ADDRESSING CONSTRAINTS in PROPAGATION of Allanblackia Spp
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Journal of Experimental Biology and Agricultural Sciences, February - 2015; Volume – 3(1) Journal of Experimental Biology and Agricultural Sciences http://www.jebas.org ISSN No. 2320 – 8694 ADDRESSING CONSTRAINTS IN PROPAGATION OF Allanblackia spp. THROUGH SEED SECTIONING AND AIR LAYERING Ofori D A1,*, Asomaning J M2, Peprah T2, Agyeman V K2, Anjarwalla P1, Tchoundjeu Z3, Mowo J G1 and Jamnadass R1 1World Agroforestry Centre, United Nations Avenue, Gigiri , Box 30677-00100, Nairobi, Kenya 2 CSIR-Forestry Research Institute of Ghana, P. O. Box UP63, KNUST, Kumasi, Ghana 3World Agroforestry Centre, WCA Regional Office, Box 16377, Yaounde, Cameroon Received – December 18, 2014; Revision – January 05, 2015; Accepted – February 23, 2015 Available Online – February 23, 2015 KEYWORDS ABSTRACT Seed germination Allanblackia species are indigenous to West, East and Central African regions with the potential of providing an alternative source of income for rural populations through sale of seed oil. The species Vegetative propagation therefore needs to be domesticated to support sustainable production of Allanblackia seed oil. Propagation of Allanblackia parviflora through seed germination and air layering was therefore Allanblackia undertaken. Stratified and non-stratified seeds or seed sections were germinated in sand, plain and black polythene bags. Air layering was undertaken on pollarded shoots growing on 1.5, 4 and 6m stumps Seed oil using coir dust as the medium. At 90 days, germination of un-stratified seeds showed significant differences for the following treatments; proximal sections (0 – 54%; p < 0.0001), longitudinal sections Marcotting (0 – 44%, p < 0.0001) and whole seed (13 - 31%, p < 0.0001). Germination of stratified seeds and seed sections also showed significant differences; proximal sections (37 - 53%, p < 0.0001), whole seed (21 - 32%, p < 0.0001). Distal seed sections did not germinate but only produced seed roots. For air layering, rooting success (P < 0.05) declined with increasing stump height from 72% to 21.4% for 1.5m and 6m stumps respectively. The results are discussed in relation to mass propagation of Allanblackia spp. to support large scale cultivation. * Corresponding author E-mail: [email protected] (Ofori D A) Peer review under responsibility of Journal of Experimental Biology and Agricultural Sciences. Production and Hosting by Horizon Publisher (www.my-vision.webs.com/horizon.html). All _________________________________________________________rights reserved. Journal of Experimental Biology and Agricultural Sciences http://www.jebas.org 90 Ofori et al 1 Introduction and incubation in plain and black polythene bags at 23-30oC, leading to seed germination of 75% and 68% in 10 months Allanblackia parviflora belonging to the family Clusiaceae is respectively (Ofori et al., 2011). This calls for new methods an indigenous tree species in the West African sub-region. It like seed sectioning that has proved to be effective in hastening has a potential of providing a source of household income for seed germination in Garcinia spp. (Joshi et al., 2006; rural populations and can also contribute to forest landscape Asomaning et al., 2011) to be tested. Based on the fact that restoration by counteracting the impacts of climate change, due Allanblackia is a dioecious species, seedlings produced may to its ability to grow in varying environmental conditions either be male or female (Peprah et al., 2009; Ofori et al., (Peprah et al., 2009). Other uses of this species include shade, 2014- Unpublished), and also have long gestation period ≥ 6 timber, medicine and seed oil for food and cosmetic products years, there was a need to explore for asexual propagation (Irvine 1961; Ofori et al. 2006).Traditionally oil extracted from method for production of true-type planting stocks (Hartman et the seed has been locally used for cooking and soap making al., 2011) that would also have short gestation period (Ofori et (Ofori et al., 2006). The seed oil is the most economic product al., 2008; Hartman et al., 2011). of the species and pressed crude oil from the dry seeds (at 3.1- 5% moisture content) is about one-third of seed dry weight 2 Materials and methods (Attipoe et al., 2006; Sefa et al., 2010). In the international market over 100,000 tons of Allanblackia oil is annually 2.1 Seed germination required but only about 200 tons are supplied annually on average from Ghana (A. parviflora= 40 tons), Nigeria (A. Seed segments namely: distal sections (DS), proximal sections floribunda= 20 tons) and Tanzania (A. stuhlmannii= 150 tons) (PS) and longitudinal sections (LS) were cut from freshly (Oppong, 2008; Kattah, 2010). Therefore, there is a need to extracted seeds of A. parviflora without seed coat using a sharp domesticate Allanblackia to sustain the supply of Allanblackia knife. Fifty seed segments each of the above named sections seeds to feed both the local and foreign markets. and / or whole seeds were prepared in four replicates and placed in plain polythene, black polythene or black polythene In an effort to domesticate a new tree crop like A. parviflora bag further enclosed in plain polythene bag without adding any and promote its cultivation on a large scale, there is a need to germination media. Seed sections/seeds were sparingly sprayed develop methods for propagation for sustainable supply of with fine mist of tap water and the open end of the polythene adequate quantity of quality planting stocks for development of bags sealed. All samples were kept in a plant house at Forestry agroforestry systems and plantations. Previous studies have Research Institute of Ghana, Kumasi. An ambient temperature shown that Allanblackia species were difficult to propagate of 23-30°C was maintained. Samples were opened and through traditional methods of propagation and thus efforts sparingly sprayed with water at intervals of 2 weeks during the must be harnessed to overcome the challenges of period of observation. domestication of the species (Anegbeh et al., 2006; Atangana et al., 2006; Ofori et al., 2008; Asaah et al., 2011; Ofori et In another set, freshly extracted whole seeds were placed in al.,2011; Ofori et al., 2013). A. parviflora seed germination moistened sand in sealed plastic bags with some perforations. rate is very slow. For instance, a seed lot usually take a long The plastic bags with seeds were stored in an incubator at period to complete germination, normally over three years temperature 25±2ºC for the seeds to undergo a period of warm (Ofori et al., 2008). Seed dormancy in A. parviflora, partly stratification for 28 days after that seeds were removed, associated with a thick and hard seed coat, contributes to the washed in tap water and prepared into various sections as lack of uniform seed germination and subsequent plant growth described above and placed for germination in polythene bags (Ofori et al., 2011). Thus the use of seeds and seedlings in A. as done for seeds that were not stratified. Treatments were parviflora domestication is therefore limited by the long seed arranged in randomized complete block design with 4 dormancy period, its recalcitrant nature, and limitations in seed replications at the plant house. Seed sections were counted storage technology of the species (Ofori et al., 2011). Current after germination when radicle and plumule attained at least best practice for seed germination is the removal of seed coat 1cm long. Table 1 Number of trees pollarded, height of pollarding and layers set Height of pollarding (m) No. of Pollarded trees No. of layers set 1.5 7 20 4.0 4 20 6.0 4 14 Total 15 54 _________________________________________________________ Journal of Experimental Biology and Agricultural Sciences http://www.jebas.org Addressing constraints in propagation of Allanblackia spp. through seed sectioning and air layering 91 2.2 Air layering soil (forest soil + soil collected under Allanblackia tree at a ratio of 3:1) and placed in a weaning chamber that maintains Fifteen (15) trees were pollarded at three different heights (1.5, high humidity (RH ≥ 75%) to reduce transpiration in order to 4 and 6 m high) and allowed to coppice. Air layering was help the plant to recover from shock and to develop extensive undertaken on the coppiced shoots by removing 10cm of the root system to absorb enough soil nutrient solution. bark of each selected shoot growing on the pollarded trees (Figure 1). Figure 2a Whole seed showing epicotyl at proximal ends and seed roots at the distal ends. Figure 1 Air layering on shoots growing on a tree pollarded at 2.3 Data analysis 1.5 m high. For seed germination, data per replicate were presented in Due to the differences in coppicing ability of Allanblackia percentages. The percentage data were arcsine transformed to trees, the number of layers set for the different treatments conform to normal distribution before subjecting them to varied (Table 1). Another set of air layers was set up on the analysis of variance using SAS 9.2 edition. Mean separation same trees during the same season in the following year and was done by using least significant difference (LSD). Results these two sets of air layers were treated as replicates. The were presented graphically and LSD values inserted on the rooting medium used was coir dust, which was applied at the graphs to depict significant differences among treatments. place of bark removal and tied securely with a string. Layering experiment was analysed by transforming number of Assessment was done at four weeks after layering and then two rooted layers per treatment (pollarding height) into weeks intervals afterwards. The distal ends of the layered percentages, as (x/y)*100, where x = number of successful shoots were removed to enhance production of fresh shoots layers and y = total number of layers set. The transformed data just after root development. Successful layers were harvested were then used for analysis of variance, using Microsoft Excel for potting at four weeks after severance of the distal ends.