COMPOUND MYCORRHIZAL FUNGUS GROWTH PROMOTING AGENT AND AGRICULTURAL-PHOTOVOLTAIC COMPLEMENTARY PLANTING METHOD FOR DIOSCOREA COMPOSITA

Abstract

The present disclosure relates to the technical field of agricultural microorganisms and crop cultivation and more specifically relates to a compound mycorrhizal fungus growth promoting agent and an agricultural-photovoltaic complementary planting method for Dioscorea composita. The compound mycorrhizal fungus growth promoting agent for Dioscorea composita includes Glomus mosseae, Streptomyces chartreusi and plant growth promoting rhizobacteria, and can greatly improve photosynthesis of Dioscorea composita under a photovoltaic panel and promote growth and development of Dioscorea composita. The compound mycorrhizal fungus growth promoting agent is used, an unoccupied land under a solar photovoltaic panel is utilized, and a high-ridge close planting method is used to combine a solar photovoltaic industry and Dioscorea composita planting. The whole planting process is easy to operate, the cost is low, and three-dimensional value-added utilization of land is achieved.

Claims

1. A compound mycorrhizal fungus growth promoting agent for Dioscorea composita, wherein the compound mycorrhizal fungus growth promoting agent consists of Glomus mosseae, Streptomyces chartreusi and Flavisolibacter ginsengiterrae; spore suspensions of the Glomus mosseae, Streptomyces chartreusi and Flavisolibacter ginsengiterrae have a concentration equal to or greater than 4,000 spores/mL; and based on volumes of the spore suspensions with the same concentration, a use amount ratio of the Glomus mosseae, Streptomyces chartreusi and Flavisolibacter ginsengiterrae is 3:3:1.

2. Use of the compound mycorrhizal fungus growth promoting agent for Dioscorea composita according to claim 1 in an agricultural-photovoltaic complementary planting for Dioscorea composita.

3. Use of the compound mycorrhizal fungus growth promoting agent for Dioscorea composita according to claim 1 in preparing a microbial preparation, wherein the microbial preparation is capable of promoting growth and improving photosynthetic efficiency of Dioscorea composita in an agricultural-photovoltaic complementary planting for Dioscorea composita.

4. A microbial preparation for promoting growth and improving photosynthetic efficiency of Dioscorea composita, containing the compound mycorrhizal fungus growth promoting agent for Dioscorea composita according to claim 1.

5. An agricultural-photovoltaic complementary planting method for Dioscorea composita, wherein a Dioscorea composita seedling is planted after being infected with the compound mycorrhizal fungus growth promoting agent according to claim 1.

6. The agricultural-photovoltaic complementary planting method for Dioscorea composita according to claim 5, wherein the infection treatment is as follows: soaking a root of a Dioscorea composita cutting seedling with the compound mycorrhizal fungus growth promoting agent according to claim 1 and then field-planting the seedling in nutrient soil containing the compound mycorrhizal fungus growth promoting agent according to claim 1.

7. The agricultural-photovoltaic complementary planting method for Dioscorea composita according to claim 6, wherein the nutrient soil is obtained by cultivating Trifolium repens with the compound mycorrhizal fungus growth promoting agent for Dioscorea composita in the soil, and preparing the nutrient soil containing a spore, a mycelium and an infected root segment.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0057] FIG. 1 is a schematic diagram of a Dioscorea composita planting area under a photovoltaic panel;

[0058] FIG. 2 shows photosynthetically active radiation intensities in a direct sunlight area and a photovoltaic planting area in different periods of time;

[0059] FIG. 3 shows a net photosynthetic rate change of Dioscorea composita under different photosynthetically active radiation intensities;

[0060] FIG. 4 is a schematic diagram of infection of each experimental group and comparative group; wherein G.m+WZ+PGPR group is example 4; CK-1 group is comparative example 1; CK-2 group is comparative example 2; G.m group is comparative example 3; WZ group is comparative example 4; and G.m+WZ group is comparative example 5;

[0061] FIG. 5 shows net photosynthetic rate changes of Dioscorea composita cutting seedlings under inoculation treatment with different compound mycorrhizal fungus growth promoting agents.

DESCRIPTION OF THE EMBODIMENTS

[0062] The present disclosure is further described with reference to the drawings and specific examples of the description, but the examples are not intended to limit the present disclosure in any form. Unless otherwise specified, the reagents, methods and equipment used in the present disclosure are conventional in the art.

[0063] Unless otherwise specified, the reagents and materials used in the examples are commercially available.

[0064] Sources of strains used in examples 1-3: Glomus mosseae (G.m) and Streptomyces chartreusi WZS021 (WZ) are from the Institute of Microbiology, Guangdong Academy of Sciences; and plant growth promoting rhizobacteria are selected from Flavisolibacter gingsengiterrae (Fg) and from Ningbo MingzhouBio.

[0065] The soil used by the present disclosure is taken from Huaiji, Zhaoqing. It is determined that the organic matter content is 30.9 g/kg, the alkali-hydrolyzable nitrogen is 151 mg/kg, and the rapidly available phosphorus is 53.8 mg/kg.

Example 1

[0066] A preparation of a compound mycorrhizal fungus growth promoting agent for Dioscorea composita is as follows: [0067] (1) strain activation and spore suspension preparation: the Glomus mosseae, Streptomyces chartreusi and plant growth promoting rhizobacteria were respectively activated in a dark place in an incubator at 25° C., and then the strains were respectively prepared into spore suspensions with a concentration of 4,000 spores/mL using purified water; and [0068] (2) the three spore suspensions were mixed at a ratio of 3:3:1 to obtain the compound mycorrhizal fungus growth promoting agent for Dioscorea composita.

Example 2

[0069] A preparation of a compound mycorrhizal fungus growth promoting agent for Dioscorea composita is as follows: [0070] (1) strain activation and spore suspension preparation: the Glomus mosseae, Streptomyces chartreusi and plant growth promoting rhizobacteria were respectively activated in a dark place in an incubator at 20° C., and then the strains were respectively prepared into spore suspensions with a concentration of 5,000 spores/mL using purified water; and [0071] (2) the three spore suspensions were mixed at a ratio of 1:1:1 to obtain the compound mycorrhizal fungus growth promoting agent for Dioscorea composita.

Example 3

[0072] A preparation of a compound mycorrhizal fungus growth promoting agent for Dioscorea composita is as follows: [0073] (1) strain activation and spore suspension preparation: the Glomus mosseae, Streptomyces chartreusi and plant growth promoting rhizobacteria were respectively activated in a dark place in an incubator at 28° C., and then the strains were respectively prepared into spore suspensions with a concentration of 6,000 spores/mL using purified water; and [0074] (2) the three spore suspensions were mixed at a ratio of 10:10:1 to obtain the compound mycorrhizal fungus growth promoting agent for Dioscorea composita.

Example 4

[0075] An agricultural-photovoltaic complementary planting method for Dioscorea composita was inoculating the compound mycorrhizal fungus growth promoting agent of example 1 into a Dioscorea composita cutting seedling for planting.

[0076] In a specific practical industry, the agricultural-photovoltaic complementary planting method for Dioscorea composita included a planting link and a management link,

[0077] wherein the planting link included the following steps: [0078] (1) land selection: a loose, breathable and fertile flat land or sandy land with a deep soil layer is selected, and the land with a flat terrain, a good drainage and no waterlogging threat was selected as far as possible; [0079] (2) ploughing preparation: time for ploughing preparation was from late autumn to early spring of the next year and weeds in a field were comprehensively removed by spraying glyphosate before the ploughing preparation and the land is exposed under the sun for 20 days after the spraying; [0080] (3) compartment forming and fertilization: the land was arranged by a small machine and deeply ploughed into a compartment with a compartment ditch depth of 50 cm and a compartment ditch width of 100 cm, a length of a compartment ditch follows the terrain, and the compartment was exposed to the sun for about one month after being ploughed and backfilled with a base fertilizer; and 50 kg/mu of lime was spread in the compartment ditch, organic wastes such as weeds, sugarcane leaves and straws were spread, then 50 kg/mu of lime was spread, 1 kg/plant of a farmyard manure was added with 3,500 kg of the manure was fertilized in each mu, then a layer of soil was covered on the farmyard manure, and 300 kg/mu of a calcium magnesium phosphate fertilizer was fertilized on the soil layer; [0081] (4) compartment (planting land) management and film covering: the compartment was managed using a small agricultural machine, after the compartment ditch was leveled, as shown in FIG. 1, a compartment surface was 20 cm higher than the ground, a lower compartment width was 100 cm, an upper compartment width was 80 cm, a compartment length follows the terrain, and two drainage ditches with a ditch width of 40 cm and a ditch depth of 30 cm are respectively arranged at two sides of the compartment length; one sides, far away from the compartment, of the two drainage ditches are respectively provided with a solar photovoltaic module, and specifically, the solar photovoltaic module is a solar photovoltaic panel; a distance between one side, far away from the compartment, of the drainage ditch and a pile foundation at a bottom part of the solar photovoltaic module is 210 cm; and a mulching film was covered on the managed compartment surface, evenly covered on the compartment surface, and compacted with soil to prevent air leakage and heat dissipation; [0082] (5) seedling (cutting seedling) cultivation: Dioscorea composita was transplanted into a cutting nursery for culture, white small spots can be seen at a bud of a base part after about 15 days of cutting, white roots can grow after about 20 days, and a small amount of tender buds can grow after about 30 days, humidity of a seedbed of the cutting nursery was controlled, a compound fertilizer at a mass concentration of 0.2% and carbendazim at a mass concentration of 0.1% were sprayed, and a Dioscorea composita cutting seedling was obtained after leaving the nursery when the Dioscorea composita cutting seedling was cultured to about 85 days and a length of a tuber of the cutting seedling was equal to or greater than 2 cm; [0083] (6) nutrient soil cultivation: pure river sand was selected as a culture matrix, and the culture matrix was firstly sprayed with 0.5% of a potassium permanganate solution, then covered by a film and exposed to the sun for 3 days, and air-dried by lifting the film for 3 days; ⅓ of the culture matrix was firstly arranged on the culture seedbed, the compound mycorrhizal fungus growth promoting agent for Dioscorea composita prepared in example 1 was sprayed (criteria for spraying amount: based on a basin with a size of 80 cm*50 cm*10 cm (length*width*height), 1,000-2,000 ml/basin), then after ⅓ of the culture matrix was spread, Trifolium repens seeds were scattered (since the compound mycorrhizal fungus growth promoting agent cannot be used for complete and pure culture, the Trifolium repens seeds and the compound mycorrhizal fungus growth promoting agent were used together for symbiotic propagation, then 2 cm of the culture matrix was spread, and water was performed; a nutrient solution at ½ strength was watered for 1 time per week in a seedling stage (within 30 days) of Trifolium repens (all nutrient elements were halved and criteria: based on a basin with a size of 80 cm*50 cm*10 cm (length*width*height), 300-500 ml/basin); a nutrient solution was watered for 1 time per week after a Trifolium repens seedling was grown; and nutrient soil containing a spore, a mycelium and an infected root segment was harvested 3 months later; [0084] (7) growth promoting agent infection: a root of the Dioscorea composita cutting seedling in step (5) was soaked in the compound mycorrhizal fungus growth promoting agent for Dioscorea composita prepared in example 1 for 6-8 h; and the soaked Dioscorea composita cutting seedling was field-planted in the nutrient soil in step (6) and the residual compound mycorrhizal fungus growth promoting agent for Dioscorea composita after the soaking was sprayed in the nutrient soil; and [0085] (8) planting (transplanting): optimal planting time of the Dioscorea composita cutting seedling in the south China was a period from the Beginning of Spring to the Qingming Festival, or a mould rain season, in this period, the Dioscorea composita cutting seedling growing and developed in (7) was transplanted to the compartment in (4) for planting according to a specification of a plant spacing of 30 cm and a compartment row spacing of 30 cm, a small hole was dug in the compartment surface, the Dioscorea composita cutting seedling inoculated with the growth promoting agent was planted, 3 rows were planted in each compartment, and then the soil was backfilled; and the Dioscorea composita cutting seedling was buried in the soil as a whole and covered with 2-3 cm of soil, root-fixing water was watered thoroughly after the field-planting, and the amount of the watering can be gradually reduced until the Dioscorea composita cutting seedling germinated and grew.

[0086] The management link included the following steps: [0087] (1) rack erecting for leading vines: a rack was erected for leading vines before the Dioscorea composita cutting seedling grew to have a climbing capability, generally, the rack was erected when the Dioscorea composita cutting seedling grew to a height about 30 cm, a height of the rack for leading vines was equal to or greater than 1.5 m, the rack for leading vines was mainly a herringbone rack, and at the same time, a photovoltaic rack can be used as a support point; and the rack for leading vines used the photovoltaic rack as a support point, such that use of bamboo poles can be reduced, and the planting cost was further reduced; [0088] (2) watering: watering was performed in time to facilitate seedling recovery and rooting if the soil moisture was insufficient in a whole cultivation period; [0089] (3) fertilization: within 6 months of the field-planting, in a manner of “small amount in multiple times and low to high concentrations”, a foliar nitrogen fertilizer at a mass concentration of 0.3% or monopotassium phosphate at a mass concentration of 0.1% were sprayed every 15 days; a leaf back and a leaf surface were uniformly sprayed each time until water drops dropped downwards preferably; after the field-planting for 3 months, a fertilizer was applied for the first time to a root part to accelerate growth of the seedling; within 6 months of the field-planting, the seedling was mainly applied with a growth nitrogen fertilizer (namely, a mass fraction of the growth nitrogen fertilizer in the fertilizer was greater than 50%); and during 6-12 months of the field-planting, the seedling was mainly applied with a phosphorus and potassium fertilizer (namely, a mass fraction of the phosphorus and potassium fertilizer in the fertilization was greater than 50%) to accelerate growth and expansion of an underground tuber of the seedling; for Dioscorea composita with a planting period more than one year, during top dressing in spring of the second year, a phosphorus and potassium fertilizer was mainly applied (namely, a mass fraction of the phosphorus and potassium fertilizer in the fertilizer was greater than 50%), and hole-expanding fertilization was performed for one time before beginning of spring; and a hole was dug in a position 10 cm away from each seedling at a width of 15 cm and a depth of 10-15 cm, each seedling was applied with 100 g of a compound fertilizer, and daily management was performed according to a conventional method; and weeds were timely removed in the seedling stage and Dioscorea composita tubers and root systems should not be damaged to avoid influence on growth of the Dioscorea composita; [0090] (4) disease and pest control: after the field-planting for 2 months, 500-600 times of a water diluent of mancozeb at a mass concentration of 80%, or 900-1,000 times of a water diluent of thiophanate-methyl at a mass concentration of 50%, or 1,000-1,500 times of a water diluent of carbendazim at a mass concentration of 50% were sprayed to prevent and treat root rot and anthracnose; and if insect pests appeared, 1,500 times of a water diluent of dimethoate emulsifiable concentrate at a mass concentration of 40%, or 1,000 times of a water diluent of a dichlorvos emulsion at a mass concentration of 80% or 1,000 times of a water diluent of a phoxim emulsifiable concentrate at a mass concentration of 50% was sprayed for control; [0091] (5) vine management: after the planted Dioscorea composita was managed for one year, the Dioscorea composita grew faster in the second year, vines of the Dioscorea composita were wound, trimmed and cleaned, such that the Dioscorea composita had a good plant type and growth vigor; and when the Dioscorea composita had a large amount of male flowers, female flowers and old leaves, the Dioscorea composita was trimmed and cleaned to ensure a good permeability, a large amount of nutrient consumption on a flowering branch was avoided, and expanded growth of an underground tuber was influenced; [0092] (6) topping: when the main vines of the Dioscorea composita grew to 100 cm, artificial topping was performed, i.e. a part 10 cm from a top bud of the Dioscorea composita was picking off by hands or sprayed with a pesticide (chlormequat chloride), and multiple topping was performed in a whole field growth stage; and the topping can promote a large amount of new branches and leaves of the Dioscorea composita to rapidly form and further improved a photosynthetic product; and [0093] (7) harvesting: Dioscorea composita grown in 2-3 years was harvested using a small agricultural machine, wherein an optimal harvesting period of the Dioscorea composita was from November per year to May of the next year.

[0094] It was determined that by using the agricultural-photovoltaic complementary planting method for Dioscorea composita of the example, under a normal growth state, a 1-year-old tuber of the Dioscorea composita had an average depth of 30-40 cm, a root width of 15-20 cm, and an average net weight of 0.6-1.2 kg; a 2-year-old tuber had an average height of 40-45 cm, a root width of 40-50 cm, an average single plant net weight of 3-6 kg, and a highest single plant net weight of 10 kg; and a 3-year-old tuber had an average height of 50-60 cm, a root width of 50-65 cm, an average single plant net weight of 8-12 kg, and a highest single plant net weight of 20 kg.

Comparative Example 1

[0095] Comparative example 1 differs from example 4 in that: the Dioscorea composita in comparative example 1 was planted in a normal direct sunlight area and no solar photovoltaic module was arranged on two sides of a compartment surface to shield sunlight; and the Dioscorea composita in comparative example 1 was not inoculated with the compound mycorrhizal fungus growth promoting agent for Dioscorea composita.

Comparative Example 2

[0096] Comparative example 2 differs from example 4 in that: the Dioscorea composita in comparative example 2 was not inoculated with the compound mycorrhizal fungus growth promoting agent for Dioscorea composita.

Comparative Example 3

[0097] Comparative example 3 differs from example 4 in that: an ingredient microorganism in the growth promoting agent inoculated into the Dioscorea composita in comparative example 3 was Glomus mosseae.

Comparative Example 4

[0098] Comparative example 4 differs from example 4 in that: an ingredient microorganism in the growth promoting agent inoculated into the Dioscorea composita in comparative example 4 was Streptomyces chartreusi.

Comparative Example 5

[0099] Comparative example 5 differs from example 4 in that: ingredient microorganisms in the growth promoting agent inoculated into the Dioscorea composita in comparative example 5 were Glomus mosseae and Streptomyces chartreusi.

Test Example 1

[0100] (1) Light Intensity Detection of Different Planting Areas

[0101] In order to investigate whether conditions such as light intensity and soil under a solar photovoltaic module are suitable for a planting requirement of Dioscorea composita, a light intensity detection on an area under the solar photovoltaic module on the spot was carried out at an early stage (Huaiji, Zhaoqing).

[0102] As shown in FIG. 2, the results showed that under sunny days in winter, the light intensity of the area under the solar photovoltaic module was about 100-200 μmol.Math.m.sup.−2.Math.s.sup.−1. In addition, due to different slope gradients, distances among photovoltaic panels on each slope were varied, when the slope gradient was larger, the distance among the photovoltaic panels were larger, and a photosynthetically active radiation intensity of a slope with a larger slope gradient was improved by about 10-20%. The lowest light intensity of the direct sunlight area was 1,200 μmol.Math.m.sup.−2.Math.s.sup.−1.

[0103] (2) Simulated Measurement of Net Photosynthetic Rate of Dioscorea composita

[0104] Photosynthesis is a basis of plant growth. A net photosynthetic rate may reflect a rate of net organic accumulation in a plant. A greater net photosynthetic rate indicates a greater net production by a plant and a greater photosynthesis.

[0105] Aiming at environmental conditions of a solar photovoltaic planting area, a simulated measurement of a net photosynthetic rate of Dioscorea composita was carried out. As shown in FIG. 3, it was found that a maximum light saturation point of Dioscorea composita was between 500-1,000 μmol.Math.m.sup.−2.Math.s.sup.−1. At the same time, a net photosynthetic rate of about 3.8 μmol.Math.m.sup.−2.Math.s.sup.−1 can be maintained at 100 μmol.Math.m.sup.−2.Math.s.sup.−1. Under the condition, Dioscorea composita hardly grew well.

Test Example 2

[0106] 1. The growth promoting agent of example 1 was taken as an example, according to the method of example 4, a planting experiment under a solar photovoltaic module was performed in Huaiji, Zhaoqing, and example 4 was compared with comparative examples 1-5 (as shown in FIG. 4); and net photosynthetic rate changes of the examples and comparative examples were tested at different photosynthetically active radiation intensities.

[0107] 2. Experimental Results

[0108] (1) Net Photosynthetic Rate Change of Each Group

[0109] As shown in FIG. 5, the net photosynthetic rate of the Dioscorea composita cutting seedling in comparative example 2 was much lower than that of the Dioscorea composita cutting seedling in comparative example 1, which indicated that growth of the Dioscorea composita planted under the solar photovoltaic planting area was obviously inhibited and the Dioscorea composita cannot grow well.

[0110] As shown in FIG. 5, when different mycorrhizal growth promoting agents were inoculated, a utilization degree of light energy by Dioscorea composita leaves showed different changes. With regard to a light compensation point of leaves of Dioscorea composita cutting seedling, the net photosynthetic rate of example 4 was better than that of comparative examples 5, 4 and 3, and the net photosynthetic rate of comparative example 2 was the worst. When a photosynthetic effective intensity was greater than 50 μmol.Math.m.sup.−2.Math.s.sup.−1, the net photosynthetic rate of leaves of example 4 was obviously better than that of comparative examples 3-5, the net photosynthetic rate of leaves of comparative example 5 was also obviously better than that of comparative example 2, and the net photosynthetic rate of leaves in comparative example 4 was the lowest.

[0111] (2) Influence of Compound Mycorrhizal Fungus Growth Promoting Agent for Dioscorea composita on Dioscorea composita Photosynthesis

[0112] As shown in Table 1 above, the treatment with the compound mycorrhizal fungus growth promoting agent for Dioscorea composita did not greatly affect the chlorophyll content of Dioscorea composita leaves at 30 days of the treatment. However, after 60 days, the Dioscorea composita plant in example 4 inoculated with the compound mycorrhizal growth promoting agent under a photovoltaic panel had a best effect, and contents of chlorophyll and components thereof were significantly increased, wherein the content of chlorophyll a was maximally increased by about 23.7%, the content of chlorophyll b was maximally increased by 8.9%, the total chlorophyll content was maximally increased by 16.1%, and the net photosynthetic rate was maximally increased by 14.6% compared with an uninoculated plant under a photovoltaic panel. 90 days after the inoculation, compared with the plant growing under normal illumination, the plant in example 4 showed the maximum chlorophyll a content of about 97.3%, the maximum chlorophyll b content of about 98.6%, the maximum total chlorophyll content of about 97.9%, and the maximum net photosynthetic rate of about 98%. The results indicated that inoculation with the compound mycorrhizal growth promoting agent could improve the photosynthetic efficiency of the Dioscorea composita cutting seedlings. A growth state of the Dioscorea composita inoculated with the compound mycorrhizal growth promoting agent under a photovoltaic panel was basically consistent with that of the Dioscorea composita under normal illumination.

TABLE-US-00001 TABLE 1 Influence of compound mycorrhizal growth promoting agent on chlorophyll content and net photosynthetic rate of Dioscorea composita Net Total photosynthetic Sampling Chlorophyll Chlorophyll chlorophyll rate time Treatment a (%) b (%) (%) (μmol .Math. m.sup.−2 .Math. s.sup.−1) 30 d Comparative 4.76a 3.72a 8.48a 4.7a example 1 Comparative 3.35b 2.98b 6.33b 3.8b example 2 Comparative 3.76b 3.11a 6.87b 4.1a example 3 Comparative 3.25b 2.85b 6.10b 3.6b example 4 Comparative 4.12a 3.27a 7.39a 4.3b example 5 Example 4 4.35a 3.54a 7.89a 4.5a 60 d Comparative 9.68a 8.53a 18.21a 4.9a example 1 Comparative 7.56b 7.78b 15.34b 4.1b example 2 Comparative 7.96b 8.12a 16.08b 4.3a example 3 Comparative 7.48b 7.65b 15.13b 4.0b example 4 Comparative 8.75a 8.17a 16.92a 4.5a example 5 Example 4 9.35a 8.47a 17.82a 4.7a 90 d Comparative 9.78a 9.72a 19.5a 4.9a example 1 Comparative 8.12b 7.89b 16.01c 4.1b example 2 Comparative 8.34b 8.14b 16.48b 4.2b example 3 Comparative 7.98b 7.63b 15.61c 4.0b example 4 Comparative 8.95a 8.54a 17.49b 4.7a example 5 Example 4 9.52a 9.58a 19.10a 4.8a Note: data in the table were average values of 5 plants; and different letters in each column indicated a 0.05significant level.

[0113] (3) Influence of Compound Mycorrhizal Fungus Growth Promoting Agent for Dioscorea composita on Growth Amount of Dioscorea composita

[0114] As shown in Table 2, after inoculated with different compound mycorrhizal fungus growth promoting agents for Dioscorea composita, the nutritional growth of the Dioscorea composita cutting seedling was improved to different degrees, wherein an effect of example 4 was the best. After 60 days, a plant height of the inoculated plant planted under a photovoltaic panel was increased by about 29% compared with the uninoculated plant, a fresh weight of an overground part was increased by 14.1%, and a fresh weight of an underground part increased by 19.6%. At 90 days of inoculation, compared with the plant grown under normal illumination (i.e. comparative example 1), the plant in example 4 had a plant height about 91.7%, a fresh weight of an overground part about 90.3% and a fresh weight of an underground part about 92.7%. In addition, the number of secondary roots of the inoculated plant planted under a photovoltaic panel was obviously more than that of the uninoculated plant under a photovoltaic panel and the plant grown under normal illumination, indicating that the inoculation with the compound mycorrhizal growth promoting agent can obviously promote the nutritional growth of the Dioscorea composita cutting seedling.

TABLE-US-00002 TABLE 2 Influence of compound mycorrhizal growth promoting agent on growth amount of Dioscorea composita Fresh weight of Fresh weight of overground underground Number of Sampling Infection Plant height part part secondary time Treatment rate (cm) (g/plant) (g/plant) roots/plant 30 d Comparative / 40a 70a 13a 13b example 1 Comparative / 41a 65a 12a 12b example 2 Comparative 47% 43a 66a 12a 12b example 3 Comparative 35% 41a 64a 11a 11c example 4 Comparative 51% 42a 67a 13a 17a example 5 Example 4 65% 45a 71a 15a 19a 60 d Comparative / 85a 175a 112a 27a example 1 Comparative / 62c 149c 92c 23b example 2 Comparative 65% 70b 163b 103b 25b example 3 Comparative 55% 65c 151c 95c 21b example 4 Comparative 69% 73b 167b 105b 30a example 5 Example 4 79% 80a 170a 110a 32a 90 d Comparative / 120a 362a 192a 31a example 1 Comparative — 90c 266d 153c 27b example 2 Comparative 75% 100b 295c 161b 29b example 3 Comparative 67% 93c 275d 155c 25b example 4 Comparative 80% 105b 302b 167b 32a example 5 Example 4 87% 110a 327a 178a 35a Note: data in the table were average values of 5 plants; and different letters in each column indicated a 0.05 significant level.

[0115] The foregoing examples are merely illustrative and used to explain some features of the method of the present disclosure. The appended claims are intended to claim a conceived broad scope as much as possible and the examples presented herein are demonstrated by results of actual tests by the applicant. Accordingly, it is the applicants' intention that the appended claims are not to be limited by choices of examples illustrating features of the present disclosure. Some value ranges used in claims also include all sub-ranges subsumed therein and variations within the ranges are also intended to be encompassed by the appended claims hereto where possible.