62 MAIZE BREEDING. 



strain we could then be certain of the result, so long as the recessive 

 seed is pollinated by plants bearing the recessive character from, 

 generation to generation. For example, let us take a white and 

 yellow mealie, yellow being dominant over whiteness. Take the 

 pollen from the yellow variety and dust the silks of the white. 

 The grain produced will all be yellow. This seed is then sown the 

 following season, and if we have sufficient grains, say several 

 thousands, we shall find that the progenv from the first cross will 

 give us 25% of white grains and the remaining 75^0 ^^'1^ bear 

 yellow, and yellow and white, on the same cobs. The 25%, which 

 shews the recessive characters, will therefore from this date on breed 

 pure. Twenty-five per cent, of the dominant grains would also' 

 breed pure, but these being of the dominant character it is impossible 

 to isolate them from the remaining two-thirds which still have the 

 recessive character present, as the colour is the same. If. however. 

 we get another characteristic present, such as earlierness over late- 

 ness or 7'tce versa this would be possible. 



Mr. G. N. Colhns. Assistant Botanist in the United States De- 

 partment of Agriculture, however states that too much attention 

 has been bestowed upon uniformity and close selection, so that the 

 more practical side of the question, namely that of producing the 

 heaviest crop per acre, has been overlooked, and the reason why we 

 have not realised the danger of close breeding is that we have always 

 selected to obtain the biggest crop, and bred closely in that direction, 

 and close breeding and heavy cropping are antagonistic, but always 

 selecting for the biggest crop has prevented us from seeing this 

 clearly. He proposes a scheme which opens up quite a new field 

 as far as the mealie breeder is concerned, and that is to select twO' 

 very desirable varieties of corn and sow these in alternate rows in 

 two different fields. We will suppose that the varieties are called 

 A and B. both white and possessed of desirable characteristics. 

 In the one field the variety A is detasselled throughout and is 

 therefore fertilised by pollen from the variety B. Thus the de- 

 tasselled plants will all give a cross-bred seed. B fertilising itself 

 and therefore remaining pure. In the other field B is detasselled. 

 and is fertilised by the pollen from A, so we get B a cross-bred and 

 A remaining pure. Thus in the two fields we keep the original 

 A and B pure and in both fields we also have a cross-bred seed. 

 A and B remaining pure gives us the opportunity of re-sowing 

 these year after year and at the same time procuring cross-bred 

 seed. It is well-known to all stock and crop breeders that bo 

 th a cross-bred animal and plant are generally stronger than the 

 pure-bred, and it is hoped by sowing this cross-bred seed for one 

 season only to materially increase the yield, this means that seed 

 from the first cross must be sown every vear. 



Reasons for Crossing and Seed-Breeding. 



In America practically all the land capable of producing maize 

 is now annually laid down to this crop, and so to meet the increasing 

 demand increased production per acre is necessary. Therefore 

 everything is done to bring this about. In Cape Colony this is not 

 the case, but it is fullv realised that maize is not likely to retain its 



