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- Author or Editor: James W. Cameron x
- Journal of the American Society for Horticultural Science x
Abstract
A high degree of inheritance for resistance and susceptibility in sweet corn (Zea mays L.) to acute ozone leaf injury under field conditions was shown during 2 and 3 generations of breeding with 3 series of cultivars. Crosses of highly susceptible × resistant inbreds gave notably susceptible F1's. F2 families segregated quantitatively but extremes were sometimes recovered. Distribution in F2 was skewed toward low injury. Resistant X resistant crosses gave almost fully resistant F1's and F2's. A study involving a second series of inbreds also showed a close relationship between susceptibility in a parent and in its derived F1's. Three generations of selection and inbreeding, beginning with a segregating population, resulted in near fixation in resistant sublines but showed continued segregation in progenies from susceptible selections.
Abstract
Titratable acidity and total soluble solids were measured in F1 populations from crosses of an acidless pummelo [Citrus grandis (L.) Osbeck] with an acidless orange [C. sinensis (L.) Osbeck], an acidless mandarin-lime (C. limonia Osbeck), and an acidless sweet lime (C. limettioides Tan.). No acidless individuals were found among a total of 291 hybrids. Acidity ranges were those which might be expected if acid forms of the orange and the limes had been crossed with the acidless pummelo. In each cross, however, acidities averaged lower than the acidities of some acid cultivars which were compared to the acidless parents. This effect is attributed largely to the influence of the acidless pummelo. Two bud-propagation trees from another acidless orange accession have regularly produced acid fruit at Riverside; this may be the result of cell substitution between histogenic layers. The acidless orange and acidless lime parents may all be chimeral for the acidless factor. Alternatively, the factor in these parents may be different from that in the acidless pummelo. Levels of total soluble solids in the hybrids were mostly within the ranges of the parents, and showed no appreciable relationship to acidity levels.
Abstract
Titratable acidity and total soluble solids were measured in F1 hybrid citrus populations involving an acidless pummelo [Citrus grandis (L.) Osbeck] and an acidless orange [Citrus sinensis (L.) Osbeck] respectively, as one parent. Three advanced crosses were also studied. Crosses of the pummelo with 5 medium acid cultivars produced no acidless individuals but many with low to medium acidity and a few with acidities above 1.6% in their main seasons of use. The overall mean titratable acidity was 1.1%. Crosses of the acidless orange with 4 medium-acid cultivars produced only a few low to medium-acid individuals, and many with acidities above 1.6%; the overall mean acidity was 2.0%, significantly higher than with the pummelo. Mean levels of total soluble solids had a range which was similar between the 2 types of crosses, although the overall mean was significantly higher in the orange crosses. There were significant correlations between acid and total soluble solids levels in only 2 out of 11 progenies among all of the crosses.
Twelve of 40 individuals were essentially acidless in an F2 population involving the acidless pummelo as a grandparent. There were no acidless individuals, but there were many moderately-acid ones in 2 populations of acidless pummelo hybrids backcrossed to acid cultivars. These proportions suggest simple inheritance for the acidless character of the pummelo. In contrast, the high acid levels of the F1 populations with acidless orange imply a different basis for the latter’s lack of acidity.