Conventional And Non Conventional Propagation Of Tree Species: Development Of Appropriate Methods For Arid Land Tree Propagation
Mbaratha, Jane Mumbi
MetadataShow full item record
Three species ef Terminalia L namely T. brownie, T. kilimandscharica and T. spinosa were used for the experimentation. The trees were located in different regions in the dry zones of Kenya. Seeds were collected from the trees at different maturity stages and tried for germination in different conditions. Hydration of the mature seed was assessed to determine the hydration curves of the seeds and deduce if the entry of water and its status of the seed would hinder the prompt germination of the seed after direct sowing. The mature T. spinosa seeds were found easy to germinate if picked before the hardening of the peri carp , unlike the T. brownii and T. kilimandscharica seeds. It was established that the barrier to prompt germination after direct sowing was due to the hard pericarp. The hard coat allowed entry of water into the seed through the suture but there was no way out foi the radicle. The seed had to lie in the ground for long periods while mictobial attack weakened the pericarp. After the rainy season, the hydrated seed was able to force open the pericarp and emerge through the suture. Different pre-treatments were tried to weaken the perlcarp. Acids softened the hard coat allowing faster hydration. No prompt germination, however, was obtained after planting acid treated seeds, raising the possibility of a gaseous exchange barrier to germination. Mechanical extraction though tedious, proved successful. The extracted seed easily germinated if micro-organisms' contamination was avoided. This was achieved through the use of sterile media and a fungicide (Zineb) that controlled fungal attack, where sterile soil and vermiculite were used. Vegetative propagation, using cuttings and micropropagation techniques was carried out on these trees. The cuttings though, thought to be potentially an easy and cheap method, proved unsuccessful. Leafy, central and basal cuttings were tried with and without use of a rooting hormone (Indole butyric acid) in different propagating media. Meristem culture, shoot tip culture, leaf culture and stem culture were tried In different sterile media with limited success.