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Abstract
This paper describes a system for predicting container mixture physical and chemical properties from component properties. An additive model is presented that assumes that a mixture property is the weighted sum of the properties contributed by the individual components. To test this hypothesis, 24 combinations of sandy loam soil (Typic Xerothent), sand (Typic Xeropsamment), bark, and perlite were tested for bulk density, total and air-filled porosities, container capacity, available water, saturated hydraulic conductivity, pH, and cation exchange capacity. The measured experimental data were compared with values predicted from the additive model. Measured and predicted values were in good agreement for most properties, except saturated hydraulic conductivity and air-filled porosity for mixtures with low total porosity. Application of the same approach also worked well for previously published data.
Abstract
The inheritance of Fusarium wilt resistance was studied using 3 varieties of watermelon. ‘Summit’ and ‘Charleston Gray’ differed in their level of resistance. ‘Summit, carrying a high level of resistance, acted in a completely dominant manner to the susceptible variety ‘New Hampshire Midget’. On the other hand, ‘New Hampshire Midget’ was partially dominant to the moderately resistant variety ‘Charleston Gray’. The relationship of ‘Summit’ to ‘Charleston Gray’ was not clear, although the data suggested dominance of ‘Summit’ to ‘Charleston Gray’.
Three gene models were postulated, a one-locus multiple-allelic model and 2 two-locus models. The deviations from regression (model adequacy) for the multiple-allelic model and for one of the 2-locus models were nonsignificant as shown by the Chi-square test. The coefficient of determination (R2) for the multiple-allelic model was .973 with 5 genetic parameters and for the 2-locus model, R2 = .970 with 4 genetic parameters. Neither model was considered superior to the other.
It was suggested that a variety such as ‘Summit’, with a high level of resistance, inherited in a completely dominant manner, could be of value in obtaining Fi hybrids highly resistant to Fusarium wilt, as well as aid in the development of highly resistant open-pollinated varieties.