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  • Author or Editor: G. W. Bohn x
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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

When free choice was available in the Geld, build up of melon aphid (Aphis gossypii Glover, Western Biotype) was extremely low on Cucumis melo L. breeding line U 90234 derived from PI 175111, even if it was next to heavily infested suscepts. LJ 90234 infested with large no. of aphids which were given no choice for food survived with little injury while treated susceptible hosts were killed. Melon aphid nymphs confined on young mature leaves of LJ 90234 often died and survivors grew slowly to small body size and their fecundity was reduced. LJ 90234 is attacked by other insects, however. LJ 90234 appears to exhibit nonpreference, apparent tolerance, and apparent antibiosis to the melon aphid.

Open Access

Abstract

Resistance to muskmelon necrotic spot virus (MNSV) was transferred by successive backcrossing without selection from Cucumis melo L. cv. Gulfstream to a breeding line of muskmelon resistant to the melon aphid, Aphis gossypii (Glover), as a single recessive gene. This hypothesis is supported by the shift of resistant plants from 50 to 100% resistance in backcrossed and inbred progenies. The same gene, designated nsv for necrotic spot virus, for resistance was shown to be present in ‘PMR-5′ and ‘Planters Jumbo’. This finding documents the value of repeated backcrosses in breeding programs designed to transfer single gene characters from exotic sources into adaptive cultivars.

Open Access

Abstract

Reproduction of the melon aphid, Aphis gossypii Glover, varied on different plants of Cucumis melo L., PI 371795, and its inbreds. Successive generations of selection and inbreeding increased uniformity and potency of antibiosis. Aphid reproduction on F1, F2, and backcross hybrids from a resistant × susceptible cross indicated that a single, dominant major gene conferred some antibiosis; but variation within resistant and susceptible classes indicated that additional, minor genes caused effects similar to those found in resistant inbreds.

Open Access

Abstract

Greenflesh Honeydew (GFHD) musk-melon (Cucumis melo L.) is an erratic performer in the varied environments of Arizona, California (Imperial Valley and San Joaquin Valley), and Texas. The vines are susceptible to powdery mildew caused by Sphaero-theca fuliginea (Schlecht. ex. Fr.) Poll, and the cucurbit mosaic viruses including papaya ringspot virus (watermelon mosaic virus, see ref. 3), watermelon mosaic virus 2, and zucchini yellow mosaic virus. Common quality defects of the fruit include traces of net, nonuniform shapes and sizes, low soluble solids, thin flesh, the cavity becoming watery prior to best edibility, and poor flavor. This report describes PMR Honeydew, a recently released powdery mildew resistant honeydew breeding line.

Open Access

Abstract

Cultivated and wild accessions of Cucumis melo L. were evaluated for salt tolerance to identify germplasm useful in breeding programs. Entries were tested for seed germination and seedling emergence in a -6.0 bar osmotic solution of NaCl + CaCl2 (2:1 molar ratio) under laboratory conditions. Seedling growth was measured in the greenhouse as fresh weight of plants grown in sand cultures irrigated with saline nutrient solutions of -0.3, -1.7, and -3.3 bars osmotic potential. Salinity decreased emergence and growth, but quantitative responses varied with differences in environmental conditions between experiments. A wide range of variation in response to salt stress was found for both emergence and vegetative growth. Several plant introductions had better emergence rates and growth than the cultivar ‘Top Mark’ under saline conditions. Salt tolerance exhibited by these introductions may be useful in breeding programs to improve muskmelon performance under saline conditions.

Open Access

Abstract

The melon (or cotton) aphid (Aphis gossypii Glover), an economically important pest throughout the world (1), is an important vector of muskmelon viruses (6), and often causes damage by feeding large populations on this favored host (7). Resistance to the melon aphid was found in muskmelon PI 371795 from India (4).

Open Access

Abstract

WMR 29 is a productive, watermelon mosaic virus (WMV) 1 resistant muskmelon adapted for desert culture with excellent shipping characters: nearly spherical shape; heavily netted; dry stem scar; firm blossom end; very firm flesh at full slip; bright salmon-orange flesh; high soluble solids; small, dry seed cavity; and pleasant taste and aroma. Watermelon mosaic virus causes severe stunting and malformation of stems and leaves, and yield reduction of muskmelons in the American desert Southwest. WMV 1 and WMV 2 are contributing factors in declining muskmelon acreage in Imperial Valley during the last 40 years. It is common for Imperial Valley fields to be 100% infected by end of harvest. Dominant, single gene resistance to WMV 1 was found in PI 180280 (1). Resistance to WMV 2 has not yet been reported although cultivars appear to vary in field tolerance to WMV 2.

Open Access

Abstract

Potentially useful levels of resistance to the leafminer, Liriomyza sativae Blanchard (= munda Frick), in Cucumis melo L. were identified in greenhouse and field studies in different years and widely separated locations. Resistant lines were identified as those having the least number of mines per leaf in a given test. Two apparently distinct sources of resistance were found in Plant Introduction (PI) 282448 from Africa and PI 313970 from India. In a single test of F1 hybrids the resistance of PI 282448 appeared to be controlled by recessive genes, while that of PI 313970 appeared to be controlled by partially dominant genes. Plant introductions from Central Asia and East Asia were, in general, the most susceptible.

Open Access

Abstract

Nomenclature rules are proposed for naming genes of species in the Cucurbitaceae. Genes of cucumber, muskmelon, watermelon, squash, and other cucurbits are reviewed and, when necessary, changes in gene symbols are proposed. The number of known qualitative factors include 68 genes for the cucumber, 37 for muskmelon, 25 for watermelon, and 30 for Cucurbita species.

Open Access