included true-to-type seed, white seed colour, and high seed oil content. Reasonable market price, resistance to crop diseases, drought tolerance, resistance to crop insect pests, higher seed yield, higher thousand-seed weight, higher oil content, white seed colour, early maturity, and good oil qualities such as aroma and taste were the vital farmer-preferred attributes in order of significance. Hence, these traits should be integrated in current and future sesame breeding programs. The second study evaluated 100 sesame germplasm under field conditions at two locations using a 10 x 10 lattice design with two replications. The findings revealed a higher genotypic coefficient of variation and h2b values for the number of primary branches (NPB), number of secondary branches (NSB), thousand seed weight (TSW), seed yield per hectare (SYH) and oil yield per hectare (OYH), suggesting that high genetic gains can be achieved through selection. Higher direct effects of OYH and number of seeds per capsule (NSPC) were recorded affecting SYH, while SYH, number of capsules per plant (NCPP) and TSW had a higher direct effect on OYH. Genotypes Hirhir Kebabo Hairless-9, Setit-3, Orofalc ACC-2, Hirhir Humera Sel-6, Setit-1 and ACC-NS-007(2) were selected for further breeding based on their high seed yield, oil content and oil yield. In the third part of the study, 100 sesame entries were field evaluated at two locations in Ethiopia for agro-morphological traits and seed oil content using a 10 × 10 lattice design with two replications. Also, test genotypes were profiled using 27 polymorphic SSR markers at the Oil Crops Research Institute of the Chinese Academy of Agricultural Sciences. Analysis of variance revealed significant (p≤ 0.05) entry by environment interaction for plant height, internode length, number of secondary branches, and grain yield. Genotypes such as Hirhir Kebabo Hairless-9, Setit-3, Orofalc ACC-2, Hirhir Humera Sel-6, ABX = 2-01-2, and Setit-1 recorded grain yield of >0.73 ton ha−1. Grain yield had positive and significant (p < 0.01) associations with oil yield (r = 0.99), which is useful for simultaneous selection. Moderate gene diversity and polymorphic information content values of 0.30 and 0.25 were recorded based on SSR analysis, respectively. The genotypes were separated into two and four major distinct groups based on cluster and population structure analyses, respectively, thus enabling selection and subsequent crossing to develop breeding populations for cultivar development. Based on phenotypic and genomic divergence, the following superior and complementary genotypes were selected: Hirhir Humera Sel-6, Setit-3, Hirhir Kebabo Hairless Sel-4, Hirhir Nigara 1st Sel-1, Humera-1 and Hirhir Kebabo Early Sel-1 (from cluster II-a), Hirhir kebabo hairless-9, NN-0029(2), NN0068-2 and Bawnji Fiyel Kolet, (from cluster II-b). The selected genotypes will serve as parents for sesame breeding program in Ethiopia.

Iqoqa

I-Sesame (Sesamum indicum L.; 2n = 2x = 26) iyisitshalo sembewu kawoyela enezinhloso eziningi ephakela izimboni ukudla, izimboni eziphakelyo, nezimboni zezimonyo emhlabeni jikelele. I-Sesame iyisitshalo esiyigugu kakhulu sase-Ethiopia esithunyelwa ngaphandle ngemuva kwekhofi (i-Coffea arabica L.), esinegalelo ekuthuthukisweni kwenhlalakahle yezomnotho. Nokho, ukukhiqiza kwezitshalo kuphansi ngomklamo ka (<0.6 ton ha-1) futhi kumile e-Ethiopia nakwezinye izindawo ezinkulu ezitshala i-sesame e-sub-Saharan Africa ngenxa yobuningi bezingqinamba zokukhiqiza. Isivuno esiphansi se-sesame sibangelwa wukuntuleka kwezinhlobo ezikhiqiza kakhulu futhi eziguquguqukayo, ezinokuqhekeka okuncane kwekhepsuli; ukucindezeleka kwe-biotic kanye ne-abiotic; ukuntuleka kobuchwepheshe besimanje bokukhiqiza izitshalo nengqalasizinda ethuthuke kahle. I-Sesame isalokhu iyisitshalo esingacwaningiwe futhi esisetshenziswa kancane e-Ethiopia naphezu kokubaluleka kwayo kwezomnotho ekuhwebeni kwasekhaya, kwesifunda kanye nakwamanye amazwe. Kunesidingo sohlelo oluzinikele lokuthuthukisa izakhi zofuzo ze-sesame ukuze kuthuthukiswe futhi kusetshenziswe izinhlobo ezintsha ezithuthukisiwe ezinezimpawu ezikhethwa abalimi nezimakethe. Ngakho-ke, izinhloso eziqondile zalolu cwaningo kwakuyilezi: i) ukubhala amathuba nezingqinamba zokukhiqiza i-sesame kanye nezinhlobo nezici ezikhethwa abalimi nezimakethe empumalanga naseningizimu-ntshonalanga ye-Ethiopia njengomhlahlandlela wokuzalanisa; ii) ukunquma izingxenye ezihlukene, ukutholakala komqondo obanzi (h2b) kanye nokuhlotshaniswa kwezici ezihlobene nembewu nesivuno sikawoyela ku-germplasm ye-sesame yase-Ethiopia ukuze zizale ngempumelelo; iii) ukunquma izinga lokuhlukahluka kofuzo phakathi kwamaqoqo e-sesame germplasm ayikhulu (100) ahlukahlukene ase-Ethiopia kusetshenziswa izimpawu ze-phenotypic kanye nezimpawu eziphindaphindayo ezilandelanayo, phecelezi, i-Simple Sequence Repeat (SSR) nokukhetha izinhlobo zofuzo ezihlukile nezihlukile zokuzalanisa kanye iv) ukunquma ukuhlukahluka kofuzo kanye nobudlelwano phakathi kwamaqoqo e-sesame germplasm yase-Ethiopia kusetshenziswa okuqukethwe kukawoyela wembewu kanye nokuqanjwa kwe-esidi enamafutha kanye nezimpawu zokuxilonga ze-SSR bese ukhetha imigqa yabazali eyingqayizivele nethembisayo yokuzalanisa. Kwenziwa imisebenzi yocwaningo eyahlukene kodwa ehambisanayo ukuze kuzuzwe izinjongo.

Ucwaningo lokuqala lwenziwa kusetshenziswa i-participatory rural appraisal (PRA) ebandakanya abalimi abayikhulu namashumi aysithupha (160) ezifundeni ezimbili ezikhethiwe ezitshala i-sesame kanye nezifunda ezine e-Ethiopia. Ingxenye enkulu yabalimi abaphendulile (56.0%) babike ukuthi balima i-sesame besebenzisa izimbewu zezinhlobo ezingaziwa ezivame ukutholakala emkhakheni wembewu ongekho emthethweni. Izithiyo ezibaluleke kakhulu ekukhiqizweni kwe-sesame ezindaweni zocwaningo kwaba ukuntula ukufinyelela kwembewu ethuthukisiwe (okubikwe ngabangu- 83.0% abaphendulile), isivuno esiphansi sezinhlobo ezikhona (73.8%), izifo (69.4%), kanye nentengo ephansi yemakethe (68.8%). Lezi zingqinamba zidalwe ukushoda kohlelo oluzinikele lokuzalanisa, umkhakha wembewu osemthethweni, izinsiza eziqinile zokwandisa, kanye nengqalasizinda ethuthuke kahle ngaphambi nangemuva kokuvuna. Okubaluleke kakhulu izici ezikhethwa yizimakethe ze-sesame zihlanganisa imbewu yohlobo lwangempela, umbala wembewu emhlophe, nokuqukethwe kwamafutha embewu ephezulu. Intengo enengqondo yemakethe, ukumelana nezifo zezitshalo, ukubekezelela isomiso, ukumelana nezinambuzane zezitshalo, isivuno esiphezulu sembewu, isisindo sembewu eyinkulungwane, uwoyela ophakeme, umbala wembewu emhlophe, ukuvuthwa ngaphambi kwesikhathi, kanye nezimfanelo ezinhle zikawoyela njengephunga nokunambitha kwaba izici ezibalulekile ezikhethwa ngumlimi ngokulandelana kokubaluleka. Ngakho-ke, lezi zici kufanele zihlanganiswe ezinhlelweni zamanje nezesikhathi esizayo zokuzalanisa ama-sesame.

Ucwaningo lwesibili luhlole i-germplasm ye-sesame eyikhulu (100) ngaphansi kwezimo zensimu ezindaweni ezimbili kusetshenziswa idizayini ye-lattice engu-(10 x 10) enezimpinda ezimbili. Okutholakele kuveze inani eliphakeme le-genotypic coefficient ye-variation kanye namanani e-h2b yenani lamagatsha ayisisekelo, (i-NPB), inombolo yamagatsha esibili, phecelezi, number of secondary branches (NSB), isisindo sembewu eyinkulungwane, (i-TSW), isivuno sembewu ngehektha ngalinye, (i-SYH) kanye nesivuno samafutha ngehektha ngalinye, (i-OYH), ephakamisa ukuthi izinzuzo eziphezulu zofuzo zingatholakala ngokukhethwa. Imiphumela eqondile ephakeme ye-OYH kanye nenani lembewu nge-capsule ngayinye (NSPC) zarekhodwa ezithinta i-SYH, kuyilapho i-SYH, inani lamaphilisi ngesitshalo ngasinye (NCPP) kanye ne-TSW ibe nomthelela oqondile ophezulu ku-OYH. I-Genotypes u-Hirhir Kebabo Hairless-9, i-Setit-3, i-Orofalc ACC-2, i-Hirhir Humera Sel-6, i-Setit-1 kanye ne-ACC-NS-007(2) bakhethelwe ukuqhubeka nokuzalaniswa ngokusekelwe emvuzweni yabo ephezulu yembewu, okuqukethwe kukawoyela namafutha. Engxenyeni yesithathu yocwaningo, okufakiwe okuyinkulungwane (1000) kwe-sesame kwahlolwa ezindaweni ezimbili e-Ethiopia ukuze kutholwe izici ze-agro-morphological kanye nokuqukethwe kwamafutha embewu kusetshenziswa idizayini ye-lattice engumashumi aphindwe kashumi (10 × 10) enezimpinda ezimbili. Futhi, ukuhlolwa kohlobo lwe-genotype kwenziwa iphrofayili kusetshenziswa omaka be-SSR be-polymorphic abangamashumi amabili nesikhombisa (27) e-Oil Crops Research Institute ye-Chinese Academy of Agricultural Sciences. Ukuhlaziywa kokuhluka kuveze okubalulekile (p ≤ 0.05) ukungena ngokusebenzelana kwemvelo ngobude besitshalo, ubude be-internode, inombolo yamagatsha esibili, nesivuno sokusanhlamvu. Ama-Genotypes afana no-Hirhir Kebabo Hairless-9, i-Setit-3, i-Orofalc ACC-2, i-Hirhir Humera Sel-6, i-ABX = 2-01-2, kanye ne-Setit-1 erekhodiwe isivuno sokusanhlamvu esingu->0.73 ton ha−1. Isivuno sokusanhlamvu sasinezivumelwano ezinhle nezibalulekile (p <0.01) nesivuno samafutha (r = 0.99), okuwusizo ekukhetheni ngesikhathi esisodwa. Ukuhlukahluka kwezakhi zofuzo okumaphakathi kanye namanani okuqukethwe kolwazi lwe-polymorphic we-0.30 no-0.25 arekhodwa ngokusekelwe ekuhlaziyweni kwe-SSR, ngokulandelanayo. Izinhlobo ze-genotype zahlukaniswa zaba amaqembu amabili namaqembu amane, amakhulu, ahlukene ngokusekelwe ekuhlaziyweni kweqoqo kanye nesakhiwo sabantu, ngokulandelana, ngaleyo ndlela kuvumela ukukhetha nokuwela okulandelayo ukuze kuthuthukiswe imiphakathi yokuzalanisa futhi kuthuthukiswe izimila. Ngokusekelwe ekwehlukeni kwe-phenotypic kanye ne-genomic, lawa ma-genotype alandelayo aphezulu futhi ahambisanayo akhethiwe: u-Hirhir Humera Sel-6, u-Setit-3, u-Hirhir Kebabo Hairless Sel-4, u-Hirhir Nigara 1st Sel-1, u-Humera-1 no-Hirhir Kebabo Early Sel-1 (kusuka ku-cluster II-a), i-Hirhir kebabo hairless-9, i-NN-0029(2), i-NN0068-2 kanye ne-Bawnji Fiyel Kolet, (kusuka ku-cluster II-b). Ama-genotype akhethiwe azosebenza njengabazali bohlelo lokuzalanisa u-sesame e-Ethiopia.