Genetic diversity of Uapaca kirkiana Muel. Årg. populations as revealed by amplified fragment length polymorphisms (AFLPs)

Uapaca kirkiana is a priority fruit tree species for domestication in miombo woodlands of Southern Africa. Natural populations of U. kirkiana are declining through out the woodlands due to deforestation, forest fragmentation and wildfires. Knowledge of population structure and genetic diversity is prerequisite for development of conservation strategies. Amplified fragment length polymorphisms (AFLP) were used to assess the genetic diversity of eight populations from three geographical regionsof Malawi. AFLP markers revealed moderate differentiation (GST =0.079) among the populations collected from the three regions, however, there were no significant genetic variations among the regional collections. Analyses of molecular variance (AMOVA) found very high variation (92%) among individuals within populations and 6.8% among populations. The variations between populations indicate that populations can not be considered a single panmictic unit. Analyses of genetic similaritybased on unweighted pair group method of arithmetic averages (UPGMA) suggested that the 8 populations fall into three clusters with 5 populations in one cluster, two in another and the lake shore population of Chesamu in its own cluster. Based on results presented it would be cost effective tosample a small number of populations represented by a large number of individuals for germplasm conservation purposes. In view of the wide distribution of U. kirkiana in the miombo woodlands in Southern Africa there is need for a more intensive genetic study to include populations growing in different countries to produce a wider picture of levels of distribution of genetic diversity of the specie

Genetic diversity of Annona senegalensis Pers. populations as revealed by simple sequence repeats (SSRs)

Annona senegalensis Pers. is one of the wild fruit tree for domestication in southern Africa. An assessment of the genetic diversity in A. senegalensis would assist in planning for future germplasmcollection, conservation and fruit domestication programmes. During 2004 to 2006 nine populations were collected from different locations in Malawi and genetic diversity was evaluated using microsatellites or simple sequence repeats (SSRs) developed in Annona cherimola. In total 23 alleles were detected in the populations studied and genetic diversity parameters revealed high levels of heterozygosity with 4.0 to 14 alleles per locus and the populations were genetically different by 19% as given by the value of theta. Results demonstrated association between genetic and geographical distance in the species indicating that large-scale geographical and ecotypic differentiation wasreflected by the SSR markers. The high genetic diversity is attributed to biological characteristics of the tree species and habitat heterogeneity. The study has revealed evidence of application of SSR markersfrom A. cherimola towards genetic fingerprinting of A. senegalensis. Implications of the SSR marker data for optimizing genetic management of the species are discussed

Morphological characterization of cashew (Anacardium occidentale L.) in four populations in Malawi

An assessment of the genetic diversity in cashew (Anacardium occidentale L.) would assist in planning for future selection of good high yield germplasm that will produce nuts of high quality and fetch highprices on the market. The genetic diversity and relationship among 40 accessions of cashew collected from 4 populations (Liwonde, Nkope, Kaputu and Chikwawa) was characterized using quantitative andqualitative traits. The study results have revealed similarity values between 35 to 66%. Analyses of genetic similarity based on unweighted pair group method of arithmetic averages (UPGMA) grouped the 40 accessions into 4 clusters with 14 sub-clusters and the principal component analysis revealed that apple length, apple nut ratio, nut weight, kernel weight, out turn percent and flower sex ratio accounted for most of the variation. The variation could be attributed to genetic history, ecogeographic origin andselection for desired agronomic traits by farmers. Accessions LW41, NE2, NE4, CH18 and PAL26 showed potential for selection in nut and kernel weight and out turn percent suggesting that this could be a valuable source of variation for tree improvement programme in cashew nuts. The findingssuggest availability of broad genetic base that could be exploited for future cashew selection and breeding in Malawi

Yield performance of dwarf bean (Phaseolus vulgaris L.) lines under Researcher Designed Farmer Managed (RDFM) system in three bean agro-ecological zones of Malawi

An on-farm study was carried out under rain-fed condition in 2003 - 2004 and 2004 - 2005 growing seasons in five sites namely Ntchenachena and Ngong’a in Rumphi district, Chipuka in Ntchisi district, Thondwe and Matapwata in Zomba and Thyolo districts respectively representing three bean agroecological zones of Malawi. Seven dwarf bean entries; DC 96-95, PC 490-D8, BCMV-B2, SDDT-54-C5, APN 130, F6BC (19) and DOR 715 were evaluated for their yield stability across sites and two seasons under Researcher Designed Farmer Managed (RDFM) system. Yield stability of the entries across years varied significantly. Entries SDDT-54-C5, PC490-D8 and DOR 715 were stable across all sites and between the two seasons. DOR 715 was also high yielding entry in Thondwe and Ntchenachena sites followed by BCMV B2 though the latter was unstable. Among sites, Thondwe was the best because yields of most of the bean entries were stable at this site

Performance of climber common bean (Phaseolus vulgaris L.) lines under Researcher Designed Farmer Managed (RDFM) system in three bean agro-ecological zones of Malawi

An on-farm study was carried out in 2003-2004 and 2004-2005 growing seasons under rain-fed condition in five sites namely Thondwe and Matapwata in Zomba and Thyolo districts respectively, Chipuka inNtchisi district, Ntchenachena and Ngong’a in Rumphi district representing three bean agro-ecological zones of Malawi. Seven climber common bean entries; CAB 19, RWV 1046, BCMV B4, AND 659, RWV1042-2-3, 5P/5 and DC 86-244 were evaluated for their performance and stability across sites and two seasons under Researcher Designed Farmer Managed (RDFM) system. Entries DC 86-244, AND 659 andBCMV B4 were early maturing in most sites of the trial. DC 86 244 and AND 659 were also high yielding and had larger seed sizes compared to other entries. RWV 1046 and RVW 1042-2-3 were also highyielding though had smaller seed sizes. Stability analysis identified entries CAB 19 and DC 86 244 as stable entries across sites and seasons. Among environments, Ng’onga, Chipuka and Thondwe werehigh yielding. Ntchenachena was more stable but lower yielding compared to other sites. Matapwata was highly unreliable as heavy rains followed by dry spells characterised the site which resulted in lossof all bean entries in 2004-2005 growing season

Indigenous knowledge of rural communities in Malawi on socio-economic use, propagation, biology, biodiversity and ecology of Uapaca kirkiana Muell. Arg

Uapaca kirkiana Muell Arg. is one of the most popular indigenous fruit trees in the Miombo woodlands of southern Africa. An investigation into existing indigenous knowledge and socio- economic use ofthis fruit tree was conducted in Malawi. The survey revealed that U. kirkiana fruits contribute considerably to livelihood as a food supplement and for income generation among local communities.However, U. kirkiana trees are not widely cultivated due to lack of improved planting materials and difficulties in establishment outside their natural habitats. The results from the survey indicate thatfruits are the main non-timber products that contribute to demand for domestication and the attributes preferred by the rural communities for improvement are mainly related to fruit taste and yield. Poormanagement and anthropogenic activities have resulted in the destruction of forest reserves and the local people do not have maximum stewardship of U. kirkiana trees in the forest reserve. Theindigenous knowledge on U. kirkiana trees provides a valuable basis for domestication, propagation and improvement of fruit and tree attributes, and management issues on both co-managed and government forest reserve

Application of amplified fragment length polymorphism (AFLPs) for detection of sex–specific markers in dioecious Uapaca kirkiana Muell. Årg.

Uapaca kirkiana Muell. Årg is a dioecious fruit tree species for priority domestication in Southern Africa. It reaches reproductive maturity in eight to ten years with male plants making up 50% of breeding populations. Early identification of sex of seedlings is a prerequisite for selection and tree improvement. The amplified fragment length polymorphism (AFLP) technique was used to amplify DNAsegments of U. kirkiana male and female plants to identify sex-specific markers. A total of 84 selective primer combinations were screened using bulked segregant analysis (BSA) for males and females.More than 110 polymorphic markers were obtained but each of the four primer pairs (E-ACT/M-CTG, EACA/ M-CAA, E41+A/M-CTA and E-AGG/M-CTC) showed one band that was linked to sex. When the fourprimer pairs were tested in ten individuals from different populations only one primer pair (E-ACT/MCTG) amplified a 320 bp band in female plants only. It is possible that this marker is linked to a sexdetermininglocus. The results suggest that the gene that determines sex of U. kirkiana is autosomal in nature and this marker may be important during fruit domestication and tree improvement programmes. The marker has been sequenced and sequence characterised amplified region (SCAR) marker will be developed and used for precise and rapid identification of female plants

Performance of parental genotypes and inheritance of Angular Leaf Spot (Phaeosariopsis griseola) resistance in the common bean (Phaseolus vulgaris)

Two studies, one on performance of six common bean parental genotypes and another on inheritance of resistance to Phaeosariopsis griseola (Pg) in the common bean were carried out in Malawi. Common bean entries namely; Chimbamba, Nasaka, RC 15, CAL 143 and Mexico 54 were evaluated on station in the 2004/2005 growing season at Bunda, Dedza, Ng'onga and Ntchenachena sites. The second study started by generating F1s and then F2 and F3 seeds in greenhouse at Bunda College. CAL 143 and Mexico 54 were sources of Pg resistance genes while Chimbamba, Nasaka and RC 15 were susceptible recipient parents. Following green house trials, Pg resistance was evaluated on station in the samesites. CAL 143 was highest yielding but unstable across sites. RC 15 was stable and gave the highest yield at the dry-spell-stricken Ng’onga whereas Mexico 54 was superior at Ntchenachena but highly unstable across sites. Yield was strongly correlated to number of effective pods per plant in all genotypes. The inheritance study showed that resistance to Pg in the common bean is controlled by one gene using both CAL 143 and Mexico 54 as resistant parents.&#160

Phenotypic variation in fruit, seed and seedling traits of nine Uapaca kirkiana provenances found in Malawi

Uapaca kirkiana is one of the priority indigenous fruit tree species for domestication in southern Africa. Natural populations of U. kirkiana are declining due to deforestation, forest fragmentation and wildfires. Knowledge of genetic variation is prerequisite for development of conservation strategies. A provenance evaluation study was conducted at Bunda College of Agriculture in Lilongwe, central Malawi to determine the variability in fruit, seed and seedling characteristics of nine populations found in the southern, central and northern regions of Malawi. Results showed significant differences (P≤0.05) between provenances in fruit weight, seed weight, seed length and seed width. The central Malawi provenances of Dzalanyama and Chimaliro had the heaviest mean weight of fruits of 23.9g and 23.8 g respectively, the lightest fruits (14.6g) were found in Namoni Katengeza provenance. There were no significant differences (P ≤0.05) in number of seeds per fruit within and between provenances. The provenances differed significantly in cumulative germination percentage, ranging from 26% for Tsamba provenance in southern Malawi to 87% for Dzalanyama provenance in central Malawi. There was a consistent regional variation in stem collar diameter and height growth with central Malawi (Dzalanyama and Chimaliro) and northern Malawi provenances having taller seedlings ranging from 5.2 to 9.0 cm, with the exception of Namoni Katengeza provenance in central Malawi. The root collar diameters were significantly higher for Dzalanyama and Chimaliro (2.5 to 3.9 cm) than southern Malawi provenances whose seedling collar diameter averaged 2.3 centimetres. The nursery provenance trial has shown existence of considerable variation in seed germination, fruit and seed traits in U. kirkiana. Seed and seedling growth traits may prove to be important criteria for selection of provenances for domestication to provide farmers with sustained fruit production for consumption and economic benefits. Keywords: domestication, germination, height, indigenous fruit, seed, seedling, provenance, Uapaca kirkiana Southern African Forestry Journal Vol. 208, 2006: 15-2

Minituber production potential of selected Potato (Solanum tuberosum L.) genotypes in different propagation media

Potato farmers in Malawi and other developing countries lack healthy and quality potato seed. This is mainly due to limited seed multiplication programmes to provide farmers with clean potato seed. A study to evaluate minituber production potential for selected genotypes in different media types would assist in planning for future selection of good high yielding varieties. It will also assist in planning for rapid seed multiplication programme of pathogen free planting materials to increase production of potato in the country. Three different propagation media (vermiculite, sand and sawdust) and seven different genotypes (two local genotypes- Magalabada and Rosita, five introduced genotypes-Up to date, Buffelspoort, Van der plank, Lady Rosetta and Bp 1 2007) were investigated. Plantlets grown on vermiculite performed better with higher mini tuber yield of 1740 g/m2 for all genotypes while 850 and 292 g/m2 in sand and sawdust, respectively. Among the genotypes ‘Up to date’ and Lady Rosetta produced more tubers of between 12 tubers/plant and 10 tubers/plant. Thus, vermiculite increases the number and size of Minitubers which is a very important step for rapid multiplication of potato seed. The study findings provide valuable information for potential genotypes and propagation media to assist in scaling up seed multiplication programmes for pathogen free planting materials. Keywords: Propagation media, genotype, potato, minituber.African Journal of Biotechnology, Vol 13(48) 4430-443