Effect of seed size and pre-treatment methods of Bauhinia thonningii Schum. on germination and seedling growth

Bauhinia thonningii Schum. a multipurpose tree species found in the savanna wood lands is a priority tree species for conservation in Malawi. The different plant parts are used in traditional medicine to treat different ailments. However, the seeds are dormant and the tree species remain undomesticated. A study was conducted to evaluate the effect of pre-sowing seed treatment and seed size on germination and seedling growth of B. thonningii in a nursery at Bunda College. Seeds grouped into two categories: small (1 to 5 mm) and large (>5 to 10 mm) were subjected to five main pre-sowing seed treatment methods namely; soaking in cold water for 12 h, soaking in hot water for 10 min, nicking, soaking in potassium nitrate (0.2%) for 10 min and soaking in concentrated hydrochloric acid (0.3 M) for 5 min, and a control where seeds were sown without any treatment. The results showed that the combination of nicking and large seeds produced the highest (100%) germination and highest height and diameter growth. Hot water treatment was also observed to be effective in both seed sizes producing 40 and 53.3% germination for small and large seeds, respectively. The increased seed germination and height for physically scarified seeds through nicking suggest that seed dormancy in B. thonningii is mainly due to relatively hard seed coat which renders the seed testa impermeable to water and gases required for germination process.Key words: Bauhinia thonningii, dormancy, germination, pre-sowing treatment, seed size

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 within and among Southern African provenances of Uapaca kirkiana müell. Årg using morphological and AFLP markers

Domestication of Uapaca kirkiana Müell. Arg is a high priority for improving rural livelihoods of smallholder farmers in southern and eastern Africa. Domestication efforts require knowledge of ecological adaptive traits and intra-specific variation. Morphological traits and amplified fragment length polymorphic (AFLP) markers were used to assess genetic variation in twelve provenances of U. kirkiana collected from five countries in southern and eastern Africa. Assessment of tree morphological traits showedsignificant differences (p< 0.05) between provenances where Zimbabwean and Zambian provenances grew much faster than those from Tanzania and Malawi (except Phalombe). Mean Nei’s (H) genetic diversity of AFLP showed high diversity within the provenances H= 0.181 to 0.321 with mean of 0.256. An analysis of molecular variance (AMOVA) showed that most genetic variation (90.8 %) resided within provenances, while only 8.2 % was variation among provenances. There was no geographical pattern of variation in growth and morphological traits among the seed sources. Chipata provenance from Zambia was the most diverse while Mapanzure from Zimbabwe was the least diverse but more superior in height growth and earliest in fruiting. The pattern of genetic diversity in U. kirkiana indicates existence of genetic drift and high gene flow between provenances suggesting that regional collections and conservationstrategies should consider differences by focussing on the main range of the species.Keywords: AFLP - Conservation-Domestication- Genetic diversity- Provenance- Uapaca kirkiana- UPGM

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

A decision support tool for propagating Miombo indigenous fruit trees of southern Africa

Indigenous fruit trees (IFTs) contribute to the livelihoods of rural households as sources of food, income and medicine. Conservation and domestication of IFTs involve germplasm selection, collection,multiplication and evaluation. In addition, biodiversity and genetic improvements have been realized through propagation. However, there are numerous challenges when propagating indigenous trees andthe choice of appropriate propagation techniques determines the success of domestication programme. In this paper we synthesize different propagation methods used for indigenous fruit trees,and propose a decision support tool based on desirable attributes of individual IFT, technical requirements, expertise of the propagators and relative cost of implementing the technology in addition to field performance and tree management. Depending on circumstances, this decision support tool can be used to quickly choose a propagation method for a given fruit tree so as to maximize on germplasm collection, multiplication and evaluation without compromising field performance and management of the fruit trees

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

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

Effect of seed collection times and pretreatment methods on germination of Terminalia sericea Burch. ex DC

A nursery experiment was conducted to study the effects of seed collection times and pretreatment methods on the germination of Terminalia sericea Burch. ex DC. (Combretaceae). T. sericea is amultipurpose tree species occurring in the miombo woodlands whose seedling production is hampered by very low seed germination rate. Seeds were subjected to four treatment methods each at fourdifferent duration of exposure; soaking in hot water, immersion in concentrated sulphuric acid (95%), nicking and soaking in cold water and fire scorching. First collection was done when 60% of the fruitswere deep-green to brown while second collection was done when all fruits were purple-brown to pinkpurple. Nicking and soaking in cold water for 12 h gave the highest cumulative germination percentage(51%) for the first collection and appears to be the most feasible and suitable pretreatment method for small scale farmers than use of sulphuric acid. Soaking in hot water for 15 and 20 min and immersion inconcentrated sulphuric acid (95%) for 3 and 4 h gave poorest germination (0%). However, in the second collection, use of concentrated sulphuric acid for 2 h gave highest germination (14%) followed by nicking and soaking in cold water for 24 h (12%). Sulphuric acid is expensive, requires proper handling techniques; therefore nicking and soaking in cold water for 12 h is being recommended as a cheaper and less hazardous pretreatment method to improve germination in T. sericea