338 



Trials of New Varieties of Cereals. 



[July, 



Some aggregates originating from selected individual plants 

 having a hybrid ancestry, although apparently uniform in all 

 their inherited characters, ultimately prove to be more or less 

 variable. This fact must be recognised in interpreting results 

 of variety trials but is too complex for discussion in this Paper. 



Racial Characters. — The most valuable characters of any 

 cereal race are those which affect its relative productivity in 

 respect of grain as compared with other races of the same species. 

 The measure of productivity is the weight of dry grain harvested 

 and threshed from some unit of area. 



Next in value to the grower is the quality of the grain in 

 relation to the purpose for which it is most likely to be used. 



Morphological or physiological characters and combinations of 

 characters of any kind will be of value in proportion as they 

 contribute to yield or to quality. The quantity and quality of 

 the straw as feeding material or for other uses must also be taken 

 into account. 



From the above it is evident that variety trials of cereals are 

 complex affairs. Moreover, the problem has many limitations 

 and is beset by difficulties and sources of error especially in 

 estimates of productivity, both in execution and in the interpre- 

 tation of the results obtained. It is desirable to set forth some of 

 these limitations and difficulties before describing in detail the 

 methods which have been designed to deal with the problems 

 involved. 



Limitations of Yield Testing. — It is very improbable that with 

 our present knowiedge any new race of cereal will be produced 

 which will give a higher yield of grain per acre than any and 

 everv already existing race of the same species under every 

 condition of soil, season and cultivation. The same applies, 

 although perhaps to a less extent, to quality of grain, The 

 problem of the plant breeder is that of adaptation of the plant to 

 external conditions, and all that can be expected from him is that 

 he will produce • new races better adapted to definite sets of 

 external conditions than existing races in average seasons and 

 under the best methods of cultivation. 



In Great Britain there are no wide areas of uniform soil. The 

 " lay of the land " and the dip of the strata combine to make 

 uniformity impossible. There are doubtless many farms of 500 

 acres in Great Britain on which the soil is so variable that no one 

 race of any species of agricultural plant is the best race for 

 all parts of the farm. This may seem a hard saying, but let 

 any critic try to find two adjacent pastures showing equal pro- 



