Two strains of tomatoes and their reciprocal hybrids were grown in a greenhouse experiment involving five treatments. The strains were L. esculentum cerasiforme, originally collected in Mexico (designated 9), and a L. esculentum strain from Manchuria (designated 8). Both were obtained from the collection of the late E. W. Lindstrom; both are small (cherry) fruited varieties. The treatnents were five levels of moisture ranging from treatment 1, a bare survival level, to treatment 5, a virtual constant saturation.
The material was grown as a factorial experiment with five replications, there being one hundred plants in the experiment. Data were collected on a number of characters and an analysis of variance made for each. Table 1 presents the results of these analyses for ten characters, presented as the significance level shown for each source of variation. Table 2 presents the genotype and treatment means for each of these characters together with the standard deviation associated with each trait.
TABLE 1
_______________________________________________________________
Trait Reps Treat- Var. Rec. Parents I vs H Trt. x
ments ieties Var.
_______________________________________________________________
1 Total dry weight + +++ n.s. n.s. n.s. n.s. n.s.
2 Shoot weight ++ +++ n.s. n.s. n.s. n.s. n.s.
3 Root weight n.s. +++ +++ n.s. ++ ++ n.s.
4 Root/shoot ratio +++ +++ +++ n.s. +++ ++ n.s.
5 Indentation^1 n.s. +++ n.s. n.s. + n.s. n.s.
6 Shape^2 n.s. n.s. +++ n.s. +++ n.s. n.s.
7 Shape^3 n.s. n.s. +++ n.s. +++ n.s. n.s.
8 Minimum width n.s. ++ +++ n.s. +++ + n.s.
9 Maximurn width n.s. +++ +++ n.s. +++ n.s. n.s.
10 Length of + +++ ++ n.s. ++ ++ n.s.
terminal leaflet
_______________________________________________________________
Table 1. n.s.: not significant; +: significant at 5% level; ++:
significant at 1% level; +++: significant at .1% level. Traits
5 through 10 are concerned with measurements of the terminal
leaflet of the first fully expanded leaf.
1. Measured as difference between maximum and minimum width.
2. Measured as ratio of length to minimum width.
3. Measured as ratio of length to maximum width.
TABLE 2a
_______________________________________________________
Trait Genotypes
_______________________________________________________
9 8 9x8 8x9
_______________________________________________________
1. Total dry weight 4.86 4.74 4.87 5.41
2. Shoot weight 3.74 3.85 3.76 4.20
3. Root weight 1.12 0.90 1.11 1.21
4. Root/shoot ratio 0.29 0.23 0.28 0.28
5. Indentation 11.88 14.00 12.64 13.36
6. Shape 1/min. w. 4.38 3.02 3.43 3.50
7. Shape 1/max. w. 2.25 1.79 2.00 2.01
8. Minimum width 12.32 18.60 17.04 16.56
9. Maximum width 24.20 32.60 29.84 29.92
10. Length of terminal 105.68 113.56 116.20 116.16
leaflet
_______________________________________________________
TABLE 2b
______________________________________________________________
Treatments stand.
Trait 1 2 3 4 5 dev.
______________________________________________________________
1. Total dry weight 1.79 2.55 3.73 6.20 10.59 1.29
2. Shoot weight 1.43 2.04 2.95 4.97 8.03 1.08
3. Root weight 0.36 0.51 0.78 1.22 2.56 0.26
4. Root/shoot ratio 0.26 0.25 0.27 0.25 0.32 0.04
5. Indentation 10.45 11.30 11.80 15.05 16.25 3.02
6. Shape 1/min. w. 3.51 3.39 3.72 3.64 3.66 0.62
7. Shape 1/max. w. 2.00 2.05 2.08 1.97 1.95 0.17
8. Minimum width 14.65 16.00 14.55 18.00 17.45 3.22
9. Maximum width 25.10 27.50 26.35 33.05 33.70 3.73
10. Length of 97.80 107.50 105.95 127.05 126.20 7.48
terminal leaflet
______________________________________________________________
Table 2a + 2b Traits 1, 2, and 3 given in grams; traits 8, 9,
and 10 given in millimeters. Genotype and treatment means.
The three degrees of freedom for "varieties" were broken down into three
orthogonal components for "reciprocal hybrids", "parental lines", and "inbreds
vs. hybrids", respectively. The mean square corresponding to the single
degree of freedom for testing the difference between reciprocal hybrids was
non-significant for all traits. In one case (indentation) the hybrids
diverged in the direction of their maternal parents. The difference was not
significant (P=0.5), but it is mentioned in the light of the difference
between reciprocal hybrids noted by Sclosser (Z.I.A.V. 69: 159-192. 1935) for
leaf shape. It is considered worthy of further study.The mean square for "inbreds vs. hybrids" provided a test for the deviation of the hybrids from the mid-parental value (for the scale of measurement used). It will be noted that for the majority of traits the hybrids did not differ significantly from the mid-parent value. Thus, dominance was lacking, inheritance was intermediate for these traits.
Of the traits exhibiting dominance, one (lenth) showed evidence of heterosis, i.e., the hybrids lay outside the parental range. The three degrees of freedom in this case were broken down into a set of orthogonal comparisons such that one degree of freedom was available to test the difference of the hybrids from the high parent. This difference was not significant.
For two of the traits, total weight and shoot weight (actually a single trait is involved) no parental differences were found. In no case did the treatment variety interaction show significance.