School of graduate studies environmental science program
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- Bu səhifədəki naviqasiya:
- Investigation of Desiccation Sensitivity of Seeds and Ethnobotany of Syzygium guineense ( Willd.) DC.
- Investigation of Desiccation Sensitivity of Seeds and Ethnobotany of Syzygium guineense (Willd.) DC.
- TABLE OF CONTENTS ........................................................................................................................ II
- LIST OF FIGURES ................................................................................................................................ IV
- 1 INTRODUCTION ................................................................................................................................. 1
- 2 LITERATURE REVIEW .................................................................................................................. 6
- 3. MATERIALS AND METHODS ....................................................................................................... 19
- 4. RESULTS AND DISCUSSION ......................................................................................................... 25
- 5. CONCLUSION AND RECOMMENDATIONS .............................................................................. 34
- 7. APPENDICES..................................................................................................................................... 47
- List of Figures
- 1 Introduction
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ADDIS ABABA UNIVERSITY SCHOOL OF GRADUATE STUDIES ENVIRONMENTAL SCIENCE PROGRAM
Investigation of Desiccation Sensitivity of Seeds and Ethnobotany of Syzygium guineense ( Willd.) DC.
By Sinework Dagnachew
February 2008
Syzygium guineense (Willd.) DC.
By
Sinework Dagnachew
A thesis submitted to the School of Graduate Studies of the Addis Ababa University in partial fulfillment of the requirements for the Degree of Master of Science in Environmental Science
Addis Ababa University Faculty of Science, Environmental Science Program
February 2008 Addis-Ababa
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Acknowledgement
First and for most I would like to express my deepest sense of gratitude and the heart felt appreciation to my advisors Dr. Girma Balcha and Dr. Zemede Asfaw for their consistent and stimulating advice, valuable suggestions, providing appropriate books and critical reading of the manuscripts.
I am also very grateful to the Institute of Biodiversity Conservation (IBC) for the provision of vehicles and laboratory facilities. I also wish to extend my sincere thanks to Forestry Department of IBC for field trip facilitation, staff assignment and office and its facilities provision during the write up of my thesis. I thank members of drying room and germination laboratory technicians of the Institute of Biodiversity Conservation for their hospitality and for so generously sharing their time with me throughout my laboratory work.
I also wish to thank tree seeds laboratory technicians of Forestry Research Center (FRC) for their advice and encouragement during germination experiment of my study.
Finally, I would like to thank all my families and friends who gave me unconditional help through out my educational life.
Thanks to God!
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Table of Contents ACKNOWLEDGEMENT......................................................................................................................... I
1.1
B ACKGROUND AND JUSTIFICATION ................................................................................................... 1
1.2 P ROBLEM STATEMENT ..................................................................................................................... 4
1.3 O BJECTIVES OF THE STUDY ............................................................................................................... 5
2.1
C ONSERVATION MEASURES OF BIODIVERSITY ................................................................................... 6
2.2 R OLES OF SEED BANKING FOR BIODIVERSITY CONSERVATION ........................................................... 8
2.3 E STABLISHING PRIORITIES FOR PLANT CONSERVATION PROGRAM ..................................................... 9
2.4 S EED STORAGE BEHAVIOR AND GENERAL STORAGE PRINCIPLES ..................................................... 10
2.5 A PPROACHES TO PREDICT STORAGE BEHAVIOR OF SEED ................................................................. 12
2.6 F ACTORS AFFECTING SEED LONGEVITY ........................................................................................... 14
2.7 S EED AGEING .................................................................................................................................. 16
2.8 D ESCRIPTION OF S YZYGIUM GUINEENSE ......................................................................................... 18
3.1
S TUDY SITE AND SPECIES IDENTIFICATION ...................................................................................... 19
3.2 F IELD AND LABORATORY METHODS ................................................................................................ 20
3.3. S AMPLING ...................................................................................................................................... 22
3.4 G ERMINATION EXPERIMENTS .......................................................................................................... 22
3.5 E THNOBOTANICAL DATA COLLECTION ............................................................................................ 24
3.6 D ATA ANALYSIS .............................................................................................................................. 24
4.1
I MPACTS OF DESICCATION ON THE GERMINATION OF SEEDS OF S. GUINEENSE ................................ 25
4.2 E THNOBOTANY OF S. GUINEENSE .................................................................................................... 29
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List of Tables Table 1. Results of one way analysis of variance (ANOVA) for germination tests..... 26
Table 2. Local peoples' perception of factors threatening S. guineense in Regi, West Arsi Zone of Oromia Region ............................................................................ 31
Table 3. Local people’s perception about conservation status of S. guineense in Regi, West Arsi zone of Oromia Region.................................................................. 33
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List of Figures Figure 1. Processing of S. guineense seeds at IBC ........................................................ 21
Figure 2. An illustration of the set up used for the germination experiment................ 23 Figure 4. Germination percentage of the seeds of S. guineense after desiccation to different levels of moisture .............................................................................. 27
Figure 5. Germination percentages of seeds of S. guineense after storage at different moisture content for different weeks .............................................................. 28
Figure 6. Local uses of S. guineense in Regi, West Arsi Zone of Oromia Region........ 30
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Abstract
afromontanum (Myrtaceae) were investigated based on both field and laboratory experiments. The field study component includes ethnobotanical data and seed collection. The laboratory work includes moisture content determination and viability test. Desiccation sensitivity of seeds were assessed based on germination tests following desiccation and indigenous knowledge of the local communities using semi structured interview in the locality of Bombaso Regi peasant association of Arsi Negele Woreda, West Arsi Zone of Oromia Region where the seeds were collected. Seeds with initial moisture content of 51% had 99% germination percentage. The germination percentage declined significantly following desiccation until none of the seeds germinated at 24% moisture content. The germination percentage declined slowly from 99% (initial) to 78% at 37% moisture content. There was an abrupt loss of germination percentage from 78% to 16% below 37% moisture content which indicates that the critical moisture content was around 37%. The result has shown that seeds are very sensitive to desiccation which exhibited that the species could be classified as recalcitrant seed storage behaviors. It was also investigated that the local people have considerable indigenous knowledge about this tree and its use as construction material, timber, fuel wood, charcoal making, and local medicine and as wild edible fruit have been recorded. In addition to having desiccation-sensitive seeds, the plant has been locally threatened with high degree of exploitation with no actions of conservation. Therefore, there should be urgent implementation of conservation options suitable for the species. In addition to in-situ conservation options further research should be done to find suitable alternatives for long term conservation option as cryopreservation.
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Plants are vital part of world’s biological diversity and essential resources for human well- being. Forests play particularly important roles in peoples’ livelihoods by providing goods and services. Besides crop plants that provide the basic food, many thousands of wild plants have great economic and cultural importance and potential to provide food, medicine, fuel, clothing and shelter for vast number of people throughout the world. Forests provide services such as waste absorption, regulating soil erosion, maintenance of the natural balances of water bodies, reduction of greenhouse gases and provision of aesthetic values. Trees are the basic constitute of forests and have essential roles in protecting the soil from erosion by wind and water, providing fuel wood, fodder for livestock and habitats for wildlife.
Different factors have contributed to the very high rate of deforestation. Increasing demand for agricultural land as a result of the growth of population, settlements and increasing investment needs are subjecting the natural forest resources to decline. Due to agricultural expansion naturally occurring plant species are replaced by the small number of introduced species. In tropical areas, forests are cleared and converted into permanent arable land under permanent cultivation. Seeds of climax tree species become scarce for regeneration and woody growths are eliminated by continuous burning and weeding (Demel Teketay, 1996).
condition are little or none which makes the situation both worst and alarming (Elias Taye, 2004). Forests are being destructed even before they have been surveyed, described and studied thoroughly (Demel Teketay, 1993). Legesse Negash (1995) pointed out that some decades ago Ethiopia was covered by various indigenous tree species including Podocarpus, Acacia, wild olive and others. About 35% (42 million hectare) of the land cover of Ethiopia was once covered with high forests (EFAP, 1994). It was also reported that the high forest cover was 3.6% by the early 1980s, 2.7% by 1989 and less than 2.3% in 1994; IBCR, 2001 According to Girma Balcha (1996), Seed storage for genetic conservation in Ethiopia concentrated mainly 2 on agricultural species. But now, research towards the preservation of plant material should be crucial before it is too late to save forest seed particularly of rare species.
According to Taye Bekele (2004), knowledge of the genetic structure, mating system and storage behavior of the tree/shrub species is necessary for the selection of appropriate conservation measures to achieve specific conservation objectives. One of the methods to preserve tree species is storage of their seeds in genebanks. Unfortunately, not all seeds can be stored without loss of viability.
To survive long-term storage in the dehydrated state, seeds have to be able to withstand
desiccation to low water contents. A large group of so-called orthodox seeds have this ability, whereas another group of mainly
tropical seeds, designated recalcitrant, are damaged during
drying. The ability of seeds to tolerate desiccation could play a role in determining conservation strategies.
seeds which can be desiccated to 2-6% moisture level (Hong and Ellis, 1996). Recalcitrant seeds killed by desiccation at high moisture level as high as 20-30% and are difficult to manage; hence they cannot withstand moisture loss without loss of viability (Pritchard et al., 2004). The third category which is intermediate between orthodox and recalcitrant seeds can
withstand partial dehydration, but they cannot be stored under conventional genebank conditions because they are cold-sensitive
and desiccation does not increase their longevity (Ellis et al., 1990; Girma Balcha et al., 2000).
As many tree species or their habitats are being threatened, it is important to learn about the seed biology of these species (Demel Teketay, 1993). Knowledge of the storage behavior of tree species is necessary for the selection of appropriate conservation measures to achieve specific conservation objectives. In order to obtain preliminary information for their storage it is important to examine the desiccation responses of seeds of unknown storage behavior.
A successful reforestation program depends on a continuous supply of healthy seedlings. This process begins with successful seed collection, storage, processing and sowing practices (Leaden, 1996). Inadequate work has been done on establishing the seed storage behavior of native species resulting in only limited availability of ex-situ conservation seed collection
3 especially with respect to native forest species (Girma Balcha et al., 2003). Studies undertaken on Coffee arabica (Ellis et al., 1990) and Podocarpus falcatus (Girma Balcha, 1996; Girma Balcha, 2000) classified these species as having intermediate storage behavior.
Endemic and threatened plants can be protected directly through establishment of seedbanks and indirectly through the documentation of information concerning the geographic distribution and population size of target plants and threats to them. Indigenous people in an area can be sources of information about individual species using ethnobotanical studies. Ethnobotany is quantitative evaluation of the use and management of plant resources (Martin, 1995). Ethnobotanical studies also used raise awareness in local communities as discussions are set in motion during data collection.
Ethiopia. S. guineense has become one of the species which needs urgent need of conservation actions (Elias Taye, 2004). Girma Balcha (1996) also claimed that the species is one of Ethiopia’s indigenous tree species with no published reports on the storage behavior of the species. The species is in the list of priority species for conservation by IBC along with Hagenia abyssinica , Cordia africana, Podocurpus falcatus, Prunus africana, Accacia abyssinica and many other indigenous tree species (Taye Bekele et al., 2004).
The main purpose of this research was to investigate the desiccation sensitivity and to asses the available ethnobotanical information on S. guineense. This species has three subspecies in Ethiopia and the present study is based on S. guineense (Wild.) DC. ssp. afromontanum. F. White (Friis, 1995).
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