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  • Author or Editor: J.D. McCreight x
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Abstract

Three male-sterile genes are available for use in hybrid muskmelon (Cucumis melo L.) seed production. Although ms-1 and ms-2 were described in 1949 (2) and 1964 (1), they have been used little, if at all, for commercial hybrid seed production. It is too soon to predict the usefulness of ms-3, because it was only recently described (5). In a previous study of phenotypic variation of ms-1 and ms-2 segregates, I showed that fertile plants produce at a low frequency aberrant staminate flowers that might be mistakenly identified as male sterile (4).

Open Access
Authors: and

A new chlorophyll-deficient mutant is the first cytoplasmically inherited trait described in melon. This mutant is characterized by yellow apices with the leaves and stems progressively turning green in color as the branches mature. A protocol is proposed for naming and symbolizing cytoplasmic traits in melon. This mutation is named yellow-tip and symbolized cyt-Yt.

Free access

Abstract

A 3rd recessive, male-sterile gene in muskmelon (Cucumis melo L.) is named male sterile-3 and symbolized ms-3. Male sterile-3 is phenotypically distinct from male-sterile genes ms-1 or ms-2.

Open Access
Authors: and

Abstract

A program is described which stores, lists, searches, corrects, appends, and duplicates pedigree records.

Open Access

Genetic variation in cucumber (Cucumis sativus L.) accessions from India was assessed by examining variation at 21 polymorphic isozyme loci. Forty-six accessions acquired by the U.S. National Plant Germplasm System (NPGS) before 1972 were compared with 146 accessions collected during a 1992 U.S.–India expedition to the states of Rajasthan, Madhya Pradesh, and Uttar Pradesh, India. Two distinct groups (Group 1 and Group 2) were identified within accessions collected in 1992 (0.025 < P < 0.01). Variation at Ak-2, Fdp-2, Gr, Mdh-2, Mpi-1, Per, Pgm, and Skdh was important in the detection of this difference. Group 1 contained 37 (27 Madhya Pradesh + 10 Uttar Pradesh) accessions and Group 2 contains 102 (84 Rajasthan + 18 Madhya Pradesh) accessions. Seven accessions (5 Madhya Pradesh + 2 Rajasthan) were not associated with either group. Isozymic variation in U.S. NPGS accessions acquired before 1972 differed significantly (P < 0.005) from those collected during 1992. When Indian accessions taken collectively (collected before 1972 and in 1992) were compared with an array of 707 C. sativus U.S. NPGS accessions examined previously, relationships differed between accessions grouped by country or subcontinent.

Free access

Abstract

Cripshead (iceberg) lettuce accounts for the major portion of commercially produced lettuce in the U. S. Crisphead types are not, however, commonly grown by home gardeners because of misunderstandings about cultural practices necessary to ensure head formation. Two important factors are planting date and thinning of seedlings. Lettuce should be planted when temperatures are favorable: 17-28°C day and 3-12°C night (2). Warmer temperatures will cause bushiness, bolting, and tipbum. Cooler temperatures will delay head formation and reduce head size. Lettuce should be thinned at the 2-3 leaf stage to increase postthinning survival and ensure even maturity; plants should be spaced 25-35 cm apart (2). If the home gardener is successful in producing a well-formed head, it is often too large to be consumed in a single meal, and if stored in the refrigerator, it loses its ‘fresh-picked’ quality and appeal. Leaf and cos types of lettuce are more popular with home gardeners because they do not form heads and individual plants produce high-quality leaves over a long period of time. An objective of this program was to produce a highquality iceberg lettuce with smaller sized heads for home gardeners.

Open Access

Abstract

Cos (romaine) lettuce (Lactuca sativa L.) accounted for less than 5% of California lettuce production in 19783. Cos lettuce adds color, flavor, and texture to tossed (chopped) lettuce salads. In addition, cos lettuce is more nutritious than crisphead lettuce (1).

Open Access

Abstract

Salt tolerance differences among 115 plant introductions of lettuce (Lactuca sativa L.) were screened in sand cultures under greenhouse conditions. Leaf and root fresh weights of plants grown for 4 to 5 weeks in salinized sand cultures were compared to a benchmark cultivar, ‘Buttercrunch’. Plant introductions showed a wider range of salt tolerance than standard cultivars of the United States and therefore have some potential in breeding programs designed to increase the salt tolerance of this crop.

Open Access

Abstract

Red stem, found in PI 157083, is controlled by a single recessive gene, r. Red pigment appeared in vascular traces of hypocotyls about 2 weeks after planting. Seed coat color of red-stemmed plants was reddish or tan, in contrast to white or yellow seed coats of green-stemmed plants. Pale, a spontaneous mutant in a second backcross hybrid from ‘Campo’ × PI 180280, is controlled by a single partially dominant gene, Pa, which acts as a recessive lethal: Pa/Pa plants die; Pa/+ are pale; and +/+ are normal. Pale did not affect expression of red stem. Testcross segregations fit the expected ratio for independent assortment of the 2 loci.

Open Access

Abstract

Aqueous extracts of thawed, transverse slices of cucumber fruit (Cucumis sativus L.) gave reliable measurements of reducing sugar and total carbohydrate concentrations. Fruit fresh weight increased throughout a 20-day sampling period, averaging 0.6, 13.4, and 389 g at anthesis, 5, and 20 days after anthesis, respectively. Reducing sugar and total carbohydrate concentrations were highly correlated (r=.97), but were not correlated with fruit fresh weight (r=.40) or commercial fruit size (r=.52). Reducing sugar concentration at anthesis averaged 6.3 mg/g fresh weight and increased to a plateau averaging 22.7 mg/g from 5 to 20 days after anthesis. Reducing sugar concentration of 585 plant introductions and cultivars ranged from 7.1 to 52.8 mg/g and averaged 31.1 and 22.6 mg/g at 2 harvest dates.

Open Access