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Cucurbitaceae, the gourd family of flowering plants, is a very large and diverse family, the order Cucurbitales, contains 95 genera and 950–980 species of food and ornamental plants, and wild and weedy species mostly with high genetic diversity. This review is focused on the most important cucurbit crops (Cucumis sativus, Cucumis melo, Cucurbita spp., Citrullus lanatus, Momordica charantia, Lagenaria siceraria, and Luffa acutangula) and some their wild relatives as hosts of cucurbit powdery mildews (CPM). Powdery mildews (PM) (Ascomycota, Erysiphales) are one of the most frequently encountered and easily visible groups of plant pathogenic fungi with > 900 species. They are obligate biotrophs, they colonize above-ground plant tissues, mostly leaves, though they may also colonize stems, petioles, flowers and fruits, and they are usually debilitators, not killers. These parasitic fungi have been problematic on cucurbits for a long time world-wide, causing serious economic losses in yield and quality. All economically important cucurbit crops host CPM. Seven PM species with different taxonomic positions, host ranges, geographic distributions and ecological requirements are known on cucurbits. CPM species taxonomy and denomination rapidly changed during last few decades through detailed analyses and clarifications. At least three PM species frequently parasitize cucurbits: the endoparasite Leveillula taurica (Lt) with marginal economic importance; and two ectoparasitic species, Golovinomyces orontii (Go), and Podosphaera xanthii (Px), which are economically important world-wide. The two pathogens differ in ecological requirements and distribution, though they may occur together in mixed infections. They are highly variable at the population level for virulence, race identities, and fast adaptation of pathogens. Cucurbit-CPM species interactions are diverse and complicated, and differ between hosts and their respective pathogen genera and species. Here we present a critical overview of obstacles, gaps and recent progress in these matters for six cucurbit genera with respect to resistance resources, genetics of resistance, genetic mapping and development of molecular markers, physiology and mechanisms of resistance, developments in mlo-mediated resistance, patents, and CPM resistance breeding. [ABSTRACT FROM AUTHOR]

Watermelon [Citrullus lanatus (Thunb.) & Nakai] is widely grown on plastic mulches in the southeast United States, but responses of plants to plastic mulch color are not well understood. The objectives of this study were to determine the effects of colored plastic mulches and changes in root zone temperature (RZT) on fruit yield of watermelon fruit. The mulches (152 cm wide) evaluated were: black, blue, gray, red, silver (metallic), and white. During the first weeks after transplanting, canopy development was more rapid on black, blue, and red than silver and white mulches. As the season progressed and temperatures increased, differences in canopy development among mulch treatments tended to decrease. Watermelon plant growth benefited from soil warming using plastic film mulches, mainly blue, black, and red. There were no differences in fruit yield among different colored mulches, indicating that under the temperature conditions of the present study, the RZTs during fruiting were within optimal range for watermelon which is estimated to be 28.3°C. [ABSTRACT FROM AUTHOR]

An alternative to reduce the undesirable effects of antineoplastic agents has been the combination of classical treatments with nutritional strategies aimed at reducing systemic toxicity without decreasing the antitumor activity of already used drugs. Within this context, this study evaluated the possible reduction of toxicity when cisplatin treatment is combined with watermelon pulp juice supplementation in C57BL/6 mice with melanoma. Watermelon is a fruit rich in vitamins, minerals, proteins, lycopene, carotene, and xanthophylls, which has shown effectiveness in the treatment of cardiovascular diseases, weight loss, urinary infections, gout, hypertension, and mutagenicity. The following parameters were analyzed: animal survival, bone marrow genotoxicity, serum creatinine and urea, histopathological features of the tumor tissue, tumor weight and volume, and weight of non-tumor tissues (kidney, liver, spleen, heart, and lung). The results showed that watermelon had no antitumor effect but reduced the toxicity of cisplatin, as demonstrated by an increase in the number of bone marrow cells and a decrease in serum creatinine and urea levels. The data suggest that watermelon pulp juice can be an alternative for reducing the side effects of antineoplastic agents. [ABSTRACT FROM AUTHOR]

Watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai] is a cucurbit with high value in Burkina Faso. It is appreciated for its fruits, which are widely consumed. In the literature, watermelon is described as an important source of bioactive compounds beneficial to health. There is very little scientific data on this supposed nutraceutical potential of the watermelon. This study aimed to characterize the nutraceutical and antioxidant potential of the pulp of five watermelon cultivars grown in Burkina Faso to identify the best cultivars for consumers. The study focused on the physicochemical, nutraceutical, and antioxidant activity characterization of the cultivars using standard methods. This study revealed a significant variation in total phenolics, flavonoids, β-carotene, and lycopene contents between the five cultivars while the color did not show significant variation. The color parameters with ΔE ranging from 40.62 ± 4.87 (SB cultivar) to 48.90 ± 15.81 (KK cultivar) determined did not reveal any significant difference between cultivars. For the phytochemical parameters: total phenolic compounds, total flavonoids, β-carotene, and lycopene, the cultivars KK and KA showed the highest content. The statistical analysis of the results shows positive correlations between phytochemical composition and pulp color. The color could thus, depending on the cultivar and its maturity, constitute a preliminary indicator of choice for the estimation of the content of bioactive compounds. [ABSTRACT FROM AUTHOR]

The growing realization of nutritional and health benefits, and the potential of watermelon (Citrullus lanatus L.) as a cash-producing crop has renewed interest in reducing loss in its post-harvest handling. Information on the extent of loss in different parts of its post-harvest system under tropical conditions is scarce. Key constraints identified by producers were insect infestation, insufficient working capital, poor handling of produce, lack of access to market, and lack of technology while inadequate access to funds, lack of storage facilities, and poor packaging of produce were identified by marketers. Post-harvest trouble spots were determined through adequate evaluation of the proportion of loss and associated factors along the watermelon supply chain. The majority of producers and marketers experienced loss of up to 40%, some >60%. Interventions in trouble-spots can have an impact on the reduction of post-harvest loss. A better understanding of loss along the supply chain was developed which can lead to the determination of effective strategies to manage watermelon loss in the tropics. [ABSTRACT FROM AUTHOR]

There is a growing realization in African countries for the need to enhance the production of xerophytic crops, including Watermelon, Citrullus lanatus L., in the face of climate change. The objective of this review is to explore challenges and opportunities in watermelon production in Africa. Watermelon is adaptable to most of tropical, and subtropical, Africa, due to its low water requirement and has the potential to be a commercial crop. However, minimal research has been applied to its breeding and production in the continent. Lack of improved varieties, poor production systems, perishable nature of the fruit, and lack of harvest and post-harvest preservation technology hamper large-scale production. Research, particularly in watermelon production practices and breeding, is needed if its true potential in Africa is to be realized. [ABSTRACT FROM AUTHOR]

Two new phenolic glycosides, named lanatusosides C (1) and D (2), together with four known compounds (3-6), were isolated from the seeds of Citrullus lanatus. Among them, compounds 3 and 4 were isolated from Cucurbitaceae for the first time, and compound 5 was reported from this plant for the first time. Their structures were elucidated by means of extensive spectral analysis, including HR-ESI-MS, 1H and 13C NMR techniques. The isolated new compounds were evaluated for cytotoxic activity against HepG2 cell line, of which compound 1 demonstrated weak cytotoxicity against the tested cell line. [ABSTRACT FROM AUTHOR]

Herbaceous grafting can be used to manage numerous soilborne pathogens in cucurbits. Rootstocks have been reported to increase the growth of the scion possibly due to more efficient use of nitrogen compared with non-grafted plants. The first objective of this study was to determine if the commercial rootstocks 'Strongtosa', 'Carnivor', or 'Macis' improve growth and production of the watermelon 'Melody' scion. The second objective was to determine whether these rootstocks have different nitrogen requirements in open-field production compared with non-grafted 'Melody'. Field studies were conducted in 2013 and 2014 on the Sandhills Research Station in Jackson Springs, North Carolina. Nitrogen fertiliser was applied via drip irrigation at 0, 84, 126, 168, and 252 kg⋅ha−1. A linear relationship between nitrogen rate and rootstock cultivar existed; however, in all cases the non-grafted plants produced more than all grafted plants. Average fruit weight from the non-grafted plants was also higher than the grafted plants. Fruit from 'Carnivor'- and 'Strongtosa'-grafted plants had higher flesh firmness compared with non-grafted 'Melody'. Our findings suggest that rootstocks do not increase yield or growth in the scion nor do they require different nitrogen application rates. However, some rootstocks do improve overall fruit quality. [ABSTRACT FROM AUTHOR]

Watermelon [Citrullus lanatus (Thunb.)] marketing efficient distribution is needed to maximize economic returns to marketers and consumers. An economic analysis of watermelon marketing was done in Lagos state, Nigeria, between January and February 2018. Data were collected using a questionnaire employed to collect information from 56 marketers in the study area. Half of the marketers used urban markets as points of sale and watermelon were supplied weekly. Watermelon marketing was profitable. The major constraint encountered by marketers was their inability to access credit. Regardless of level of education sufficient market information enhanced economic returns of watermelon marketers. [ABSTRACT FROM AUTHOR]

Fruit set represents the very first step of fruit development. This study investigated the effect of different fruit-setting methods [1-(2-chloro-4-pyridyl)-3-phenylurea (CPPU) treatment, artificial pollination, and honey bee pollination] on the concentrations of fructose, glucose, and sucrose, and the activities of sucrose metabolising enzymes of watermelon fruit under plastic film greenhouse conditions. No significant difference in fructose and glucose concentrations was observed among the three treatments at fully ripe stage of fruit [33 days after anthesis (33 DAA)]. However, artificial and honey bee pollination significantly increased sucrose concentration. Measurement of sucrose metabolising enzyme activities and correlation analysis demonstrated that the increased activity of SuSy-s (sucrose synthase, synthesis direction) is the key mechanism of increased sucrose concentration in the artificially pollinated and honey bee pollinated fruits. The concentrations of fructose, glucose, and sucrose were similar between artificially pollinated and honey bee-pollinated fruits at fully ripe stage (33 DAA). Therefore, we can conclude that artificial and bee pollination can improve the sweetness of watermelon fruit. In addition, the honey bee can provide a pollination service that is similar to that of artificial pollination for watermelon grown in a protected cultivation system. [ABSTRACT FROM AUTHOR]

In the tropics, low yield of watermelon [(Citrullus lanatus var. lanatus (Thunb.)] is, in part, due to use of low-yielding watermelon cultivars. Use of adaptable, high-yielding cultivars in tropical areas may enhance watermelon productivity. This study was undertaken to assess the influence of environmental conditions on growth and yield of watermelon cvs. Sugarbaby South Africa, Sugarbaby East Africa, Crimson Sweet, Patanegra F1, Zuri F1, and Sukari F1. The field experiment was conducted between October 2011 and February 2012 (dry season) and March 2012 and May 2012 (wet season). Data on yield, vegetative and reproductive performance were collected. Cultivar affected vine length and fruit weight. There was little difference between cultivars regarding growth and development and yield. There was a significant, positive correlation for number of fruit to number of nodes and fruit weight. Cultivars with better performance on these traits may have good yield. It appears that for improved yield it is better to produce these varieties during the wet season. [ABSTRACT FROM AUTHOR]

Water deficiency is an environmental factor affecting crop yield especially in arid and semiarid regions. It is necessary to improve water use efficiency in watermelon (Citrullus lanatus Thunb), a high-water requiring crop. The edible accessions, "TN-94-766," "TN-94-769," "TN-94-545," "TN-94-485," and "Crimson Sweet," and the wild-type Colocynth were treated with the irrigation regimes of 100%, 80%, 60%, or 40% of soil available water. In all accessions, leaf area and shoot length decreased and root length increased as water availability decreased up to 40% AW. Colocynth had long shoots and roots, and high ascorbate peroxidase activity, and exhibited high resistance to water deficit. Yield of Colocynth exposed to severe water-deficit level was not changed. The edible accession "TN-94-766" was the most tolerant to water deficit having longer roots, more total fruit yield, and higher catalase and guaiacol peroxidase activities at 60% AW. [ABSTRACT FROM AUTHOR]

Zucchini yellow mosaic virus(ZYMV) has a wide distribution in Mecca regions and is considered to be a serious threat on watermelon production. The aim of this study was to evaluate the antiviral activity of five medicinal plant extracts, against ZYMV-infecting watermelon plants. The experiment consisted of four application of soaking seeds,in vitroandin vivoexperiments. The results of greenhouse experiments with individually treatments by decoction and infusion of Nigella sativa (NS) seeds in soaking andin-vitroexperiment, bougainvillea and neem in pre-inoculation and thuja extract following nigella decoction in post inoculation were efficient to reduce and\or inhibit symptoms expression infecting watermelon seedling, whereas, decoction exhibited higher antiviral activity against ZYMV than infusion. The decoction and infusion of NS seed increased the total photosynthesis pigments, total soluble intracellular protein and total phenol contents. In conclusion, the results of the present investigation propose that the bougainvillea and neem extracts may perhaps play a central function in the mechanism of acquired systemic resistance and may produce pathogenesis-related proteins that play a significant role in watermelon seedling resistance against ZYMV. [ABSTRACT FROM AUTHOR]

Watermelon [Citrullus lanatus(Thunb.) Matsum. & Nakai var.lanatus] is a cross-pollinating diploid species and is one of the most important dicotyledonous plants belonging to the familyCucurbitaceaedue to its high nutritional value, rapid growth, sweet and juicy taste, and refreshing nature as a summer fruit. However, the insertion–deletion (InDel) markers available for watermelon cannot satisfy the demand to identify and map resistance genes in this major crop. In this study, we have characterised and developed numerous polymorphic InDel markers using Illumina re-sequencing of a male parental line that is resistant toFusariumwilt. In total, 25,701 potential InDel markers were identified, with a mean size of 18 bp. From these, 7,387 potential InDel markers > 10 bp were selected and tested as candidate InDel markers to locate resistance genes for map-based cloning and polymorphism analysis. We designed and synthesised 69 primer pairs using Primer 3 software. Overall, 54 primer pairs detected polymorphism between theFusarium-susceptible female parent ‘JSw01-1’ and theFusarium-resistant male parent ‘JRw08-3’. Among the 69 InDel markers, 54 (78.3%) exhibited polymorphism at 179 PCR loci. Polymorphic information content (PIC) values ranged from 0.04 to 0.91, and the number of alleles per primer ranged from 1 to 11. The 54 InDel markers that were mined and exploited via Illumina re-sequencing of watermelon could accelerate the development of marker-assisted breeding and the progression of genetic research to understand resistance toFusariumwilt in watermelon. [ABSTRACT FROM PUBLISHER]

Pesticide-free vegetables are in demand at farmers' markets featuring locally grown products. Weeds often are deleterious in such crops, and managing them without herbicides is difficult. Stale seedbeds and rolled–crimped winter rye (Secale cereale L.) cover crops are nonchemical methods that may help manage weeds effectively. These methods were compared over two growing seasons as they affected fruit yield, fruit quality, and hand-weeding times in west-central Minnesota for transplanted cucumber (Cucumis sativus L.), pumpkin (Cucurbita pepo L.), and watermelon (Citrullus lanatus [Thunb.] Matsum. & Nakai). Cumulative hand-weeding times were 82–85 h·ha−1 in stale seedbed systems but 5–18 h·ha−1 in rolled–crimped rye mulch systems. Even without hand-weeding, cucumber yields and quality scores in rye mulch were similar to those in stale seedbeds augmented with preemergence herbicide and hand-weeded. Pumpkin yields were reduced by 25% in rye mulch systems, but quality was not affected. Watermelon had yield reductions up to 75% in rye mulch compared to stale seedbeds with weed control. Cucumber, pumpkin, and watermelon have high, moderate, and low potential, respectively, for herbicide-free production in rolled–crimped winter rye mulch in cold–temperate growing regions. [ABSTRACT FROM AUTHOR]

Most information on effects of rootstocks on watermelon [Citrullus lanatus (Thunb.) Matsum and Nakai] quality is derived from studies on disease resistance. The current study was undertaken to determine effects on yield and fruit morphometric and physicochemical characteristics of large-fruited, diploid and small-fruited, triploid watermelon cultivars grafted to interspecific hybrid rootstocks. Two yearly field experiments were conducted between April and July at the Zygi Experimental Station in Cyprus. Grafting increased marketable yield by 43% on average over nongrafted controls. No cultivar–rootstock combination resulted in commercially unacceptable (<10%) soluble solids content (SSC); only triploid cv. Extazy exhibited a rootstock-dependent decrease in SSC. Flesh firmness was increased by grafting on all rootstocks by an average of 36% over the nongrafted control. Variability in rind thickness was derived mainly from the scion. Rootstocks did not affect lycopene content and their effect on flesh color was minimal. Though grafting enhanced yield and fruit quality, choice of rootstock may adversely affect SSC of certain cultivars. [ABSTRACT FROM AUTHOR]

Production of watermelon (Citrullus lanatusL.) is a highly profitable crop in the Southeastern United States; however, adequate weed management is lacking due to the limited number of registered herbicides. Field studies were conducted in the summer of 2011 and 2012 in Auburn, Alabama, to evaluate the efficacy of selected preemergence (pre) and postemergence (post) herbicides in combination with a winter rye cover crop for controlling yellow nutsedge and smooth and redroot pigweed. Herbicide treatments included all combinations of two levels of ethalfluralin applied pre (none and 1900 g·ha−1) along with 4 levels of post-applied herbicides. The four post herbicides included halosulfuron (54 g·ha−1), glufosinate (340 g·ha−1), carfentrazone (35 g·ha−1), and none. The treatment consisting of no pre or post herbicides is referenced as cover crop only (CCO). Pigweed density was reduced by all herbicide treatments in comparison to the CCO treatment. Ethalfluralin applied pre followed by glufosinate post provided the greatest control of pigweed and was similar to ethalfluralin pre followed by either halosulfuron or carfentrazone post as well as glufosinate post (no pre). In comparison to the CCO treatment, yellow nutsedge density was significantly reduced by both treatments containing halosulfuron (ethalfluralin pre plus halosulfuron post; halosulfuron post) in addition to plots treated with glufosinate post. Watermelon yield and subsequent crop value was highest in plots receiving ethalfluralin pre followed by glufosinate post and was similar to the treatment of ethalfluralin pre followed by carfentrazone post. Use of pre- and post-applied herbicides along with a rye cover crop could improve control of pigweed species and yellow nutsedge and led to an increase in watermelon yield and subsequent crop value. [ABSTRACT FROM AUTHOR]

In the present study, a modified Osborne fractionation method was followed to isolate albumin (Calb), globulin (Cglo), prolamin (Cpro) and glutelin (Cglu) successively from seeds of Citrullus lanatus (watermelon). This research work was undertaken to investigate the antimicrobial and antioxidant activities of isolated protein fractions of C. lanatus seed. Amino acid composition and molecular weight distribution were determined to establish their relationship with antimicrobial and antioxidant activity. Among all the fractions, Cpro was found to be most effective against A. baumannii followed by Calb and Cglo. The results showed that growth of inhibition of these protein fractions differ significantly from each other (p ≤ 0.05). In view of antioxidant potential, Cglo exhibited strongest antioxidant capacity while Cglu showed weakest antioxidant potential. [ABSTRACT FROM AUTHOR]

Deplorable soil fertility characterising resource-poor agrarian communities remain a major constraint for sustainable global food security. Re-mineralisation through application of rock dust encourages maintainable productivity of degraded soils. This study was planned to appraise the effect of rock dust on root-knot disease ofCitrullus lanatuscaused byMeloidogyne incognita(Mi). The experiment was laid out in Randomised Complete Block Design with three replications. Soil and root populations of the nematode were estimated and galling damage of the crop was diagnosed and censured at 60 days after inoculation. Additional data were collected on vine length, number of leaves, days to 50% flowering and dry matter content. Data collected were subjected to analysis of variance and the means were separated using least significant difference. The treated watermelon plants were low in root-knot disease, significantly reduced Mi nematode populations and flowered far much earlier (p = 0.05) than the untreated organic watermelon plants. [ABSTRACT FROM PUBLISHER]

Inter-generic grafting of highly nematode susceptible watermelon (Citrullus lanatus) cultivars onto nematode-resistant wild watermelon (Cucumis africanus) and wild cucumber (Cucumis myricoarpus) had on average 36% graft survival ratios, which was attributed to unequal stem diameters at the graft union. Cucumis species had smaller stem diameters at the graft union, whereas Citrullus had bigger ones. The objective of the study was to improve inter-generic graft compatibility of Citrullus and Cucumis through optimizing the sizes of stem diameters during grafting. Cucumis species were raised in a 160-hole seedling tray and primed seeds of Citrullus were raised in a 200-hole seedling tray seven days after emergence of Cucumis in order to reduce the stem diameters. At grafting, stem diameter ratios in various treatments were equal to one, whereas at 66 days after grafting the ratios were grater than one, with the exception of those of intact plants. Survival of grafts from grafting to 66 days after grafting was 100%, translating into relative improvement of 186%. Improved survival of grafts would invariably promote the potential uses of inter-generic grafting among wild and cultivated watermelon in management of soil-borne pathogens. [ABSTRACT FROM AUTHOR]

Wild watermelon (Cucumis africanus) and wild cucumber (Cucumis myriocarpus), which are highly resistant to the southern root-knot nematode (Meloidogyne incognita) race 2, have the potential for serving as seedling rootstocks for the highly nematode-susceptible watermelon (Citrullus lanatus) cultivars. In South Africa, due to high labour costs, most cotton farmers are turning to watermelon production. In these regions, there is high incidence of M. incognita race 4. A pot experiment in the greenhouse was, therefore, initiated to investigate the host-status and host-sensitivity of Cucumis africanus and Cucumis myriocarpus to M. incognita race 4, when inoculated with 0, 200, 600, 100, 1400, 1800 and 2200 eggs and second-stage juveniles (J2s). At harvest, 56 days after inoculation, the reproductive factor values at all levels of inoculation were less than one. Penetration indices on both plant species were greater than one, suggesting that the resistance was post-infectional and therefore, introgressible. Sex (male: female) ratios of M. incognita race 4 on the two Cucumis species were greater than one, suggesting that more J2s were converted into males. Infection of Cucumis species by the test nematode had no effect on yield components of the two plant species due to poor feeding sites. The two Cucumis species were, therefore, resistant to M. incognita race 4, with post-infectional resistance, where the sex ratio was skewed towards maleness. Thus, the two Cucumis species have the potential to be used as nematode-resistant rootstocks in watermelon production. [ABSTRACT FROM AUTHOR]

The carotenoid content and in vitro accessibility of the 'Sugar baby' variety of watermelon and the 'Horana red' variety of guava from Sri Lanka was determined using high-performance liquid chromatography. The high-performance liquid chromatography chromatogram showed that the Guava 'Horana red' variety contained almost exclusively lycopene (45.3 ± 8.0 μg/g fresh weight (FW)), with a small amount of lutein (2.1 ± 0.6 μg/g FW), β-carotene (2.0 ± 0.2 μg/g FW) and β-cryptoxanthin. As far as carotenoids in the sugar baby variety of watermelon are concerned, it contained lycopene, lutein and β-carotene of 37.2 ± 4.0 μg/g FW, 2.1 ± 0.6 μg/g FW and 0.3 ± 1 μg/g FW, respectively. The studies showed that guava contains more lycopene (45.3±8.0 μg/g FW) than watermelon (37.2 ± 4.0 μg/g FW), and that the in vitro accessibility of lycopene in guava (73%) is more than that in watermelon (25.8%). Therefore it can be concluded that guava can be used as a better lycopene source than watermelon. [ABSTRACT FROM AUTHOR]

Application of compost in horticultural crops has the potential to provide many benefits and yet there are concerns regarding accumulation of heavy metals in the crop and on human health. Effects of amending soil with compost made from mixed municipal solid waste (MSW) on yield of okra (Abelmoschus esculentus L.) and watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai] and on heavy metal concentrations (Cd, Cu, Cr, Ni, Pb, and Zn) in pods of okra and pulp and juice of watermelon were investigated. Four MSW compost rates were applied, 25, 50, 75, and 100 Mg·ha-1, and compared to a non-amended control with no compost application. Addition of MSWC increased yield of okra and weight of watermelons over the control. There were no differences among treatments in heavy metal concentrations in okra pods, watermelon pulp, or juice. [ABSTRACT FROM AUTHOR]

A statewide survey of watermelon production was conducted in 1998 and 1999 in Oklahoma. Data from the survey was used to classify production systems and management intensities among watermelon producers. Cluster analysis was used to identify the most closely associated of 24 abiotic and biotic variables affecting productivity. Five clusters were identified each year, or when data were pooled across years. Cluster I combined factors of grower experience, crop rotation, fertilization, and cultivation (mechanical weed control). Cluster II combined factors of cultivar ploidy, black plastic mulch, irrigation frequency, hoeing frequency, row arrangement, pollination, and planting method. Close distances among components implied that these two clusters had the strongest associations; indicating that two primary production systems exist. To measure management intensity of these production systems, a method was developed by: (1) partitioning four economic categories as machinery, labor, supply, and risk for each survey variable; (2) assigning weight scores of 0 or 1 to each category; and (3) summing the weight scores across economic categories for all factors involved in each production system. The most commonly used production system (>50%) consisted of Cluster I, which was considered of intermediate management intensity with scores ≥12 and ≤36. The production system considered as high management intensity with scores >36 was rarely used. but always combined components within Clusters I and II. This is the first attempt to describe complete production systems for watermelon in terms of analytical methods and measurements of crop management intensity. [ABSTRACT FROM AUTHOR]

While using end-of-day (EOD) red or far-red (FR) light had been previously successful in regulating the seedling growth of selected vegetable transplants, no study has evaluated this transplanting regulating technique for watermelon, or whether it has effects on fruit production after the seedlings are transplanted to the field. As such, the influence of end-of-day (EOD) red (R) or far-red (FR) light on watermelon [Citrullus lanatus (Thunb) Matsum and Nakail, cv. Sugar Baby, seedling growth and subsequent fruit production after transplanting to the field was investigated. Seedlings were exposed to low intensity EOD R (15 mm), EOD FR (15 mm), EOD FR + R (15 mm of FR followed by a is mm of R treatment), or no EOD light (control) treatments at.the end of each photoperiod to determine if these light treatments affected plant growth in a manner that might he beneficial for transplant production (e.g.. shorter more stocky plants that might be less prone to lodging and more easily used with mechanical transplanters, or larger taller plants that might have greater early growth after transplanting) without deleterious effects on subsequent fruit production. EOD FR treated seedlings had longer petioles and internodes than seedlings in any of the other EOD R and EOD FR + R or control light treatments. EOD R treated seedling growth was not different than control seedlings. The EOD FR + R treatment negated the EOD FR light growth effects suggesting involvement of phytochrome in the light regulated growth of watermelon seedlings. When EOD treated watermelon seedlings were transplanted to the field there were no subsequent effects on fruit production. [ABSTRACT FROM AUTHOR]

Corn gluten meal (CGM) may be used as a preemergent or preplant-incorporated herbicide for organic weed control of young developing or emerging weed seedlings. Unfortunately, CGM can also adversely impact seedling survival of bertain direct-seeded vegetable crops. Various vegetable crop seedlings respond differently to CGM applications, and the impact of CGM applications on direct-seeded cucurbit crops or dry beans has not yet been determined. Field research was conducted in southeast Oklahoma (Lane, OK) to determine the phytotoxic impact of CGM application and incorporation methods on seedling establishment of black and pinto bean (both Phaseolus vulgaris L.), cantaloupe (Cucurnis melo and watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai]. A factorial experiment was repeated twice during the 2001 growing season with 5 CGM application rates, 3 incorporation methods, 4 crops, and 4 replications. The Bernow fine-loamy, siliceous, thermic Glossic Paleudalf soil was prepared for planting by plowing, fertilizing, and forming raised beds. CGM was applied by hand at 1,000, 2,000, 4,000, and 8,000 kg·ha-1. An untreated control was included. Three incorporation methods included tilling prepared beds to a depth of 2.5 to 5.0cm either before or after application of CGM, or leaving the beds undisturbed. 'Black Knight' black bean, 'Apache' pinto bean, 'Magnum 45' cantaloupe, and 'Allsweet' watermelon were direct-seeded on raised beds. Stand data were collected 14, 20, and 31 days after planting. CGM applications adversely affected seedling establishment of all direct-seeded vegetable crops. Injury and morality occurred prior to seedling emergence. In all but 2 isolated instances the lowest CGM rate significantly decreased seedling establishment. Seedling mortality percentages at 1,000 kg·ha-1,averaged across evaluation dates and incorporation methods, were 66% (black bean). 58% (pinto bean), 50% (cantaloupe), and 58% (watermelon) increased as COM application rate increased. Although alt of the CGM applications rates significantly decreased seedling survival for these crops, the potential usefulness of CGM as an organic herbicide should encourage additional research to develop safer application methods for CGM. Once seedlings of these crops are established, as transplants or emerged direct-seeded plants, COM may be safe to use. Research should investigate the impact of application rates below 1000 kg·ha-1 on direct-seeded vegetables, CGM applications on other cucurbit crops, different application methods, and weed control efficacy of CGM when used with these vegetable crops. [ABSTRACT FROM AUTHOR]

Due to the increasing popularity of seedless watermelons [Citrullus lanatus (Thumb.) Matsum. & Nakai] and decreasing sales of seeded watermelons, much of the U.S. production has shifted from seeded to seedless watermelons. To achieve successful fruit set in triploid watermelon, a diploid watermelon cultivar must be planted as a pollen source. The characteristics of four diploid cultivars were compared with determine how they may perform as pollenizers. Numbers of male flowers produced, degree of fruit set, and fruit weight were compared. All cultivars began flowering over a period of 7 days and all were still flowering when sampling was terminated at 64 days after field transplanting. The cv. 'SP-1' consistently had higher numbers of male flowers than did cvs. 'Companion', 'Jenny', or 'Mickylee' through most of the season. 'SP-1' set the most fruit while 'Companion' set the least. 'Mickylee' had the largest melons and 'SP-1' the smallest. All cultivars were in peak male flower production during triploid fruit set and all would be expected to produce adequate seedless watermelon yields. doi:10.1300/J512v13n02_07 [ABSTRACT FROM PUBLISHER]

Cultural practices can affect quality and phytonutrient content of watermelon [Citrullus lanatus var. lanatus (Thunb.) Matsum. & Nakai]. Knowing which cultivars perform well under various production systems, and how these systems affect quality, yield, and phytonutrient content is imperative to ensure high quality and yield. There is limited information on how watermelon cultivars perform when grown with organic practices. Production characteristics of six watermelon cultivars from certified organic seed sources were compared under high (black plastic and mechanical cultivation for weed control) and low input (no-till) organic culture. The high input production method almost doubled the number of fruit produced for all cultivars; producing greater yields and heavier average fruit weights, but fruit had decreased quality (lower Brix and lycopene content) compared with the low-input production. 'Triple Star' was the most productive seedless cultivar in terms of number of fruit in both organic fields and had the highest marketable yield in the low-input field. 'Early Moonbeam' produced the largest number of fruit and the smallest fruit of the seeded cultivars. 'Allsweet', a seeded cultivar, had the highest marketable yield due to its larger size. 'Triple Star' had the highest quality (high lycopene and Brix content) in the low input field, but all triploid cultivars had similar quality aspects in the high input field. Among seeded cultivars, 'Allsweet' had the best quality at both locations; however, average lycopene content/fruit under low-input production was not significantly different when compared with 'Sugar Baby'. [ABSTRACT FROM AUTHOR]

Tomato and watermelon plants were grown in nutrient solutions in which nitrogen (N) was supplied as NO3− (6 mM-N) or NH4+ (6 mM-N). The experiments were conducted to evaluate the effect which different N sources exert on iron (Fe) uptake and accumulation, on the enzymatic activities of aconitase (Aco), chelate reductase (FeCH-R), peroxidase (POD), catalase (CAT), and Fe-superoxide dismutase (FeSOD), and on biomass production. For both species of plants, fertilization with NH4+ caused the total Fe concentration to be lower, in the roots and in the leaves in relation to the concentrations recorded in plants fertilized with NO3−. The response of the enzymes related to Fe correlated with their concentration. The plants treated with N[sbnd]NO3− registered the highest activities in Aco, FeCH-R, POD, and CAT for both tomato and watermelon. On the other hand, only in the tomato plants was the superoxide dismutase (SOD) activity appreciably influenced primarily by NH4+, due possibly to the toxic effect of this N source. Finally, in relation to biomass production, fertilization with NH4+ drastically reduced growth in the tomato plants, while in watermelon plants, no significant alteration was detected in dry-matter production, regardless of the N form used. It was concluded that the response of the parameters analyzed to NH4+ fertilization, in tomato and watermelon, compared to fertilization with NO3− was similar. By contrast, tomato plants, but not watermelon plants, were negatively influenced by NH4+. [ABSTRACT FROM AUTHOR]

A field study on watermelon [Citrullus lanatus (Thunberg) Matsumura and Nakai] in 1997, 1999, and 2000 revealed that management intensity affected profitability. Management intensity reflected a combination of cultural practices and levels of usage. Low intensity management (LM) included only soil fertilization and weed control. High intensity management (HM) additionally involved plastic mulch, drip irrigation, insect pest control, and plant disease control. Use of partial budget analysis simplified evaluation of the effect of management intensity on profitability, which was defined as a difference in net return between HM and LM. The difference in net return between HM and LM (∆ð) was based on market price (P), changes in yield (∆Y), and changes in production cost (∆I) due to increased intensity of management: ∆ð = P x ∆Y - ∆I. We used means of daily wholesale market price for midseason (July to August) at Dallas, TX, for seeded and seedless red melons each year, means of yield difference between HM and LM for each cultivar each year, and concurrent estimates of production cost difference between HM and LM in our empirical analyses. HM was more profitable than LM in two of the three years with increased net return up to almost 8,000 $ha-1, but the level of profitability varied among cultivars and years. Triploid (seedless) cultivar had higher yield difference between HM and LM and received higher prices, resulting in larger profits than did diploid open-pollinated or diploid hybrid (both seeded) cultivars in all three years. The difference in net return between HM and LM corresponded positively with yield differences between HM and LM, but not in proportion because of differences in production cost between HM and LM and in market price among years. In our sensitivity analyses, we introduced the concept of rate of change in net return as ∆ð%. Based on mean values of the market price and differences in yield and in production cost between HM and LM over this 3-year study as modes of variation, we demonstrate that the rate of change in net return betweenHMandLMwas more sensitive to the yield difference and market price than to the cost difference betweenHMand LM. This is the first time information of production cost and profit based on this model of partial budgeting has been developed for watermelon. When yield difference was small or when market price was low, the rate of net return increased more effectively in response to increasing management intensity. Therefore, higher yield brought about by HM can easily compensate for the higher cost incurred by HM. [ABSTRACT FROM PUBLISHER]

Corn rootworms compulsively feed on cucurbitacins (bitter compounds found in many cucurbits), while most other pest insects are repelled by them. Several hypotheses have been proposed for this activity, but the results have been equivocal. One recent hypothesis suggested that cucurbitacin may provide protection against soil borne fungal entomopathogens, both in the adult corn rootworm and in the eggs laid in the soil. Any antifungal activity would preclude the use of this feeding stimulant to enhance the activity of fungal pathogens used in biocontrol. To test this hypothesis, we exposed two fungal pathogens of corn rootworm, Beauveria bassiana and Metarhizium anisopliae, to an extract from a bitter mutant of Hawkesbury watermelon, which contained about 0.05% cucurbitacin E glycoside. The extract inhibited the growth of both fungi. However, when the extract was sterilized by passing through a 0.45 micron filter, this inhibitory activity disappeared. Purified cucurbitacin E glycoside did not inhibit the growth of either fungus. Four Bacillus isolates (identified as Bacillus subtilis var. globigii and B. amyloliquefaciens) were isolated from this extract which were able to inhibit the growth of both fungi. All of these bacteria excreted the inhibitory activity into the medium. Thus, the inhibition of fungal growth attributed to cucurbitacin may actually be due to bacteria incidentally associated with cucurbits. [ABSTRACT FROM AUTHOR]

Controlled pollinations are an essential part of watermelon hybrid seed production, and the use of male sterility will reduce labor required. Profitable seed production must employ good cultural practices and timely harvest. Triploid hybrid seed production varies considerably from diploid hybrid seed production. The generation of tetraploid parents has been enhanced considerably with the use of tissue cultural and chromosome doubling agents other than colchicine. Tri-ploid hybrids, with two chromosome sets from the female parent and one from the pollen parent offers more variety to the consumer as well as more strategies for the employment of past resistance. New triploids can be deployed quickly to meet new pest problems and market demands. [ABSTRACT FROM AUTHOR]

The volatile components of watermelon fruit were isolated by simultaneous steam distillation/solvent extraction. The fruit had 7.6 mg/kg of total volatile compounds. Major components were ethyl acetate, acetaldehyde, tetradecanoic acid and methyl acetate. [ABSTRACT FROM AUTHOR]