of Solanum Nigrum as a Mentor in Training of Tomato
As tomato is a self-pollinated plant, in the course of long period of self-fertilization, it gradually diminishes its original variability and cultivated quality, and cannot be adapted to unfavorable external environment. The Variety UN 2 is a good example. When it was grown in Nanking, for continuously 6 years, its variability and disease-resistance lowered year after year.
According to the theory of Michurin's biology, the variability of a plant is related to the degree of internal contradiction within the plant and its variability can be increased by means of hybridization, either sexual or vegetative.
In the spring of 1951, S. nigrum was taken from the fields to use as a mentor in training of tomato var. UN. 2, by means of vegetative hybridization, with on attempt to increase its variability or to change some other characters of this variety. The F1 was also studied.
Experiments showed that the disease-resistance of F1 increased very significantly. More than 64% of the hybrids flowered earlier than the control (maternal plants) by 5-11 days; among the remaining 36% though their first flower cluster opened about the same time as the control, their second flower cluster generally opened a little earlier.
Therefore, the F1 of vegetative hybrid can also be used for agricultural production, just as the F1 of sexual hybrid.
The fruit production of the early-blooming F1 plants was 24%-536% greater than that of the control plants.
The characters of the hybrid plants even obtained from seeds of the same fruit vary greatly. It may be caused by differed degree of assimilation and desimilation between individuals.