The southern root-knot nematode, Meloidogyne incognita [(Kofoid & White) Chitwood], causes serious economic losses to melon (Cucumis melo L.) production in the United States. The present study was conducted to determine if separable differences in nematode resistance of Cucumis melo could be found at some inoculum level. Five C. melo lines were compared with Cucumis metuliferus Naud. (C701A), a highly resistant species, for root necrosis, galling, egg mass production, and reproduction when inoculated at 0, 500, 1000, 2000, or 5000 nematode eggs per plant. Using these criteria, melon line C880 inoculated with 1000 eggs per plant was highly susceptible, while PI140471, PI 183311, and the cultivars Chilton, Georgia 47, Gulf Coast, Planters Jumbo, and Southland were less susceptible. In greenhouse tests with an inoculum level of 1000 eggs per plant, low levels of resistance were evident. A thorough screening of the available germplasm against M. incognita may identify higher levels of root-knot nematode resistance for incorporation into improved melon cultivars.
Growth of `Earligold' muskmelon (Cucumis melo L.), expressed as plant dry weight from transplanting to anthesis, could be predicted using a multiple linear regression based on air and soil temperatures for 11 mulch and rowcover combinations. The two independent variables of the regression model consisted of a heat unit formula for air temperatures, with a base temperature of 14C and a maximum reduced threshold of 40C, and a standard growing-degree day formula for soil temperatures with a base temperature of 12C. Based on 2 years of data, 86.5% of the variation in the dry weight (on a log scale) could be predicted with this model. The base temperature for predicting developmental time to anthesis of perfect flowers was established at 6.8C and the thermal time ranged between 335 and 391 degree days in the 2 years of the experiment.
A simple method to predict time from anthesis of perfect flowers to fruit maturity (full slip) and yield is presented here for muskmelon (Cucumis melo L.) grown in a northern climate. Developmental time for individual muskmelons from anthesis to full slip could be predicted from several heat unit formulas, depending on the temperature data set used. When temperature at 7.5 cm above soil level was used, the heat unit formula resulting in the lowest coefficient of variation (cv=6.9%) accumulated daily average temperatures with a base temperature of 11 °C and an upper threshold of 25 °C. With temperatures recorded at a meteorological station located 2 km from the experimental field, the method showing the lowest cv (8.9%) accumulated daily maximum temperatures with a base temperature of 15 °C. This latter method was improved by including a 60-degree-day lag for second cycle fruit. The proportion of fruit volume at full slip of 22 fruit from the first cycle could be described by a common Richards function (R2=0.99). Although 65% of the plants produced two fruit cycles, fruit from the first cycle represented 72% of total yield in terms of number and mass. The blooming period of productive flowers lasted 34 days, each cycle overlapping and covering an equal period of 19 days. Counting the number of developing fruit >4 cm after 225 degree days from the start of anthesis (when 90% of the plants have at least one blooming perfect flower) could rapidly estimate the number of fruit that will reach maturity.
Muskmelon [Cucumis melo L. (Reticulatus Group)] fruit sugar content is directly related to potassium (K)-mediated phloem transport of sucrose into the fruit. However, during fruit growth and maturation, soil fertilization alone is often inadequate (due to poor root uptake and competitive uptake inhibition from calcium and magnesium) to satisfy the numerous K-dependent processes, such as photosynthesis, phloem transport, and fruit growth. Experiments were conducted during Spring 2003 and 2004 to determine if supplemental foliar K applications during the fruit growth and maturation period would alleviate this apparent inadequate K availability in orange-flesh muskmelon `Cruiser'. Plants were grown in a greenhouse and fertilized throughout the study with a soil-applied N-P-K fertilizer. Flowers were hand pollinated and only one fruit per plant was allowed to develop. Starting at 3 to 5 days after fruit set, and up to 3 to 5 days prior to fruit maturity (full slip), entire plants, including the fruit, were sprayed with a glycine amino acid-complexed potassium (potassium metalosate, 24% K) solution, diluted to 4.0 mL·L-1. Three sets of plants were sprayed either weekly (once per week), biweekly (once every 2 weeks) or not sprayed (control). Fruit from plants receiving supplemental foliar K matured on average 2 days earlier than those from control plants. In general, there were no differences in fruit maturity or quality aspects between the weekly and biweekly treatments except for fruit sugar and beta-carotene concentrations, which were significantly higher in the weekly compared to the biweekly or control treatments. Supplemental foliar K applications also resulted in significantly firmer fruit with higher K, soluble solids, total sugars, ascorbic acid (vitamin C) and beta-carotene concentrations than fruit from control plants. These results demonstrate that carefully timed foliar K nutrition can alleviate the developmentally induced K deficiency effects on fruit quality and marketability.
Responses of muskmelon (Cucumis melo L. ‘Classic’), with respect to root development, stem and leaf growth, petiole mineral concentration and yield, to trickle irrigation and planting method (direct-seeded vs. transplanted) were evaluted. Field studies were conducted on a southwestern Indiana Lyles silt loam or fine sandy loam soil during 2 successive years using black plastic mulch. Trickle irrigation decreased depth of penetration of muskmelon roots as compared with no irrigation. Trickle irrigation significantly increased the stem length and diameter, leaf area, mean fruit weight and yield, but decreased soluble solids in fruit. Direct-seeded muskmelon plants produced deep, taproots exhibiting positive geotropism, whereas transplants produced more extensive lateral, plagiotropic or geotropically insensitive roots. Direct-seeded muskmelons had significantly larger stem length and diameter, leaf area, soluble solids, and petiole Mn concentration, and lower petiole Fe and Na concentration than transplants. Significant correlations were established between various components of muskmelon growth and development.
Short-internode (SI) muskmelon (Cucumis melo L.) genotypes Ky-P7(si-1 gene for SI) and Main Dwarf (si-3 gene for SI) were compared with the normal-internode (NI) cultivar Mainstream at various plant spacings or planting densities over 3 years. SI `Honey Bush' (si-1 gene for SI) and `Bush Star' (si-1 gene for SI) were included in 2 years. At double the population, SI plants (si gene type) produced ≈35% fewer fruit than `Mainstream' plants grown at one-half the population density. Spacing generally had no effect on average fruit weight, but increasing plant density of SI genotypes decreased the number of fruit per plant. Generally, doubling the density reduced leaf area and total plant dry weight, but had minimal effect on the amount of shaded leaf area. Ky-P7, `Honey Bush', and `Bush Star' plants had more leaf shading than `Mainstream' and Main Dwarf plants.
In the early 1970s, a study was begun to find resistance to feeding in muskmelon, Cucumis melo L., by banded cucumber beetles, Diabrotica balteata LeConte. Bitter seedlings were observed to be more susceptible to feeding than nonbitter seedlings. We noticed reduced damage levels in both bitter and nonbitter seedlings in 1974. Genetic study of resistant materials showed that in addition to the recessive form of the bitter gene, bibi, a 2nd recessive gene, cbl cbl, conditioned reduced seedling susceptibility. Subsequent tests involving spotted (Diabrotica undecimpunctata howardi Barber), striped [Acalymma vittata (Fabricius)], and banded beetles on leaf disks of several C. melo cultivare showed that homozygous double recessive, bibi cblcbl, plants were more resistant to all 3 species of cucumber beetles than nonbitter, bibi Cbl — and bitter Bi—Cbl— plants. This double-recessive resistance provides muskmelon breeders with germplasm which can be incorporated into breeding lines and hybrids.
Fruits of muskmelon (Cucumis melo L., cv. Honey Dew and Powdery Mildew Resistant No. 45) were harvested at weekly intervals after anthesis, and weight, shape, flesh firmness, flesh color, and the content of total solids, alcohol insoluble solids, total sugars, reducing sugars, glucose, fructose, and sucrose were measured. Total sugars (mainly sucrose) increased rapidly between the 28th and 42nd days; hence early harvest must inevitably lead to loss in quality. Ethylene treatments of fruits harvested less than fully mature did not alter sugar content since melons have no starch reserve.