Physiological impact of Trichoderma viride agents on the quality and production of melon that is grown on soils continuously cropped to melon

Trichoderma is a probiotic that can enhance the physiological traits of crops, encourage their growth, and raise their yield and quality. The issue of ongoing cropping barriers is getting worse as melon planting area in various countries steadily grows, and the melon industry’s sustainable sustainable growth is being negatively impacted by the steadily diminishing yield and quality of the fruit. It is worthy of study that the effects of Trichoderma on the growth, physiological traits, and yield of melon grown on soils continuously cropped to melon.

Introduction

Melon (Cucumis melo L.) is ranked among the top 10 fruit vegetables in the world. Melon’s rich flavor and crispy texture make it a popular choice among customers. Simultaneously, persistent cropping barriers in the industrialization and intensive melon cultivation process are getting more serious, which eventually results in a decline in melon quality and yield. This has become a significant factor limiting farmers’ income and adversely affecting the long-term growth of melon industry. The demand for superior cantaloupe is rising in tandem with the expansion of the economy and the ongoing improvement in the standard of living of the people. In the present melon production cycle, improving melon quality and yield has emerged as a key research area. In actual production, different agricultural management techniques such as soil treatment, sensible rotation, soil sterilization, and artificial introduction of beneficial microorganisms have become the main means of improving melon yield and quality due to the diversity and uneven quality of melon varieties, as well as differences in storage and transportation and disease resistance. One of the primary methods of improving soil microbial environment and growth of plant is thhe application of Trichoderma spp.

Trichoderma is one of the most researched and utilized of all the biocontrol fungi. Trichoderma has a positive regulatory effect on the morphology, physiology, nutrient dissolution and absorption, yield growth, and induced disease resistance of plants by speeding up their growth and development, increasing their absorption of nutrients, improving their tolerance to biotic and abiotic stress, and improving the rhizosphere environment. Disease resistance is induced, stress resistance is reinforced, and plant development is promoted.

Trichoderma products have been used all around the world for more than 60 years. Trichoderma can produce mycelium, conidia, and chlamydospores during the course of its life cycle. At present, there are many commercial Trichoderma preparations at home and abroad, such as Trichoderma harzianum T22 strain in the United States and Trichoderma harzianum T39 strain in Israel; Trichoderma preparations Trichodry and Trichoflow in New Zealand; Trichoderma preparations Myc01 in Russia; Trichoderma YC458 from South Korea; and the mixed biocontrol agents TUSAL of Trichoderma harzianum and Trichoderma viridis in Spain. Therefore, creating stable Trichoderma conidium preparations is crucial for producing plants with high yields and good quality. In this study, the physiological effects of Trichoderma viride on the seedling morphogenesis, yield, and quality formation of melon grown on soils continuously cropped to melon with the aim of providing technical assistance for promoting the quality and secure production of melon and providing a theoretical foundation development and promotion of Trichoderma agents.

Materials and methods

2.1 Soil characteristics
The soil used in the seedling-phase experiment came from a greenhouse where melons were continuously planted for 3 years. The soil is suitable for usage after it has been filtered using a 1 mm sieve. The basic agrochemical characteristics of the soil used for seedling testing were are shown in Table 1. Melons were grown continuously for 3 years in greenhouses at the fruit-phase experiment.

Index	Value
Organic matter	33.81 g/kg
Alkali-hydrolyzed nitrogen	163.53 mg/kg
Available phosphorus	25.62 mg/kg
Available potassium	236.14 mg/kg
pH	7.5

2.2 Preparation of Trichoderma viride conidia powder
Trichoderma viride was cultured on PDA culture material for 3 days at 28℃ in the dark as an activation culture. To make the Trichoderma spore solution, five samples from the margins of each colony, each measuring 5 mm in diameter, were collected. After that, these samples were put into PDA culture media and kept at 28℃ in the dark for 7 days. Then, distilled water was used to cleanse the spores before they were extracted. After diluting it with a sterile water gradient, it is coated over the Trichoderma selective medium and inverted for a couple of days at 25-28℃. By counting the colonies, determine the number of Trichoderma conidia. For a full night, clean, room-temperature water was used to soak barley grains, sterilizing them. One kilogram of fresh-keeping bags were then filled with the remaining mixture after the water was removed. After chilling, suspensions of Trichoderma viride were added, and they were cultivated for 2-3 weeks at 25℃. When the spore has gotten too big, rinse with sterile water and filter the grain away. After adding 10% talcum powder, the filtrate was crushed, filtered, and dried to produce Trichoderma viride conidium powder. With 1.1 × 10¹⁰ CFU/g of Trichoderma viride conidiomyces, the administered dose was calculated in compliance with the test requirements.

2.3 Experimental design and treatments
The soil from the greenhouse where melons were continuously planted for 3 years for seedlings was then placed in plastic seedling culture plates (30.5 cm × 20.5 cm × 8.6 cm), each of which contains 5.25 kg of soil along with varying concentrations of Trichoderma viride conidia agents. Following germination treatment, 140 melon seeds were added to each plate, and 100 seedlings of a similar size were saved. After sowing, melons were given 1,000 mL of water every 2 days to maintain a normal growth stage.

Each of the five treatments in this study contained 100 seedlings spread across five dishes. Four times the experiment was run, with a different set of seedlings being chosen at random each time.

The following were the treatment groups:

(1) 1.0 × 10⁴ cfu/g Trichoderma viride conidia agents (T1); (2) 8.0 × 10⁴ cfu/g Trichoderma viride conidia agents (T2); (3) 6.4 × 10⁵ cfu/g Trichoderma viride conidia agents (T3); (4) 5.12 × 10⁶ cfu/g Trichoderma viride conidia agents (T4); (5) No Trichoderma viride agents (CK) were applied.

The root-shoot ratio and strong seedling index, as well as seedling morphological indices and material accumulation indices for melon seedlings, were calculated for 40 plants from each treatment at 30 days after sowing (10 plants per replication) high furrow cultivation.

At fruiting stage test, the soil at the plastic greenhouse was fertilized with 225 kg of diammonium phosphate, 300 kg of potassium sulfate, and 375 kg of organic fertilizer per acre. The ground was completely prepared for beds. Choose healthy seedlings that have steady growth and place them in a plastic greenhouse where melons were grown continuously for 3 years on April 25, 2022, when the melon seedlings have reached the size of three leaves and one heart. Bedding cultivation is used in plastic greenhouses with a randomized block arrangement. Place a blank space between each bed. The bed measures 6 meters in length, 1.0 meters in width, 1.2 meters in width, 1:100 in slope, and 10 cm in depth. The cultivation of melon in the top beds uses double row planting, with 15 plants placed in each bed with a plant spacing of 40 cm and a row spacing of 50 cm.

After a delayed seedling, the melon was selected on the fourth leaf, grown on two vines, and watered every 3 days. When the seventh leaf was extended, the plants started to hang. Double vines are used to prune the melon plant, and after about 2-3 knots, the fruit vines begin to grow continually. Select 3-4 uniform and sturdy fruits from each melon plant when the fruit’s longitudinal diameter reaches 2-3 cm, discard the other fruits, and pluck the heart from the vine’s 20-25 leaves.

Female flowers from the same node and blossoming time were used to label 75 plants on the day of pollination. Sampling started on the tenth day following pollination, and it was done five times in total, once every 5 days. In the adult plant stage, 4-5 leaves on the fruit vine were used as the aim source from 9:00 to 10:00 a.m. to determine the physiological and biochemical indices. At 30 days following pollination, 16 fruits (4 fruits per replication) were randomly chosen from each treatment, and the quality indices were assessed using mixed fruit samples. In addition, the plot yield and hectare yield were determined while 16 randomly chosen fruits (4 fruits per replication) from each treatment were measured for fruit transverse diameter, longitudinal diameter, and single melon weight.

2.4 Measured parameters
2.4.1 Determination of morphological indicators
The distance between the stem base and its growth point on each seedling was measured with a ruler to calculate the plant height. By measuring the diameter of the stem 1 cm below the cotyledon with a vernier caliper, the diameter of the stem was determined.

By using the weighing method, the leaf area was calculated. A leaf with a particular area (A1) was first gathered and layered with other leaves. Next, round sheets were created using a 1-cm puncher pin. The weights of the round sheets and the remaining leaves were then measured, and from there, the weight of the leaf with a particular area (W1) and the weights of the other leaves (W2) were computed. The formula A = [A1(W1 + W2)]/W1 was used to calculate the leaf total area (A) based on these measurements.

2.4.2 Determination of material accumulation indicators
The plants were periodically cleaned with clear water before being dried on absorbent paper. The fresh weight of the plants was computed based on their above- and below-ground parts. After that, the fresh samples were baked to a consistent weight at 70℃ after being dried at 105℃ for 15 min. The above- and below-ground components’ dry weights were calculated using an electronic scale with a resolution of 1/1,000.

Using Gou et al. (2022) method, the root-shoot ratio was calculated using the following formula:

Root-shoot ratio = fresh weight of underground part/fresh weight of above-ground part.

The strong seedling index was calculated using the following formula in accordance with Liu X. J. et al. (2022) methodology:

Strong seedling index = (Stem diameter/Plant height + underground dry weight/above ground dry weight) × dry weight of whole plant.

2.4.3 Determination of physiological and biochemical indicators
The ethanol technique was used to determine the content of chlorophyll. For nitrate nitrogen content, the phenolic disulfonic acid technique was utilized. The anthrone colorimetric method was used to estimate the content of sucrose. The 3, 5-dinitrosalicylic acid technique was used to determine the content of reducing sugar. By using sulfosalicylic acid in an acid ninhydrin extraction, the content of free proline (Pro) was discovered. In vivo spectrophotometry was used to evaluate nitrate reductase (NR) activity. The guaiacol technique was used to assess the peroxidase (POD) activity. The nitrogen blue tetrazole photochemical reduction technique was used to examine the activity of superoxide dismutase (SOD).

2.4.4 Determination of fruit quality indicators
The content of soluble solids was calculated using an Abel refractometer. The anthrone colorimetric method was used to quantify the content of soluble sugar. The Coomassie Brilliant Blue G-250 staining procedure was used to quantify the content of soluble protein. UV spectrophotometry was used to assess the vitamin C content. Using the 0.1 mol/L sodium hydroxide standard solution technique, the total acid content was titrated.

2.4.5 Determination of yield indicators
Vernier calipers were used to measure the transverse and longitudinal diameters of melon fruit. A single melon fruit was weighed using an analytical balance, with an accuracy of 0.01 g.

Results

3.1 Effect of Trichoderma viride agents on the morphology of melon grown on soils that were continuously cropped to melon seedlings
The root-shoot ratio and strong seedling index were calculated on day 30 after sowing using the morphological indices of plant height, stem diameter, leaf area, and material accumulation indices of fresh weight and dry weight in the aboveground and underground parts of melon grown on soils continuously cropped to melon seedlings treated with various Trichoderma viride agents. The results are shown in Table 2.

Treatment	Plant height (cm)	Steam diameter (cm)	Leaf area (cm2)	Fresh weight of whole plant (g)	Dry weight of whole plant (g)	Root shoot ratio	Strong seeding index
CK	9.625±0.263d	0.311±0.012c	20.126±1.426d	2.204±0.084e	0.162±0.006d	0.068+0.003d	0.015±0.003e
T1	13.247±0.568c	0.357±0.008b	21.584±1.595c	2.640±0.071d	0.200±0.008c	0.078±0.004c	0.020±0.002d
T2	16.237±0.714b	0.392±0.018a	25.314±1.633b	3.629±0.062b	0.287±0.005b	0.096±0.005b	0.039±0.007b
T3	18.325±0.832a	0.455±0.027a	27.683±1.429a	3.997±0.057a	0.325±0.004a	0.103±0.006a	0.051±0.006a
T4	14.635±0.638c	0.378±0.016b	22.519±1.574c	3.032±0.041c	0.238±0.004c	0.093±0.008b	0.029±0.003c

Melon seedlings treated with 1.0 × 10⁴, 8.0 × 10⁴, 6.4 × 10⁵ and 5.12 × 10⁶ cfu/g Trichoderma viride agents had considerably greater morphogenetic indices and material accumulation indices than those treated with CK(no Trichoderma viride agents were used). The best effects on plant height, stem diameter, leaf area, fresh weight, dry weight, root-shoot ratio, and strong seedling index were seen with T3 (6.4 × 10⁵ cfu/g Trichoderma viride agents). It grew by 90.39, 46.30, 37.55, 81.35, 100.62, 51.47, and 240.00% when compared to CK, respectively. These findings suggested that Trichoderma viride at the right concentration could encourage melon grown on soils continuously cropped to melon seedling morphology.

3.2 Effect of Trichoderma viride agents on physiological and biochemical indices of melon grown on soils continuously cropped to melon during its fruiting stage
3.2.1 The contents of chlorophyll and nitrate nitrogen
The chlorophyll and nitrate nitrogen content of melon leaves treated with T. viride agents during the fruiting stage exhibited a trend of first increasing and then decreasing with the passage of pollination time, with peaks occurring 25 days after pollination, as seen in Figures 1A,B. At 10, 15, 20, 25, and 30 days after pollination, the chlorophyll and nitrate nitrogen content of melon leaves showed an increasing trend followed by a decreasing trend with the increase of T. viride agents treatment concentration. T3 melon leaves had the highest levels of both chlorophyll and nitrate nitrogen. Melons treated with T3 had the maximum chlorophyll content at 10, 15, 20, 25, and 30 days following pollination, as seen in Figure 1A. The chlorophyll content of melon leaves rose by 39.30, 38.43, 41.94, 35.49, and 34.68%, respectively, when treated with T3 as opposed to CK. According to Figure 1B, the T3 treatment had the highest nitrate nitrogen content in melon leaves at 10, 15, 20, 25, and 30 days following melon pollination, which was noticeably higher than that of the other treatments. The nitrate nitrogen concentration of melon leaves rose by 34.97, 46.91, 75.86, 117.03, and 115.05% during T3 treatment as opposed to CK.

3.2.2 The contents of sucrose and reducing sugar
Melons treated with T. viride agents during the fruiting stage exhibited a trend of initially increasing and then declining with the passage of pollination time, with peaks occurring 25 days following pollination, as illustrated in Figures 2A,B. The sucrose and reducing sugar content in melon leaves indicated a trend of initially rising and then falling with the increase in T. viride agents treatment concentration at 10, 15, 20, 25, and 30 days after melon pollination. In terms of sucrose and decreasing sugar content, T3 melon leaves were the greatest. Figures 2A illustrates that at 10, 15, 20, 25, and 30 days following melon pollination, T3 treatment produced the highest sucrose content in melon leaves, increasing the sucrose content by 35.73, 38.23, 34.71, 31.27, and 33.47%, respectively, in comparison to CK. Figures 2B displays the highest content of reducing sugars in melon leaves at 10, 15, 20, 25, and 30 days following melon pollination, increasing the reducing sugar content in melon leaves by 33.38, 28.49, 25.42, 42.45, and 27.33%, respectively.

3.2.3 Free proline content and nitrate reductase activity
The amount of free proline in melon leaves treated with T. viride agents during the fruiting stage exhibited a trend of steadily rising levels as pollination time passed, as illustrated in Figures 3A,B. During the fruiting phase treated with T. viride agents, the NR activity of melon leaves exhibited a tendency of first rising and then falling with the passage of pollination time, peaking 25 days after pollination. The amount of free proline and NR activity in melon leaves at 10, 15, 20, 25, and 30 days after pollination exhibited a trend of initially rising and then falling as the concentration of T. viride agents treated increased. The highest levels of free proline and nitrate reductase activity were seen in T3 melon leaves. The T3 treatment had the maximum amount of free proline in the melon leaves at 10, 15, 20, 25, and 30 days following pollination, as seen in Figure 3A. T3 treatment raised the amount of free proline in melon leaves by 51.95, 26.46, 26.63, 50.98, and 26.44%, respectively, in comparison to CK. The NR activity of T3 melon leaves was the highest and considerably higher than that of other treatments at 10, 15, 20, 25, and 30 days after melon pollination, as illustrated in Figure 3B. Melon leaves’ NR activity rose by 56.21, 53.91, 48.48, 39.92, and 37.84% with T3 treatment, respectively, in comparison to CK.

3.2.4 The activities of peroxidase and superoxide dismutase
The POD and SOD activities of melon leaves treated with T. viride agents during the fruiting stage exhibited a trend of first rising and then falling with the passage of pollination time, with peaks occurring 25 days after pollination, as seen in Figures 4A,B. The POD and SOD activities of melon leaves exhibited a tendency of initially rising and then falling with the increase in T. viride agent treatment concentration at 10, 15, 20, 25, and 30 days following melon pollination. T3 melon leaves had the highest POD and SOD activity. Figures 4A illustrates that the POD activity of T3 melon leaves was the highest and substantially higher than that of other treatments at 10, 15, 20, 25, and 30 days following melon pollination. Melon leaves’ POD activity rose by 54.22, 48.29, 35.05, 73.97, and 61.20% with T3 treatment, respectively, in comparison to CK. Figures 4B illustrates that the SOD activity of T3 melon leaves peaked 10, 15, 20, 25, and 30 days after melon pollination. Melon leaves’ SOD activity rose by 78.20, 50.01, 28.33, 18.62, and 22.60% with T3 treatment, respectively, in comparison to CK.

3.3 The effect of Trichoderma viride agents on yield and quality of melon grown on soils that were continuously cropped to melon
3.3.1 The effect of Trichoderma viride agents on yield traits of melon
After 30 days of pollination, melon fruit weight, transverse diameter, and longitudinal diameter were measured under various T.viride agents treatments, and melon yield was computed, as shown in Table 3. As the concentration of T. viride agent treatment increased, the transverse diameter, longitudinal diameter, single fruit weight, and yield of melon fruits treated with the agent exhibited a trend of initially increasing and then dropping. With transverse diameter of 8.621 cm, longitudinal diameter of 13.106 cm, single fruit weight of 521.726 g, and yield of 26321.254 kg/hm², T3 was the largest. In comparison to CK, T3 rose by 27.87, 39.81, 62.23, and 93.99%, respectively.

Treatment	Fruit transverse diameter (cm)	Fruit vertical diameter (cm)	Average single fruit weight (g)	Yield (kg/hm2)
CK	6.742±0.084d	9.374±0.342d	321.587±3.587c	13568.274±632.564c
T1	7.308±0.065c	9.915±0.101c	381.362±1.362b	17638.262±863.954b
T2	8.463±0.062a	11.007±0.131b	516.328±2.358a	23957.674±903.625a
T3	8.621±0.058a	13.106±0.801a	521.726±3.698a	26321.254±869.362a
T4	7.751±0.085b	10.326±0.126bc	394.304±2.684b	19586.681±963.625b

3.3.2 The effect of Trichoderma viride agents on quality of melon
A variety of melon quality indices were measured 30 days after pollination using various T. viride agents treatments. The results are displayed in Table 4. As the concentration of T. viride agent treatment increased, the soluble solids content, vitamin C content, soluble protein content, soluble sugar content, and sugar acid ratio of melon fruit treated with T. viride agents showed an increasing trend, followed by a decreasing trend. The T3 fruit exhibited the highest levels of soluble solids, vitamin C, soluble protein, soluble sugar, and sugar acid ratio, with respective contents of 12.064%, 266.381 mg/100 g, 1294.746 mg/kg, 64.095 mg/g, and 15.493. Comparing T3 to CK, the increases were 50.16, 58.07, 85.56, 50.03, and 90.82%, respectively. Compared to CK, T3 fruit had the lowest total acid content (4.137 g/kg), which was 27.19% lower.

Treatment	Soluble solids content (%)	Vitamin C content/ (mg/100g)	Soluble protein content (mg/kg)	Total acid content (g/kg)	Soluble sugar content (mg/g)	Sugar-acid ratio
CK	8.034±0.089d	168.526±6.097d	697.749±10.541c	5.262±0.011a	42.722±0.962c	8.119±0.108c
T1	9.343±0.053c	195.082±8.370c	885.138±12.969b	4.677±0.009c	51.728±1.325b	11.060±0163b
T2	11.036±0.058b	249.289±5.324a	1250.269±77.845a	4.223±0.019d	61.058±1.385a	14.458±0.174a
T3	12.064±0.442a	266.381±7.068a	1294.746±33.544a	4.137±0.014d	64.095±1.652a	15.493±0.214a
T4	10.949±0.093b	223.390±5.725b	926.767±45.695b	4.935±0.017b	54.745±1.847b	11.093±0.141b

Discussion

Melon’s root vitality is impeded and its weight and growth of roots and leaves are greatly reduced as a result of long-term continuous cropping. This leads to a significant degradation of the soil’s physical and chemical properties, reduced organic matter content, and an inbalanced soil nutrient. Simultaneously, the build-up of autotoxic chemicals in soil alters the soil microenvironment, impacts physiological functions as crop photosynthesis and enzyme activity, and prevents crop growth. Trichoderma, a popular biological control agent, can successfully reduce ongoing cropping barriers in the production of melon.

Trichoderma can spread quickly in soil, persist for a long period on the surface of plant roots, and release a number of chemicals that can aid in the growth of plants. This study’s findings demonstrated that T. viride agents treatment might stimulate the morphogenesis of melon seedlings, with T3 (6.4 × 10⁵ cfu/g) having the most favorable results. Trichoderma viride Tv 911 was shown by Zaw and Matsumoto (2020) to promote the growth of Japanese mustard, tomato, and radish. As a result, the plant height of mustard and tomato increased by 16.22 and 50.26%, respectively, and the fresh branch and root weight of radish increased by 23.83 and 58.86%, respectively. This is so because Trichoderma regulates the physiological and biochemical metabolism processes of plants, which in turn promotes plant growth.

Plants’ physiological metabolism can be enhanced by Trichoderma, in addition to its growth-promoting effects. The content of physiological chemicals such as MDA and Pro is impacted by the secondary metabolites, such as CAT, POD, APX, SOD, and others, that Trichoderma secretes during plant-microbe contact. Plants may become resistant to these chemicals on a systemic level. According to the study’s findings, application of the T. viride agents improved the physiological properties of melons, with application of T3 having the greatest impact. According to Yu et al. (2021), T. asperellum spore solution raised the amount of soluble protein and soluble sugar in leaves, enhanced the activity of nitrate reductase and catalase, and boosted the plant height and stem thickness of tomato seedlings. According to Ahmad et al. (2022) research, T. harzianum Th23 treatment could boost tomato growth, increase the total chlorophyll content of leaves, and boost the activities of protective enzymes like PPO, CAT, and SOD. According to Cao et al. (2022) the growth of continuous cropping cucumber was enhanced by the treatment of both biochar and Trichoderma in combination. There was a notable increase in root activity as well as the activities of POD, CAT, and SOD in leaves, along with a decrease in the amount of MDA. This is due to the fact that Trichoderma is a biological control pathogen that also stimulates plant development. In addition, its secondary metabolites have the ability to create hormone analogs and plant growth regulators, both of which stimulate plant growth. This is in line with research conducted by Martínez-Medina et al. (2014) on the impact of four distinct strains of Trichoderma on the biological control activity of melon wilt disease and the promotion of plant growth. The outcomes demonstrated a substantial association between Trichoderma induction of auxin and stimulation of plant development, as well as an increase in auxin content that stimulated plant growth and a decrease in cytokinin and abscisic acid content.

The findings of this study demonstrated that T.viride agents treatment enhanced the physiological properties of melons and encouraged the development of melon yield and quality, with T3 treatment having the most favorable results. The results of a study by Liu L. et al. (2022) on the effects of T. harzianum biofilter on the growth, yield, and quality of bupleurum as well as the microbial reaction revealed that T. harzianum biofilter encouraged bupleurum growth and increased its yield and quality. Bupleurum had an increase in plant height, stem diameter, root diameter, and total plant weight compared to the control, respectively, of 20.52, 21.82, 38.36, and 126.70%. Saikosaponins A, C, and D levels in Bupleurum were also significantly higher thanks to T.harzianum bio-fertilizer, increasing by 8.06, 47.73, and 9.23%, respectively, in comparison to the control. According to Zhang et al. (2023), T. viride T23 enhanced the microbial community’s biomass and diversity, enhanced the physical and chemical characteristics of the soil, boosted the synthesis of soil-active substances, removed a barrier to melon continuous cropping, and encouraged the formation of melon yield.

Trichoderma is a common antagonistic microorganism found in nature that can help plants absorb nutrients, enhance the soil environment, speed up the breakdown of organic matter in the soil, and boost crop quality and yield. The results of this study showed that T. viride applied in varying amounts can promote the formation of melon yield and quality. The yield and quality also decreased as the application amount increased. The results of this study showed that the best concentration for melon growth was 6.4 × 10⁵ CFU/g, which may be attributed to the necessity to maintain a specific degree of diversity and balance in the soil microbial community. Even helpful bacteria, excessive development can squeeze the living space of other microorganisms, resulting to a decline in soil ecosystem variety, which is not conducive to soil health and crop growth. Therefore, it is essential to regulate the volume of application while using various Trichoderma microbial agents.

Numerous researchers have found that Trichoderma has a strong capacity to colonize soil, enhance soil physicochemical conditions, boost soil fertility, encourage the formation and upkeep of beneficial microbial communities in soil, and increase crop development and yield. The effects of T. viride agents on the soil environment of melon cultivated on soils that have been constantly cropped to melon will be further investigated in future studies.

Conclusion

Overall, our research showed that different T. viride agent application rates improve the root shoot ratio and seedling strength index of melon seedlings, improve the morphological development at the seedling stage and the physiological and biochemical characteristics at the fruiting stage, and increase the yield and quality of melon grown on soils that are continuously cropped to melon. The findings of the study offer fresh concepts for overcoming the challenges associated with melons’ continuous production and encouraging the melon industry’s sustainable growth. Additionally, they offer physiological mechanisms for the quick study and development of Trichoderma agents as well as a foundation for research to guarantee the high-quality and high-yield production of melons grown on soils that are consistently cropped with Trichoderma agents.