Section 13 — Plant Genetics and Breeding 



The first progeny of hybrids (Fi) from these 

 crosses was grown in various conditions: some 

 Fi plants from each combination were sown in 

 spring as usual, the rest in late fall (early win- 

 ter) (on the 5th of October). The second off- 

 spring (F2) was sown in spring and was grown 

 in the same conditions. It appeared that growing 

 conditions of Fi affected the characters of F2 

 plants to a considerable extent, especially their 

 segregation (variability) according to the dura- 

 tion of their growing periods, especially when 

 parental forms (varieties) greatly differed in this 

 respect. In this case the following phenomenon 

 was observed: when Fi was sown in spring F2 

 plants entered their heading stage simultaneously 

 with the early-maturing parental form or earlier, 

 and finished it simultaneously with the late- 

 maturing parental form. Most F2 plants had 

 passed through their heading stage by the time 

 the earlier parent finished it. 



If Fi was sown in late fall (early winter), the 

 behaviour of F2 plants was quite different. The 

 beginning of their heading also coincided with 

 the beginning of that of early-maturing parental 

 forms, but when Fi plants had already passed 

 this stage, the number of F2 plants with devel- 

 oped heads was about 20 per cent. 



Most hybrid plants formed their heads 

 simultaneously with their late parent and the 

 considerable number of plants (about 20 per 

 cent) formed their heads later than their parental 

 form. This latter part of hybrid plants formed 

 their heads for a very long time and finished it 

 a month later than the late matured parental 

 form. In this case only 3 per cent of plants 

 reached their tillering stage before winter 

 dormancy, i.e. they became winter crops. 



When parental forms did not considerably 

 differ in the duration of their growing periods or 

 if both of them were comparatively early-matur- 

 ing, early winter sowing of Fi also led to the 

 obviously prolonged period of heading of F2 

 plants, but this period was not so long as it 

 was in the first case. There were no winter crops 

 here. 



Growing conditions of Fi also affected the 

 variability of other characteristics of F2 plants, 

 head productiveness in particular. When Fi 

 was sown in early winter F2 plants of all combi- 

 nations in our experiments were characterized 

 by higher productivity index as compared with 

 Fi sown in spring. 



In that way growing conditions of Fi can affect 

 the characteristic of F2 to a considerable extent. 

 This can be explained by the fact that the stability 

 (conservatism) of the heredity of Fi plants is 

 shattered and therefore they are easily trans- 

 formed being affected by changing growing 

 conditions. 



13.84. About Bieeding of Sprouting Resistant Cereals . 

 Herbert W. Mueller (Bernburg/Saale, Ger- 

 many). 



Beginning in 1953 we crossed the resistant 

 "Wjatka-rye" with "Petka" and "Champagner". 

 293 ears were artificially pollinated and tested. 

 In Fi, sprouting was dominant. Only 2.7 per 

 cent of the kernels were as resistant as the "Wjat- 

 ka-rye". This was partially caused by the low 

 weight of the kernels. The average was 24 per 

 cent lighter than the average of the parents. 

 After crossing of barley the result in Fi was, that 

 there are reciprocal differences between the 

 crosses of the sprouting resistant "Neuga" and 

 the fast sprouting sorts "Mansholts" and 

 "Nordland". The differences are caused by 

 the matroclin parent, probably a result of the 

 covering layers of the kernel. The Fi in average 

 was equal to the better sprouting parent. 



The spring wheat combination "Koga" x 

 "Bernburg 38626" was tested with 42 ears in 

 Fi, and sprouting was as quickly as "Koga". 



In following years the combinations were 

 tested starting with the F2. The descendants of 

 the Fi- kernels were examined with the Eosin- 

 test. The reaction of the populations was not 

 uniform, but the effectiveness of an F2-selection 

 was very unsatisfactory. The correlation values 

 of the selected resistant descendants in F2 to 

 reaction in following generations were only: 



rye r = 0.09 wheat r = 0.12 



oat r = 0.10 barley r = 0.12 



The following conclusions are possible: 



1. The heritability of sprouting is regulated 

 by many genes. 



2. The effectiveness of a selection in F2 is so 

 small, that for breeding purposes there is no 

 applicability. 



The intensive testing of 10 winter barley popula- 

 tions on the other hand showed the possibility 

 of negative results of F2-selection. 



Comparing the populations selected in F3, 

 higher correlations between the selected parents 

 and their descendants were possible. Averaging 

 all combinations we get following values: 



winter barley r = + 0.46 



winter wheat r = + 0.38 



spring wheat r = + 0.48 



oat r = + 0.39 



The values are satisfactory for cereal breeding. 



The correlations of F4-se!ections were some- 

 what higher but there are many technical 

 difficulties to select a greater number of popula- 

 tions and to test their descendants. It would be 

 more economic to test a greater number of 

 populations in F3. 



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