Search Results (30)

This study investigates arthropod assemblage in cowpea, hemp, and watermelon grown both as monocrops and intercrops using three sampling techniques: direct visual counts, sticky cards, and pan traps. A total of 31,774 arthropods were collected, spanning two classes [Arachnida (0.07%) and Insecta (99.93%)], 11 orders, and 82 families representing diverse functional groups. Arachnids were represented by a single family (Araneae). Among insects, the composition included Diptera (36.81%), Thysanoptera (24.64%), Hemiptera (19.43%), Hymenoptera (11.58%), Coleoptera (6.84%), Lepidoptera (0.076%) and Blattodea, Odonata, Orthoptera, Psocodea (≤0.005%). Roughly 10% of the total arthropods were pollinators, while the remainder were primarily herbivores and predators. Apidae were abundant in all treatments except for watermelon monocrops. Intercropping supported more pollinators, particularly Apidae, Halictidae, and Sarcophagidae. However, herbivores dominated (>50%) in each system, largely due to high presence of thrips and cicadellids. Predators accounted for approximately 30%, with dolichopodids (Diptera) being the most dominant. Watermelon yield increased by 30–60% in the intercrop systems. While intercropping increases overall arthropod abundance, it also creates a more balanced community where beneficial organisms are not heavily outnumbered by pests and contributes to enhanced ecological resilience and crop performance. Full article

Improving the fertility status of nutrient-depleted soils is critical to achieving food security. The negative effects of chemical fertilizers on soils necessitate the global quest for eco-friendly, effective, and sustainable alternatives. This work assessed the effect of black soldier fly (BSF) residue application on soil properties and watermelon growth. The study was set up in a completely randomized design with six replications. The treatments were BSF1 (BSF applied at 10 t ha⁻¹), BSF2 (20 t ha⁻¹), BSF3 (30 t ha⁻¹), and control. The plant data collected in this study were vine length, leaf width, number of leaves, and stem girth, and the soil’s physicochemical properties were determined. The results show that BSF residue-treated soils had 20.4–49.5% higher aggregate stability and 50–160% higher hydraulic conductivity than the control treatment. BSF residue-treated soils had significantly (p ≤ 0.05) higher pH, total N, available P, exchangeable K, and organic carbon than the control treatment. BSF3 treatment had the highest effect on available P and soil pH relative to other amended treatments. High rates of BSF residue application did not significantly increase the total available N and P contents, which could suggest that BSF application at 30 t ha⁻¹ may not pose a risk of N and P pollution to water systems. BSF residue-treated soils improved (p < 0.05) watermelon growth parameters relative to the control. Watermelon leaf length was significantly (p ≤ 0.05) longer for BSF residue-treated soils than the control treatment. A similar trend was observed for the number of leaves, leaf width, and stem girth. At 4, 6, and 10 weeks after sowing, BSF residue-treated plants had 38.2–104%, 22.7–118%, and 25.7–103% longer vine lengths than the control treatment, respectively. The study results suggest that BSF residue application can enhance the fertility status of a coarse-textured ultisol for watermelon production. Full article

Jiaosu is a multifunctional solution derived from the fermentation of a mixture of fruit or vegetable wastes, sugar, and water for a typical period of three months. The present study evaluated the changes in pH, proteins, phenolics, carbohydrates, alcohols, and organic acids (oxalic, tartaric, malic, lactic, acetic, citric, and succinic) as well as amylase, protease, and lipase activities of different groups of jiaosu throughout one year of natural fermentation. Three jiaosu groups, each with different types of fruit peels, were prepared: orange–papaya–watermelon (OPW), grapefruit–mango–pineapple (GMP), and durian–jackfruit–passion fruit (DJP). A total of 18 jiaosu samples (days 0, 7, 14, 21, 28, 42, 56, 70, 84, 120, 150, 180, 210, 240, 270, 300, 330, and 360) were analyzed for each group. Using repeated measures multivariate analysis of variance (MANOVA) over the one-year fermentation period, the pH, the concentrations of proteins, phenolics, carbohydrates, alcohols, and lactic acid, and the amylase, protease, and lipase activities were significantly different (p < 0.05) between all three groups of jiaosu. Notably, GMP showed the highest total protein and phenolic concentrations and the lowest specific protease activity (p < 0.05) among the jiaosu groups. Meanwhile, DJP exhibited higher specific lipase activity and lactic acid concentration, but lower total alcohol concentration (p < 0.05) compared to OPW and GMP. The results indicated that the biochemical contents and enzyme activities of jiaosu were influenced by fermentation duration and the types of fruit peels used for the fermentation. Full article

Intercropping is an effective approach for enhancing soil organic carbon (SOC) sequestration. However, the effects of intercropping on SOC dynamics and the underlying factors in rhizosphere and bulk soils are still unclear. In this study, we examined the impacts of sugarcane monoculture and sugarcane–watermelon intercropping on soil properties, soil respiration, SOC fractions, and microbial C limitation with continuous two years in 2023–2024 years in the Nala area of Guangxi Province. Our results revealed that intercropping significantly decreased CO₂/SOC by 25% and microbial C limitation by 21% in the rhizosphere, with more pronounced reductions observed in bulk soil by 33% and 25%, respectively. This means that the intercropping reduced soil respiration and this effect can be offset by the rhizosphere effects. Additionally, the sugarcane–watermelon intercropping increased the contents of mineral-associated organic carbon (MAOC) by 15~18% and particulate organic carbon (POC) by 34~46%. The random forest analysis indicated that enzyme activities (explaining 20~38% of variation) and soil properties (explaining 22% of variation) were the primary drivers of reduced CO₂ emissions. The PLS-PM showed that intercropping decreased microbial C limitation by influencing soil pH and soil water content (SWC), and then increased MAOC, which finally led to a decline in CO₂ emissions. Overall, these findings highlight the decreasing CO₂ emissions during the use of the intercropping system and the importance of microbial C limitation in the soil C cycle via soil respiration and SOC fractions. Full article

Weed and disease management in organic watermelon [Citrullus lanatus (Thunb.) Matsum. & Nakai] production is challenging. Yellow nutsedge (Cyperus esculentus L.) and Palmer amaranth (Amaranthus palmeri S. Wats.) are two competitor weeds in watermelon plasticulture production systems. Anaerobic soil disinfestation (ASD) is an emerging non-chemical approach to control weeds and soilborne plant pathogens, especially in organic farming. The effect of ASD treatments on weeds and soilborne diseases is being documented on different specialty crops. However, the impact of ASD treatments on the crop and crop genotypes; specifically watermelon has not been elucidated. Therefore, the impact of chicken manure and molasses (CMM)-induced ASD on twenty commercially available watermelon genotypes/rootstocks and major weed species was evaluated in a high tunnel experiment. The experiment was constructed as a randomized complete block design with three replications. The treatments consisted of a factorial of carbon source (1) non-treated check (CK), (2) CMM by twenty watermelon genotypes and rootstock. Soil treated with carbon CMM demonstrated significantly greater cumulative anaerobicity (246,963) activity relative to CK (575,372). Under anaerobic conditions, CMM achieved 91% weed control compared to CK. A lower number of yellow nutsedge (2) and Palmer amaranth (1) counts were recorded in CMM compared to CK (8) and (28), respectively. Among watermelon genotypes, ‘Extazy’, ‘Powerhouse’, ‘Sangria’, and ‘Exclamation’ had greater vigor 8.5, 8.4, 8.4, and 8.3, respectively, at 28 days after transplanting in CMM-treated soil. Greater watermelon plant fresh biomass was recorded in CMM-treated soil for ‘Extazy’ (434 g), ‘Powerhouse’ (409 g), ‘Exclamation’ (364 g), and ‘Sangria’ (360 g). This study demonstrated the variable response of watermelon genotypes to CMM-induced ASD and provides a guide for germplasm selection in organic watermelon production under field conditions. Full article

Valine-glutamine (VQ) motif-containing proteins play important roles in diverse plant developmental processes and signal transduction in response to biotic and abiotic stresses. However, no systematic investigation has been conducted on VQ genes in watermelon. In this study, we identified 31 watermelon VQ genes, which were classified into six subfamilies (I–VI). All of the deduced proteins contained a conserved FxxxVQxL/F/VTG motif. Eleven ClVQs were involved in segment duplication, which was the main factor in the expansion of the VQ family in watermelon. Numerous stress- and hormone-responsive cis-elements were detected in the putative promoter region of the ClVQ genes. Green fluorescent protein fusion proteins for ten selected ClVQs were localized in the nucleus, but three ClVQs also showed signals in cell membranes and the cell wall, thus confirming their predicted divergent functionality. Quantitative real-time PCR (qRT-PCR) analysis indicated that the majority of ClVQ genes were specifically or preferentially expressed in certain tissues or organs, especially in the male flower. Analyses of RNA-sequencing data under osmotic, cold, and drought stresses and Cucumber green mottle mosaic virus (CGMMV) infection revealed that the majority of ClVQ genes, especially those from subfamily IV, were responsive to these stresses. The results provide useful information for the functional characterization of watermelon ClVQ genes to unravel their biological roles. Full article

Fertilization guidelines for organic watermelon transplant production are rare. We investigated the effect of four commercial organic fertilizers and seven organic fertilizer blends, along with one conventional fertilizer (Peter’s Professional 20-20-20) on watermelon transplants. The four organic fertilizers were Nature Safe (fertilizer label: 7-7-7), Miracle-Gro (8-8-8), Dr. Earth fertilizer tea (4-4-4), and Drammatic (2-4-1). The seven blended organic fertilizers were created by supplementing Drammatic with nitrogen (N)-rich and/or potassium (K)-rich fertilizers to balance its N:phosphorus (P):K ratios. Watermelon ‘Jubilee’ was sown in organic substrate, and fertilizer treatments were applied weekly with a total of 0.4 g nitrogen/L substrate. Miracle-Gro and Drammatic had the highest N mineralization rate after 21 days and the highest inorganic N concentration, respectively, and resulted in the highest shoot dry weight among organic fertilizers. Miracle-Gro also resulted in the highest root dry weight. Dr. Earth fertilizer tea supplied the lowest N and P, and resulted in stunted transplants. Our results indicated that nitrate concentration was the most important factor influencing both shoot and root growth. Supplementing Drammatic with N-rich and/or K-rich fertilizers to balance its N:P:K ratio did not affect shoot and root dry weight. Combined, we concluded that nitrogen availability rather than nutrient balance is the key factor influencing watermelon transplant growth. Full article

This study investigates heavy metal contamination in soils, irrigation water, and agricultural produce (fruits: Vitis vinifera (grape), Cucumis melo var. saccharimus (melon), and Citrullus vulgaris. Schrade (watermelon); vegetables: Lycopersicum esculentum L. (tomato), Cucurbita pepo (zucchini), Daucus carota (carrot), Lactuca sativa (lettuce), Convolvulus Batatas (potato), and Capsicum annuum L. (green pepper)) in the Boumerdes region of Algeria. The concentrations of seven heavy metals (cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), nickel (Ni), lead (Pb), and zinc (Zn)) in soil and food samples were analyzed using atomic absorption spectrometry. Health risks associated with these metals were evaluated through the estimated daily intake (EDI), non-carcinogenic risks (using target hazard quotient (THQ), total target hazard quotient (TTHQ), and hazard index (HI)), and carcinogenic risks (cancer risk factor (CR)). Statistical analyses, including cluster analysis (CA) and Pearson correlation, were conducted to interpret the data. The results revealed the highest metal transfer as follows: Cd was most significantly transferred to tomatoes and watermelons; Cr to carrots; Cu to tomatoes; and Fe, Ni, Pb, and Zn to lettuce. Among fruits, the highest EDI values were for Zn (2.54·10⁻³ mg/day) and Cu (1.17·10⁻³ mg/day), with melons showing the highest Zn levels. For vegetables, the highest EDI values were for Fe (1.68·10⁻² mg/day) and Zn (8.37·10⁻³ mg/day), with potatoes showing the highest Fe levels. Although all heavy metal concentrations were within the World Health Organization’s permissible limits, the HI and TTHQ values indicated potential health risks, particularly from vegetable consumption. These findings suggest the need for ongoing monitoring to ensure food safety and mitigate health risks associated with heavy metal contamination. Full article

The carbon source/sink nature and the water balance of a drip-irrigated and mulched watermelon cultivated under a semi-arid climate were investigated. Biodegradable films, plants and some fruits were left on the soil as green manure. The study spanned from watermelon planting to the subsequent crop (June–November 2023). The eddy covariance technique was employed to monitor water vapor (H₂O) and carbon dioxide (CO₂) fluxes, which were partitioned into transpiration, evaporation, photosynthesis and respiration, respectively, using the flux variance similarity method.This method utilizesthe Monin–Obukhov similarity theory to separate stomatal (photosynthesis and transpiration) from non-stomatal (respiration and evaporation) processes. The results indicate that mulching films contribute to carbon sequestration in the soil (+19.3 g C m⁻²). However, the mulched watermelon crop presented in this study functions as a net carbon source, with a net biome exchange, representing the net rate of C accumulation in or loss from ecosystems, equal to +230 g C m⁻². This is primarily due to the substantial amount of carbon exported through marketable fruits. Fixed water scheduling led to water waste through deep percolation (approximately 1/6 of the water supplied), which also contributed to the loss of organic carbon via leaching (−4.3 g C m⁻²). These findings recommend further research to enhance the sustainability of this crop in terms of both water and carbon balances. Full article

Numerous plastic products are used in agriculture, including containers, packaging, tunnels, drip irrigation tubing, and mulches. Large amounts of plastics are used as mulches on the soil surface for vegetable and fruit production (tomato, cucumber, watermelon, strawberry, and vine) to reduce weed competition, increase water and fertilizer use efficiency, and enhance crop yield. Portugal uses around 4500 t/year of polyethylene to cover approximately 23,000 ha of agricultural land, and only a small amount is recovered for recycling or secondary uses because of issues of contamination with the soil, vegetation, pesticides, and fertilizers. Cleaning and decontaminating polyethylene mulch are costly, and commercial technology is often not accessible or economical. Most plastic mulch is composed of polyethylene that degrades slowly and produces a large quantity of residues in the soil, with a negative impact on the environment. In the present study, the effects of long-term cultivation of blueberry using green 100% high-density polyethylene mulch in the south Portugal were evaluated for soil chemical and biological changes. High-density green plastic mulch did not contaminate the topsoil with di(2-ethylhexyl) phthalate, and heavy metals, buttotal nitrogen, organic carbon concentrations, electric conductivity, and microbial activity were significantly reduced in the planting row compared with the bare soil without mulching. Furthermore, the presence of plastic mulch did not negatively affect the presence of nematodes, and the number of Rhabditida (bacterial feeders) increased in the planting and covered row. Full article

The current study was undertaken to investigate how organic and inorganic fertilizers shape soil bacterial communities and soil nitrogen and carbon status and to find their relationships with plant production. Soils were collected from fields under a three-year application of green manures (vetch (GMV), field bean (GMB), and wheat (GMW)), livestock manure (MF), inorganic mineral fertilizer (IF), and control (no nitrogen fertilization). The plants cultivated during the three years were tomato, watermelon, and pepper, respectively. The findings showed an increase in crop yields under both organic and inorganic fertilizers, in which the effects of leguminous green manures (GMV and GMB) were more pronounced, equal to +65–81% in tomato, +32–40% in watermelon, and +51–57% in pepper. An extensive modification in the bacterial communities was observed under organic fertilization. These changes were associated with a higher ratio of Proteobacteria (a copiotrophic phylum) to Acidobacteria (an oligotrophic phylum) in GMV and GMB, due to higher soil N content compared to IF and control treatments. Therefore, the data indicated an increase in soil N and organic C levels, as well as higher plant production by replacing IF with GMV, GMB, and MF, suggesting a promising movement to preserve the soil ecosystem. Such changes were more pronounced in MF-treated soils, where bacterial diversity improved and the heterogeneity of bacterial communities was preserved. Full article

Invertases and their inhibitors play important roles in sucrose metabolism, growth and development, signal transduction, and biotic and abiotic stress tolerance in many plant species. However, in cucumber, both the gene members and functions of invertase and its inhibitor families remain largely unclear. In this study, in comparison with the orthologues of Citrullus lanatus (watermelon), Cucumis melo (melon), and Arabidopsis thaliana (Arabidopsis), 12 invertase genes and 12 invertase inhibitor genes were identified from the genome of Cucumis sativus (cucumber). Among them, the 12 invertase genes were classified as 4 cell wall invertases, 6 cytoplasmic invertases, and 2 vacuolar invertases. Most invertase genes were conserved in cucumber, melon, and watermelon, with several duplicate genes in melon and watermelon. Transcriptome analysis distinguished these genes into various expression patterns, which included genes CsaV3_2G025540 and CsaV3_2G007220, which were significantly expressed in different tissues, organs, and development stages, and genes CsaV3_7G034730 and CsaV3_5G005910, which might be involved in biotic and abiotic stress. Six genes were further validated in cucumber based on quantitative real-time PCR (qRT–PCR), and three of them showed consistent expression patterns as revealed in the transcriptome. These results provide important information for further studies on the physiological functions of cucumber invertases (CSINVs) and their inhibitors (CSINHs). Full article

Fusarium oxysporum f. sp. niveum (Fon) is a devastating soil-borne fungus causing Fusarium wilt in watermelon. The present study investigated the biochemical mechanism underlying the antifungal activity exhibited by the antagonistic bacterial strain DHA41, particularly against Fon. Molecular characterization based on the 16S rRNA gene confirmed that DHA41 is a strain of Bacillus subtilis, capable of synthesizing antifungal lipopeptides, such as iturins and fengycins, which was further confirmed by detecting corresponding lipopeptide biosynthesis genes, namely ItuB, ItuD, and FenD. The cell-free culture filtrate and extracellular lipopeptide extract of B. subtilis DHA41 demonstrated significant inhibitory effects on the mycelial growth of Fon, Didymella bryoniae, Sclerotinia sclerotiorum, Fusarium graminearum, and Rhizoctonia solani. The lipopeptide extract showed emulsification activity and inhibited Fon mycelial growth by 86.4% at 100 µg/mL. Transmission electron microscope observations confirmed that the lipopeptide extract disrupted Fon cellular integrity. Furthermore, B. subtilis DHA41 emitted volatile organic compounds (VOCs) that exhibited antifungal activity against Fon, D. bryoniae, S. sclerotiorum, and F. graminearum. These findings provide evidence that B. subtilis DHA41 possesses broad-spectrum antifungal activity against different fungi pathogens, including Fon, through the production of extracellular lipopeptides and VOCs. Full article

Watermelons grown in sandy soil are rich in trace elements, particularly selenium, and are therefore also known as selenium-rich sand watermelons. However, continuous watermelon cultivation in the same sandy field decreases soil fertility and degrades the ecosystem, ultimately resulting in low-quality watermelons. Introducing different crops into the crop pattern could alleviate the problems posed by continuous cropping. A field experiment was conducted to explore the effects of different crop patterns on soil microbial communities and soil properties via standard techniques. The results showed that 14,905 bacterial and 2150 fungal operational taxonomic units were obtained and assigned to eight bacterial and five fungal phyla, respectively. Soil bacterial communities primarily comprised Proteobacteria, Planctomycetes, Actinobacteria, and Acidobacteria, and the soil fungal community was dominated by Ascomycota, Chytridiomycota, and Basidiomycota. Different crop patterns had a significant effect on the Chao and ACE indexes of fungal communities in the soil. The rotation of six years of watermelon and one year of wheat had the highest richness indexes of all the rotations. Different crop patterns had significant effects on soil properties, such as organic matter (OM), total nitrogen (TN), total potassium (TK), available phosphorus (AP), available K, nitrate nitrogen (NN), and pH. The soil OM, TN, NN, and pH of six years of watermelon and one year of wheat cultivation were significantly higher than those of the other three crop patterns. In addition, the soil TK and AP of the continuous watermelon planting treatment were significantly higher than those of the other three crop patterns. Redundancy analysis results revealed many complex relationships between soil properties and soil bacterial or fungal communities. Employing different crop patterns plays an important role in the effective regulation of soil microbial diversity and properties. Full article

To deal with climate emergency and reduce environmental impact, agro-industrial wastes are gradually gaining interest and are being used for new products and applications. The large production of watermelons represents an opportunity because of the many byproducts that can be transformed into innovative and valuable foodstuffs. In this study, we examined the lycopene-rich whole dietary fiber (WDF) obtained from the watermelon pomace of a peculiar cultivar, Gavina^® (Oristano, Italy) a seedless fruit from Sardinia (Italy). The volatile chemical composition of the WDF was investigated using Solid-Phase Microextraction-Gas Chromatography/Mass Spectrometry (SPME-GC/MS). The aim was to follow the evolution of the Volatile Organic Compounds (VOCs) fraction during storage and verify its stability over time. Since watermelon is an excellent source of carotenoids, their byproducts were the most abundant VOCs of the freshly prepared samples, but their overall abundance decreased significantly during storage. The opposite trend was observed for acids and aldehydes, whose increase over time is related to amino acid degradation. Freshly prepared WDF can be used in the food industry as an antioxidant-rich dietary fiber that imparts a characteristic and pleasant aroma. Over time, its aroma profile and carotenoid content change considerably, reducing its health properties and limiting its potential application as a natural flavor. Full article