Method for improving growth and drought resistance of oats by using arbuscular mycorrhizal fungi

Abstract

The invention relates to the technical field of agricultural micro-ecological application, and discloses a method for improving the growth and drought resistance of oats by using arbuscular mycorrhizal fungi, the arbuscular mycorrhizal fungi having a close symbiotic relationship with the oats are selectively utilized, and the symbiotic relationship between the arbuscular mycorrhizal fungi and the oats is established in a condition control mode. Oat growth is promoted, and drought adaptability is improved. The AM fungi used in the method are selected from rhizosporidium intraradices or glomus mosseae, corn or trifolium repens is taken as a host, the two AM fungi are propagated in a propagation medium respectively, then two arbuscular mycorrhizal fungi inoculants and oat are co-cultured in a symbiotic culture medium respectively, and the two arbuscular mycorrhizal fungi inoculants and oat are co-cultured in a symbiotic culture medium respectively. An effective way for improving beneficial symbiosis of AM fungi and hosts under adverse conditions is provided, the infection symbiosis relation of the AM fungi to host plants is improved manually, and the yield of dry land oats is increased.

Description

Technical Field

[0001] The invention relates to the technical field of agricultural microecological applications, and in particular to a method for improving the growth and drought resistance of oats by utilizing arbuscular mycorrhizal fungi. Background Art

[0002] Drought is a global problem. More than one-third of the world's arable land is in arid or semi-arid state. Drought seriously restricts the development of agriculture.

[0003] Oats (Avena sativa L.), belonging to the genus Avena (Avena L.) of the Poaceae family in plant classification, are annual crops used for both food and feed. They are important forage varieties in the development of my country's agriculture from a dualistic structure to a ternary structure and in the conversion of food to feed. High-quality oat grass plays an increasingly important role in the development of my country's animal husbandry, especially in high-altitude and cold areas where high-quality forage is lacking. Oats in my country are mainly planted in the northern spring and summer sowing and planting areas and the southern autumn sowing and planting areas, specifically in North China, Northwest China, Southwest China and Northeast China. More than half of them are planted on dry land. Drought can simultaneously affect oats' photosynthesis, respiratory metabolism, water conditions, changes in various enzymes and other physiological metabolic processes, and have a wide and serious impact on oat growth.

[0004] Arbuscular mycorrhizal (AM) fungi can achieve mutualism with host plants by exchanging carbohydrates and soil nutrients with the host plants through the extended mycelium. In recent years, the application of mycorrhizal technology has enabled plants to better adapt to the living environment under drought conditions, and the conclusion that mycorrhizal technology can enhance the drought resistance of forest trees has been confirmed in many host plants. However, current research mainly focuses on forest plants, and no research has been found on inoculating AM fungi in crops and forages to improve drought resistance. Summary of the invention

[0005] In view of this, the purpose of the present invention is to provide a method for utilizing arbuscular mycorrhizal fungi to effectively improve the growth and drought resistance of oats, so as to reasonably and efficiently exert the mutualistic symbiotic relationship between AM fungi and host plants under drought stress and increase the yield of oats grown in dry land.

[0006] The technical scheme of the present invention is as follows: a method for improving the growth and drought resistance of oats by using arbuscular mycorrhizal fungi, the method selectively uses arbuscular mycorrhizal fungi that have a close symbiotic relationship with oats, and establishes a symbiotic relationship between arbuscular mycorrhizal fungi and oats through conditional control, promotes the growth of oats, improves drought adaptability, and improves the yield and quality of oats under drought planting conditions. Then, the effect of arbuscular mycorrhizal fungi on the host's drought coping ability is further studied through water control treatment. The method comprises the following steps: Step 1, obtaining an arbuscular mycorrhizal fungus inoculant: using corn and white clover as hosts, inoculating arbuscular mycorrhizal fungi into a propagation matrix for propagation to obtain an arbuscular mycorrhizal fungus inoculant, wherein the arbuscular mycorrhizal fungus is selected from one of Rhiaophagus intraradices and Funneliforrmis mosseae, and the inoculation amount of the arbuscular mycorrhizal fungus is 1%-2% of the weight of the propagation matrix, and the arbuscular mycorrhizal fungus inoculant comprises mycorrhizae, soil containing spores, and extraradical hyphae mixed with the soil; Step 2, co-cultivation: co-cultivating the arbuscular mycorrhizal fungi inoculant obtained in step 1 and oats in a symbiotic culture matrix, wherein the inoculation amount of the arbuscular mycorrhizal fungi inoculant is 2%-3% of the weight of the symbiotic culture matrix; The propagation matrix and the symbiotic culture matrix are obtained by mixing river sand and field soil in a volume ratio of 1:1 and then sterilizing them.

[0007] Preferably, the arbuscular mycorrhizal fungal infection rate of the mycorrhiza is 75-80%.

[0008] Preferably, the spore content in the spore-containing soil is 80-110 spores / 20g soil.

[0009] Preferably, the physical and chemical properties of the soil are pH 6-7, total nitrogen 1.2-1.3 mg / g, and total phosphorus 0.45-0.5 mg / g.

[0010] Preferably, the arbuscular mycorrhizal fungi are selected from Rhiaophagus intraradices, and the inoculation amount of the arbuscular mycorrhizal fungi is 1% of the weight of the propagation substrate.

[0011] Preferably, the river sand and field soil are sterilized by high-temperature sterilization at 210°C for 2 hours.

[0012] Preferably, the inoculation method of the arbuscular mycorrhizal fungus inoculant in step 2 is to divide the arbuscular mycorrhizal fungus inoculant into two parts according to the ratio of A:B=20:3, wherein A is fully mixed with the symbiotic culture matrix and then sown with oat seeds, and then B is spread on the surface of the oat sowing layer and covered with 5-6 cm of the symbiotic culture matrix.

[0013] The two fungi used in the present invention were purchased from the Institute of Root Biology of Yangtze University and deposited in the Chinese Arbuscular Mycorrhizal (AM) Fungal Germplasm Resource Bank (BGC), wherein the accession number of Rhiaophagus intraradices is BGC BJ09, and the accession number of Funneliforrmis mosseae is BGC XZ02A.

[0014] The present invention adopts the beneficial symbiotic technology between AM fungi and plants, and provides a new way to increase the yield of dryland oats that takes into account both economic and environmental ecological benefits. Although there is no strict host specificity between AM fungi and plants, different AM fungi have certain preferences for host plants. The method of the present invention is based on the mutualistic symbiotic relationship between oats and AM fungi. AM fungi with certain preferences for oats are screened, and inoculants containing AM fungal spores, root segments and hyphae are obtained by using reasonable substrates and cultivation patterns. The inoculants are buried together with oats to construct plants with good mycorrhization. By exploring the preferential relationship between AM fungi and specific hosts, an effective way to improve the beneficial symbiosis between AM fungi and hosts under adverse conditions is provided, and the infection symbiotic relationship of AM fungi on host plants is improved by artificial means, thereby increasing the yield of dryland oats.

[0015] Beneficial effects of the present invention: 1. The results showed that both AM fungi had a high mycorrhizal infection rate under sufficient water supply conditions, indicating that the two AM fungi selected in the present invention have a high preference for oats; for drought-resistant varieties of oats, the mutualistic relationship between Rhiaophagus intraradices and oats is closer; for water-sensitive varieties of oats, the mutualistic relationship between Funneliforrmis mosseae and oats is closer.

[0016] 2. Both AM fungi inocula can effectively promote the growth of oats, regardless of whether they are in sufficient water supply or severe drought conditions. The plant height, aboveground biomass and ear weight of the two mycorrhizal plants are significantly higher than those of the control group without AM fungi inoculation. This shows that inoculation with AM fungi can promote the growth of oats and help improve the drought adaptability of host plants. In particular, it can also improve the drought resistance of host plants under low water stress.

[0017] 3. Under drought stress conditions, inoculation of two mycorrhizal fungi can increase the relative water content and chlorophyll content of oats, improve the net photosynthetic rate and instantaneous water use efficiency, alleviate the photosynthetic limitation caused by drought, and promote the growth of oats.

[0018] 4. Under drought stress conditions, inoculation of two mycorrhizal fungi can increase the activities of SOD, CAT, and POD in leaves and roots, reduce the AAS content in leaves and roots, and reduce the levels of GSH / GSSG in leaves and roots, thereby improving the plant's stress defense ability, reducing the damage of drought stress to oat seedlings, and promoting oat growth.

[0019] 5. Under drought stress conditions, inoculation with Rhizospora intraradicata can significantly regulate the levels of ABA, IAA and SA in oat leaves and roots, thereby improving the drought resistance and growth vitality of oat cells under drought stress. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a bar graph showing the relative water content of Qingyan No. 1 leaves changing with cultivation conditions; Figure 2 This is a bar graph showing the relative water content of Qinghai sweet oat leaves changing with cultivation conditions; Figure 3 This is a bar graph showing the net photosynthetic rate of Qingyan No. 1 changing with cultivation conditions; Figure 4 This is a bar graph showing the net photosynthetic rate of Qinghai sweet oats changing with cultivation conditions; Figure 5 This is a bar graph showing the stomatal conductance of Qingyan No. 1 changing with cultivation conditions; Figure 6 This is a bar graph showing the stomatal conductance of Qinghai sweet oats changing with cultivation conditions; Figure 7 This is a bar graph showing the intercellular CO2 concentration of Qingyan No. 1 changing with cultivation conditions; Figure 8 This is a bar graph showing the intercellular CO2 concentration of Qinghai sweet oats changing with cultivation conditions; Fig. 9 This is a bar graph showing the instantaneous water use efficiency of Qingyan No. 1 changing with cultivation conditions; Fig.10 This is a bar graph showing the instantaneous water use efficiency of Qinghai sweet oats changing with cultivation conditions; Fig.11 This is a bar graph showing the changes in H2O2 content in the leaves of Qingyan No. 1 as the cultivation conditions change; Fig.12 This is a bar graph showing the changes in H2O2 content in the roots of Qingyan No. 1 as the cultivation conditions change; Fig.13 This is a bar graph showing the changes in H2O2 content in the leaves of Qinghai sweet oats with cultivation conditions; Fig.14 This is a bar graph showing the changes in H2O2 content in the roots of Qinghai sweet oats as the cultivation conditions change. DETAILED DESCRIPTION

[0021] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments. It is understood that the specific embodiments and drawings are only exemplary descriptions of the present invention and should not be regarded as the entirety of the present invention or as a definition or limitation of the technical solution of the present invention. Unless otherwise specified, the fungicide, agent and crop seeds used in the following experiments can all be obtained through conventional commercial channels.

[0022] 1. Co-cultivation experiment of arbuscular mycorrhizal fungi and oats Rhiaophagus intraradices or Funneliforrmismosseae (purchased from the Institute of Root Biology, Yangtze University) were used as fungal inoculants. AM fungi were propagated before the experiment to obtain arbuscular mycorrhizal fungi inoculants. The specific steps of the propagation work were as follows: corn and white clover were used as hosts indoors, a 1:1 mixture of sieved sterile sand and sterilized field soil was used as propagation cultivation soil, 50g of fungal agent was added to each pot and mixed thoroughly with 5kg of soil, and AM fungi were propagated for 4 months. Hoagland nutrient solution was used regularly to supplement soil nutrients during the cultivation period. The arbuscular mycorrhizal fungi inoculants obtained included mycorrhizae (mycorrhizal infection rate was 79.5%), soil containing spores (80-110 spores per 20g), and extraradical hyphae mixed with soil.

[0023] The experiment was carried out in a potted manner using round plastic pots (20 cm in height and 20 cm in diameter) with holes in the bottom.

[0024] The experiment set up three factors: 1. Water factor, which was normal water (CK, 75% FC) and moderate drought (MD, 50% FC); 2. AM fungus inoculation factor, which was F. mosseae inoculation treatment (denoted as Fm), R. intraradices inoculation treatment (denoted as Ri) and no inoculation treatment (denoted as NM); 3. Variety factor, which was drought-resistant oat variety "Qingyan No. 1" (denoted as B) and water-sensitive oat variety "Qinghai Sweet Oats" (denoted as W). Combined with these three influencing factors, the experiment set up 12 treatments, each with 18 replicates, a total of 216 pots, the specific experimental numbers are shown in Table 1 below.

[0025] Table 1. Test number table

[0026] Before inoculation, the cultivation soil (a sandy soil mixture of river sand and field soil in a volume ratio of 1:1) was sterilized at 210℃ for 2h to ensure that there were no microbial propagules in the soil and that the water content of the cultivation soil used was consistent. The soil physical and chemical properties were: pH 6.9, total nitrogen 1.292 mg / g, and total phosphorus 0.459 mg / g. 115g of arbuscular mycorrhizal fungi inoculant was applied to each pot in the inoculation treatment group, of which 100g was mixed with 4.9kg of sandy soil mixture, and 15g was spread on the surface of the soil mixture close to the oat sowing layer. The total weight of the inoculant and sandy soil mixture was 5.015kg. In the treatment without AM fungus inoculation, 115g of sterilized arbuscular mycorrhizal fungi inoculant was applied to each pot, and the inoculant application method was the same as that of the inoculation treatment group.

[0027] All materials were sown on May 26, 2023, with 20 seeds per pot, and 800 ml of water was irrigated after sowing. All potted plants were placed in the rain shelter of the Provincial Key Laboratory of Qinghai Academy of Animal Husbandry and Veterinary Medicine. The average temperature in summer was 9 ℃-24 ℃, with natural light. During the three-leaf period, 5 oat seedlings with uniform growth and health were retained in each pot. Before drought treatment, all materials were cultured with normal water (75% FC) and irrigated with 100 ml Hoagland nutrient solution every 15 days. After 30 days, water control began to be carried out for drought treatment, and soil moisture was supplemented every evening to keep the soil moisture content at 45-50% FC and sampled after 30 days. When sampling, 5 pots were randomly selected to harvest leaf and root samples and quickly placed in liquid nitrogen for freezing. After the samples were collected, they were stored in a -80℃ refrigerator; 5 pots were randomly selected to wash the roots, separate the roots, leaves, stems, and spikes, and placed in a 105℃ oven for 15 min to kill the green, and then dried at 80℃ to a constant temperature and weighed for storage. Pots in the remaining treatments continued to be grown under normal water conditions (75% FC) or moderate drought conditions (45-50% FC) until maturity and then harvested.

[0028] 2. Test parameter determination 2.1 Determination of oat mycorrhizal infection rate Fresh root samples were collected on the 30th day after drought, and the surface soil and impurities were washed off. The water was dried with absorbent paper. 0.5g of fine root samples were weighed for each root sample, cut into small segments of about 1cm, placed in a test tube, and 5% KOH was added for shock. The samples were heated in a 90°C water bath for 40 minutes. The fine root samples were then taken out and cleaned. After that, 2% HCl solution was added for 5 minutes. Trypan blue (0.05%) was added and dyed in a 90°C water bath for 10-30 minutes. The samples were washed with distilled water, and the samples were placed in a beaker containing a decolorizing solution (3ml NaOH+30ml 10% H2O2+H2O to 600ml, prepared and used immediately). The samples were decolorized at room temperature for 2-3 days. After decolorization, 30-50 root segments were randomly selected for slide preparation, and 10 roots were pressed on each slide. The infection rate was determined using the cross method under a 200× microscope. One of the microscope crosshairs was parallel to the root system, and the other was observed to see if there were intersections with the hyphae, arbuscules, and vesicles. Ten fields of view were observed for each root segment, for a total of 100 fields of view. The grid line intersection method was used to detect the percentage of AMF infection in the root system under a 200x magnifying glass.

[0029] 2.2 Determination of leaf relative water content The relative water content (RWC) of oat leaves was determined as follows: leaves were picked from the same part (the fifth from the rhizome to the top), and the fresh weight of the leaves was quickly weighed (W1). The leaves were then completely immersed in distilled water and fully absorbed for 30 min. The leaves were taken out, and the water on the surface of the leaves was absorbed with absorbent paper. The saturated fresh weight (W2) was weighed. The leaves were dried in an oven at 80°C to constant weight, and the dry weight (W3) of the leaves was weighed.

[0030] The calculation formula of RWC is as follows: RWC (%) = (W1 - W3) / (W2 - W3) × 100% Wherein, W1: leaf fresh weight (g); W2: leaf saturated fresh weight (g); W3: leaf dry weight (g).

[0031] 2.3 Chlorophyll content determination Six oat leaves were selected for each treatment. After collection, 0.1 g of fresh oat leaves were weighed and cut into pieces, placed in a 5 ml centrifuge tube, and 2 ml of alcohol-acetone (v:v=1:1) mixture was added. The leaves were soaked at 4°C in the dark for 1 week until all the oat leaves turned white. Chlorophyll a, chlorophyll b, and lutein were determined by the alcohol-acetone extraction method. The mixed extract was used as the 0 blank, and the OD of each treatment was measured using a full-wavelength microplate reader (ThermoFisher Multiskan GO, USA). 663 OD 645 OD 470 The contents of chlorophyll a, chlorophyll b and lutein were calculated, and 6 replicates were measured for each treatment.

[0032] The content of chlorophyll a, chlorophyll b and lutein was calculated using the following formula: Chlorophyll a content Chla (mg / g) = (12.7D 663 -2.69D 645 )×V / (1000W) Chlorophyll b content Chlb (mg / g) = (22.9D 645 -4.68D 663 )×V / (1000W) Lutein content Cxc (mg / g) = (1000D 470 -3.27Cl a-104Cl b) / (229V) / (1000W) Where V represents the volume of the extract (ml), and W represents the mass of the extracted material (g).

[0033] 2.4 Determination of photosynthetic parameters Photosynthetic parameters of all treatments were measured on the 21st to 24th day of drought treatment. Four fully expanded, undamaged oat leaves were randomly selected from each treatment. A portable LI-6800 photosynthetic meter (Li-COR, Lincoln, NE, USA) was used to measure oat leaf gas exchange parameters, including net photosynthetic rate (P N ), stomatal conductance (gs), intercellular CO2 concentration (Ci) and transpiration rate (E). The parameters were set as follows: measuring light 1500 μmol∙m-2∙s-1, CO2 concentration in the sample chamber 400 μmol / mol, leaf temperature 25℃±1℃, and relative humidity 60%. The measurement time was 8:30-11:30 am on a sunny day. Instantaneous water use efficiency (iWUE) was calculated according to the following formula.

[0034] iWUE (μmol / mol) = P N / gs Where P N :Net photosynthetic rate [μmol∙m -2 ∙s -1 ]; gs: stomatal conductance [mol∙m -2 ∙s -1 ].

[0035] 2.5 Antioxidant capacity determination The root and leaf samples required for physiological indicators were collected on the 25th day after drought. The root samples were quickly washed with water and dried with absorbent paper. The roots and leaves were wrapped with tin foil and quickly frozen in liquid nitrogen and stored in a -80°C refrigerator. Superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), free amino acids, total soluble protein, glutathione reductase (GR), reduced glutathione (GSH), and oxidized glutathione (GSSG) were determined using the microtiter kit produced by Suzhou Keming Company, and the above indicators were determined using a full-wavelength microplate reader (ThermoFisher MultiskanGO, USA).

[0036] 2.6 Hormone determination Extraction and determination of abscisic acid, indoleacetic acid and salicylic acid Weigh 2 g of cryopreserved oat leaf and root samples inoculated with R. intraradices under different water treatments, grind them thoroughly with liquid nitrogen, add 20 ml of pre-cooled 80% methanol, transfer to 50 ml centrifuge tubes, shake at 160-180 r / min for 6 h at 4℃ in the dark, and stand at 4℃ in the dark for 22 h. Centrifuge at 12000 r / min and 4℃ for 20 min, aspirate the supernatant into a 50 ml centrifuge tube, add 10 ml of 80% pre-cooled methanol to the residue, extract by ultrasonic for 10 min, centrifuge, combine the supernatant, and discard the residue. All supernatants (25-30 ml) were concentrated to 20 ml at 40℃ under reduced pressure, add 10 ml of petroleum ether, shake well, and stand for decolorization once, then add 10 ml of petroleum ether to repeat the decolorization once, centrifuge at 10000 r / min for 10 min, and leave the liquid phase and discard the upper ether phase. The lower liquid phase was concentrated to 1 / 3 under reduced pressure at 40°C, extracted with 10 ml of ethyl acetate and left to stand, and the upper ester phase was retained. Another 10 ml of ethyl acetate was added, and the supernatants were combined after centrifugation. All the supernatants were concentrated to near dryness under reduced pressure at 40°C, re-dissolved with 2 ml of chromatographic methanol, and stored at 4°C in the dark.

[0037] The processed samples were sent to the National Key Laboratory of Qinghai University for determination of abscisic acid (ABA), indoleacetic acid (IAA), and salicylic acid (SA) contents using a Fourier transform ultra-high resolution liquid spectrometer (Thermo Q Exactive, USA).

[0038] 3. Test results and analysis 3.1 Effects of AMF on mycorrhizal infection rate, growth and yield of oats Table 2 shows the effects of inoculation with Rhiaophagus intraradices and Funneliforrmis mosseae on the mycorrhizal infection rate, growth and single ear grain weight of different varieties of oats.

[0039] Table 2

[0040] As can be seen from Table 2, drought stress has a significant effect on the mycorrhizal infection rate, plant height, aboveground biomass and ear weight of the two oat varieties. However, whether under normal water (CK) or moderate drought (MD) conditions, the inoculation treatment can improve the growth characteristics and ear weight of oats, indicating that inoculation with Rhizospora intraradicata (Ri) and Glomus mosseae (Fm) can promote the growth of oats and help increase oat yield. Under drought stress, the mycorrhizal infection rate of inoculation with Fm is higher than that of inoculation with Ri. However, for drought-resistant varieties of oats, inoculation with Fm and Ri has a positive effect on the growth characteristics of oats. For water-sensitive varieties of oats, the growth characteristics of oats inoculated with Fm are better than those inoculated with Ri.

[0041] 3.2 Effects of AMF on physiological and biochemical parameters of oats 3.2.1 Effect of AMF on relative water content (RWC) of oat leaves Figure 1 The effect of inoculation with Rhiaophagus intraradices and Funneliforrmis mosseae on the relative water content of leaves of Qingyan No. 1 under different water treatment conditions is shown; Figure 2 The results show the effect of inoculation with Rhiaophagus intraradices and Funneliforrmismosseae on the relative water content of sweet oat leaves under different water treatments.

[0042] from Figure 1 and Figure 2 It can be seen that drought stress significantly reduced the relative water content (RWC) of leaves of "Qingyan No. 1" and "Qinghai Sweet Oats", but the inoculation treatment could increase the leaf RWC under both normal water (CK) and moderate drought (MD) conditions, indicating that inoculation with Rhizospora intraradicata (Ri) and Glomus mosseae (Fm) could promote the increase of RWC of oat leaves and promote the growth of oats. Among them, under drought stress conditions, for drought-resistant varieties of oats, the increase in RWC after inoculation with Ri was better than that with Fm, and for water-sensitive varieties of oats, the increase in RWC after inoculation with Fm was better than that with Ri.

[0043] 3.2.2 Effects of AMF on chlorophyll levels in oat leaves Table 3 shows the leaf chlorophyll content of different varieties of oats under different water and inoculation treatments.

[0044] Table 3

[0045] As can be seen from Table 3, drought stress reduced the concentrations of Chl a and Chl b in oats and increased the concentration of Cxc in oats. For the drought-resistant variety "Qingyan No. 1", whether under normal water (CK) or moderate drought (MD) conditions, the inoculation treatment can increase the concentrations of Chl a and Chl b and reduce the concentration of Cxc; for the water-sensitive variety "Qinghai Sweet Oats", whether under normal water (CK) or moderate drought (MD) conditions, the inoculation treatment can increase the concentrations of Chl a and Chl b, and under MD conditions, the inoculation treatment can reduce the concentration of Cxc.

[0046] From the chlorophyll level and relative water content of leaves, it can be seen that drought stress caused different degrees of damage to both varieties of oats. However, under drought conditions, inoculation treatment can increase the relative water content and chlorophyll content of oats, thereby promoting the growth of oats.

[0047] 3.2.3 Effects of AMF on gas exchange parameters in oat leaves Figure 3 , Figure 4 The effects of different water and inoculation treatments on the net photosynthetic rate of two varieties of oats are shown; Figure 5 , Figure 6 The effects of different water and inoculation treatments on the stomatal conductance of two varieties of oats are shown; Figure 7 , Figure 8 The effects of different water and inoculation treatments on the intercellular CO2 concentration of two varieties of oats are shown; Fig. 9 , Fig.10 The results show the effects of different water content and inoculation treatments on the instantaneous water use efficiency of two varieties of oats.

[0048] from Figures 3 to 10 It can be seen that although drought reduced the gas exchange parameters of the two oat varieties to varying degrees, AMF had a positive effect on the instantaneous water use efficiency of oats under drought, and inoculation of Ri had a more significant improvement in instantaneous water use efficiency. AMF alleviated the photosynthetic limitation caused by drought and reduced the damage of drought stress to oat seedlings.

[0049] 3.2.4 Effect of AMF on the antioxidant process of oats (1) H2O2 content in oat leaves and roots Figures 11 to 14 Shows the effect of different water and inoculation treatments on the H2O2 content in leaves and roots of two oat varieties. Figures 11 to 14Drought stress increased the H2O2 content in oat leaves; whether it was the drought-resistant variety B or the water-sensitive variety W, under normal water (CK) and moderate drought (MD) treatment conditions, the inoculation treatment would increase the H2O2 content in the roots, among which the H2O2 content in the roots inoculated with Ri was higher than that inoculated with Fm; under MD treatment conditions, the inoculation treatment would reduce the H2O2 content in the leaves, among which the H2O2 content in the leaves inoculated with Ri was lower than that inoculated with Fm.

[0050] (2) Antioxidant enzyme content in oat leaves and roots Table 4 shows the antioxidant enzymes (catalase CAT, superoxide dismutase SOD, peroxidase SOD) contents in leaves and roots of different varieties of oats under different water and inoculation treatments.

[0051] Table 4

[0052] As can be seen from Table 4, the inoculation treatment has a positive effect on the improvement of antioxidant enzymes under drought.

[0053] (3) Free amino acid content in oat leaves and roots Table 5 shows the free amino acid content in leaves and roots of different varieties of oats under different water and inoculation treatments.

[0054] Table 5

[0055] As can be seen from Table 5, drought significantly increased the free amino acid (AAS) levels in oat leaves and roots. Under different water conditions, specific inoculation treatments could reduce the AAS content in oat leaves and roots. Under moderate drought conditions, inoculation Ri could reduce the AAS content in leaves and roots of both drought-resistant variety B and water-sensitive variety W.

[0056] (4) Metabolism of oat glutathione Table 6 shows the levels of glutathione-related indicators (glutathione reductase GR, oxidized glutathione GSSG, reduced glutathione GSH) in leaves and roots of different varieties of oats under different water and inoculation treatments.

[0057] Table 6

[0058] As can be seen from Table 6, the changes in glutathione metabolism in oats are relatively active, and the changes in glutathione metabolism are more significant in "Qingyan No. 1". Under drought, the inoculation treatment reduced the GSH level in oat leaves and roots, and the inoculation of R. i significantly increased the GR level in oat leaves and reduced the GR level in oat roots. Under drought, the inoculation of R. i significantly increased the GSSG level in oat leaves and roots. Comparison of GSH / GSSG found that under drought, the inoculation treatment significantly reduced the GSH / GSSG ratio in oat leaves and roots.

[0059] In summary, inoculation treatment can increase the H2O2 content in the oat roots, improve the SOD, CAT, and POD activities in the leaves and roots, reduce the AAS content in the leaves and roots, and reduce the GSH / GSSG levels in the leaves and roots, thereby improving the plant's stress defense ability, reducing the damage of drought stress to oat seedlings, and promoting the growth of oats.

[0060] 3.3 Effects of R. intraradices inoculation on endogenous hormones in oats Plant hormones are a class of organic substances produced by plant metabolism that can regulate plant growth, development and differentiation. Abscisic acid (ABA) is the most important growth inhibitor in plants, which can promote the shedding of leaves, flowers and fruits; auxin (IAA) can promote plant growth; salicylic acid (SA) can improve the stress resistance of crops.

[0061] Table 7 shows the ABA, IAA and SA contents in leaves and roots of different varieties of oats inoculated with Ri under different water treatments.

[0062] Table 7

[0063] As can be seen from Table 7, inoculation of Ri under drought can significantly regulate the levels of ABA, IAA and SA, thereby improving the cell drought resistance and growth activity of oats under drought stress.

[0064] In summary, the results of the co-cultivation experiment of arbuscular mycorrhizal fungi and oats showed that: 1. Rhizocystis natrii (Ri) and Glomus mosseae (Fm) have preferences for both varieties of oats. For drought-resistant varieties of oats, the mutualistic relationship between Ri and oats is closer; for water-sensitive varieties of oats, the mutualistic relationship between Fm and oats is closer.

[0065] 2. The two AM fungi provided by the present invention can both promote the growth of oats under drought stress and increase the yield of oats.

Claims

1. A method for improving the growth and drought resistance of oats by using arbuscular mycorrhizal fungi, characterized in that: The method comprises the following steps: Step 1, obtaining an arbuscular mycorrhizal fungus inoculant: using corn or white clover as a host, inoculating arbuscular mycorrhizal fungi into a propagation matrix for propagation to obtain an arbuscular mycorrhizal fungus inoculant, wherein the arbuscular mycorrhizal fungi are selected from Rhiaophagus intraradices or Funneliforrmis mosseae, and the inoculation amount of the arbuscular mycorrhizal fungi is 1%-2% of the weight of the propagation matrix, and the arbuscular mycorrhizal fungus inoculant comprises mycorrhizae, soil containing spores, and extraradical hyphae; Step 2, co-cultivation: co-cultivating the arbuscular mycorrhizal fungi inoculant obtained in step 1 and oats in a symbiotic culture matrix, wherein the inoculation amount of the arbuscular mycorrhizal fungi inoculant is 2%-3% of the weight of the symbiotic culture matrix; The propagation matrix and the symbiotic culture matrix are obtained by mixing river sand and field soil in a volume ratio of 1:1 and then sterilizing them.

2. The method according to claim 1, characterized in that: The arbuscular mycorrhizal fungi infection rate of the mycorrhizae in the arbuscular mycorrhizal fungi inoculant is 75-80%.

3. The method according to claim 1, characterized in that: The spore content in the soil containing spores in the arbuscular mycorrhizal fungus inoculant is 80-110 spores / 20g soil.

4. The method according to claim 1, characterized in that: The physical and chemical properties of the soil are pH 6-7, total nitrogen 1.2-1.3 mg / g, and total phosphorus 0.45-0.5 mg / g.

5. The method according to claim 1, characterized in that: When the oat variety is a drought-resistant oat variety, the arbuscular mycorrhizal fungus is Rhiaophagus intraradices, and the inoculation amount of the arbuscular mycorrhizal fungus is 1% of the weight of the propagation substrate.

6. The method according to claim 1, characterized in that: When the oat variety is a moisture-sensitive oat variety, the arbuscular mycorrhizal fungus is Funneliforrmis mosseae, and the inoculation amount of the arbuscular mycorrhizal fungus is 1% of the weight of the propagation substrate.

7. The method according to claim 1, characterized in that: The sterilization method of the river sand and field soil is high temperature sterilization at 210° C. for 2 hours.

8. The method according to claim 1, characterized in that: The inoculation method of the arbuscular mycorrhizal fungus inoculant in step 2 is to divide the arbuscular mycorrhizal fungus inoculant into two parts, A and B, in a ratio of A:B=20:3, wherein the A part of the arbuscular mycorrhizal fungus inoculant is fully mixed with the symbiotic culture matrix, and the B part of the arbuscular mycorrhizal fungus inoculant is spread evenly on the surface of the oat sowing layer.

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