UNITED STATES DEPARTMENT OF AGRICULTURE 



DEPARTMENT BULLETIN No. 1134 



PROFESSIONAL PAPER 



Washington, D. C. 



April 26, 1923 



SELF-FERTILIZATION AND CROSS-FERTILIZATION 

 IN PIMA COTTON 



By 



THOMAS H. KEARNEY, Physiologist in Charge of Alkali and Drought Resistant 

 Plant Investigations, Bureau of Plant Industry 



CONTENTS 



Page 



introduction 1 



Vicinism, or natural hybriduation, in cotton 2 



Structure of the flower in relation to pollination . . . 



Ontogeny of the flower in relation to pollination . . . 



Locus of pollen deposition in relation to self-fertilization 

 and cross-fertilization 



Relative earliness of arrival of self-deposited and of insect- 

 carried pollen 



Deposition of self pollen and of foreign pollen by insects . 



Pollen-carrying insects at Sacaton 



Relative compatibility of like and of unlike pollen . . 



Page 

 Pollen competition as a factor in self-fertilization and 



cross-fertilization 42 



Relative completeness of insect pollination at different 



localities 49 



Seasonal variations in relative completeness of fertilization . 51 



The inferior fertilization of bagged flowers S3 



Boll shedding in relation to pollination and fertJizalion . 55 



Inbreeding in relation to fertility 56 



Summary 61 



Literature cited ........./ 66 



WASHINGTON 

 GOVERNMENT PRINTING OFFICE 



192S 



