Aug. 14, 1916 Agricultural Value of Impermeable Seeds 789 



thereafter until about the middle of May. Very few appeared later than 

 May 20. Wherever these seedlings were densely shaded by healthy 

 plants of the preceding season they grew tall and slender at first and 

 ultimately disappeared. 



Table XIII shows the calculated percentages of the impermeable seeds 

 of lots originally containing large percentages of impermeable seeds 

 which produced seedlings during the first 16 to 18 days, the first spring 

 and summer, during the following winter, during the following spring, and 

 the total percentages of impermeable seeds which produced seedlings in 

 the field and which germinated in the chamber in 12^ months. 



1. From 5 to 16 per cent of the impermeable seeds of alsike clover, 

 white clover, and sweet clover and 31 per cent of the impermeable red- 

 clover seeds germinated in the chamber in 12^ months. During the 

 same time 74 per cent of the impermeable red-clover seeds and from 50 

 to 58 per cent of the impermeable seeds of the other kinds of clover pro- 

 duced seedlings in the field. Of these seedlings from one-twentieth to 

 one-fourth appeared during the season in which the seeds were planted, 

 from one-twelfth to one-third appeared during the following winter, but 

 were killed before the winter was over, and the remainder, representing 

 from one-fourth to one-half of the whole number of impermeable seeds 

 planted, appeared in the spring of 191 4 and produced the 1914 stand of 

 plants. 



2. Of the impermeable alfalfa seeds 74 per cent produced seedlings in 

 the field during the first season and 1 per cent the following winter, while 

 only 66 per cent germinated in the chamber in i2}4 months. No obser- 

 vations were made on this lot in the field in the spring of 1914. 



3. From one-fourth to one-half of the impermeable seeds of the differ- 

 ent kinds either remained impermeable in the soil or softened and died. 



Figure 6 shows graphically the percentages of seedling production in 

 the field and of germination in chamber in 12^ months, and the sum of 

 percentages of germination and of impermeable seeds according to 

 chamber test. The different lots of seed are represented in the same 

 order here as in figure 5, and the curve at the top of the figure is the same 

 as occurs at the top of figure 5. 



At the end of a year the seedling production by all the lots which con- 

 tained large percentages of impermeable seeds had surpassed the germi- 

 nation in the chamber by an amount roughly proportional to the per- 

 centages of impermeable seeds which they contained. With all the lots 

 which contained small percentages of impermeable seeds except sweet 

 clover 1 19982 the percentages of seedling production in the field, even 

 after 12J/2 months, were less than the percentages of chamber germination 

 in eight days. 



