Vegetative Propagation methods theory Ebenezar Asaah ICRAFWCAHT BP

Vegetative Propagation methods - theory Ebenezar Asaah ICRAF-WCA/HT BP 16317 Yaounde, Cameroon Tel: (+237) 223 75 60 Fax: (+237) 223 74 40 Email: e. asaah@cgiar. org 1 African Humid Tropics Regional Programme – World Agroforestry Centre

Topics for discussion Definition of vegetative propagation l Vegetative propagation methods l Rationale for vegetative propagation l Application of vegetative propagation in the domestication of Agroforestry trees: case of Allanblackia l 2 African Humid Tropics Regional Programme – World Agroforestry Centre

Definition of Propagation l What is propagation? l l l Propagation is the natural mechanism by which plants regenerate. Propagation is most often by seeds produced by a plant or by plant parts like vines, roots, tubers, stem cuttings etc. . 3 African Humid Tropics Regional Programme – World Agroforestry Centre

Vegetative Propagation l Asexual propagation (vegetative propagation) = reproduction of plant material from vegetative organs (leaf, stem, root, bud) so that the offspring will contain the exact characteristics of the parent plant with regards to genotypes and health status. 4 African Humid Tropics Regional Programme – World Agroforestry Centre

Vegetative Propagation method… 1 Cuttings: severed uninodal leafy shoot or root fragments usually place into a suitable rooting substrate and kept under high humidity in propagators until adventitious roots and shoots are formed respectively. 5 African Humid Tropics Regional Programme – World Agroforestry Centre

Allanblackia propagation by cuttings Coppice shoots Weaned cuttings Cuttings in propagator CS of propagator African Humid Tropics Regional Programme – World Agroforestry Centre 6

Vegetative Propagation method… 2 l Grafting is a technique used to untie ‘parts’ of different plants by bring the cambium of each into contact and then creating a situation under which the cut surfaces can unite and grow away together. Field grafted AB wilding Yaounde, Cameroon 7 African Humid Tropics Regional Programme – World Agroforestry Centre

Grafting terminologies l Scion -The part of the graft that will provide the new system. The scion maybe united either at the apex or side of the rootstock. l Rootstock – the lower part of the graft. It normally posses a root system that will support the subsequent shoot development from the scion 8 African Humid Tropics Regional Programme – World Agroforestry Centre

Grafting of Allanblackia 9 African Humid Tropics Regional Programme – World Agroforestry Centre

Grafting of Allanblackia l Grafting experiments registered 80 % survival rate in A. gabonensis and flowering while still in the nursery. 10 African Humid Tropics Regional Programme – World Agroforestry Centre

Grafting of Allanblackia l In situ grafting of A. floribunda wildings and coppiced shoots under shade open light registered 45% vs 35% survival rate respectively. 11 African Humid Tropics Regional Programme – World Agroforestry Centre

Vegetative Propagation method… 3 l l l Air layering (marcotting) technique is similar to cuttings with the advantage that the propagule is detached from the parent tree only after development of roots. Its multiplication rate is lower than that of cuttings Used in capturing the attributes of elite trees within genetically diverse wild populations, so avoiding the long, slow process of tree breeding. Rooted Marcot 12 African Humid Tropics Regional Programme – World Agroforestry Centre

Air layering Allanblackia trees 13 African Humid Tropics Regional Programme – World Agroforestry Centre

Capture of traits by air layering Noel cultivar 14 African Humid Tropics Regional Programme – World Agroforestry Centre

Vegetative Propagation method… 5 Micropropagation specialized propagation with small pieces of plant tissues on artificial media under sterile conditions. It embraces the regeneration from: §shoot & root tips, §callus tissue, § leaves, §seed embryo, §anthers and even single cells. 15 African Humid Tropics Regional Programme – World Agroforestry Centre

When is it appropriate to use vegetative propagation l When the species in question: l l l is an out breeder; is dioecious; has recalcitrant seeds; has low germination rates; flowers and fruits erratically and; to capture their genetic diversity. 16 African Humid Tropics Regional Programme – World Agroforestry Centre

Rationale for vegetative propagation. … 1 l Maintaining superior genotypes l Most tropical tree species are outbreeders implying that through the recombination of genes during sexual reproduction, many important characteristics might disappear. If a superior individual tree has been identified by farmers or researchers, its genetic information can be 'fixed' through vegetative propagation, thus allowing the reproduction of the same superior individual in the next generation 17 African Humid Tropics Regional Programme – World Agroforestry Centre

Creation of a cultivar Variation in Allanblackia fruits Anticipated earlier fruiting, smaller trees and uniform quality Allanblackia fruits 18 African Humid Tropics Regional Programme – World Agroforestry Centre

Rationale for vegetative propagation. … 2 l Problematic seed germination and storage l l Some tree species produce seedless fruits (e. g. off-season Dacryodes edulis, ) and need to be propagated vegetatively, others bear fruit very scarcely or erratically (Prunus africana) or seeds difficult to gereminate (Allanblackia spp). In these cases, vegetative propagation might be a suitable and cheaper alternative to seedling production. 19 African Humid Tropics Regional Programme – World Agroforestry Centre

Rationale for vegetative propagation. … 3 Shortening time to flower and fruit l Most vegetative progaules originate from scions or cuttings from mature trees, and maintain the characteristics of maturity after grafting or rooting. Flowering Allanblackia graft African Humid Tropics Regional Programme – World Agroforestry Centre 20

Rationale for vegetative propagation. … 4 l Combining more than one genotype in one plant l l l Grafting is a unique way of combining desired characteristics from two or more plants into a single one. Graft scions with particular fruit characteristics onto rootstocks with other desirable characteristics: l disease resistance and adaptability to environmental constraints. Another possibility is the grafting of more than one cultivar or species onto the same stem, for example Irvingia gabonensis (sweet fruits) grafted to an Irvingia wombolu (bitter fruits) rootstocks and a male AB pollinator branch grafted to a female tree. 21 African Humid Tropics Regional Programme – World Agroforestry Centre

Rationale for vegetative propagation. … 5 l Uniformity of plantations l For many commercially grown species, Irvingia spp, Dacryodes edulis, Cola spp, Allanblackia spp. etc. uniformity of growth form or fruiting season is important economically. 22 African Humid Tropics Regional Programme – World Agroforestry Centre

Application of vegetative propagation in Tree domestication l Selection and Capture of desirable traits l l Mass propagation l l Suitable techniques include layering (marcotting) and grafting Suitable techniques include propagation by cuttings and to a lesser extent grafting. Micropropagation is most suitable but expensive and skill demanding. Tree Improvement l Vegetative propagation techniques can provide an exact copy of the mother tree from which the seed was harvested and retain the desired fruit quality in the following generation if the traits are heritable 23 African Humid Tropics Regional Programme – World Agroforestry Centre