114 



Journal of Agricultural Research 



Vol. XVII, No. 3 



EFFECT OF WATER UPON THE VIABILITY OF PLUM POLLEN 



The effect of water on the viability of plum pollen was tested in the 

 sand cherry (P. Besseyi). The results are presented in Table II. The 

 time of soaking, lo minutes, while relatively short, was decided upon 

 because it was thought that if water was injurious at all, it would be 

 desirable to test its effect at the shorter exposure. The time of soaking, 

 however, is much shorter than the actual time the pollen was subjected to 

 water, since it required some time to dry. Sixteen hours elapsed before 

 this pollen was applied to the stigma. It will be seen from these results 

 that soaking pollen of this species in water and drying before using has 

 no injurious effect. 



Table II. — Viability test of Sand Cherry (P. Besseyi) pollen after being soaked lo minutes 

 in water and then allowed to dry for l6 hours, the pollen in one series having been taken 

 from unopened anthers and allowed to dry in the sun and in the other series from open 

 anthers and allowed to dry in the shade 



Cross made and pollen treatment. 



Treated : 



Tree No. 

 Tree No. 

 Tree No. 

 Tree No. 

 Tree No. 

 Tree No. 

 Tree No. 



Checks: 



Tree No. 

 Tree No. 

 Tree No. 

 Tree No. 

 Tree No. 

 Tree No. 

 Tree No. 

 Tree No, 



iX, pollen, 

 iX, pollen, 

 2X, pollen, 

 2X, pollen, 

 3X, pollen, 

 iX, pollen, 

 3X, pollen, 



soaked 

 soaked 

 soaked 

 soaked 

 soaked 

 soaked 

 soaked 



10 minutes. 

 10 minutes. 

 10 minutes. 

 10 minutes. 

 10 minutes. 

 10 minutes. 

 10 minutes. 



iX, pollen, 

 2X, pollen, 

 1X2, pollen 

 2X1, pollen 

 3X4. pollen 

 3X5, pollen 

 4X3, pollen 

 5X3, pollen 



not soaked . . 

 not soaked . . 



not treated. 



not treated . 



not treated . 

 , not treated . 

 , not treated . 



not treated . 



Condition of 

 anthers. 



Unopened 



, . .do 



..do 



..do 



..do 



Opened. . . 

 ..do 



Num- 

 ber of 



flowers 

 on 



May 25. 



9 



26 



31 

 28 



Num- 

 ber 

 swell- 

 ing on 

 June IS 



6 



6 



20 



9 



25 



Num- 

 ber 

 set on 

 June 26. 



4 

 6 



19 

 9 



4 

 9 



7 



II 



13 

 II 



3 



I 



In addition to this, germination tests were made with selected varieties 

 to determine the effect of the rain of April 26 and 27 upon the viability 

 of pollen. Pollen was taken from anthers which had been closed by the 

 rain and placed in a hanging drop of 20 per cent cane-sugar solution. 

 There was no germination even in the checks from tented trees or from 

 unopened anthers subjected to rain. The temperature, however, which 

 was very changeable, w^as quite low a good part of the time, especially 

 at night, and the negative results with the check make it impossible to 

 draw conclusions as to rain injury to pollen under orchard conditions. 



It has been shown that on account of anther adjustment less pollen 

 is actually washed away than has been supposed. Also, considerable 

 quantities of pollen may be retained by anthers which have opened 



