Genetics of Witchweed (Striga Hermonthica (Del.) Benth) Resistance in Sorghum (Sorghum Bicolor (l.) Moench).
ABSTRACT
Study on the genetics of witchweed (Striga hermonthica (Del.) Benth) resistance in sorghum (Sorghum bicolor (L) Moench) was conducted in a randomised complete block design experiment at the Institute for Agricultural Research Samaru, (Northern Guinea Savanna 110 11′ N: 70 38′ E, 686m) Zaria, Kaduna state, Nigeria.
Five sorghum varieties: two Striga resistant varieties (ICSR94405 and ICSR94407) and three susceptible varieties, (SAMSORG40, SAMSORG14 and SAMSORG17) were used for the study.
The study was undertaken to determine the variability for resistance to Striga and other agronomic traits in sorghum, to determine inheritance of resistance to Striga in sorghum, gene action involved in the inheritance of Striga resistance in sorghum, and to determine genetic advance for Striga resistance and other agronomic traits in sorghum.
TABLE OF CONTENTS
Content……………………………………………………………………………Page
TITLE PAGE…………………………………………………………………………….i
DECLARATION …………………………………………………………………………………………… ii
CERTIFICATION ………………………………………………………………………………………… iii
DEDICATION……………………………………………………………………………………………… iv
ACKNOWLEDGEMENTS …………………………………………………………………………….. v
ABSTRACT ………………………………………………………………………………………………… vi
TABLE OF CONTENTS ………………………………………………………………………………. vii
LIST OF TABLES ………………………………………………………………………………………… ix
LIST OF FIGURES ………………………………………………………………………………………. xi
LIST OF ABBREVIATIONS ………………………………………………………………………… xii
1 CHAPTER ONE …………………………………………………………………………………….. 1
1.0 INTRODUCTION …………………………………………………………………………….. 1
1.1 General objective of the study: …………………………………………………………….. 3
2 CHAPTER TWO ……………………………………………………………………………………. 5
2.0 LITERATURE REVIEW……………………………………………………………………. 5
2.1 Striga plant ………………………………………………………………………………………. 5
2.1.1 Economic importance of Striga ……………………………………………………… 6
2.1.2 Mode of parasitism of Striga …………………………………………………………. 7
2.1.3 Effects of Striga on sorghum ………………………………………………………… 9
2.1.4 Mechanism of host response to Striga …………………………………………… 10
2.1.5 Germination stimulant production ………………………………………………… 12
2.1.6 Environmental requirement of Striga ……………………………………………. 14
2.1.7 Striga management ……………………………………………………………………. 14
2.1.8 Source of Striga resistance among cereals ……………………………………… 16
2.2 Breeding for durable resistance to Striga in sorghum …………………………….. 17
2.3 Heritability and Genetics of Resistance to Striga in Sorghum ………………….. 20
3 CHAPTER THREE ……………………………………………………………………………….. 22
3.0 MATERIALS AND METHODS ……………………………………………………….. 22
3.1 Description of the Study Site……………………………………………………………… 22
3.2 Description of the Plant Materials ………………………………………………………. 22
3.3 Development of Genetic Populations ………………………………………………….. 24
3.3.1 The F1 hybrids ………………………………………………………………………….. 24
3.3.2 The F2 Populations …………………………………………………………………….. 25
3.3.3 The Backcross. …………………………………………………………………………. 25
3.3.4 Evaluation of Genetic Populations ……………………………………………….. 26
4 CHAPTER FOUR …………………………………………………………………………………. 35
4.0 RESULTS ……………………………………………………………………………………… 35
4.1 Analysis of variance…………………………………………………………………………. 35
4.2 Means, Ranges and Coefficient of variation …………………………………………. 37
4.3 Estimates of gene effects …………………………………………………………………… 51
4.4 Segregation ratios and chi-square for Striga damage score ……………………… 65
4.5 Heritability and Genetic advance ……………………………………………………….. 68
5 CHAPTER FIVE…………………………………………………………………………………… 72
5.0 DISCUSSION…………………………………………………………………………………. 72
5.1 Analysis of variance…………………………………………………………………………. 72
5.2 Mean, range and coefficient of variation ……………………………………………… 72
5.3 Chi-square values at expected segregation ratios …………………………………… 74
5.4 Estimate of gene effects ……………………………………………………………………. 75
5.5 Heritability …………………………………………………………………………………….. 78
6 CHAPTER SIX …………………………………………………………………………………….. 80
6.0 SUMMARY, CONCLUSIONS AND RECOMMENDATIONS ……………… 80
REFERENCES ……………………………………………………………………………………………. 83
INTRODUCTION
Sorghum (Sorghum bicolour (L.) Moench) is a major cereal in the semi-arid tropics of sub-Saharan Africa. It belongs to the family Poaceae, and probably originated from south of the Sahara in Africa.
It is an important world crop, used for food, fodder, production of alcoholic and non-alcoholic beverages, as well as biofuels. Some varieties are drought and heat tolerant and are especially important in arid regions, where the grain is a staple or one of the staples for the poor and rural people.
It is the “fifth most important cereal crop grown in the world after rice, maize, wheat and barley” (Kuhlman et al., 2010). Nigeria’s annual production of sorghum was 6.8 million metric tons in 2011 (FAO, 2012) and 6.9 million metric tons in 2012 (FAO, 2013).
REFERENCES
AATF (2005). “Controlling witchweed in sub-saharan Africa. Annual-Report ”Web.7 Dec2010.www.aatfafrica.org/userfiles/file/controlling%20witchweed%20In%20SSA AATF_Annual-Report_2005.pdf
Aggarwal, V. O., (1986). “An approach to cowpea Striga control through plant breeding. All-Africa Govt. Consultation on Striga Control”, Maroua, Cameroun, Oct 20-24, 1986.
Agrions, G. N. (2005) Plant Pathology. 5th ed. London: Elsevier Academic press. pp. 114-116
Akintayo, I. and Sedgo, J. (2001). Towards sustainable sorghum production, utilization, and commercialization in West and Central Africa. In: Akintayo I, Sedgo J (eds) Proceedings of a Technical Workshop of the West and Central African Sorghum Research Network, 19-22 April 1999, Lomé, Togo. Bamako, BP 320, Mali: West and Central Africa Sorghum Research Network, and Patancheru 502 324, Andra Pradesh, India: International Crops Research Institute for the Semi- Arid Tropics, 162pp. ISBN 92-9066-4330-9. Order code CPE 131.
Allard, R. W. (1960). Principles of Plant Breeding. John Wiley and Sons Inc., New York, USA. Berner, D. K., Kling, J. G., and Singh, B. B. (1995). Striga research and control. Plant dis. 79:652-660.
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