1920.] 



Plant Breeding at Aberystwyth. 



633 



plants. The method of sowing in boxes and subsequently 

 planting out employed in Denmark has therefore been 

 adopted. The box culture section in the main garden is 

 shown in Plate V. This consists of brick-sided trenches 

 12 J in. deep, and 3 ft. 7 in. broad. Strong boxes of a con- 

 venient size for lifting are used; when watering becomes 

 necessary the trenches are flooded in sections. The trenches 

 are placed in a large mesh cage sufficient to keep out wood 

 pigeons (which are a particular nuisance in the district) and 

 other large birds. Special " lots " are started in this manner, 

 both for garden and small-scale field trials, the plants being 

 put out in spaced rows with ample room between them. 



A further difficulty has to be contended with in the form of 

 " volunteers " of the species under investigation. There is 

 the danger that such seed may be in the soil and so con- 

 taminate the seedlings, and it is essential, when dealing with 

 pedigree cultures, that this undesirable seed should be killed. 

 Arrangements are being made to provide a suitable plant to 

 beat sufficiently the soil used for the boxes so as to kill 



volunteer " seeds before sowing; in the meantime a useful 

 method applicable to such small lots of seed as those from a 

 single head of a grass or a clover has been under investiga- 

 tion during the past season. The method consists of starting 

 the seed on an incubator in a greenhouse, and pricking off the 

 germinated seeds and planting in boxes in spaced rows. It 

 has been found that with careful handling the minute seedlings 

 transplant quite satisfactorily. This plan affords the additional 

 advantage of safeguarding germination and providing a 

 germination test. 



Work on herbage plants, the great majority of which are 

 cross fertilized, demands special precautions and methods with 

 a view to regulating pollination. The question of pollen-proof 

 cages and capsules is exceedingly important and especially 

 difficult when working in a wet climate, and investigations 

 are being made as a preliminary to the more serious study of 

 the fertilization affinities of the commoner grasses and 

 clovers.* It was early apparent that all pollination work and 

 studies would have to be conducted under grave disadvantages, 

 not only on account of the common occurrence of wet weather 

 during May, June and July, but also because of the strong 

 Winds and gales which are a feature of the prevailing climatic 



* It will be necessary to ascertain whether under the climatic conditions 

 prevailing in Wales the findings of Continental and American workers apply 

 to the grasses and clovers under investigation. 



