SWEET CLOVER: GROWING THE CROP. 



19 



CHOICE OF SEED. 



On account of the low germination of much of the sweet-clover 

 seed offered for sale it is very important that seed be tested for ger- 

 mination before planting. Low germination Usually is due to the 

 fact that many of the seeds remain hard after they have been in 

 the germinator or soil for a month or more. The seed coats of hard 

 s\yeet-clover seeds become permeable to water very slowly, if at all, 

 in storage. The germination of such seeds is greatly increased, how- 

 ever, when they are subjected for a time to alternating temperatures, 

 such as freezing and thawing. It is on this account that unhulled 

 seed, which germinates poorly in the laboratory, often will produce 

 good stands when sown during the winter. When sweet clover is to 

 be sown in the spring it is very important that only hulled seed 

 which germinates 75 per cent or more be sown. As explained later 

 under the heading " Seeding/' unhulled seed which has a low germi- 

 nation should be used for seeding only during the winter months, so 

 that there will be sufficient time for the alternating temperatures of 

 winter and early spring to cause it to germinate, during favorable 

 weather. 



Hulled seed usually germinates much better than unhulled seed. 

 as is shown in Table I. 



TABLE I. Germination and hard-seed content of samples of sirect-elovcr seed, 

 hulled and iinhulled, from different sou/ 



Table I shows that northern-grown seed germinates better than 

 southern-grown seed and imported seed better than either. The low 

 germination of the southern- grown seed is probably due to the fact 

 that a very large percentage of it is flailed out and sown in the hull. 

 Xorthern-grown seed generally is thrashed with either a grain sep- 

 arator or a clover huller. Imported seed always is hulled. In hull- 

 ing seed the rasps or concaves of the machines scratch the seed coats 

 sufficiently to permit water to penetrate them, so that the germina- 

 tion is greatly increased. Apparently there is no reason why south- 

 ern-grown seed when it is properly hulled should not germinate as 

 well as northern-grown seed. 



