422 THE WHEAT PLANT 



consideration the variety of wheat, the time and method of sowing, and 

 the average size of the seed. 



Variety. There are very considerable differences among wheats in 

 regard to their grain production under the same soil and climatic condi- 

 tions. This is chiefly due to the difference in the length of their growing 

 period. Many of the rapid-growing short-lived spring varieties complete 

 their life-history in 95-120 days. On the other hand, some of the winter 

 wheats require 180-200 days for their growth. The latter produce more 

 stems, leaves, and ears, and usually yield not less than 25 per cent more 

 grain than spring varieties on the same land. 



Even among spring and winter varieties certain forms are found to be 

 more efficient than others when grown under the same conditions. For 

 example, it is generally believed that Marquis wheat produces more grain 

 than many other spring forms on most of the spring wheat-growing areas 

 of the American continent, and among winter wheats in Western Europe 

 the Squarehead types almost invariably give higher yields than any of the 

 lax-eared forms. 



Time of Sowing. There are two periods at which wheat is generally 

 sown, namely (i) autumn and (2) in spring. On account of the longer 

 growing period allowed by autumn sowing, the yield is invariably higher 

 for wheats sown at that time than after winter. The autumn-sown plants 

 are already established and possess several shoots before the later-sown 

 plants make a start, and this advantage is never lost. 



The loss varies with the kind of wheat, the deficiency being least in 

 the case of the spring wheats, whose growing period is naturally short, and 

 greatest in the winter wheats, which require a long period for their highest 

 development. 



Where the sowing of autumn wheats is delayed until February or 

 March there is generally a loss in yield of not less than 15-20 per 

 cent, and on land in poor condition it may amount to as much as 50 

 per cent. 



At the College Farm, Reading, forty kinds were sown on October 21, 

 1910; and again on February 9, 1911. In all the varieties there was a loss 

 of yield of grain through sowing at the later date : the percentage de- 

 ficiency of a few showing the greatest and least variation are given below : 



Loss per cent. 



Red Dantzig ... 55 



Chidham .... 49 



Noe 49 



Partridge .... 46 



Red Nursery ... 44 



Golden Drop 37 



Swan . . . . 37 



Loss per cent. 



Sicilian .... 30 



Hungarian ... 28 



Japanese . . . . 26 



Talavera .... 17 



March .... 14 



Fern .... n 



Californian . 10 



