ALFALFA SEED PRODUCTION. 



25 



Table XV. — The setting of alfalfa pods by flowers 'when the standard was removed and 



the keel severed at base. 





Place. 



Year. 



Num- 

 ber of 

 plants. 



Number 

 of flowers 

 tripped. 



Number 

 of pods 

 formed. 



Flowers 

 bearing 

 pods. 



Number of seeds. 



Observer. 



Total. 



Average 

 per pod. 



Westgate 



Washington, D.C. 



Arlington farm 



... do 



1908 

 1908 

 19091 

 1909 2 

 1909 



13 

 10 

 6 



8 



246 

 120 

 22 

 27 

 76 



52 

 19 

 12 

 11 

 13 



Per cent. 

 21.1 

 15.9 

 64.0 

 40.8 

 17.1 







28 

 23 

 19 



1.4 



Do 



1.9 



Do 



do 



1.7 





Pullman, Wash . . . 











1 Plants screened. 



2 Plants not screened. 



The proportion of pods to flowers is in fair agreement with those 

 tripped otherwise. It would seem, therefore, that no importance can 

 be attached to the keel as a passive agent of friction when the column 

 retracts. 



ARTIFICIAL AGENCIES EFFECTIVE IN TRIPPING. 



Any force giving sufficient pressure on the keel, either laterally or 

 vertically, will result in tripping the flower. This may be accom- 

 plished by means of the fingers or even by the hand in grasping an 

 entire cluster or bunch of clusters. Tripping may also be accom- 

 plished by means of a stick, straw, or pencil point inserted into the 

 flower and then separating the posterior processes of the wing petals. 

 In order to determine the relative effect of these various means, an 

 experiment was carried out in which tripping was accomplished in 

 the following ways: (1) Each flower tripped with a small piece of 

 wood, (2) with a pencil point, and (3) rolled between the fingers. 



The data obtained (Table XVI) show little difference in the effects 

 produced by these various methods of trippyig. 



Table XVI. — Effect of tripping alfalfa flotuers by different mechanical methods, at 

 Arlington farm, Virginia. 





Year. 



Plant. 



Number 



of 

 flowers. 



Number 

 of pods. 



Flowers 

 bearing 

 pods. 



Number of seeds. 



Method of tripping. 



Total. 



Average 

 per pod. 



With a small piece of 

 wood. 



With a pencil point . . 



By rolling between the 

 thumb and fingers. 



( 1908 

 \ 1909 

 / 1908 

 \ 1909 

 f 1908 

 \ 1908 

 [ 1909 



F.C. LNo. 18 



F.C.I.No.l 



F.C. I. No. 18 



F.C.I.No.l 



F.C.I. No. 18 



F.C.I.No.l 



do 



21 

 12 

 76 

 42 

 75 

 22 

 43 



3 

 4 

 18 

 22 

 40 

 7 

 21 



Per cent. 

 14.2 

 33.3 

 23.7 

 52.3 

 53.3 

 3L8 

 48.8 



7 

 5 

 33 

 38 

 71 

 9 

 42 



2.3 

 1.2 

 1.8 

 L7 

 1.7 

 1.3 

 2.0 









