378 THE MONTHLY BULLETIN. 



RESULTS FROM SOWING HARD SEEDS. 



"Within ordinary limits neither the depth of planting nor the firm- 

 ness of the soil affects the germination of impermeable clover and 

 alfalfa seeds under greenhouse conditions. These factors may affect 

 the stand secured by preventing some of the seedlings from reaching 

 the surface, and even under the most favorable conditions only a small 

 proportion of impermeable red clover, alsike clover, white clover and 

 white sweet clover seeds produce seedlings promptly in the soil when 

 sowed in warm weather. 



"Impermeable seeds of red clover, alsike clover, white clover and 

 white sweet clover will pass the winter in the soil in a freezing climate 

 without injury. At least 50 to 60 per cent of them may be expected 

 to germinate in the soil the following spring unless a part of them 

 germinate during the warm weather in the winter. If this occurs, the 

 seedlings produced in the winter are liable to be killed by subsequent 

 freezing. Frequently a large proportion of impermeable alfalfa, crim- 

 son clover, okra and hairy vetch seeds will germinate in the soil during 

 the first few months after planting, some of them early enough to be of 

 importance to the crop. Nearly all alfalfa and okra seeds, even if they 

 are impermeable in the fall, are killed when they pass the winter in the 

 soil or on the plants out of doors in a freezing climate. A small pro- 

 portion of the impermeable alfalfa seeds survive with their vitality 

 unimpaired. Some of the okra seeds remain impermeable during the 

 winter, but the majority even of those which remain impermeable are 

 killed by the winter's exposure."^ 



VALUE OF HARD SEEDS. 



The value to the farmer of impermeable seeds occurring in any lot 

 of seed will vary according to the kind of seed, the germinating capacity, 

 the percentage of impermeable seeds in the lot of seed under considera- 

 tion, the age of the seed, and the time of sowing the seed. Imper- 

 meable alfalfa seed sowed late in the spring is of more value to the 

 crop than impermeable sweet clover seed sowed at the same time. 



If the percentage of impermeable seed in a given lot is small (10 per 

 cent or less), and the rest of the lot consists of strong, germinable 

 seeds, the impermeable seeds are of little importance both because of 

 their fewness in comparison with the seeds which germinate readily, 

 and because of the varying quantities of seed which are sowed accord- 

 ing to common practice. It is when the impermeable seeds constitute 

 a large percentage of the seed in a given lot that their real value 

 becomes a question of agricultural importance. 



In seed that is several years old the viability of the permeable seeds 

 may have become so low that the impermeable seeds, which lose their 

 vitality more slowly, are relatively much more important than in lots 

 of fresh, new seeds. 



^The winter temperatures referred to in this article are those of the Eastern States. 

 Our California winters are rarely cold enough to kill seeds planted in the fall. 



