SCREENING Passiflora SPECIES FOR DROUGHT TOLERANCE, COMPATIBILITY WITH PURPLE PASSION FRUIT, FUSARIUM WILT RESISTANCE AND THE RELATIONSHIP BETWEEN IRRIGATION, DRENCHING AND MEDIA COMPOSITION IN THE CONTROL OF FUSARIUM WILT A Dissertation Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By Gesimba Robert Morwani, B.Sc. HORTICULTURE M.S. CROP SCIENCE ***** The Ohio State University 2008 Dissertation Committee: Dr. Daniel K. Struve, Advisor Approved by: Dr. John Finer, Dr. Mark Bennett, _______________________________ Dr. Landon Rhodes. Advisor Horticulture and Crop Science Graduate Program Copyright by Gesimba Robert Morwani 2008 ABSTRACT Drought and Fusarium wilt are the main constraints in growing purple passion fruit (Passiflora edulis) in Kenya. There is need for drought and Fusarium wilt-resistant rootstock. In an effort to develop a drought and Fusarium wilt resistant Passiflora rootstock, a series of experiments were conducted at The Ohio State University and Egerton University in Kenya, to study vegetative propagation, graft compatibility, drought tolerance, Fusarium wilt resistance in Passiflora species and to identify an integrated control method for Fusarium wilt. In the vegetative propagation, graft compatibility and drought tolerance studies, 20 Passiflora species were screened. Species of the subgenus Passiflora rooted in higher percentages than species of the Decaloba subgenus (81 vs 64%). Cuttings from vines and liana type species rooted in higher percentages than cuttings from annual species when treated with 0.1% indole-3-butyric acid powder (82, 73 vs 44%). Cuttings of Passiflora gerbertii L., Passiflora caerulea L. and Passiflora subpeltata Ortega. could be rooted in high percentages and were compatible rootstocks with the purple passion fruit. Passiflora incarnata, P. caerulea and P. subpeltata had higher drought-tolerance than the other species. In the Fusarium wilt resistance studies, nine Passiflora species were screened using ii Fusarium oxysporum f. sp. passiflorae isolates from four locations in Kenya. Passiflora edulis f. flavicarpa and P. suberosa were resistant to Fusarium wilt implying that the P. edulis f. flavicarpa plants currently being used by farmers may not be true-to-type and hence susceptible. Passiflora incarnata and P. mollisima were moderately resistant to Fusarium wilt. Passiflora suberosa, P. incarnata and P. caerulea can be improved for use as rootstock alternatives for purple passion fruit. For Fusarium resistant P. suberosa, breeding should focus on improving graft compatibility and drought tolerance. For drought-tolerant P. incarnata, improvement should focus on improving compatibility and Fusarium wilt resistance. Since P. caerulea is compatible with P. edulis and is drought-tolerant, improvement should focus on Fusarium wilt resistance. In the study the effect of irrigation and substrate type in the occurrence and suppression of Fusarium wilt in a passion fruit orchard, two substrates, native soil in Kenya and a formulated substrate comprising of 20% soil, 60% pumice and 20% decomposed bovine manure were evaluated. Substrate treatment was by pasteurization, or three chemicals; Root-guard and Rodozin (both under trials) with Terraclor Super® as a commercial control. Irrigation methods comprised of a novel integrated container-irrigation system (ICIS-pot) and black plastic mulch with integrated irrigation system (ICIS-mulch), micro irrigation (dripper), basin irrigation and no irrigation as control. Three month old seedlings were inoculated with 2.0 x 106 cfu. of Fusarium oxysporum f. sp. passiflorae iii macroconidia obtained from infected passion fruit plants. ICIS-pot and ICIS-mulched plots in the field and greenhouse as well as plots treated with Root-guard and Rodozin had low pathogenic Fusarium colony populations. Also ICIS-mulched plots had the highest colony populations of non-pathogenic Fusarium per gram of substrate. In the greenhouse and field, the ICIS-pot and ICIS-mulch irrigation methods significantly reduced Fusarium wilt occurrence 75 days after substrate treatment. ICIS-pot irrigated passion fruits had longer vines in the field. Thus, the use of ICIS-pot and ICIS-mulch together with either Rodozin or Root-guard treatment give short term suppression of Fusarium wilt and increase passion fruit vegetative growth. iv Dedicated to Margaret, Mark, Angela, Tracy and Titus. for your patience and understanding. v ACKNOWLEDGMENTS I would like to thank my advisor, Dr Daniel K. Struve for his guidance, support encouragement and patience throughout my studies. I also thank members of my Student Advisory Committee, Drs John Finer, Mark Bennett and Landon Rhodes for your help. Special thanks to Dr. Richard Mulwa for the role he played during my field work in Kenya. I wish to express my gratitude to the United States Agency for International Development (USAID) and the Department of Horticulture and Crop Science (The Ohio State University) for providing funds that enabled me to complete my studies. Many thanks to Egerton University (Njoro) for allowing me to carry part of this work in their laboratories. I wish to thank members of the International Programs in Agriculture (OSU) particularly Dr. Mark Erbaugh, Ms Pat Rigby for their friendship and support. My deepest gratitude goes to my wife, Margaret Cheptoo Morwani and children Mark, Angela, Titus and Tracy Morwani for their immense and unwavering support. A special thought is devoted to my parent’s Sabina Nyaboke and Joseph Gesimba. Finally I thank God for good health. vi VITA Date of Birth:………. 25th January 1967. 1987-1990:…………. Diploma in Horticulture Egerton University, Kenya. 1992-1995:…………..BSc Horticulture Egerton University, Kenya. 1997-2000:…………..MSc Crop Science Egerton University, Kenya. Sept 2005 - Dec 2008: Graduate Research Associate (PhD), Department of Horticulture and Crop Science, The Ohio State University, Columbus, OH. PUBLICATIONS 1. Gesimba, R.M. 2000. Selection of drought tolerant bread wheat through shoot and root characteristics at seedling stage. MSc Thesis, Egerton University. 2. Gesimba, R.M., Njoka, E. and M. Kinyua 2004. Selection of drought tolerant bread wheat through root screening. Asian Journal of Plant Science 3: (4) 512-515. 3. Gesimba, R.M., Langat, M.C., Wolukau, J. and Q. Liu 2005. The tea industry in Kenya: the challenges and positive developments (Review). Journal of Applied Science 5: (2) 334-336. 4. Gesimba R.M. and M.C Langat 2005. A Review on weeds and weed control in oil crops with special reference to soybeans (Glycine max L.) in Kenya. Agricultura Tropica Et Subtropica 38 (2) 56-61. 5. Langat M.C., Okiror M.A., Ouma J.P. and R.M. Gesimba 2006. The effect of intercropping groundnut (Arachis hypogea L.) with sorghum (Sorghum bicolor L. Moench) on yield and cash income. Agricultura Tropica Et Subtropica 39(2) 87-91. vii 6. Langat, M.C., Okiror, M.A., Gesimba, R.M. and J. Ouma 2007. The effect of intercropping groundnut with maize on yield and cash income. Botswana Journal of Agriculture 21:11-28. 7. Gesimba, R.M. Struve, D.K., Rhodes, L. and R.M.S Mulwa 2008. Screening Passiflora rootstocks for Fusarium wilt resistance chitinase production and activity (submitted Botswana Journal of Agriculture). FIELD OF STUDY Major Field: Horticulture and Crop Science. viii TABLE OF CONTENTS Page Abstract...............................................................................................................................ii. Dedication...........................................................................................................................v. Acknowledgments..............................................................................................................vi. Vita.....................................................................................................................................vii. List of tables.......................................................................................................................xiv. List of figures.....................................................................................................................xx. List of plates……………………………………………………………………………..xxii. Chapter 1............................................................................................................................ ..1. Introduction.............................................................................................................. 1. Passion fruit…………………….............................................................................. 1. The passion fruit industry in Kenya..........................................................................1. Statement of the problem......................................................................................... .2. Justification…………………………....................................................................... 3. Objectives……..........................................................................................................3. Hypothesis……………………………………………………………………….....4. References………………………………………………………………………….5. Chapter 2...............................................................................................................................6. Developing Passiflora rootstocks: Part I. Vegetative propagation, graft compatibility and mechanical strength of Passiflora species Abstract..................................................................................................................