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Abstract
The practical significance of incorporating TMV resistance into F 1 hybrid tomatoes can hardly be over-estimated. Internal browning, graywall and blotchy ripening disorders continue to plague the greenhouse tomato grower and constitute perhaps his greatest current disease problem. Lewis and Taylor (6) pointed out the confusion which exists with regard to the association of TMV with these disorders.
Abstract
Field studies of crosses involving lines of peas which produce predominantly 1, 2 and 3 pods at each peduncle showed that inheritance of number of pods is quantitative. As many as 8–9 genes appear to differentiate pod number of the cultivars used in this study.
Estimates of heritability showed that about 50% of the total field variance of pods per peduncle was due to genetic causes. Of this about 17% was due to additive genetic effects.
Abstract
Lines of peas which produce predominantly single, double, and triple pods, respectively, at each peduncle were crossed and growth of the parental lines and the F1, F2 and backcross progenies was compared at 2 temperature regimes—45° night-6O° day and 60° night-75° day—in the growth chamber.
The single-and double-podded parental lines were extremely uniform, producing almost 100% single and double pods, respectively, at both temperature regimes. The triple-podded parent produced almost all 3-podded determinant peduncles at the lower temperature but tended to produce indeterminant peduncles with 2, 3, and 4 pods at the higher temperature.
The F1 of all crosses produced almost all double pods at both temperatures.
The mean numbers of pods per peduncle produced on the F2 plants was somewhat higher at the high than at the low temperature. The F2 and backcross generation plants segregated as they would for a character which is dependent on several genes but for which genes for 2 pods per peduncle showed some dominance. These results contrast with field studies where pod number was extremely variable for all lines and where genes for low pod number appeared to be somewhat dominant.
Abstract
The variability, mode of inheritance, and gene action for soluble solids was studied in a cross of 2 divergent lines, Mo. Accession 223, a selection of PI 272689, and 1-417-1. About 3 gene pairs were indicated to control soluble solids. Additive gene action accounted for a heritability of about 35%. In the broad sense, heritability was about 59%, suggesting that non-additive genetic variance was about 25%. Evidence for dominance and for epistatic interactions of genes appeared to be lacking.
Abstract
The variability, mode of inheritance, and gene action for tomato fruit weight was studied in a cross of 2 divergent lines, Mo. Accession 223 (a selection of USD A P.I. 272689), and 1-417-1. The data indicated that more than 10 gene pairs, and possibly as many as 20, differentiated the parents for fruit weight in this cross. Partial dominance of small fruit weight genes was shown. No evidence of epistatic interaction was found. Gene action was largely geometrically cumulative. Heritability estimates in the broad sense was 29%. Little additive genetic variance was detected.
Abstract
The interrelationships between tomato fruit weight, Brix, pH and titratable acidity were studied in 2 constant parent groups of F1’s, their 11 parental lines and 2 sets of P-F1’s. Estimates of genetic and phenotypic correlations between high Brix and high titratable acidity and between low pH and high titratable acidity suggested considerable pleiotropic role of genes. The desirable assocation of high Brix with low pH was phenotypically unstable and appeared to have little detectable genetical basis. Fruit weight was poorly correlated with quality traits. Implications of these findings in a breeding program are discussed.