Abstract
Continuous application of chemical fertilizers in plant cultivation can lead to the deterioration of the soil environment, resulting in reduced crop yield and quality. Currently, organic fertilizers, such as vermicompost, can partially replace chemical fertilizers and maximize yields while maintaining soil fertility. However, the effects of chemical fertilizers combined with vermicompost on watermelon (Citrullus lanatus) yield and quality are unclear. A field experiment was carried out on the watermelon cultivar Lihua No. 6. Six treatments were applied: no fertilizer (CK, control, 0N–0P–0K), 100% chemical fertilizer [CF, 5.4N–1P–5.4K (256, 47, and 255 kg·ha−1)], 75% chemical fertilizer + 25% organic fertilizer [A1, 5.4N–1P–5.4K (192, 35, and 191 kg·ha−1) + 2250 kg·ha−1 vermicompost], 50% chemical fertilizer + 50% organic fertilizer [A2, 5.4N–1P–5.4K (128, 24, and 127 kg·ha−1) + 4500 kg·ha−1 vermicompost], 25% chemical fertilizer + 75% organic fertilizer [A3, 5.4N–1P–5.4K (64, 12, and 64 kg·ha−1) + 6750 kg·ha−1 vermicompost], and 100% organic fertilizer (A4, 9000 kg·ha−1 vermicompost). Indices related to the growth, yield, and quality of watermelons were determined. Compared with CK, chemical fertilizer alone or in combination with organic fertilizers significantly increased growth parameters (plant height and leaf area) and chlorophyll content. The five fertilizer treatments enhanced the single fruit weight, yield, and biomass. In addition, the yield of reduced chemical fertilizer plus organic fertilizer was comparable to that of watermelons treated with CF. Compared with CF, the fertilizer treatments, especially the 1:1 mixture of chemical and organic fertilizer (A2) group, had elevated fruit-soluble solids and soluble sugar content, and reduced organic acid levels. Therefore, a combination of 50% chemical fertilizer and 50% organic fertilizer can effectively enhance the yield and quality of watermelons. These findings have important implications for guiding the management of watermelon fertilization and development of sustainable agriculture.
As an annual plant of Cucurbitaceae species, the watermelon (Citrullus lanatus) is an important commercial vegetable and fruit worldwide, with China being the leading watermelon producer (Gülüt 2021). Watermelon pulp is highly nutritious and rich in essential vitamins, natural sugars, and minerals, which can play vital roles in the maintenance of human health (Fulgoni and Fulgoni 2022). Given the significant economic returns, watermelon production has consistently increased in China (Feng et al. 2022). In recent years, continuous watermelon cropping has resulted in low yield, poor fruit quality, and susceptibility to infectious diseases (Huang et al. 2016). Continuous cropping has a recognized negative effect on plant growth and plant disease occurrence (Zhou et al. 2023). Continuous cropping causes the soil to harden, the plow layer to become shallow, and the organic matter content, soil fertility quality, and land productivity level to reduce, which will affect root growth, nutrient absorption, and utilization efficiency, ultimately leading to a decrease in yield (Tan et al. 2021). Fertilizers are widely used to improve soil fertility. Recent soil management evidence has shown that the combined application of chemical and organic fertilizers can change soil properties and improve the rhizosphere microenvironment, and consequently enhance fruit quality (Iqbal et al. 2022). However, there is a lack of scientific, systematic, and efficient fertilization guidelines for the field management of watermelons.
Vermicompost can convert various wastes, such as sewage sludge, into soil improvement fertilizers (Ghorbani and Sabour 2021). It is a nutrient-rich organic matter that can be used as a tonic for plantations and has attracted considerable attention from researchers and farmers. Vermicompost improves soil fertility in multiple ways. Vermicompost treatment improves the physical properties of the soil in terms of air permeability, water retention, and porosity (Przemieniecki et al. 2021). In addition, it can improve the soil organic matter content and efficiently decompose residues of pesticides in contaminated soils (Yen et al. 2021). Vermicompost can potentially reduce continuous cropping negative impact and achieve sustainable crop production by improving the physicochemical properties of the soil. For example, a previous study has demonstrated that deep tillage combined with vermicompost significantly decreased soil salinization and enhanced wheat (Triticum aestivum L.) growth and yield (Ding et al. 2021). In addition, vermicompost increased the antimicrobial and antioxidant activities of pigeonpea [Cajanus cajan (Linn.) Millsp] leaves (Das et al. 2017). Although vermicompost is beneficial for crop development, it contains high concentrations of soluble salts and its inappropriate use may negatively affect plant growth (Lim et al. 2015). Notably, multiple studies suggest that the balanced application of bio-organic fertilizers, such as vermicompost combined with chemical fertilizers, can be beneficial for the production of fruits and vegetables (Babalar et al. 2023; Mardani-Talaee et al. 2017; Wang et al. 2022b). This technique reduces fertilizer waste through standardized field management, and effectively improves the crop yield (Wang et al. 2021). Currently, vermicompost is mainly used for the cultivation of staple crops such as rice (Oryza sativa) and wheat (Ding et al. 2021; Gopalakrishnan et al. 2014). Currently, the use of vermicompost is common on major crops, but there is a need to understand more about the application in horticultural crops, such as watermelons. Thus, it is necessary to explore the appropriate concentration of vermicompost to optimize fertilizer management for watermelon.
In this study, a field experiment involving reducing chemical fertilizer combined with different contents of vermicompost was conducted in watermelon. Plant growth, yield, and fruit quality–related indices were determined to evaluate the effects of different fertilizer application methods on the economic value of watermelons.
Materials and methods
Experimental materials
The watermelon cultivar ‘Lihua No. 6’, an early-maturing variety planted in the Shanxi Province, was used as the plant material. The organic fertilizer was vermicompost [organic matter of 47.5 g·kg−1, of which there was total nitrogen (N) of 10.3 g·kg−1, available phosphorus (P) of 1510.7 mg·kg−1, and available potassium (K) of 1832.0 mg·kg−1, pH = 7.3], purchased from Shanxi Rongde Agricultural Science and Technology Co., LTD (Taiyuan, Shanxi, China). The vermicompost was produced with cattle manure. The manure was laid into long strips (10 m in length, 1.5 m in width, and 0.5 m in height), and after undergoing natural aging in the open air for 30 d, the material was inoculated with earthworms and covered with grass curtain. The composting process lasted for 2 to 3 months. The chemical fertilizers in this experiment were commercial fertilizer and consisted of urea (N ≥ 46%; Shandong Runyin Bio-Chemical Co., Taian, Shandong, China), potassium sulfate (K2O ≥ 52%; K+S Minerals Agricultural Technology Co., Shenzhen, Guangdong, China), and calcium superphosphate (P2O5 ≥ 12%; Jiangsu Meile Fertilizer Co., Zhenjiang, Jiangsu, China).
Experimental site description
This study was conducted at the Dongyang Experimental Demonstration Base of Shanxi Agricultural University (37°32′N, 112°40′E, 1032 m a.s.l.) during the 2023 watermelon growing season (May to August). This region has a warm temperate continental climate, with average annual temperature and rainfall of 9.7 °C and 440.7 mm, respectively. The experimental site consisted of sandy loam soil with a pH of 8.27. The soil in the 0 to 20 cm tillage layer contained 0.183% total N, 1008 mg·kg−1 of total P, and 2230 mg·kg−1 of total K.
Experimental design and treatment details
The plastic greenhouse in this research was constructed with a stainless-steel tube structure and enveloped in a high-light transmittance waterproof plastic film to form an arched greenhouse for watermelon cultivation. The test greenhouses were 78 m in length and 10 m in width, with the film thickness of 0.12 mm. Watermelon seeds were raised with plug transplant and then transplanted to plastic greenhouses on May 1 and harvested by the end of July. Six treatments with different fertilization methods were applied in this study: i) no fertilization (control, CK, 0N–0P–0K); ii) chemical fertilization [100% chemical fertilizer, CF, 5.4N–1P–5.4K (256, 47, and 255 kg·ha−1]; iii) 75% chemical fertilizer + 25% organic fertilizer [A1, 5.4N–1P–5.4K (192, 35, and 191 kg·ha−1) + 2250 kg·ha−1 vermicompost]; iv) 50% chemical fertilizer + 50% organic fertilizer [A2, 5.4N–1P–5.4K (128, 24, and 127 kg·ha−1) + 4500 kg·ha−1 vermicompost]; v) 25% chemical fertilizer + 75% organic fertilizer [A3, 5.4N–1P–5.4K (64, 12, and 64 kg·ha−1) + 6750 kg·ha−1 vermicompost]; vi) 100% organic fertilizer (A4, 9000 kg·ha−1 vermicompost). All treatments were designed in a randomized block arrangement with three replicates for each treatment, a total of 18 experimental fields in this study and 32 watermelon plants per treatment.
Management strategy
The different treatments were isolated by trenching each experimental field to prevent the bunching of water and fertilizer. Fertilizer management was divided into base and topdressing. Briefly, base fertilizer [vermicompost and chemical fertilizer (1/3 total N + 1/3 total K + 100% total P)] was applied once 7 d before transplanting, and the remaining fertilizer was applied with water throughout the growth period (elongation stage and fruit expansion stage). Topdressing fertilizers adopted chemical fertilizer (2/3 total N + 2/3 total K). The nutrient applications for each experimental treatment are listed in Table 1. The remainder of the management strategy remained consistent for all treatments.
Specific nutrient application on watermelon plants for each treatment group.
The irrigation method adopted drip irrigation under film and water-fertilizer integrated fertilizer. The drip irrigation belts were covered with black plastic film with a thickness of 0.01 mm and a width of 1 m (Shouguang Xianong Plastic Products Factory, Weifang, Shandong, China). The polyehtylene material patch-type drip irrigation belt has a diameter of 16 mm, a wall thickness of 0.3 mm, a drop head span of 10 cm, and a flow rate of 2 to 3 L in·h−1 (Hua Wei water-saving Technology Co., Ltd, Shanghai, China). Specifically, watering once after 5 to 7 d of planting; watering every 7 to 8 d during the stretching period; watering 2 to 3 times during swelling period; stop watering 7 to 10 d before fruit harvest. During watermelon cultivation, weeds and fallen leaves on the mulch and in the greenhouse were removed regularly and timely. In addition, for the management of pests and diseases, priority was given to agricultural and physical control, supplemented by chemical control. The measures of prevention and control in this study included deep plowing of soil before planting, choosing resistant varieties, implementing crop rotation with non-melon crops, and regular pruning to improve ventilation and light exposure. During the fruit enlargement stage, we sprayed 6 to 10 g of 46% Fluoridine dipyrimidine water dispersible granules per MU (1:5000 to 8000 dilution) to eliminate aphid (Aphidoidea) infestation, with two applications spaced 7 d apart (1 MU = 0.067 ha).
Plant growth measurements
In addition, SPAD readings of watermelon leaves were recorded using a SPAD-502 plus chlorophyll meter (Konica Minolta Sensing Inc., Osaka, Japan) to measure the plant’s relative chlorophyll content.
Watermelon yield determination
During watermelon harvest time, 10 plants per treatment were randomly selected for yield determination. The average individual fruit mass was estimated and converted into hectare yield. After collecting dry biomass, aboveground samples were collected and dried in a blast furnace at 105 °C for 30 min, followed by drying at 80 °C to a constant mass.
Fruit biochemical properties measurement
Biological indicators were used to assess fruit quality. Measurements were performed during the watermelon harvest period with five samples in each group. The soluble solid content was determined using a TD-45 digital refractometer (Zhejiang Top Yunnong Technology Co., Ltd, Hangzhou, Zhejiang, China), and the soluble sugar content was estimated using anthrone colorimetry (Wang et al. 2004). Furthermore, vitamin C content was detected using molybdenum blue colorimetry (Li 2002), followed by the measurement of organic acid content using the acid-base neutralization transfer method (Yang et al. 2019).
Data analysis
All data were expressed as mean ± SD and statistical analyses were performed by analysis of variance via SPSS 27.0 (IBM Corp, Armonk, NY, USA). To comprehensively evaluate the effects of different fertilization on watermelon fruit quality and yield, 15 indicators were selected as feature vectors for principal component analysis (PCA). We followed the steps of conducting a typical PCA, that is, checking the sample adequacy of the items with the Kaiser-Meyer-Olkin (KMO) measurement, and the appropriateness of the factor analysis using Bartlett’s sphericity test. A KMO value ≥ 0.5 indicates that PCA will be useful and effective for this dataset. Next, the initial eigenvalue of λ > 1 served as the basis for determining the number of principal components for PCA. Significance analysis between groups was performed using the Duncan method, with P < 0.05 as the threshold for statistical significance.
Results
Effect of organic fertilizer application on watermelon growth variables
To analyze the effects of organic fertilizers on watermelon cultivation, we measured the main vine length, stem thickness, leaf number, and leaf area to observe changes in plant growth. The results showed that both chemical and organic fertilizer treatments affected plant growth, which was superior to that of the CK treatment. In brief, the RGR-PH and RGR-SV indicators in the CF group were significantly higher than the A4 group (P < 0.05, Fig. 1A and B). No statistical significance was found for the A1, A2, and A3 group compared with the CF treatment for the RGR-PH, RGR-SV, RGR-LN, RGR-LA, and SPAD (P > 0.05, Fig. 1). However, we observed that the A2 group slightly increased in the RGR-LN, RGR-LA, and SPAD indicators than CF (Fig. 1C–E). Hence, these findings suggest that chemical and organic fertilizers combined can promote plant growth.
Effect of organic fertilizer application on watermelon growth variables. (A) Relative growth rates of plant height [RGR-PH, cm/(cm·d)]; (B) relative growth rates of stem volume [RGR-SV, cm3/(cm3·d)]; (C) relative growth rates of leaf number (RGR-LN, blade/d); (D) relative growth rates of leaf area [RGR-LA, cm2/(cm2·d)]; and (E) SPAD (relative chlorophyll content) index. Different lower-case letters indicate significant difference between treatments (Duncan test, P < 0.05). CK = no fertilization; CF = chemical fertilization; A1 = 75% chemical fertilizer and 25% organic fertilizer; A2 = 50% chemical fertilizer and 50% organic fertilizer; A3 = 25% chemical fertilizer and 75% organic fertilizer; A4 = 100% organic fertilizer.
Citation: HortTechnology 34, 4; 10.21273/HORTTECH05441-24
Effect of organic and chemical fertilizer combination applications on watermelon yield
Chemical and organic fertilizers had significant positive effects on watermelon yield (P < 0.05, Fig. 2). Among the fertilizer treatment groups, A2 had the highest single fruit weight and yield, and A4 had the lowest yield (Fig. 2A and B). Notably, the A2 treatment increased yield by 12.01% compared with CF. In addition, compared with that of CF, A2 treatment significantly enhanced plant biomass by 13.30% (P < 0.05, Fig. 2C).
Effect of organic fertilizer application on watermelon yield. (A) Single fruit weight; (B) yield; and (C) biomass. Different lower-case letters indicate significant difference between treatments (Duncan test, P < 0.05). CK = no fertilization; CF = chemical fertilization; A1 = 75% chemical fertilizer and 25% organic fertilizer; A2 = 50% chemical fertilizer and 50% organic fertilizer; A3 = 25% chemical fertilizer and 75% organic fertilizer; A4 = 100% organic fertilizer; kg = Single fruit weight; kg/hm2 = weight of watermelon produced per hectare; g/plant = weight of organic matter per watermelon plant.
Citation: HortTechnology 34, 4; 10.21273/HORTTECH05441-24
Effect of organic and chemical fertilizer combination applications on watermelon quality
Center and edge soluble solids, organic acids, total soluble sugar, reducing sugar, soluble protein, and vitamin C content determine the flavor and nutritional quality of watermelons. Compared with the CK group, those relevant indexes of watermelon quality in fertilizer treatment group had a significant improvement (P < 0.05, Fig. 3).
Effect of organic fertilizer application on watermelon quality. (A) Soluble solids (center and edge) and organic acid contents. (B) Soluble/reducing sugar, soluble protein, and vitamin C content. Different lower-case letters indicate significant difference between treatments (Duncan test, P < 0.05). CK = no fertilization; CF = chemical fertilization; A1 = 75% chemical fertilizer and 25% organic fertilizer; A2 = 50% chemical fertilizer and 50% organic fertilizer; A3 = 25% chemical fertilizer and 75% organic fertilizer; A4 = 100% organic fertilizer.
Citation: HortTechnology 34, 4; 10.21273/HORTTECH05441-24
Among them, soluble solids assay in the center and edges (by 5.67% and 9.63%) and total soluble sugar (by 14.56%) were significantly increased in A2 treatment than in the CF group (P < 0.05, Fig. 3A and B). In addition, groups A2 and A3 presented the most significant reduction in organic acid concentrations, with a decline of 50% compared with the CF group (P < 0.05, Fig. 3A). There was no significant difference in reducing sugar, soluble protein, and vitamin C content between the CF and A2 groups (P > 0.05, Fig. 3B).
Ranking of comprehensive quality based on PCA
To comprehensively evaluate the influence of different fertilizers on the quality and yield of watermelon fruits, 15 indicators from the five treatments were used as feature vectors. After performing the KMO and Bartlett’s test, we observed KMO value of 0.826 with P value <0.05, allowing for PCA. The advantage of this analysis is that it can overcome the limitations of evaluating fertilizer effects using a single factor. The two dimensions of PCA explained 67.38% (PC1) and 9.94% (PC2) of the variance (Table 2). Among all the fertilizer treatment groups, the composite score revealed that the A2 group ranked first, followed by the A1 and CF groups (Fig. 4).
Score of the comprehensive parameters calculated in a PCA.
Ranking of comprehensive quality based on PCA. CK = no fertilization; CF = chemical fertilization; A1 = 75% chemical fertilizer and 25% organic fertilizer; A2 = 50% chemical fertilizer and 50% organic fertilizer; A3 = 25% chemical fertilizer and 75% organic fertilizer; A4 = 100% organic fertilizer; PCA = principal component analysis.
Citation: HortTechnology 34, 4; 10.21273/HORTTECH05441-24
Discussion
Chemical fertilization is a rapid method used to provide plants with essential macronutrients and micronutrients for optimal growth and yield (Miransari 2011). In recent years, with the rapid expansion and development of agriculture, chemical fertilizers are widely used to improve crop yield. However, the excessive application of chemical fertilizers has not maximized the yield and led to serious environmental pollution problems (Wang et al. 2019). Currently, reducing the use of non-renewable fertilizer sources by combining them with organic fertilizers can alleviate the negative impact of the sole use of chemical fertilizers, which is a reasonable way to maintain the sustainable development of agricultural ecosystems (Caris-Veyrat et al. 2004). Moreover, organic fertilizers can replace 23% to 52% of N fertilizers without crop yield losses, such as wheat and maize (Zea mays) (Li et al. 2023). In watermelon cultivation, chemical fertilizer combined with organic fertilizer (ratio: 85/15) further promoted the utilization of organic phosphorus by the root system via enhancing the activity of root-associated acid phosphatase, and improved plant quality (Wang et al. 2022a). In addition, partial substitution of chemical fertilizer with organic fertilizer (50%, 75%, and 100%) increased the proportion of soil macroaggregates as well as the concentrations of total organic acid and permanganate oxidizable carbon, thus increasing watermelon yields (Du et al. 2022). To date, there have been few reports on the combined application of vermicompost organic and chemical fertilization on watermelon quality.
In this study, the addition of vermicompost organic fertilizer significantly improved the fruit quality and biomass of watermelon compared with 100% chemical fertilizer. Notably, the results revealed that A2 treatment (1:1 mixture of chemical and organic fertilizer) had the best outcomes. In terms of production, the A2 treatment increased the yield by 12% and biomass by 13.3% compared with the CF treatment. Regarding fruit quality, the A2 treatment elevated soluble solids at the center and edges by 5.67% and 9.63%, respectively, whereas organic acids were reduced by 50% compared with CF, indicating an improvement of watermelon quality. Therefore, replacing chemical fertilizer with vermicompost organic fertilizer met the requirements of crop growth, and 50% chemical fertilizer combined with 50% organic fertilizer (A2 group) greatly enhanced the fruit quality of watermelon, with the best performance in terms of the comprehensive score. Similar to our findings, vermicompost supplementation improved the nutritional value of date palm fruits (Al Jaouni et al. 2019). Overall, vermicompost provides favorable conditions for plant growth, and the application of organic fertilizers combined with chemical fertilizers can provide balanced nutrition for watermelon growth.
We also observed that vermicompost organic fertilizer (50%) had substantial effects on the total soluble solids, soluble sugar, and organic acids of watermelon, which were superior to CF. It has been reported that the application of vermicompost increases the hormonal and metabolic activity of plants, enhances carbohydrate synthesis in fruits, and improves fruit nutrition (Adekiya et al. 2020). Conversely, organic fertilizers, such as vermicompost, allow plants to absorb nutrients in the soil for a longer period of time, which indirectly affects the fruit quality of tomatoes (Lycopersicon esculentum Mill.) and kiwifruit (Actinidia deliciosa) by increasing the content of soluble solids (Gutiérrez-Miceli et al. 2007; Sharma et al. 2022). Similarly, other authors found that biochar combined with vermicompost enhanced the soluble sugar content and tomato fruit yield, which may be attributed to the fact that vermicompost improves plant growth and quality by regulating soil properties and slowing soil nutrient depletion (Xu et al. 2023). Moreover, an increase in chlorophyll content can enhance the efficiency of photosynthesis, which increases carbon input to fruits and induces the production of soluble sugars (Liu et al. 2011). Hence, the improved watermelon quality observed in this study may be attributed to the improvement of soil properties and chlorophyll content. Organic acids are key factors affecting the sensory quality of fruits, and a decrease in their accumulation is due to the enhancement of sugar synthesis and ripening-related secondary metabolism (Lombardo et al. 2011). Therefore, we speculate that the significant reduction in organic acids in the A2 group was associated with elevated sugar levels.
Our study, for the first time, confirmed that partially replacing chemical with organic fertilizers could improve the biomass and quality of watermelon, and that the combination of 50% chemical fertilizer and 50% vermicompost was the best strategy. Vermicompost supplementation may affect plant nutrient availability by altering soil nutrient content (Ghorbani and Sabour 2021). These substances are converted into active ingredients that can be easily absorbed by plants with the assistance of microorganisms to promote the accumulation of nutrients, thus improving fruit quality (Fritz et al. 2012; Jiang et al. 2023). This eco-friendly fertilization technique provides a scientific basis for the sustainable development of watermelon cultivation. Nevertheless, this study is preliminary research, and the specific mechanism of soil improvement by vermicomposting as well as the comprehensive effect and reproducibility of organic fertilizer application need to be further explored. Future research should focus on the structural changes and functions of soil microorganisms and confirm the reliability of our results with replicate experiments at other sites.
Conclusion
In summary, the replacement of chemical fertilizer with an appropriate proportion (50%) of vermicompost organic fertilizer was optimal for improving the quality of watermelon, which could help enhance the soluble solids and sugar content, and reduce the organic acid content. In addition, this optimized fertilizer management method maximized watermelon yield and quality, while reducing chemical fertilizer application. This study confirmed that the combined application of vermicompost and chemical fertilizer is a promising eco-friendly practice and can be promoted for watermelon production in the region evaluated by this study.
References cited
Adekiya AO, Ejue WS, Olayanju A, Dunsin O, Aboyeji CM, Aremu C, Adegbite K, Akinpelu O. 2020. Different organic manure sources and NPK fertilizer on soil chemical properties, growth, yield and quality of okra. Sci Rep. 10(1):16083. https://doi.org/10.1038/s41598-020-73291-x.
Al Jaouni S, Selim S, Hassan SH, Mohamad HSH, Wadaan MAM, Hozzein WN, Asard H, AbdElgawad H. 2019. Vermicompost supply modifies chemical composition and improves nutritive and medicinal properties of date palm fruits from Saudi Arabia. Front Plant Sci. 10:424. https://doi.org/10.3389/fpls.2019.00424.
Babalar M, Daneshvar H, Díaz-Pérez JC, Nambeesan S, Tabrizi L, Delshad M. 2023. Effects of organic and chemical nitrogen fertilization and postharvest treatments on the visual and nutritional quality of fresh-cut celery (Apium graveolens L.) during storage. Food Sci Nutr. 11(1):320–333. https://doi.org/10.1002/fsn3.3063.
Caris-Veyrat C, Amiot M-J, Tyssandier V, Grasselly D, Buret M, Mikolajczak M, Guilland J-C, Bouteloup-Demange C, Borel P. 2004. Influence of organic versus conventional agricultural practice on the antioxidant microconstituent content of tomatoes and derived purees; consequences on antioxidant plasma status in humans. J Agric Food Chem. 52(21):6503–6509. https://doi.org/10.1021/jf0346861.
Das S, Hussain N, Gogoi B, Buragohain AK, Bhattacharya SS. 2017. Vermicompost and farmyard manure improves food quality, antioxidant and antibacterial potential of Cajanus cajan (L. Mill sp.) leaves. J Sci Food Agric. 97(3):956–966. https://doi.org/10.1002/jsfa.7820.
Ding Z, Kheir AMS, Ali OAM, Hafez EM, ElShamey EA, Zhou Z, Wang B, Lin XE, Ge Y, Fahmy AE, Seleiman MF. 2021. A vermicompost and deep tillage system to improve saline-sodic soil quality and wheat productivity. J Environ Manage. 277:111388. https://doi.org/10.1016/j.jenvman.2020.111388.
Du S, Ma Z, Chen J, Xue L, Tang C, Shareef TME, Siddique KHM. 2022. Effects of organic fertilizer proportion on the distribution of soil aggregates and their associated organic carbon in a field mulched with gravel. Sci Rep. 12(1):11513. https://doi.org/10.1038/s41598-022-15110-z.
Feng Z, Bi Z, Fu D, Feng L, Min D, Bi C, Huang H. 2022. A comparative study of morphology, photosynthetic physiology, and proteome between diploid and tetraploid watermelon (Citrullus lanatus L.). Bioengineering (Basel). 9(12). https://doi.org/10.3390/bioengineering9120746.
Fritz JI, Franke-Whittle IH, Haindl S, Insam H, Braun R. 2012. Microbiological community analysis of vermicompost tea and its influence on the growth of vegetables and cereals. Can J Microbiol. 58(7):836–847. https://doi.org/10.1139/w2012-061.
Fulgoni K, Fulgoni VL. 2022. Watermelon intake is associated with increased nutrient intake and higher diet quality in adults and children, NHANES 2003-2018. Nutrients. 14(22). https://doi.org/10.3390/nu14224883.
Ghorbani M, Sabour MR. 2021. Global trends and characteristics of vermicompost research over the past 24 years. Environ Sci Pollut Res Int. 28(1):94–102. https://doi.org/10.1007/s11356-020-11119-x.
Gopalakrishnan S, Vadlamudi S, Bandikinda P, Sathya A, Vijayabharathi R, Rupela O, Kudapa H, Katta K, Varshney RK. 2014. Evaluation of Streptomyces strains isolated from herbal vermicompost for their plant growth-promotion traits in rice. Microbiol Res. 169(1):40–48. https://doi.org/10.1016/j.micres.2013.09.008.
Gülüt KY. 2021. Nitrogen and boron nutrition in grafted watermelon I: Impact on pomological attributes, yield and fruit quality. PLoS One. 16(5):e0252396. https://doi.org/10.1371/journal.pone.0252396.
Gutiérrez-Miceli FA, Santiago-Borraz J, Montes Molina JA, Nafate CC, Abud-Archila M, Oliva Llaven MA, Rincón-Rosales R, Dendooven L. 2007. Vermicompost as a soil supplement to improve growth, yield and fruit quality of tomato (Lycopersicum esculentum). Bioresour Technol. 98(15):2781–2786. https://doi.org/10.1016/j.biortech.2006.02.032.
Huang C, Bu Y, Shan Z, Dai C. 2016. Research advances in mechanisms of watermelon continuous cropping disease and its biological control. Chinese Journal of Ecology. 35:1607–1676.
Iqbal A, Ali I, Yuan P, Khan R, Liang H, Wei S, Jiang L. 2022. Combined application of manure and chemical fertilizers alters soil environmental variables and improves soil fungal community composition and rice grain yield. Front Microbiol. 13:856355. https://doi.org/10.3389/fmicb.2022.856355.
Jiang X, Lu C, Hu R, Shi W, Zhou L, Wen P, Jiang Y, Lo YM. 2023. Nutritional and microbiological effects of vermicompost tea in hydroponic cultivation of maple peas (Pisum sativum var. arvense L.). Food Sci Nutr. 11(6):3184–3202. https://doi.org/10.1002/fsn3.3299.
Li X, Fang J, Shagahaleh H, Wang J, Hamad AAA, Alhaj Hamoud Y. 2023. Impacts of partial substitution of chemical fertilizer with organic fertilizer on soil organic carbon composition, enzyme activity, and grain yield in wheat-maize rotation. Life (Basel). 13(9):1929. https://doi.org/10.3390/life13091929.
Li Y. 2002. Determination of reduced vitamin C in fruits by molybdenum blue colorimetry. Tianjin Chemical Industry. 01:31–32.
Lim SL, Wu TY, Lim PN, Shak KPY. 2015. The use of vermicompost in organic farming: Overview, effects on soil and economics. J Sci Food Agric. 95(6):1143–1156. https://doi.org/10.1002/jsfa.6849.
Liu Y-F, Qi H-Y, Bai C-M, Qi M-F, Xu C-Q, Hao J-H, Li Y, Li T-L. 2011. Grafting helps improve photosynthesis and carbohydrate metabolism in leaves of muskmelon. Int J Biol Sci. 7(8):1161–1170. https://doi.org/10.7150/ijbs.7.1161.
Lombardo VA, Osorio S, Borsani J, Lauxmann MA, Bustamante CA, Budde CO, Andreo CS, Lara MV, Fernie AR, Drincovich MF. 2011. Metabolic profiling during peach fruit development and ripening reveals the metabolic networks that underpin each developmental stage. Plant Physiol. 157(4):1696–1710. https://doi.org/10.1104/pp.111.186064.
Mardani-Talaee M, Razmjou J, Nouri-Ganbalani G, Hassanpour M, Naseri B. 2017. Impact of chemical, organic and bio-fertilizers application on bell pepper, Capsicum annuum L. and biological parameters of Myzus persicae (Sulzer) (Hem.: Aphididae). Neotrop Entomol. 46(5):578–586. https://doi.org/10.1007/s13744-017-0494-2.
Miransari M. 2011. Soil microbes and plant fertilization. Appl Microbiol Biotechnol. 92(5):875–885. https://doi.org/10.1007/s00253-011-3521-y.
Przemieniecki SW, Zapałowska A, Skwiercz A, Damszel M, Telesiński A, Sierota Z, Gorczyca A. 2021. An evaluation of selected chemical, biochemical, and biological parameters of soil enriched with vermicompost. Environ Sci Pollut Res Int. 28(7):8117–8127. https://doi.org/10.1007/s11356-020-10981-z.
Sharma S, Rana VS, Rana N, Sharma U, Gudeta K, Alharbi K, Ameen F, Bhat SA. 2022. Effect of organic manures on growth, yield, leaf nutrient uptake and soil properties of kiwifruit (Actinidia deliciosa Chev.) cv. Allison. Plants (Basel). 11(23):3354. https://doi.org/10.3390/plants11233354.
Tan G, Liu Y, Peng S, Yin H, Meng D, Tao J, Gu Y, Li J, Yang S, Xiao N, Liu D, Xiang X, Zhou Z. 2021. Soil potentials to resist continuous cropping obstacle: Three field cases. Environ Res. 200:111319. https://doi.org/10.1016/j.envres.2021.111319.
Wang B, Wang Y, Sun Y, Yu L, Lou Y, Fan X, Ren L, Xu G. 2022a. Watermelon responds to organic fertilizer by enhancing root-associated acid phosphatase activity to improve organic phosphorus utilization. J Plant Physiol. 279:153838. https://doi.org/10.1016/j.jplph.2022.153838.
Wang H, He P, Shen C, Wu Z. 2019. Effect of irrigation amount and fertilization on agriculture non-point source pollution in the paddy field. Environ Sci Pollut Res Int. 26(10):10363–10373. https://doi.org/10.1007/s11356-019-04375-z.
Wang JL, Liu KL, Zhao XQ, Zhang HQ, Li D, Li JJ, Shen RF. 2021. Balanced fertilization over four decades has sustained soil microbial communities and improved soil fertility and rice productivity in red paddy soil. Sci Total Environ. 793:148664. https://doi.org/10.1016/j.scitotenv.2021.148664.
Wang Q, Su Z, Zhang S, Li Y. 2004. Soluble sugar content of clonal plant Neosinocalamus affinis at module and ramet levels. Ying Yong Sheng Tai Xue Bao. 15(11):1994–1998.
Wang Z, Yang T, Mei X, Wang N, Li X, Yang Q, Dong C, Jiang G, Lin J, Xu Y, Shen Q, Jousset A, Banerjee S. 2022b. Bio-organic fertilizer promotes pear yield by shaping the rhizosphere microbiome composition and functions. Microbiol Spectr. 10(6):e0357222. https://doi.org/10.1128/spectrum.03572-22.
Xu G, Wu Z, Tian Y, Wang J, Wang X, Cao Y. 2023. Effect of in situ vermicomposting combined with biochar application on soil properties and crop yields in the tomato monoculture system. Environ Sci Pollut Res Int. 30(37):87721–87733. https://doi.org/10.1007/s11356-023-28572-z.
Yang M, Bie Z, Wu M, Yi H, Feng J. 2019. Changes of organic acids and related metabolic enzymes in melon fruit development. China Cucurbits and Vegetables. 32:233–234.
Yen Y, Chen K, Yang H, Lai H. 2021. Effect of vermicompost amendment on the accumulation and chemical forms of trace metals in leafy vegetables grown in contaminated soils. Int J Environ Res Public Health. 18(12):6619. https://doi.org/10.3390/ijerph18126619.
Zhou W, Zhou X, Cai L, Jiang Q, Zhang R. 2023. Temporal and Habitat dynamics of soil fungal diversity in gravel-sand mulching watermelon fields in the semi-arid Loess Plateau of China. Microbiol Spectr. 11(3):e0315022. https://doi.org/10.1128/spectrum.03150-22.
