Natural Crossing in Tomatoes as Related to Distance and Direction

Abstract

Although the amount of natural crossing in tomatoes is known to be low as compared to certain other crops , it is usually sufficient to cause serious contamination in breeding and seed growing work. It is generally considered to be the result of insect pollenizers since the pollen is not carried by wind. Lesley (1) reported 4.9 per cent cross-fertilization for the Magnus variety and only 0.59 per cent for Dwarf Champion. He explained that the difference might be due to differences in floral structure. In order to determine the effects of distance between plantings of different varieties and direction of prevailing winds upon the percentage of natural crossing, tests were conducted at Charleston, South Carolina and at St. Paul, Minnesota. The plan was identical, at the two locations except that the rows were planted east and west at St. Paul and north and south at Charleston.