Section 13 — Plant Genetics and Breeding 



3. In F2 of Vigna sinensis hybrids: black x 

 white seed coat, segregated plants with (a) 

 black, (b) white, (c) black with small brown 

 dots, (d) brown with large white sector seed coat. 

 Through selection homozygous plants with the 

 mentioned seed coat colours were obtained. 

 After irradiation of black seed of parental ge- 

 notype in R2, somatic segregation of the same 

 seed colours as in F2 hybrids, plus some reddish 

 seeds ocurred. From the irradiated white seed of 

 the parental genotype only plants with white seed 

 coat have developed. The parental genotype of 

 white seed is recessive for the mentioned 

 characteristics. 



4. In year 1927 a natural mutation of decus- 

 sated position of leaves and branches on tassels 

 was first observed in one maize inbred. Now, 

 between many dozens of genetically very differ- 

 ent inbreds of Zea mays which have developed 

 from seed irradiated with gamma-rays only in 

 one inbred, a plant with decussated position of 

 leaves and branches on tassel has developed. 

 The mentioned inbred line has probably genet- 

 ical ability for the development of the mentioned 

 characteristics. 



5. From seed of inbreds irradiated with 2000 

 and 3000 r the pachytene chromosomes in R2 

 were spread through the whole cell and 

 this facilitates the study of their structure in 

 comparison with the nonirradiated genotypes 

 where the pachytene chromosomes are clustered 

 round the nucleolus. 



Conclusion: From the mentioned examples it 

 is possible to conclude that ionizing radia- 

 tion can be very helpful in evaluation of 

 the genetical constitution of some characteris- 

 tics in plants. 



13.104. Induced Biochemical Mutants in Corn. 



B. Andor (Godollo, Hungary). 



In 1958 an open pollinated variety (Fk) and 

 different lines have been irradiated at dosage 

 rates of 10 and 15 kr according to the usual 

 methods. 



Sensitivity to radiation proved to be different: 

 most resistant was the previous heat-treated 

 (aneuploid) material. Most sensitive were several 

 strains with high combining ability. Analysing 

 the variability of protein content in the progeny 

 of controlled ears, it ranged from 8.2-13.2 per 

 cent. The mean values of the X2 plots of lines 

 showed a variation range from 8.3 to 16.1 per 

 cent. In the X3 generation we succeeded in ob- 

 tain forms with hereditarily higher protein con- 

 tents from 6 lines (2.2-3.9 per cent). Germina- 

 tion tests performed on the strains in the labora- 



tory under exposure to low temperature (8°C) 

 proved that the stock is suitable for the breeding 

 of cold-resistant corn varieties. 



13.105. Inheritance of Alkaloids in Interspecific 

 Crosses in Lupinus. Edmund Nowacki (Poz- 

 nah, Poland). 



Among the fully successful interspecific cros- 

 ses of lupines, e.g. L. arboreus x L. polyphyllus, 

 L. arboreus X /,. argenteus, L. hartwegi x L. 

 elegans, L. mutabilis x L. ornatus and other 

 species, the inheritance of alkaloids was studied. 

 In the mentioned species there occur the following 

 main alkaloids: sparteine (I), lupanine (II), 

 and hydroxylupanine (III). The aim of this work 

 was to investigate the genetical and metabolical 

 relation shipof alkaloids. There was also breeding 

 of alkaloidless fodder plants and on the other 

 hand high sparteine-containing winter hardy 

 plants for pharmaceutical purposes. 



The observed segregation in progeny of hy- 

 brids between I and II containing plants was 

 of a type that could be explained only when as- 

 suming the conversion of I to II. Those results 

 were confirmed by feeding of labeled alkaloids. 



13.106. The Culture of the Eggs of Plants. G. W. R. 



Walker and H. F. Dietrich (Edmonton, 

 Canada). 



The microslide culture of unfertilized eggs dis- 

 sected from the ovaries at floral induration into 

 hanging drops suspended in liquid paraffin has 

 been used with Hordeum sativum, Tradescantia 

 paludosa and Milium tigrinum. Readily identi- 

 fiable spherical eggs are obtained from H. sativum 

 but no success has been achieved with the other 

 species. The effects of chemical additives to the 

 culture medium, including kinetin and ATP, 

 have been studied by continuous observation un- 

 der phase-contrast. Progressive changes following 

 kinetin administration are interpreted by the 

 authors, in the light of data from anther-culture 

 as probable manifestations of kinetin-induced cell 

 division. The administration of ATP results in a 

 rapid and coarse vacuolization of the egg. 



13.107. Breeding Aspects of Embryo Size Variations 

 in Wheat. A. Fasoulas (Thessaloniki, Greece). 



The significance of embryo size variation in 

 wheat was studied within varieties, among 



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