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  • Author or Editor: W. H. Gabelman x
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Abstract

Plants growing in nature provide a continuous array of biological efficiencies related to mineral nutrition. Nearly all of the temperate and tropical areas of the earth are covered with species adapted to the unique properties of particular soils. These properties may represent the extremes in element availability from very deficient to toxic levels and may be associated with wide ranges in pH.

Open Access

Abstract

Botrytis neck rot, caused by Botrytis allii Munn, is one of the most serious diseases of onion (Allium cepa L.) cultivars during storage. Uniform maturity of Fj hybrids has provided tolerance to natural infection in the United States. Cultivar differences in resistance to this disease have been detected by artificial inoculation in Europe. However, gain from selection for resistance by systematic artificial inoculation has not been reported (1, 2, 4, 5).

Open Access

Abstract

Dominant monogenic control of purple petiole (G) over green (g) was found in the carrot. Variations observed in intensity of purple suggested presence of modifier genes. Plants having purple petioles were easily identified at all stages of growth following true-leaf formation.

Open Access

Abstract

Genetic variation in pigment and sucrose concentrations of beet roots was investigated in a diallel cross among 9 inbred table beet lines. General combining ability (GCA) was significant for betacyanine, betaxanthine, and sucrose concentrations. Specific combining ability was significant for pigment concentrations but not percentage of sucrose. Cross × location interactions were significant and were in all cases due to the interactions of GCA with locations. Interactions of both GC A and SCA with years were detected for betacyanine and betaxanthine concentrations. Dominance, predominantly in the direction of higher percentage of sucrose, was ambidirectional for pigment concentrations. The average dominance level was in the partial range for all traits. Epistasis was not detected for percentage of sucrose, and was found for pigment concentrations only in crosses derived from one of the parents. Genotypic, phenotypic, and environmental correlations between betacyanine and betaxanthine concentrations were strongly positive. Genotypic and phenotypic correlations were not significant between percentage of sucrose and pigment concentrations.

Open Access

Abstract

Changes in betacyanine (red pigment) concentration, betaxanthine (yellow pigment) concentration, and percent dissolved solids associated with growing time and season were studied in roots of 12 cultivars of table beet (Beta vulgaris L.) Differences among cultivars and cultivar × harvest date interactions were detected for each trait. Depending on cultivar and planting date, betacyanine concentration increased, decreased, or remained constant with increased growing time, while betaxanthine concentration and percent dissolved solids invariably increased over the same period. Beets planted on July 12, 1978, had greater pigment concentrations than beets planted on June 9, 1978, when grown the same number of days. At 83 days after planting, root weight was negatively correlated with betacyanine concentration (r = −0.44) and betaxanthine concentration (r = −0.40), but after 136 days, both correlations were reduced in magnitude (r = −0.23).

Open Access

Abstract

Seven inbred onion (Allium cepa L.) lines representing a range of responses for resistance to Fusarium oxysporum Schlect. emend. Snyd. and Hans. f. sp. cepae, the causal agent of fusarium basal rot, were mated in a complete diallel. The resultant inbred, F1, and reciprocal F1 progenies were evaluated for resistance in a greenhouse seedling test. Mean squares for general combining ability, specific combining ability, and reciprocal effects for resistance to fusarium basal rot were significant (P = 0.000). The parent with the highest general combining ability for resistance was W404, particularly when used as a seed parent. Reciprocal differences were significant in several hybrid combinations. The greenhouse screening procedure is described.

Open Access

Four methods for screening carrot (Daucus carota L.) germplasm for resistance to bacterial soft rot were compared. There were differences in resistance among strains, with most severe damage caused by Erwinia carotovora pv. carotovora SR 394 (L.R. Jones) Holland and Erwinia carotovora pv. atroseptica SR 159 (van Hall) Jennison. Inoculation of cross-sectional root slices with bacteria applied in suspension-soaked paper disks produced the most consistent response. The severity of disease damage was proportional to bacterial suspension concentration. With the development of a standard screening method, it may be possible for breeders to breed carrots with reduced susceptibility to soft rot.

Free access

Abstract

A technique is reported for studying quantitatively the variability in size and shape of carrot roots. The method uses 2 measuring devices which are modifications of an instrument reported earlier by Mack and Lachman. The devices measure variables associated with root size and shape accurately and rapidly. The raw data can be readily converted to more descriptive statistics. Applying the technique to cultivars representing the broad spectrum of variability in carrots, we obtained for each cultivar a numerical description of an average root. Converting the numerical variables into a graphic display resulted in a schematic drawing which describes each cultivar. The technique was applied similarly to describe seasonal changes in root size and shape within a cultivar. The potential use of the procedure for carrot research is indicated.

Open Access