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Louisiana State University LSU Digital Commons LSU Historical Dissertations and Theses Graduate School 1960 Genetic Studies and Compatibilities in the Sweet Potato (Ipomoea Batatas). Silas Albert Harmon Louisiana State University and Agricultural & Mechanical College Follow this and additional works at: https://digitalcommons.lsu.edu/gradschool_disstheses Recommended Citation Harmon, Silas Albert, "Genetic Studies and Compatibilities in the Sweet Potato (Ipomoea Batatas)." (1960). LSU Historical Dissertations and Theses. 595. https://digitalcommons.lsu.edu/gradschool_disstheses/595 This Dissertation is brought to you for free and open access by the Graduate School at LSU Digital Commons. It has been accepted for inclusion in LSU Historical Dissertations and Theses by an authorized administrator of LSU Digital Commons. For more information, please contact [email protected]. 'This dissertation has been microfilmed exactly as received Mic 60-2978 HARMON, Silas Albert, GENETIC STUDIES AND COMPATIBILITIES IN THE SWEET POTATO (IPOMQEA BATATAS). Louisiana State University, Ph. D ., 1960 Agriculture, plant culture University Microfilms, Inc., Ann Arbor, Michigan GENETIC STUDIES AND COMPATIBILITIES IN THE SWEET POTATO (IPOMOEA BATATAS) A Dissertation Submitted to the Graduate Faculty of the Louisiana State University end Agricultural and Mechanical College in partial fulfillment of the requirements for the degree of Doctor of Philosophy in The Department of Horticulture by Silas A. Harmon B.S.A., Berry College, 1942 M.S.A., University of Georgia, 1952 June, 1960 ACKNOWLEDGEMENTS The author wishes to express his deepest appreciation to Drs. Julian C. Miller, Teme P. Hernandez, Donald W. Newsom, and Merlin T, Henderson for their helpful guidance and assitance in this study. Sincere gratitude is also expressed to Professors B. Henry Singletary, William D. Kimbrough, Lloyd G. Jones, Travis P. Hernandez, and James F. Fontenot. The advice and suggestions given by Drs. Lewis H. Flint and Weston J. Martin are greatly appreciated also. The writer is indebted to many other wonderful people in the Horticul­ ture and Agronomy Departments at Louisiana State University. The writer wishes to express thanks to the officials of the University System of Georgia for the leave of absence that made the study possible and to Director Frank P. King, Mr. Otis J. Woodard, and Mr. Harvey W. Rankin of Georgia Coa3tal Plain Experiment Station for much help and encouragement. To his wife, Josephine W. Harmon; Mrs. Juannie Gibbens and Mrs. Evelyn B. Howard at Louisiana State University; Mrs. Harold Woellert and Miss Joyce Towson at Georgia Coastal Plain Experiment Station the writer is deeply indebted for assistance and en­ couragement. ii TABLE OF CONTENTS Page I ACKNOWLEDGEMENTS........... ii II TABLE OF C O N T E N T S ..........., ................... iii III LIST OF TABLES.................................. iv 17 LIST OF FI G U R E S ................................ vi 7 LIST OF PLAT E S .................................... vii 71 ABSTRACT......................................... vili 711 INTRODUCTION . ................................ 1 Till KE7IEW OF LITERATURE............................ 3 IX MATERIALS AND METHODS .......................... 35 X RESULTS AND DISCUSSION.................. 54 A. The Cross end Self Compatibility of Several Clones ......... ... 54 B. The Inheritance of Resistance to Internal Cork .............................. 79 C. The Inheritance of Carotene............... 93 D. The Inheritance of Leaf Type, Stem Color, and 7ine Length.............................. 101 XI SUMMARY AND CONCLUSIONS.......................... 115 XII BIBLIOGRAPHY...................................... 119 XIII AUTOBIOGRAPHY.................................... 132 iii LIST OF TABLES Table Page I. The Classification of Each Parent in Regard to the Five Characters Studied ............................ 38 II. Capsule Set from Crosses Made in 1946 through 1950 . 57 III. Capsule Set from Selected Crosses in 1950 through 1956 65 IV. Capsule Set from Fifteen Bunch Porto Rico Crosses and Their Reciprocals ..... ........................ 70 V. Capsule Set from Twenty-One Unit I Porto Rico Crosses and Their R_eciproeals........................... 71 VI. Capsule Set from Crosses Made at Louisiana State Uni­ versity 1956 73 VII. Selected Crosses Showing Extremes in Compatibility . 74 Vlil. The Effect of Time of Pollination on Capsule Set - Thirty Minute Intervals......................... 78 IX, The Effect of Time of Pollination on Capsule Set - One Hour I n t e r v a l s ............................ 78 X. Percent Corky Roots in Sweet Potato Varieties and Seedlings from 1946 through 1956 .......... 81 XI. The Cork Indexes and Percentage of Roots with Cork Symptoms for Several Parental S e l e c t i o n s ....... 83 XII. The Cork Indexes and Percentage of Roots and Clones Showing Cork Symptoms for Each Cross . .......... 85 XIII. The Summarized Cork Indexes and Percentage of Roots and Clones Showing Cork S y m p t o m s ............... 87 XIV. Comparative Cork Data From Selfs of Three Parents . 89 XV. The Cork Indexes and Percentage of Clones with Symptoms, Arranged According to Female Parentage . 91 iv Table Page XVI. Percentage and Range of Carotene in Each Cross and Parent.................... ...»............... 97 XVII. Percentage of Clones with Carotene in the Various Parental Combinations ..... .......... .... 100 XVIII. Leaf Type, Stem Color, and Vine Length of Seedlings from Each Cross and S e l f ............................ 104 XIX. Leaf Type, Stem Color, and Vine Length When Each Parent was Used as Either Male or Eema l e............ 106 v LIST OF FIGURES Figure Page 1. Cross Compatibility Chart Showing the Number of Pollinations Made and the Number of Capsules Set 1946-1950 ........................................ 59 2. Cross Compatibility Chart Showing Percentage of Capsules Set 1946 to 1950 ........ ...» 60 3. Cross Compatibility Chart Showing Number of Pollinations Made and Number of Capsules Set 1950 - 1956 66 4. Cross Compatibility Chart Showing Percent of Cap­ sules Set 1950 - 1956 ............................ 67 5. Cross Compatibility Chart Showing Number of Pollina­ tions Made and Number of Seed Capsules Set .... 75 6. Cross Compatibility Chart Shov/ing Percentage of Capsule S e t ................ 76 7. The Percentage Roots by Cork Classes . ........ 90 8. Leaf Type Shown by Classes as Percentage of all Clones as Indicated........................... 107 9. Stem Color Shown by Classes as Percentage of all Clones as Indicated.............. 110 10. Vine Length Shown by Classes as Percentage of all Clones as Indicated.............................. 114 vi LIST OF ELATES I. Photograph Shov/ing Pots as Arranged in the Green­ house with the TJngrafted Stocks of Corky Porto Rico in the Background and with Newly Grafted Scions in the Foreground.................................... 45 II. Photograph Showing Close-up View of Graft Union with the Ruptured Paraffin Wrap Due to Growth Ex­ pansion of the Tissue in the Region of the Graft . 46 III. Photograph Showing how the Single Node Scions were Grafted into the Stock, the Paraffin Wraps to Hold Scions and Stocks in Contact, and the New Growth Starting from Axillary Buds on the S c i o n s ........ 47 IV. Photograph Showing Three Weeks Growth on Single Node Scions Shown in Plate I I I ..................... 48 V. Photograph Showing Three Weeks Growth of one of the Fast Growing Long-Internode Seedlings ............ 49 VI. The Size and Type of Lesions used in Classifying R o o t s ............................................ 50 VII. Corky Lesions of Sufficient Size and Typ© to Classify as Severely Infected (Class Four) ........ 51 VIII. The Typical Appearanee of the Cork Lesions Found in the Corky Stock that was Bedded for Grafting .... 52 IX. The Stem and Leaf Classes Used in Classifying the Range Observed in these Two Characters in Sweet Potatoes......... 53 X. Photograph of a Clone Having the Largest Amount of Corky Lesions Observed ............... 94 vii ABSTRACT Studies were conducted on the following problems in sweet potato breeding: 1. Compatibility among several clones 2. The evaluation of certain parents for their ability to transmit genetic characters such as resistance to the internal cork disease, carotene, leaf type, stem color, and vine length 5. The study of inheritance of the above characters The compatibility studies were made on three different groups of parents in three separate tests. The clones were studied for self and cross compatibility. Compatibility between clones varied greatly. The percent cap­ sule set varied from zero to one hundred. In crosses having 50 or more pollinations the highest percent capsule set was 81.66. Twenty- six crosses and selfed clones set no capsules. Eleven clones were self pollinated. Of these, six set a low (below 10) percent. Three clones set above 10 percent and the highest was AO.80. The average percent capsule set for all selfs and crosses was 16.76. In general a clone that set as a female parent was also equally compatible as a pollen parent. There were exceptions. Flowers on Unit I Porto Rico plants set a considerably higher percent capsules as a female than as a male. In a few crosses the original and recip­ rocal were significantly different. viii The hour from '7:30 to 8:30 a.m. was the most favorable time for pollination. Various crosses were made between parents that were known to be either resistant or susceptible to the internal cork virus or viruses. Resistant

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