282 Mr Biffen, Wheat Breeding. 



long grain over short glumes and short grain. The second genera- 

 tion of this cross has still to be grown. 



It has also proved interesting in another respect. Polish wheat 

 is noted for its habit of rapid growth and early maturation, while 

 Rivet wheat grows and ripens slowly. To ripen both in August 

 the former should be sown about the middle of March, the latter 

 during the preceding autumn. The hybrid sown in the middle of 

 March ripened its most vigorous ears by September 17th and the 

 ears from the side tillers a month later. These dates correspond 

 with those for the time of ripening of Rivet wheat sown in the 

 middle of March, so that the late ripening habit is clearly a 

 dominant character. The results of other crosses w r ith Rivet wheat 

 confirm this, both for the first and second generations. 



We have thus one pair of "constitutional" as distinct from mor- 

 phological characters obeying Mendel's laws. As many of these 

 are of far greater importance to the agriculturist than the merely 

 morphological characters, a number are being investigated in 

 detail. The most important of these is the disposition to with- 

 stand the attacks of parasitic fungi such as those causing Rust and 

 Mildew. From the preliminary experiments it appears that im- 

 munity from Rust is a definite recessive character. 



