1908.] 



Pollination of Tomatoes. 



Lupinus luteus, can be procured from Dr. A. Kiihn, Ainmiller- 

 strasse 36, Munich, price two shillings a bottle. The name of 

 the plant for which the inoculating material is required should 

 be specified. 



Several experiment stations in the United States have been 

 investigating the question of the pollination of tomatoes. As 



far back as 1890-91 it was found at the 

 Pollination of Cornell Station that the amount of pollen 

 Tomatoes. used had an important influence on the 



form and size of the fruit. More recently 

 these results have been confirmed at the Michigan Station, 

 where it has also been shown that no decided advantage was 

 gained by the cross-pollination of varieties as compared with 

 self-pollination. Four plants of each of six varieties were used 

 to determine the effect of using varying amounts of pollen. 

 All the flowers on one plant of each variety were emasculated 

 and pollinated on one side of the stigma only. These invariably 

 produced lop-sided and small fruits. All the flowers of one 

 plant of each variety were pollinated with from 1 to 5 pollen 

 grains. These produced very small solid fruits, with an average 

 weight of about 1 oz., and having no seeds or but one or two. 

 All the flowers on one plant of each variety were pollinated, 

 with a large amount of pollen, spread all over the stigma. 

 These produced fruits that were smoother and heavier than 

 those produced from flowers that received but a small amount 

 of pollen. The conclusions deduced from these experiments 

 are that when pollen falls on one side of the stigma only, a 

 one-sided tomato always results, and the larger the stigma 

 the greater the irregularity. The amount of pollen applied 

 determines to a great extent the size and smoothness of the 

 tomato, but after applying a certain amount no further increase 

 can be obtained. The small, irregular tomatoes grown under 

 glass are caused largely by insufficient pollination. 



With a view to throwing some light on the relative value of 

 cross and self-pollination the blossoms of four plants of each 

 variety were self-pollinated, and the blossoms of eight plants 

 of each variety were cross-pollinated with two other varieties. 

 All set fruit equally well. The 265 fruits produced from self- 

 pollination had an average weight of 77-3 grams. The 534 



