Band 137. Nr. 19. XXXIX. Jahrgang. I. Bd. Nr. 19. 



Botanisclies Centralblatt 



Referierendes Organ 



der 



Association Internationale des Botanistes 

 für das Gesamtgebiet der Botanik. 



Herausgegeben unter der Leitung 

 des Präsidenten: des Vice-Präsidenten : des Secretärs: 



Dr. D. H. Scott. Prof. Dr. Wm. Trelease. Dr. J. P. Lotsy. 



und der Redactions-CoTnrnissions- Mitglieder: 



Prof. Dr. Wm. Trelease, Dr. C. Bonaventura, A. D. Cotton, 



Prof. Dr. C. Wehmer und Mag. C. Christensen. 



von zahlreichen Specialredacteuren in den verschiedenen Ländern. 



Dr. J. P. Lotsy, Chefredacteur. 



No. 19. 



Abonnement für das halbe Jahr 15 Mark 

 durch alle Buchhandlungen und Postanstalten. 



1918. 



Alle für die Redaction bestimmten Senduns^en sind zu richten an: 

 Redaction des Botanischen Cenb-albiattes, Haarlem (Holland), Spaarne 17. 



Grantham, A. E. and F. Groff. Occurrence of sterile spi- 

 kelets in wheat. (Journ. agr. Research. Washington. VI. p. 

 235—250. 1916.) 



In this paper the term „sterile spikelet" is used to designate 

 those two or three spikelets at the base of the spike of wheat which 

 for some reason fail to develop and produce seed. No account was 

 taken of the sterile florets which might occasionally occur within 

 the spikelet. The absent spikelets, as shown by the naked rachis, 

 were the only ones estimated as sterile. 



The following results were obtained from the authors expe- 

 riments: 



The number of sterile spikelets per spike in wheat is directly 

 afifected by rate of seeding or the spacing of the plants. The more 

 Space allowed each plant the smaller the number of sterile spikelets 

 on each spike. 



The bearded varieties of wheat as a class have a higher per- 

 centage of sterile spikelets than the beardless varieties. Of the 188 

 varieties examined the smallest number of sterile spikelets was 

 found on a beardless variety and the largest number on a bearded 

 variety. 



Early seeding seems to increase the percentage of sterile spi- 

 kelets on each spike, Wheat seeded very late had the smallest 

 percentage of sterile spikelets. 



The application of nilrogen alone as a fertilizer produced the 

 lowest percentage of sterile spikelets. Phosphoric acid singly gave 

 the highest percentage of sterile spikelets. Where two elements of 

 fertilizers were combined, phosphoric acid and potash gave the 



Botan. Centralblatt. Band 137. 1918. 19 



