An Economic Assessment of Banana Genetic Improvement and ...

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40 CHAPTER 4 Figure 4.1 Introduction of exotic banana cultivars to Kagera Region by farmers Uganda (Gros Michel 1970s) Rwanda and Burundi (Bluggoe 1960s and Pisang Awak 1960s) Kagera Region Kilimanjaro and Tanga (Mtwishe 1980s and Mshale 1990s) Tanzania western regions; Kigoma (Bluggoe 1960s and Pisang Awak 1960s) Tanzania coast region (Kiguruwe 1980s) Tanzania southern highlands; Mbeya (Plantains 1950s) Source: Personal interviews with farmers in Kagera Region conducted by M. S. R. Byabachwezi and J. M. Nkuba. Note: In each box, the name of the region is provided, along with the name of the cultivar and the approximate period of introduction in parentheses. The solid arrows indicate the original introduction of the exotic cultivars, and the broken arrows denote subsequent exchange of planting material across regions. Germplasm Selection and Improvement Strategies Farmer Introductions of Exotic Planting Material Over the decades, farmers have continually sought pest- and disease-free planting material through exchange with farmers in other regions. For example, in Kagera Region, oral interviews with farmers suggest that a number of “exotic” (nonendemic, nonhybrids) cultivars grown today were introduced over the decades from Uganda, Rwanda, Burundi, and the coastal areas and southern highlands of Tanzania. These include Kijoge (Gros Michel, also known as “Bogoya” in Uganda), Kisubi/Kainja (Pisang Awak), Mtwishe (Medium Cavendish), Kiguruwe (Short Cavendish), Bluggoe, Plantains, and Mshale. Some EAHBs were taken from Kagera Region to other areas, where they are known as “Ndizi Bukoba” or “Ndizi Uganda.” Grande Naine, another exotic cultivar, was introduced through unknown channels in 1993 (Figure 4.1). here> 1near 4.
IMPROVED BANANA CULTIVARS AND MANAGEMENT PRACTICES 41 1990, diagnostic studies were conducted to identify and quantify banana production constraints. These studies were followed by collection of endemic germplasm with the aim of searching for cultivars resistant to the pests (weevils and nematode) and diseases (especially black Sigatoka). For the purposes of evaluating endemic materials for yield, pest, and disease reaction, two germplasm collections were established at Makerere University Agricultural Research Institute, Kabanyolo (MARIK), and Kawanda Agricultural Research Institute (KARI). Endemic germplasm was collected from farmers in different parts of the country. Development of New Genotypes in Uganda Formal banana breeding did not begin in Uganda until 1994. First, studies were conducted to identify fertile female banana cultivars (with potential to set seeds when pollinated) from the assembled set of endemic cultivars and pollen-fertile diploid clones to serve as sources of desirable attributes. A study of female banana fertility, conducted from 1996 and 1998, identified 12 of the most fertile EAHBs in the collection (Ssebuliba 2000). In addition to the low seed set in the endemic cultivars, a seed germination of only 1 percent was recorded when the seeds were sown directly into soil. Embryo culture, which is now a routine practice in Uganda, is used to improve the germination of hybrid seeds derived from inter- and intraspecific crosses. The seeds are surface sterilized and aseptically cracked to expose the embryo. The embryo is extracted and inoculated onto an appropriate medium (Murashige and Skoog 1962) to achieve germination. Seedlings are subsequently micropropagated to obtain several shoots for field evaluation. Embryo culture has increased the seed germination rate to 9 percent compared to 1 percent germination previously obtained by sowing the seeds directly into nursery potting mixture (Ssebuliba 2000; Ssebuliba et al. 2006). The first hybrids selected from the crossing of the triploid landraces (3×) and the resistant diploids (2×) were tetraploids (4×, or four sets of chromosomes). They were very fertile and therefore easily set seeds in the presence of a pollen source. The presence of seeds in bananas, especially cooking varieties, poses a quality problem and is not desirable. To circumvent this problem, the tetraploids are crossed with improved diploids to get secondary triploids (3×) that are sterile. As of mid-2005, 11 secondary triploids had been selected for in-depth screening, targeting selection of clones in which the desired traits have been maximally accumulated. The best-yielding highland bananas proved sterile and hence not amenable to conventional breeding. Genetic engineering, through which desirable genes can be inserted directly into plant cells and thus plants (new genotypes) can be regenerated without passing through seeds, appears to be the only alternative for improving these cultivars. The known method through which new genes can be engineered into bananas is based on cell suspension, where aggregations of single cells are first generated. Desirable trait genes are then inserted into these cells, after which the process of selecting transformed cells and regenerating them into plants for subsequent evaluations follows. Efforts to establish the system are progressing well, and the first plants regenerated from single cells of an EAHB cultivar (Nakyetengu) are planted out in the field to test the extent to which they are true to type (Namanya et al. 2004). Nakyetengu is now in field evaluation, and no somoclonal variation has been observed to date. Three other EAHB cultivars (Mpologoma, Nakinyika, and Nakasabira) have been regenerated and planted for field evaluation. Suspension culture methods are now being optimized for a wide range of cultivars, and arrangements to initiate gene insertions are in their final stages.
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An Economic Assessment of Banana Ge
Page 3 and 4:
Contents List of Tables List of Fig
Page 5 and 6: Tables 3.1 Net marketing margins pe
Page 7 and 8: TABLES vii 6.5 Characteristics of h
Page 9 and 10: Figures 2.1 Sample domain: Elevatio
Page 11 and 12: Acknowledgments The International F
Page 13 and 14: SUMMARY xiii en’s education--and
Page 15 and 16: Acronyms and Abbreviations AGT ARDI
Page 17: Part I. Research Methods
Page 20 and 21: 4 CHAPTER 1 practices in Africa are
Page 22 and 23: 6 CHAPTER 1 periment station. Not a
Page 24 and 25: 8 CHAPTER 1 niques (based on seed p
Page 26 and 27: 10 CHAPTER 1 Cohen, J. I., and R. P
Page 28 and 29: CHAPTER 2 Elements of the Conceptua
Page 30 and 31: 14 CHAPTER 2 ples of adoption disco
Page 32 and 33: 16 CHAPTER 2 transgenic bananas cur
Page 34 and 35: 18 CHAPTER 2 Figure 2.2 Sites sampl
Page 36 and 37: 20 CHAPTER 2 Figure 2.4 Time profil
Page 39: Part II. Research Context
Page 42 and 43: here> 1near 3. 26 CHAPTER 3 major f
Page 44 and 45: 28 CHAPTER 3 disease, which affects
Page 46 and 47: here> 1near 3. 30 CHAPTER 3 Table 3
Page 48 and 49: 32 CHAPTER 3 Table 3.2 Banana produ
Page 50 and 51: 34 CHAPTER 3 would only be able to
Page 52 and 53: 36 CHAPTER 3 Nkonya, E., J. Pender,
Page 54 and 55: here> 1near 4. 38 CHAPTER 4 cash ne
Page 58 and 59: 42 CHAPTER 4 Research Introductions
Page 60 and 61: 44 CHAPTER 4 Table 4.2 Names of the
Page 62 and 63: 46 CHAPTER 4 The most widely used m
Page 64 and 65: 48 CHAPTER 4 Ortíz, R., and D. Vuy
Page 66 and 67: here> 5.3near here>
Page 68 and 69: 52 CHAPTER 5 Table 5.4 Percentage o
Page 70 and 71: 54 CHAPTER 5 Table 5.7 Percentage o
Page 72 and 73: here> 9near 5. here> 10near 5. 56 C
Page 74 and 75: here> 12near 5. 58 CHAPTER 5 Table
Page 76 and 77: 60 CHAPTER 5 Table 5.14 Number and
Page 78 and 79: here> 18near 5. 62 CHAPTER 5 Table
Page 80 and 81: 64 CHAPTER 5 Table 5.20 Average num
Page 82 and 83: 66 CHAPTER 5 Table 5.23 Percentage
Page 84 and 85: 68 CHAPTER 5 Table 5.26 Average dis
Page 86 and 87: 70 CHAPTER 5 considerably higher in
Page 89: Part III. Economic Assessment of Te
Page 92 and 93: 76 CHAPTER 6 The agricultural house
Page 94 and 95: 78 CHAPTER 6 grow, but have grown i
Page 96 and 97: 80 CHAPTER 6 Table 6.2 Summary stat
Page 98 and 99: 82 CHAPTER 6 tion. More frequent vi
Page 100 and 101: 84 CHAPTER 6 Table 6.4 Prototype ho
Page 102 and 103: 86 CHAPTER 6 Table 6.5 Characterist
Page 104 and 105: 88 CHAPTER 6 References Cameron, A.
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90 CHAPTER 7 by-products of other f
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here> 1near 7. 92 CHAPTER 7 Table 7
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94 CHAPTER 7 ity in the two technol
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96 CHAPTER 7 Table 7.2 Definition o
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98 CHAPTER 7 The direct link betwee
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100 CHAPTER 7 Table 7.3 Factors inf
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102 CHAPTER 7 tive sign but are onl
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104 CHAPTER 7 fertility management
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106 CHAPTER 7 participatory decisio
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108 CHAPTER 7 Stevens, J. P. 2002.
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110 CHAPTER 8 defined as a function
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112 CHAPTER 8 inputs or implement c
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114 CHAPTER 8 Crop output is determ
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116 CHAPTER 8 Table 8.1 Variable de
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here> 8.6near here> 8.2near 8.3nea
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120 CHAPTER 8 Table 8.4 Production
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122 CHAPTER 8 during the SOM decomp
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124 CHAPTER 8 Supplementary Tables
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126 CHAPTER 8 Table 8A.3 Production
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128 CHAPTER 8 Thomas, G. W. 1982. E
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130 CHAPTER 9 (Nkuba et al. 1999).
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132 CHAPTER 9 be reduced through la
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134 CHAPTER 9 Table 9.2 Summary sta
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136 CHAPTER 9 Table 9.3 Coefficient
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138 CHAPTER 9 Table 9.4 Mean compar
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140 CHAPTER 9 References Anandajaya
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142 CHAPTER 10 Table 10.1 Ugandan c
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144 CHAPTER 10 (Kangire and Rutherf
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146 CHAPTER 10 Table 10.4 Predomina
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here> 7near 10. 148 CHAPTER 10 Tabl
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150 CHAPTER 10 Table 10.8 Present v
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152 CHAPTER 10 In terms of specific
Page 171:
Part IV. Conclusions
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158 CHAPTER 11 in cooking, brewing
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160 CHAPTER 11 sumption and income
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162 CHAPTER 11 4. 5. for which the
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APPENDIX A Banana Taxonomy for Ugan
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BANANA TAXONOMY FOR UGANDA 167 Tabl
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BANANA TAXONOMY FOR UGANDA 169 Tabl
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BANANA TAXONOMY FOR TANZANIA 171 Ta
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BANANA TAXONOMY FOR TANZANIA 173 Ta
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APPENDIX C Use of Improved Banana V
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DETAILS OF SAMPLE SURVEY DESIGN 177
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Page 197 and 198:
Page 199 and 200:
VILLAGE SOCIAL STRUCTURE IN UGANDA
Page 201 and 202:
List of Principal Authors and Contr
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ABOUT THE AUTHORS 187 rigation, and
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