125 



occurrence of weed seeds and their vitality, made at the Danish State Seed 

 Testing Station during the years 1896-1910). 



That report contains partly a summary of the results of experiments 

 published in earlier volumes of the journal and partly a supplement to these 

 - — viz., results of later examinations and, finally, results of investigations 

 not previously published. 



This article is in all essentials a summary of the above report, the 

 •division of which is, therefore, kept here. Those sections likely to be of 

 interest to foreign readers are mentioned somewhat in detail, whereas 

 those of particularly local interest are only reported briefly. In some cases 

 information is given which is not contained in the report, but is to be found 

 in an earlier volume of " Tidsskrift for Landbrugets Planteavl." The 

 reference to some of the series of experiments is further supplemented 

 with results obtained since 1910, several of the investigations not being 

 finished at that time. 



I. — How many weed seeds do clover and grass seed contain ? 



In this section attention is drawn to the fact that the apparently 

 small quantities by weight (most frequently 0- 1-1-0 per cent.) of weed 

 seeds which the samples of grass and clover seed in general contain, repre- 

 sent a considerable number of seeds per kilogramme of the bulk, so that even 

 in the case of a good bulk, when using 25 kg. per ha., 13-25 weed seeds are 

 often sown per square metre. " Uncontrolled seed " — i.e., seed tested 

 without the seller's knowledge or consent and sold by firms, the deliveries 

 ■of which have not been under a regular control of the Danish State Seed 

 Testing Station — frequently contains very large quantities of weed seeds. 



In three of the annual reports of the Danish State Seed Testing Station 

 ( " Tidsskrift for Landbrugets Planteavl," vol. 7, pp. 23-42 ; vol. 8, pp. 23-25 

 and vol. 10, pp. 22-23), Mag. sc. O. Rostrup has given an account of seeds 

 of tmcultivated species which were found in the samples of clover, grass, 

 root and other seed tested at the State Seed Testing Station up to 1902. A 

 ■corresponding account of the occurrence of weed seed species in the samples 

 tested of late years at this station will, presumably, be published in the near 

 iuture, possibly in the Review of the International Agricultural Institute. 



II. — The progress of germination and the germinating capacity oj seeds of 

 some indigenous plants. 



The examinations of the ability of seeds of indigenous plants to 

 germinate were, to a great extent, made by O. Rostrup during the 

 years 1896-1902, and thereafter by the writer. The results of these 

 tests are to be found in " Tidsskrift for Landbrugets Planteavl," vol. 6, 

 pp. 158-169 ; vol. 8, pp. 27-30 ; vol. 9, pp. 26-29 ; vol. 10, pp. 24-28 ; vol. 11, 

 pp. 172-175; vol. 12, pp. 43-49; and vol. 13, pp. 38-41. 



Fully matured seed was used in the tests and placed to germinate 

 shortly after it had been harvested. It has thereafter been on the ger- 

 mination apparatus until all the seeds were either germinated or decayed. 

 For most species the Jacobsen tank was used* ; only the seeds of 

 aquatic plants were tested for germination in water. The germination 

 apparatiis stood on an unheated glass verandah. The seed was in this 

 way exposed to a temperature that did not differ much from that in the 

 open air. 



The progress of germination was very different for the various 

 species. O. Rostrup has set up the groups in the lists on pp. 130-133, in 

 which all the species tested, with a few exceptions, can be placed. 



The figure stated after the name of the species is the entire germinating 

 capacity, which is high for most of the samples. This is, without doubt, due 

 to the fact that the tests were made at temperatures similar to those to 

 w^hich the seed is exposed in nature. A comparison of the results for 

 germination of some species placed on heated apparatus similar to that used 



* See pp. 32-33 in " StatsfrokontroUen 1871-1896-1921." (The Danish State 

 Seed Testing Station, 1871-1896-1921) by K. Dorph-Petersen. 



