262 



SCIENTIFIC AGRICULTURE. 



April, 1922. 



ers and gave verv satisfactory results, 

 (fig. V). 



By using control tests, it was found 

 that flowers emasculated as described 

 above and not pollinated generally proved 

 to be quite sterile ; but, when pollinated, 

 a fair percentage produced well-develop- 

 ed seed pods. 



In the seasons from 1912 to 1917, a 

 method of clearing away pollen was tested, 

 Avhich gave very satisfactory results. In- 

 stead of using a fine jet of water for this 

 purpose, the anthers and anj^ pollen grains 



Pig-, v. Method of ii „ ' ; ng-le 



branch of a plant. As the plant grows, the 



muslin-covered cage can be adjusted to any 



part of the supporting- stake. 



adhering to the surface of the stigma were 

 brushed away by using the frayed end of 

 a piece of gardener's raffia: this im- 

 provised brush was found to be very ef- 

 fective and moreover very convenient ; as 

 after each operation, tlie end of the raffia 

 may be clipped off, thus a fresh, clean 

 brush is available for each operation. 



Reliability of Method of Emasculation 

 Tested. 



During the course of tliese investiga- 

 tions, m-dny experiments have been made 

 to test the reliability of the methods of 

 emasculation described above. In one 

 series of tests, out of 189 flowers emas- 

 culated, four pods were produced; but 

 only one viable seed. In another series, 

 66 emasculated flowers produced ten pods 

 wliicli contained no fully (h'veloped seeds. 



It was found liowcvci- tluit uiulcr suit- 



able conditions when flowers were care- 

 fully emasculated and pollinated a fair 

 percentage of fertile crosses was obtained: 

 if conditions were unfa vora Die, few or no 

 fertile crosses were obtained. An average 

 result may be taken at about forty to fifty 

 per cent fertile. 



Conditions Favorable for 

 Cross-fertilization. 



The successful cross-fertilization of Al- 

 falfa depends on several factors which 

 are very difficult to control; hence, it is 

 readily seen that it is impossible to stand- 

 ardize either conditions or methods of 

 working : this is especially evident when 

 the work is being carried on under natural 

 conditions in the field. 



I Weather Conditions. — As would nat- 

 urally be expected, the state of the 

 weather affects the work very materially 

 not only on the day pollinations are made 

 but also for at least twenty-four hours 

 previous, and for a similar period after, 

 the work has been done. 



Our results show that almost invariably 

 the greatest percentage of fertile crosses 

 have been obtained during a continuous 

 period of fine weather, moderately warm 

 and without rain. 



II. Condition of the Plants. — There 

 should be sufficient moisture and plant 

 food in the soil to supply the immediate 

 needs of the plant without forcing a too 

 luxuriant growth. A steady and healthy 

 growth is very desirable : too much moist- 

 ure together with a highly manured soil 

 tends to overproduction of stem and Jeaf 

 which is detrimental to seed formation. On 

 the other hand, with an insufficient supply 

 of moisture, many of the flowers wither 

 and fall off l)efore fertilization takes 

 l)lace. 



Condition of the Pollen. — The pollen 

 should he fully mature; and yet not too 

 old. A good indication as to the proper 

 condition of Alfalfa pollen is obtained by 

 carefully observing the flowers as they 

 are being tripped by hantl. During the 

 process of tripping when the anthers burst 

 and the pollen is seen scattered in the, 

 form of a fine dust, we have an indication 

 that the iK)lleii is in a gootl, healthy con- 

 dition. 



To niiike an exact dctermiuaiton of the 



