294 STATE BOARD OF AGRICULTURE. 



POLLINATION OF FORCED TOMATOES. 



BY S. W. FLETCHER AND O. I. GREGG. 



Special Bulletin No. 39. 



The objects of these experiments were to determine the extent to 

 which the irregularity and small size of some greenhouse tomatoes are 

 due to imperfect pollination; and also to ascertain whether there is any 

 benefit to be derived from the cross-pollination of varieties as compared 

 with self-pollination. Early in the winter of 1906 these questions were 

 asked us by several Michigan greenhouse gardeners who had been having 

 trouble with the setting of tomatoes under glass and especially with 

 small and mis-shapen fruits. 



Conditions of Experiment. The varieties used in 1906 were the Loril- 

 lard, a solid, dull red, flat variety ; Frogmore, which is soft, round, bright 

 red and a tj'pical European forcing variety; and Best-of-All, which is 

 quite similar to Lorillard, except that it has a brighter color. Twenty- 

 four plants of each variety were grown in a three-quarter span green- 

 house running East and West, on a wooden bench 50 feet long and 5 

 feet wide. There were four rows fifteen inches apart and the plants 

 were 24 inches apart in the rows. They were grown to two stems. 



Methods. There were six rows of four plants each of each variety. 

 The plants of the first and sixth rows were used for pollen, the remain- 

 ing plants being used for the crosses. The flowers of the first plant of 

 the second row of each variety were emasculated and pollinated on one 

 side of the stigma only, to learn if irregular, one-sided tomatoes are 

 caused in this wa}'. The flowers of the second plant of the same row 

 were emasculated, and a large amount of pollen was spread over the 

 whole surface of the stigma. The flowers of the third plant was emascu- 

 lated, but only a small amount of pollen was placed upon the stigma. 

 The flowers of the fourth plant had only a very few pollen grains applied 

 to each stigma, the endeavor being to use but one or two grains. A 

 glass slide on which some pollen had been shaken was examined with a 

 hand lens, and the stigma touched at the point where the smallest pollen 

 mass had been separated from the rest. In some cases a single grain 

 may have been applied, but usually from three to five grains must have 

 reached the stigma. 



The flowers of the third row of plants were enclosed in paper sacks 

 before mature; they where emasculated and were pollinated with the pol- 

 len of the same variety. The flowers of the plants in the third and fourth 

 rows were emasculated and pollinated with pollen of the other two varie- 

 ties. In every case the sacks were placed over the cluster as soon as 

 the first blossoms were emasculated and were taken off daily, or every 

 other day, either to pollinate the blossoms first emasculated or to emas- 

 culate later blossoms in the cluster. The sacks were not permanently 

 removed until all danger from cross-pollination had passed. 



