PLANT BREEDING. 33 



the latest types secured will combine good malting quality and 

 high yield with very strong straw. 



The ordinary six-rowed barley commonly grown for feeding 

 purposes has two serious disadvantages. It is a bad tillerer, 

 and has a very fragile neck, which often causes it to break off 

 at the ear when harvested. Breeding work is in progress to 

 remedy these defects, and also to produce a grain giving as 

 high a percentage of nitrogen as possible. About 40 different 

 varieties have been selected for testing on a small field-plot 

 scale, and there is a prospect that from these it will be possible 

 to select a variety considerably better than those commonly 

 grown. 



Potatoes.— A series of experiments is in progress with the 

 object of raising new varieties of potatoes resistant to the serious 

 diseases of Blight, Wart Disease and Leaf Curl, and at the same 

 time preserving the high standard of the best commercial sorts 

 in regard to cropping and other necessary qualities. The work 

 was started three years ago, and certain varieties were selected 

 as parents which were known to be highly resistant to Blight 

 and Wart Disease. These were crossed with others possessing 

 the necessary commercial qualities. Considerable variation 

 appeared in the first generation amongst the 5,000 seedlings 

 raised. From these, most stringent selections have been made 

 each year, and particularly all seedlings suffering from Blight 

 and Leaf Curl have been discarded. It is worthy of note that 

 out of some 20 distinct crosses made, one family has proved 

 itself remarkably resistant to both these diseases. 



As regards Wart Disease, the immediate object in view is 

 the obtaining of heavy cropping immune earlies and an immune 

 variety of the Up-to-Date type. The tests for resistance to 

 Wart Disease are being carried out at the Ormskirk Potato 

 Testing Station. At the same time an attempt is being made 

 to discover the exact nature of the inheritance of immunity from 

 Wart Disease. It has already been found that immunity is not 

 a simple inheritable factor. Two immune varieties, for example, 

 may produce susceptible offspring. 



In potato-breeding work of this type, numerous difficulties 

 have to be overcome. In the first place there is the difficulty 

 of securing suitable parents, for many of the favourite varieties 

 now grown do not produce pollen, which, of course, is essential 

 for cross fertilisation. Then there is a marked tendency for even 

 fertiUsed flowers to drop off without producing seeds. If seed- 

 lings are successfully raised, there is the difficulty of saying 

 which of them are Hkely to give rise to successful potato plants. 



