Section 13 — Plant Genetics and Breeding 



under limited pollination). In connection with 

 the aforesaid, well-known facts of metaxenis 

 are becoming more important. 



Our trials with 15 species of floral plants 

 (especially with Nicotiana and Zea mays species) 

 together with the investigations carried out by 

 other authors showed the double role of the 

 effect of polyfatherhood. 



On one side physiological "combined action" 

 of pollen tubes maintains typical hereditary 

 disposition, on the other side the effect of poly- 

 fatherhood through changing conditions of 

 pollination and fertilization (change of qualita- 

 tive and quantitative composition of pollen, its 

 physiological state and so on) may lead to the 

 change of normal heredity. 



It may be also considered that syngamy is not 

 only a simple combination of both parents' 

 heredity, it can lead to the development of new 

 formations as a result of metabolic interactions 

 of two gametes. 



In trials with corn it was shown that the effect 

 of polyfatherhood concerns not only the first 

 progeny, in some trials this effect reaching even 

 the fourth generation. Thus, the constant 

 interrelation of fertilization processes and genetic 

 phenomena was deeper than it had been sup- 

 posed. 



In our trials we tried also to find out physiolog- 

 ical and biochemical foundation of the effect of 

 polyfatherhood. In 1953-1962 we recommended 

 and used the new method for studying fertili- 

 zation processes with the help of the pollen 

 labelled with radioactive isotopes S 35 and P 3 ' 2 . 

 For the first time these tests were direct physiolog- 

 ical evidence that pollen without taking direct 

 part in double fertilization is active in metabolic 

 processes of growing seeds. We have partly 

 studied these processes and tried to give their 

 quantitative characteristics. 



The further development of metabolic theory 

 of fertilization and the study of two most impor- 

 tant aspects of fertilization — polyfatherhood 

 and selectiveness will be of great significance 

 for genetics. 



13.77. New Methods in Cotton Hybridization. 



D. V. Ter-Avanesyan (U.S.S.R.). 



of our work at the Central Asia Experimental 

 Station of the All-Union Research Institute of 

 Plant Breeding. There was a task to work out the 

 method of cotton hybridization using the pollen 

 of heterochromosomic species and even of 

 genera of Malvaceae family. 



As it is known, in the case of hybridization of 

 G. hirsutum L. cotton species with G.herbaceum 

 L. and G. arboreum L. (African-Asiatic species) 

 having twice less chromosomes in their cells, 

 pollen tubes of the latter, as a rule, do not 

 fertilize even if they reach embryo sac of diploid 

 form. At the same time the pollen of the Mal- 

 vaceae family (Hibiscus esculentus, H. rosa 

 sinensis, H. cannabinus and Malva neglecta) 

 does not germinate on the cotton stigma at all. 



But in spite of the evident genetical incom- 

 patibility of chromosomic gametes we succeeded 

 in using them when working out two breeding 

 methods. The first method is as follows: at the 

 growing period of maternal cotton there were 

 2-3 buds left on the plant, the rest being 

 removed. This method stimulated the accumu- 

 lation of nutrients in flowers. 10-20 pollen grains 

 were placed on the stigma of emasculated flower 

 followed by unlimited pollination with the pollen 

 of a paternal form (in this case of an alien species) 

 for 3 hours. 



The second method with similar results was 

 the following: in that very evening emasculated 

 flowers were pollinated with unlimited quantity of 

 paternal pollen. Next day unlimited quantity of 

 parental pollen was again placed on the stigma of 

 the same flower, and at noon (about 20 hours 

 after emasculation) there was pollination with the 

 mixture of paternal and maternal pollen in 

 different amounts. 



The first and second generations from seeds 

 developed by the described method, gave some 

 interesting plants. The progeny considerably 

 differed from maternal plants. It got the charac- 

 ters of non-crossing cotton species and changed 

 completely its qualitative and quantitative 

 characteristics being affected by the pollen of 

 Malvaceae plants. These characters became 

 hereditarily fixed, and they were transmitted to 

 progenies. The suggested methods can be used 

 for cotton hybridization. They will improve our 

 possibilities of using diversified Gossypium genus 

 in cotton hybridization. 



Achievements in biological science reached in 

 the last decade are well known. It should be 

 noticed, however, that as profound is our knowl- 

 edge with regard to a living cell, so poor it is in 

 the field of biology of pollination and ferti- 

 lization. The experimental data remain unex- 

 plained so far, and they are strictly empirical. 

 Here are some interesting results of a long period 



13.78. The Use of Heterosis, Polyploidy and Male 

 Sterility in Sugar Beet Breeding and Seed 

 Growing in the U.S.S.R. N. Negovsky 

 (U.S.S.R.). 



On the ground of extensive use of modern 



235 



