Phenotypic Diversity among Faba Bean (Vicia faba L) Landraces from the Ethiopian Highlands

አህፅሮት ባቄላ በኢትዮጵያ የብዝሀነት ስርጭት ያለዉና ፈርጀ-ብዙ የአመራረት፣ የአመጋገብና የጤና ጠቀሜታ ያለው ሰብል ቢሆንም ምርታማነቱ በተለያዩ ማነቆዎች የተነሳ በሰፊው ከሚመረቱት የጥራጥሬ  ሰብሎች አንፃር እጅግ ዝቅ ያለ ነው፡፡ በመሆኑም የባቄላ ዝርያ ብዝh zRN ተለያይነት ማጥናት  እነኚህን የምርት ማነቆዎች ተቋቁመው የተሻሻሉ ምርት ሊሰጡ የሚችሉ ዝርያዎችን ለማግኘት ዕድል ይፈጠራል፡፡ የዚህ ጥናት ዓላማ ከኢትዮጵያ የባቄላ አምራች ደጋማ xካባቢዎች ከአገርአቀፍ የደጋ ጥራጥሬ ምርምር ምንጮች እንዲሁም ከአለም አቀፍ ምርምር ተቋማት የተገኙ 50 የባቄላ ብዝሃ-ዘሮችን በሆለታ ምርምር ማዕከል ውስጥ Randomized Complete Block Design ዘርቶ በመገምገም ያላቸውን የዝርያ ተለያይነት፣ ብዝሃነትና ስብጥር ምን እንደሚመስል ለማወቅ ሲሆን የዚህ ጥናት መረጃዎች በ ቫሪያንስ፣ bክሊስተር እና bፕሪንሲፓል ኮምፖንነት ትንተና ዘዴዎች ትንተና ውጤት እንdሚያመለክተዉ በባቄላ ብዝሃ-ዘሮቹ ስብስቦች መካከል ከፍተኛ የሆነ በሽታ የመቋቋም፣ የሞርፎሎጂ ባህሪያት፡ የምርታማነት እና የምርት ኮምፖነንት  ተለያይነት  እንዳላቸዉ ይጠቁማል፡፡ በተጨማሪ የክላስተር ትንተና በጥናቱ ውስጥ የተካተቱ 50 የባቄላ ብዝሃ-ዘሮችን ሶስት ቦታ ሲመድባቸው፤ በተለያየ ንዑስ ቡድን ተከፋፍለዋል፡፡ የዚህ ጥናት ውጤት በአጠቃላይ  የእነዚህ በባቄላ ብዝሃ-ዘሮቹ ስብስቦች መካከል መለያየት ዝርያ ለማሻሻያ መልካም አጋጣሚነትን  በመጠቀም በባቄላ ምርት ማሻሻያ ምርምር  ውስጥ ለመጠቀም የሚያስችል የባቄላ የብዝሃ-ዘር ተለያይነት እንዳለ በጥናቱ ይጠቁማል፡፡    AbstractKnowledge of phenotypic diversity is important for devising the breeding strategy for faba bean (Vicia faba L.) program in Ethiopia. This study was conducted to determine phenotypic diversity among 50 faba bean genotypes collected from the major faba bean growing areas of Ethiopia and International Centre for Agricultural Research in the Dry Areas (ICARDA). The genotypes were evaluated at two locations using a randomized complete block design with three replications. All agronomic data, yield and yield component, chocolate spot (Botrytis fabae) disease incidence disease severity were collected and analyzed using analysis of variance, principal component analysis and the Shanon-Weaver index, using SAS V9.3 and PAST V 3.0 software. There were significant differences (p< 0.001) among the genotypes on most of phenotypic traits, chocolate spot disease severity, yield and its component. The genotypes were categorized into three clusters and different sub-groups. Six principal components were identified explaining more than 80% of the total variation. The Shannon-Weaver diversity index, which ranged from 3.82 for pod weight to 7.15 for number of basal branches per plant, revealed high diversity among and within the genotypes. The observed high variation among the faba bean genotypes would be exploited in new faba bean varieties development program

Genetic variability among wheat (Triticum aestivum L.) germplasm for resistance to spot blotch disease

Spot blotch caused by Bipolaris sorokiniana (Sacc.) Shoem. is the most devastating disease limiting wheat productivity in warm and humid environments. One hundred and fifty wheat genotypes were evaluated under field conditions in 2013 and 2014 in six different locations in Zambia. The genotypes showed different levels of resistance to spot blotch. Genotypes 19HRWSN6 (Kenya Heroe), 19HRWSN7 (Prontia Federal) and 19HRWSN15 (BRBT2/METSO) were resistant lines across environments. The genotype plus genotype by environment (GGE) biplot grouped the six environments (E) into three mega-environments (ME) with respect to spot blotch severity. ME I contained Golden Valley Agricultural Research Trust (GART) (E6) only. Mpongwe (E4), Mt. Makulu (E5 and E2) and GART (E3) formed ME II, while ME III contained only Mutanda (E1). Genotypes 16HRWYT5, SB50 and 20HRWSN33 were the most susceptible genotypes in ME I, II and III, respectively. Genotype 19HRWSN7 was the most resistant across test locations. The locations in ME III were highly correlated indicating that they provided similar information on genotypes. This suggests that one location could be chosen among the locations in ME III for screening spot blotch resistance each year if the pattern repeats across years. This could aid in reducing the cost of genotype evaluation and improve efficiency as genotypes would be handled in fewer environments

Farmers’ desired traits and selection criteria for maize varieties and their implications for maize breeding: A case study from KwaZulu-Natal Province, South Africa

Adoption of hybrids and improved varieties has remained low in the smallholder farming sector of South Africa, despite maize being the staple food crop for the majority of households. The objective of this study was to establish preferred maize characteristics by farmers which can be used as selection criteria by maize breeders in crop improvement. Data were collected from three villages of a selected smallholder farming area in South Africa using a survey covering 300 households and participatory rural appraisal methodology. Results indicated a limited selection of maize varieties grown by farmers in the area compared to other communities in Africa. More than 97% of the farmers grew a local landrace called Natal-8-row or IsiZulu. Hybrids and improved open pollinated varieties were planted by less than 40% of the farmers. The Natal-8-row landrace had characteristics similar to landraces from eastern and southern Africa and closely resembled Hickory King, a landrace still popular in Southern Africa. The local landrace was preferred for its taste, recycled seed, tolerance to abiotic stresses and yield stability. Preferred characteristics of maize varieties were high yield and prolificacy, disease resistance, early maturity, white grain colour, and drying and shelling qualities. Farmers were willing to grow hybrids if the cost of seed and other inputs were affordable and their preferences were considered. Our results show that breeding opportunities exist for improving the farmers’ local varieties and maize breeders can take advantage of these preferred traits and incorporate them into existing high yielding varieties

Combining ability analysis and heterotic grouping for grain yield among maize inbred lines selected for the mid-altitude and highland zones of Rwanda

Development and identification of maize parental lines that belong to different heterotic groups is a fundamental requirement for any hybrid production programme. The objective of this study was, therefore, to determine combining ability, heterosis and heterotic patterns for grain yield among ten selected local (unknown heterotic groups) and exotic (known heterotic groups) maize inbred lines and their progenies under mid-altitude and highland conditions of Rwanda. Forty-five single crosses from a 10 x 10 half-diallel mating design plus three checkswere tested in a 6 x 8 alpha-lattice design across twelve environments. General combining ability (GCA) and specific combining ability (SCA) effects were both highly significant (P<0.001-0.01), suggesting presence of both additive and non-additive gene effects. The percentage mid-parent heterosis (MPH) for grain yield ranged from36.4to 267.7% with a mean of 164%, while high-parent heterosis (HPH) varied from 33.2% to 236% with a mean of 130.4%. Based on MPH, the seven local maize inbred lines were discriminated and assigned into four different heterotic groups (S4, S7, S4/S6 and S6/S7). The highest heterotic patterns were realized between tester S4and tester S6 (hybrid S4/S6) and between group S7 and tester S4 (hybrid S2/S4). Identified patterns would be potentially useful for maize hybrid production in Rwanda. Similarly, the resulting hybrids could be recommended in sub-Saharan African regions with similar ecosystems. Significance of both additive and non-additive geneticeffects in the current germplasm suggests that the Rwandan breeding programme could use both hybridization and recurrent selection methods

Origin-dependence of variation in seed morphology, mineral composition and germination percentage in Gynandropsis gynandra (L.) Briq. accessions from Africa and Asia

Background: Spider plant [Gynandropsis gynandra (L.) Briq.], an economically promising African leafy vegetable, characterized for leaf yield components and nutritive quality, exhibits poor seed germination that hinders a wider expansion of the crop in urban and periurban horticultural systems. So far, there is little information pertaining to seed morphological traits and mineral elements content that may be associated with higher seed germination. This research investigated the hypothesis that spider plants from different geographical areas exhibited differences in seed mineral composition, morphological traits, and germination capacity. To this end, twenty-nine accessions of Gynandropsis gynandra from West and East-Southern Africa, and Asia were screened for variation in seed size (area, perimeter, length, width), 10-seed weight, mean germination time, germination percentage and mineral content variations. The scanning electron microscopy (SEM), light microscopy and energy dispersive spectroscopy (EDS) solution were used to study seed morphology and mineral composition. Results: We show for the first time the external and internal structure of the seeds of Gynandropsis gynandra and measured eight mineral elements, including carbon (C), oxygen (O), magnesium (Mg), aluminium (Al), phosphorus (P), sulphur (S), potassium (K) and calcium (Ca). The accessions differed significantly (p < 0.001) with respect to seed size (area, perimeter, length, width), 10-seed weight, mean germination time and germination percentage. The hierarchical cluster analysis based on fourteen variables grouped the accessions into three distinct clusters, partially dependent on their geographical origin. Asian accessions exhibited smaller seeds and recorded higher values in terms of germination percentage. West African accessions had bigger seeds but with lower germination percentage. Variation in minerals such as potassium, carbon, and calcium content showed different patterns according to geographical origins. Conclusion: Smaller seeds in G. gynandra exhibited better germination capacity. The Asian germplasm is a potential source of cultivars with a higher germination percentage for improving seed quality in the species.</p

Farmers’ perceptions of navy bean (Phaseolus vulgaris L.) production constraints, preferred traits and farming systems and their implications on bean breeding: a case study from South East Lowveld region of Zimbabwe

Background Navy bean is an important legume crop in Zimbabwe. Although its production in Zimbabwe is limited by multiple constraints including biotic, abiotic and socio-economic, there is no documented evidence. Thus, this study aimed at identifying farmers’ production constraints, preferred traits and cultivars of navy bean, and strategies used to mitigate some of these constraints. Methods A Participatory Rural Appraisal approach involving transect walks, focus group discussions (FGDs), and formal surveys with semi-structured questionnaires was conducted in four villages of the Lowveld region of Zimbabwe. In each of the four villages, two FGDs (one for men and one for women) were conducted. A total of 176 (75 males and 101 females) navy bean-growing households were interviewed. Data from household interviews and FGDs was analysed using the Statistical Package for Social Scientists computer package. Results The most important constraints to navy bean production were drought stress (Females—86%, Males—73%), heat stress (Females—58%, Males—55%), power outages (Females—46%, Males—54%), poor soil fertility (Females—32%; Males—33%) and susceptibility to pod shattering (Females—32%, Males—43%). Mitigation strategies included mulching (18%), ridges (12%), reduced acreage (11%), and cultivating to retain more soil moisture (11%) for drought stress, while irrigating at night (32%), and adjusting planting dates (29%) were used to manage heat stress. Farmer-preferred traits included tolerance to drought and heat, early maturing varieties and disease resistance. Marketing constraints included non-payment for produce in hard currency, lack of diversity in terms of off-takers, high inflation, low grain producer price, delayed payment and breach of contract by contractors. Conclusion There will be increased adoption of improved navy bean cultivars if breeding programs address the aforementioned constraints and consider farmer-preferred traits when developing new cultivars. Breeders should work closely with extension officers to ensure that cultivars released are cultivated with appropriate agronomic packages for increased productivity and high adoption

Genetic diversity among maize inbred lines selected for the mid- altitudes and highlands of Rwanda

Understanding the genetic diversity and relationships among breeding materials is fundamentally considerable for any crop improvement program. This study was carried out to apply specific single nucleotide polymorphism (SNP) markers to determine the amount of genetic diversity prevailing among maize inbred lines selected for the mid-altitudes and highlands of Rwanda and classify the inbred lines according to their relationships for an effective hybrid breeding program. Seventy one maize inbred lines from different sources were genotyped with ninety two SNP markers. The unweighted pair group method with arithmetic mean (UPGMA) revealed that there was a random allocation of the inbred lines into different clusters and they were allocated into 2 major clusters regardless their origin. The highest (0.375) polymorphic information content (PIC) observed was exhibited by 3 markers; PZA00543_12, PZA00878_2, and PZA01735_1; while the lowest PIC value was revealed by the marker PZA01755_1 (0.1224).The PIC value (0.30) revealed in this study may confirm the potential for these SNP markers to discriminate between inbred lines from diverse origins and their usefulness for diversity analysis of maize inbred lines under this study. Genetic clustering information acquired from the current study would be suitable information not only for maize hybrid program establishment in Rwanda, but also for other collaborative tropical maize breeding programs. This might guide towards suitable heterotic patterns and groups as well as the combining ability of the inbred lines involved in this study

Morpho-physiological and biochemical characterization of African spider plant (Gynandropsis gynandra (L.) Briq.) genotypes under drought and non-drought conditions

The African spider plant (Gynandropsis gynandra (L.) Briq.) is a nutrient-dense, climate-resilient indigenous vegetable with a C4 carbon fixation pathway. Understanding African spider plant drought tolerance mechanisms is essential for improving its performance in water-stressed areas. The objective of this study was to evaluate the stress tolerance potential of African spider plant accessions based on thirteen morphological, physiological, and biochemical traits under three different water treatment regimes. Eighteen accessions were evaluated over two growing seasons in the greenhouse using a split-split plot design with four replications and three water treatment-regimes namely optimum (100% field capacity), intermediate drought (50% field capacity) and, severe drought (30% field capacity). The results revealed that water regime had a significant effect (P&lt; 0.01) on the accessions for the traits studied. A significant reduction across most of the studied traits was observed under drought conditions. However, proline content in all the accessions significantly rose under drought conditions. The principal component analysis revealed a considerable difference in the performance of the 18 African spider plant accessions under optimum and drought stress conditions. Several morphological and physiological parameters, including days to 50% flowering (r = 0.80), leaf length (r = 0.72), net photosynthesis (r = 0.76) and number of leaves per plant (r = 0.79), were positively associated with leaf yield under drought conditions. Cluster analysis categorized the 18 accessions and 13 measured parameters into 4 clusters, with cluster-1 exhibiting greater drought tolerance for most of the studied traits, and cluster-4 having the most drought-sensitive accessions. Among the accessions tested, accessions L3 and L5 demonstrated excellent drought tolerance and yield performance under both conditions. As a result, these accessions were selected as candidates for African spider plant drought tolerance breeding programs. These findings will serve as the foundation for future studies and will aid in improving food and nutrition security in the face of drought

Genetic potential of tropically adapted exotic maize (Zea mays L.) heat-tolerant donor lines in sub-tropical breeding programs

Breeding for heat stress tolerance became a priority in sub-Saharan Africa (SSA), as projections are showing an increase in frequency, duration, and severity. In this study, 14 heat stress tolerant-donor lines (HSTDLs) sourced from CIMMYT-India (males) were crossed with 15 locally adapted elite lines (females) developed within the CIMMYT-Zimbabwe maize-breeding program using the North Carolina Design II mating scheme. The resultant 175 single crosses were evaluated alongside five commercial hybrids and adjacent to the trial of parental lines used in the crosses across two locations representing heat stress and optimal environments in Zimbabwe. The design II analysis showed significant (p < 0.01) general combining ability (GCA) effects for exotic heat donor lines and specific combining ability (SCA) effects on grain yield under heat stress, optimal conditions, and across locations; demonstrating additive and non-additive genetic inheritance of grain yield. High Baker’s ratios observed in this study indicate predominance of additive over non-additive gene effects. Three exotic HSTDLs, namely CAL14138, CAL152, and CAL1440, exhibited significant (p < 0.001) and positive GCA effects under heat stress conditions. The results imply that these exotic lines could serve as valuable genetic resources for introgression of heat tolerant alleles into local maize populations for accelerated yield genetic gains. Single crosses, DJ265-15 × VL1018816 and DJ267-9 × CAL1440, exhibited positive and significant (p < 0.01) and (p < 0.05) SCA effects for grain yield under heat stress conditions, respectively. These crosses can be used for further breeding and can contribute to grain yield performance under heat stress conditions. The exotic HSTDLs, CAL14138, CAL152, and VL109126 showed superior per se performance under heat, optimal conditions, and across environments. Overall data demonstrate the potential of exotic HSTDLs for improving the adaptation of maize to heat stress in sub-tropical breeding programs

Breeding investigations for resistance to Phaeosphaeria Leaf Spot (PLS) and other important foliar diseases and a study of yield stability in African maize germplasm.

Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2009.Abstract not available