Nilsson: Plant-Breeding in Sweden 



295 



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ORIGIN OF A GRAY LINE OF OATS 



The principles of Mendelism were prettily exhibited in a cross of black and white oats (shown in 

 the top row, above). The first generation was all black, like one of the parents; it is shown as 

 a single seed in the middle row. The second generation, shown in the lower row, segregated 

 as was expected into the Mendelian formula: 12 black, 3 gray and one white. The genetic 

 explanation as given by Dr. Nilsson-Ehle is that the black parent strain (BG) had one factor 

 for black (B) and also one factor for gray (G) ; but the gray color was covered by the black. 

 The white sort, of course, lacked both black and gray, and is therefore represented by the 

 symbol bg. Among the possible combinations of factors in hybridization, is bG, the plant of 

 which will lack the black factor but possess the gray: its color, then, will be pure gray, without 

 any trace of overlying black, just as is shown in the three seeds of the lower row. The one 

 white seed is known as the "extracted recessive"; according to the prevailing theory, it is 

 white because, lacking factor for either black or gray, it could not be anything but white: 

 in other words, it is a mere case of presence or absence of color, which is shown to be heritable 

 by purely mathematical formulae, based on the Laws of Chance. (Fig. 7.) 



preeminent requirement (Renodlad 

 Squarehead, Bore, Pudel). In the south 

 our varieties have already supplanted 

 the native ones, but in the center, the 

 old ones are still much employed, since 

 we have not wholly gained the hardiness 

 necessary. From our new series of 

 hybridizations we hope to produce the 

 ideal. For spring wheat in that latitude 

 an early maturity is the prime requisite, 

 and we can point to great progress in 

 that direction {Pari), but still have some 

 hybridizations to make with the native 

 varieties before attaining perfection. 



As for barley, the breweries have 

 dictated the qualities needed, not only 

 as to general good quality {Chevalier II) 

 but also for the amount and stiffness of 

 straw iPrinsess) and for precocity 

 (Hannchen, Gull) which allows culture 

 in the more northern provinces. A 

 second group is composed of varieties 

 adapted to solid, moist soil, and satis- 



factory for brewing {Primus) as well as 

 for forage {Svanhals). 



In oats we have to meet the needs of 

 certain provinces which require black 

 varieties early {Fyris), with stiff straw 

 {Klock II) or late, productive sorts 

 {Storniogul) and on the other hand, to 

 satisfy the demand for white or yellow 

 varieties, yielding heavily although 

 rather late {Seger, Kron, etc.), and others 

 more precocious for northern provinces 

 {Guldrdgn, Dala). In order to meet the 

 requirements of provinces still further 

 north, where oat growing is still im- 

 portant, we have had again to fall back 

 on hybridization, and have already made 

 enough progress to inspire us with great 

 hopes. 



In rye, we have combined high yield, 

 great hardiness and good commercial 

 quality {St jam). 



As for peas, w^e have produced both 

 the kitchen varieties {Concordia, Kapi- 



