FLOWERING AND FRUITING PATIERNS IN MILICIA EXCELSA AND MILICIA REGIA WELW. Risper Nyagoy Nyong'o,' J.R. cobbinah and J. Appiah-Kwarteng Forestry Research Institute of Ghana, UST P.O. Box 63, Kumasi, Ghana ABSTRACT -:._The reproductive biology of Milicia excelsa and M. regia was studied Tne major distinguishing traits were crown shape, bark texture and leaf traite such as shape, dimension, colour, number of lateral nerves and arrangement on branchelets. Male and female trees are distinguished by the size of crown and tree trunk, forking characteristics, and distribution and .abundance of )wers in the crown. Male flowers in general are longer and slender than Lenale flowers. It takes approximately 5-6 weeks from time of fertilization to fruit maturation. Premature abscission of fruits is not uncommon. Whiles fruiting may not occur every year the results suggests that in a good fruiting year odum tree can be quite prolific. The observational studies reported here have implications in breeding programme for odum. Keywords - Milicia spp., reproductive biology, flowering patterns, fruiting patterns INTRODUCTION Odum (Milicia excelsa and Milicia lata. The attack leads to formation regia) is one of the most important of galls by the leaves and buds. timber species found in Ghana. It's The insect attack is followed by trade name is Iroko. Milicia was dieback, resulting in retarded until recently known as growth and eventually death of the Chlorophora. It is used for plant (Taylor, 1960; Wagner et ai, construction work, joinery, cabinet 1991)• -making and native food mortars (Taylor,1960). Milicia spp. are not Odum suffers a high level of normally distinguished by the exploitation. Alder (1989) esti• timber trade, as the timbers are mated that if the current rate of very similar (Hawthorne, 1990). exploitation of odum continues, the species will cease to be of Odum is found throughout the high commercial importance by the end of forest zone, in the derived• the 20th century. The high rate of woodland, and in the riverine / exploitation coupled with poor riparian forest of savannah wood• natural regeneration makes the land which is in the Antiaris• futuJ:e of odum bleak. A lot more Chlorophora Association. It prefers work, therefore, needs to be done well drained soils and cannot stand to save this valuable species from impeded drainage (Taylor, 1960; possible commercial extinction. Hall & Swaine,1981). The natural range of odum stretches from the Lack of information on the island of Zanzibar off the coast of reproductive biology of odum is one eastern Africa to the Gambia in the major problem faced in the attempt west (White,1966). Efforts to to genetically improve odum. The establish odum plrtntations have reproductive biology of a species proved futile, mo. _:I because of controls the length of its breeding the severe attack f young shoots, cycle. It is not known exactly when especially on the leaves and buds odum starts flowering but it is by an adult psyl .d fly, Phytolyma speculated that it is after 25 to 'present address - Moi University, P.O.Box 3900, Kenya Ghana Journal of Forestry Vol.' '994 19 30 years of age (Britwum, pers. necessary. The cq.tkins were "com. ). Odum' s breeding system is enclosed in paper bags. Four allogamous, thus it has hetero• buckets were placed in the labo• genous populations of heterozygous ratory, two with a fan next to the plants, giving the tree breeder bags, two without a fan. The other more genetic material to ·two buckets were placed in a screen manipulate. A species breeding house. system dictates the breeding procedure that can be used and the Seed production extent to which recombination .can be manipulated. Knowledge of Nine trees were selected in the flowering age and breeding systems 1994 season for the study of seed ar~ especially important before production at the Afram Headwaters seed orchard establishment. This Forest reserve. The trees were paper is based on a study of selected on the basis of one or flowering and fruiting patterns in more of the following odum. characteristics: STUDY AREA AND METHODOLOGY The performance of progeny in a progeny trial. Location of specimen Trees Tree form. The study was carried out mainly on 35 odum trees growing in the wild Forking characteristics. at Afram Headwaters Forest Reserve which is about 30km north of Kumasi Heights were measured from ground town in the dry semi-deciduous level to the point of forking or to forest zone. Also utilised in the the point of the lowest branch. study were nine 20 year ol~ trees Diameter was measured at breast growing at Mesewam research nursery height (DBH), whereas form was about 15km South of Kumasi in the classified as either straight or moist semi-deciduous forest zone. crooked. The following grading procedure was used to quantify Flowering and Fruiting fruiting: The studu was dare during the o - No fruiting 1992/ 1')~ an-:> ':. ['S .993/199,1 flower.L',/ s~'~',so~.;j. "':'o'"er development and structure, fruit formation and morphology and seed 2 - Sparse fruiting production were among the factors that were studied. 3 - Moderately prolific Girdling 4 - Prolific Girdling to induce flowering was 5 - Very prolific tried on the 20 year old trees growing at Mesewam research Fifty strobili were collected from nursery, in December 1992/Janu~ry these trees and the number of seeds 1993. Position and size of girdles per strobilum per tree estimated. were varied, with girdles of 1.28, 2.56, 3.84 and 5.12cm made on primary and secondary branches. RESULTS AND DISCUSSION Pollen Handling Botany and Phenology of the tree Several techniques were used to DistLnguishing characteristics for determine the best method of pollen the two species are summarised in extraction. Flower bearing branches table 1. The leaves have lateral were collected and brought to the nerves, the number ranging from 7 laboratory. These were cut and to 18 depending on species (Table placed in buckets containing ~ater, 1). The ~~ves are simD~9 and In all there were s'x ~uckets with a.ltErnate ,..~-t,.i th·~'· 'lC. L~;'!.,Les each bucket 8ontdLn~ng five caducous~ Leaves or ~~ --,':~l~!1gs, branches. Water was cnanged daily ;lnl:L~e thGse of the '1'acur:2c tree and the branch butts were cut when have serrated edges. Of the 35 Ghana Journal of Forestry Vol.1 1994 20 Table 1. Distinguishing characteristics between M. excelsa and M. regia tree~ Characteristic M. excelsa M. regia Crown smaller, flat top, larger, rounded, lighter green dark green Bark dark with white dark, reddish mottles,--rough brown and smooth in texture Leaf -interno~e short (1-4.Scm) long (1.S-7cm) shape leaf blade narrow wide and rounder and long length:width 1.7:1 1.4:1 petiole long (3-Scm) short (1-3cm) texture soft and glossy hard and dull colour light green dark green lateral nerves 11-22 7-11 arrangement alternate alternate clustered Flowers borne in clusters borne singly Table 2. Distinguishing characteristics between male and female odum trees Characteristic Male Female Tree trunk long and slender thicker Crown small, narrow, wide, big and more compact, scattered, lighter in colour darker in colour Forking less frequent almost in all cases Flowering more profuse and less profuse and o~rqrs throughout occurs on the upper ..:rown,flowers and outer parts of rlier, over a the crown ~onger period and :ore frequently Ghana Journal of Forestry Vol.1 1994 21 Figure 1. Branchlet of M. excelsa"female treei- Gh8naJournal of forestry Vol.1 1994 Figure 2. Branchlet of M. regia female tree. GhanaJournal of Forestry Vol.1 1994 23 Figure ~ ..Branchlet of M. excelsa male tree. GhanaJournal of Forestry Vol. 1 1994 24 .. Catk.itlll Figure 4. Branchlet of M. regia male tree. 25 GhanaJournal of Forestry Vol.1 1994 trees studied, 18 were H. excelsa with male trees starting around the and the rest ,H. regia. Odum is last week of December until early dieocious. Dioecy is quite Har~h. Very old flowers were found widespread among tropical forest under' four mal~ odum trees in trees (Kramer & Kozlowski, 1979). February indicating that some trees Among the 35 trees, 22 were found may start flowering in the early to be female while 13 male. This part of December. Female trees gives an approximate ratio of 2:1. begin flowering later (early However, when the individual January). Considerable variability species are considered there were exists among trees with some trees 12 female and 5 male H. excelsa starting to flower in early March. trees; and 7 female and 10 male H. regia trees. Generally, male flowers bloom and ripen several days before the There are distinct differences in females, therefore, pollen is in flower structure. The male catkins the air by-the time the females are are long while females are shorter receptive. However, long after with many protruding styles female trees have stopped flowering (Hawthorne, 1990). Apart from the (towards the end of the flowering obvious difference in flower season) flowering is still evident structure, other traits have been among a few male trees. It is observed that clearly distinguish typical of dioecious species to males from females. These differ• show profound differences in many eRces are summarised in table 2. reproductive traits (Opler & Brown, 1978) among which is the timing, Flower development duration and frequency of flowering (Kapoor-Vijay & White, 1992). Odum trees do not flower every year. Some of the trees studied In the males, flower,ing starts on that flowered in 1992/1993 did not the upper crown of the tree and flower in 1993/199~ (Table 3). later spreads to the, lower Likewise, some trees thpt flowered branches.