Graham, T. O.
Tomato plants containing dm dm, the factor for dwarf modifier have a thick main stem. For this reason it was considered that they might have the power, at the time of outdoor seed germination, to push their way up through heavy cold soils. This would give them special value in the north from the standpoint of outdoor seedling.
A number of crosses were made between dm dm plants and normal commercial tomato varieties, not dwarf in type. An F2 population was grown. The seed containing the dm dm factor did not germinate as well as the seed containing the normal non dwarf commercial plant type.
The soil in which the tomato seed was sown outside on May 29th was a Burford loam. In the first two weeks after seeding, the minimimimum temperature averaged 47.3 deg. F. A count was made on July 7th as to the number of seedlings which appeared above ground.
Germination Test 1958
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No. Percent
of Observed Expected of
seeds population population expected
Cross sown + dm + dm dm
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dm X Rhode Island 800 150 34 138 46 74%
dm X Rhode Island 800 218 43 196 65 66%
dm X Rhode Island 1632 468 96 423 141 69%
dm X Mammoth Wonder 800 103 21 93 31 69%
dm X Mammoth Wonder 800 222 33 191 64 51%
dm X Mammoth Wonder 1632 376 95 353 118 80%
dm X Fireball 800 236 52 216 72 72%
dm X Rhode Island 800 297 72 277 92 78%
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____________
Percent
germination
of total
population
____________
23%
33%
... 34%
16%
32%
29%
36%
46%
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