Method for planting apples in saline-alkali soil

Abstract

The invention discloses a method for planting apples in saline-alkali soil, and mainly relates to the technical field of plant grafting. According to the method, a salt-alkali cross-stress model is constructed by using NaCl neutral salt and NaHCO3 basic salt, and the salt-alkali tolerance of 17 apple stocks is systematically evaluated, so that the sequence of the salt-alkali tolerance from strong to weak is as follows: QZ2gt; xJ2gt; qZ1gt; qZ8gt, QZ8gt; xJ1gt; xJ < 4 > gt; t18gt, T18gt; xJ3gt; qZ < 16 > gt; qZ39gt, QZ39gt; b68gt, B68gt; qZ 20gt; pYTCgt, PYTCgt; lS4gt, LS4gt; t337gt, T337gt; g935gt, G935gt; and LS3. Compared with the prior art, according to the method for planting the apples in the saline-alkali soil, the saline-alkali resistance and drought resistance of the apples in the saline-alkali soil environment are improved by improving the saline-alkali stress degree of the apple stocks.

Description

Technical Field

[0001] This invention relates to the field of plant grafting technology, and more particularly to a method for planting apples in saline-alkali land. Background Technology

[0002] Apple (Malus pumila Mill.) belongs to the genus Malus in the family Rosaceae. It thrives in sunlight and is cold-hardy. As a popular fruit, it is highly nutritious, brightly colored, and has an excellent taste, making it a favorite for many. Apomixis refers to a reproductive method in which plants produce seeds without the fusion of male and female gametes. One important use of apomixis in the genus Malus is as rootstock. Among apomixis resources in the genus Malus, species such as Malus hupehensis and Malus simonii are already in use as apple rootstocks in production, exhibiting characteristics such as uniform growth and strong resistance to adverse conditions. The current trend in fruit tree cultivation is towards dwarfing and high-density planting. If apomixis rootstocks also possess dwarfing properties, they can overcome some of the shortcomings of existing clonal dwarfing rootstocks. For example, clonal rootstocks used as self-rooted rootstocks have poor soil stability and a narrow range of adaptability, making them unsuitable for clonal dwarfing rootstocks. If used as intercroppings, they require two graftings, resulting in a long seedling period, tall trees, and susceptibility to viral infections. Improving the drought and salt tolerance of apomixis rootstocks can expand the adaptability of apples, reduce production costs, and enable the specialized and regional utilization of apple rootstocks.

[0003] Saline-alkali soils and arid environments are two major limiting factors in global agricultural production. Improving these soils is crucial for expanding arable land resources and ensuring food security. Developing rootstocks that are both salt-tolerant and drought-resistant plays a vital role in improving the growth and development of fruit trees in saline-alkali and arid soils, enhancing their resilience, and improving fruit quality. Solving the problems of crop growth in saline-alkali and arid soils not only helps improve the overall competitiveness of the fruit industry but also has far-reaching significance for maintaining ecological balance, protecting the environment, and promoting sustainable development.

[0004] CN105830927A discloses a method for grafting apple trees in saline-alkali land. The method involves first cultivating *Malus spectabilis* seedlings, then transplanting them to saline-alkali land, and subsequently grafting apple branches onto these seedlings as rootstock. Finally, post-grafting management is implemented. The core of this method lies in rapidly propagating *Malus spectabilis* seedlings through tissue culture technology and cultivating them to withstand saline-alkali conditions, resulting in two-year-old *Malus spectabilis* rootstocks with excellent salt and alkali resistance, thereby enabling large-scale cultivation of apple trees in saline-alkali land. However, this invention limits the use of only *Malus spectabilis* rootstock, resulting in a single rootstock selection and failing to consider the varying adaptability of different rootstocks to different salinity levels in different soil types.

[0005] CN120787815A discloses a method for rapid propagation of salt-tolerant apple rootstocks via tissue culture. The steps include: first, selecting the top shoots of salt-tolerant apple rootstocks, cleaning and disinfecting them, and then inoculating them into a differentiation induction medium to obtain clustered shoots; second, transferring the clustered shoots into a proliferation subculture medium for proliferation culture to obtain proliferating shoots; and finally, inoculating the proliferating shoots into a rooting medium to induce rooting. This method can efficiently propagate superior salt-tolerant apple rootstock seedlings, shorten the seedling cultivation cycle, reduce seedling costs, and improve the survival rate and rooting rate of top shoot differentiation induction. However, this invention only addresses the rapid propagation stage of rootstock tissue culture and does not involve the application verification of rootstocks in actual saline-alkali land cultivation, lacking a connection to field planting scenarios. Summary of the Invention

[0006] In view of the above-mentioned deficiencies of the prior art, the technical problem to be solved by the present invention is to improve the salt and alkali tolerance and drought resistance of apple rootstocks, increase their relative electrical conductivity and salt and alkali stress, and make them suitable for planting in saline-alkali environments.

[0007] To achieve the above objectives, the present invention provides a method for planting apples in saline-alkali land.

[0008] The method for planting apples in saline-alkali land is as follows:

[0009] Treat apple rootstocks with salt and alkali stress, graft them into potted soil and manage them for 14-16 days. When the rootstock seedlings have grown to 24-26 leaves, transplant the apple rootstock seedlings along with the potted soil into saline-alkali land, with the pot opening 0.8-1.2cm above the ground.

[0010] The salt and alkali used for salt and alkali stress treatment is one or a mixture of NaCl and NaHCO3; preferably, the salt and alkali used for salt and alkali stress treatment is a mixture of NaCl and NaHCO3 in a weight ratio of 0.5-1.5:0.5-1.5.

[0011] The concentration of the salt-alkali stress treatment was 80-90 mmol·L⁻¹. -1 .

[0012] The pH after the salt and alkali stress treatment was 8.5-8.8.

[0013] The potting soil is one or more of saline-alkali soil, soil matrix, and vermiculite; preferably, the potting soil is a mixture of saline-alkali soil, soil matrix, and vermiculite.

[0014] Preferably, the potting soil is a mixture of saline-alkali soil, soil matrix, and vermiculite in a weight ratio of 1.5-2.5:0.5-1.5:0.5-1.5.

[0015] Preferably, the potting soil is a mixture of saline-alkali soil, soil matrix, and modified vermiculite in a weight ratio of 1.5-2.5:0.5-1.5:0.5-1.5.

[0016] The soil matrix is ​​one or more of perlite, coconut coir, and peat moss.

[0017] The modified vermiculite is prepared as follows, in parts by weight:

[0018] S1. Mix 0.5-1.5 parts vermiculite and 2-4 parts cotton stalks and calcine at 400-500℃ for 1-2 hours, then pass through a 40-60 mesh sieve to obtain biochar composite vermiculite;

[0019] S2. Add 0.5-1.5 parts of biochar composite vermiculite to 8-12 parts of 0.5-1.5wt% citric acid aqueous solution and soak for 2-4 hours. Remove and dry at 60-80℃ to obtain the modified vermiculite.

[0020] Alternatively, S1, mix 0.5-1.5 parts vermiculite and 2-4 parts cotton stalks, calcine at 400-500℃ for 1-2 hours, and pass through a 40-60 mesh sieve to obtain biochar composite vermiculite;

[0021] S2. Add 0.5-1.5 parts of biochar composite vermiculite and 0.0005-0.0015 parts of extract to 8-12 parts of 0.005-0.015wt% sodium phosphate aqueous solution, stir at room temperature for 10-15 hours, take out and dry at 65-75℃ to obtain phosphorus-loaded biochar composite vermiculite;

[0022] S3. Add 0.5-1.5 parts of phosphorus-loaded biochar composite vermiculite to 8-12 parts of 0.5-1.5wt% citric acid aqueous solution and soak for 2-4 hours. Remove and dry at 60-80℃ to obtain the modified vermiculite.

[0023] The extract is one or a mixture of two of the following: tea polyphenol extract, sophora flavescens extract, and sophora japonica extract; preferably, the extract is a mixture of sophora flavescens extract and sophora japonica extract.

[0024] The apple rootstock varieties include the following: Pingyi Sweet Tea (PYTC), Xiaojin Begonia No. 1 (XJ1), Xiaojin Begonia No. 2 (XJ2), Xiaojin Begonia No. 3 (XJ3), Xiaojin Begonia No. 4 (XJ4), Qingzhenxi rootstock No. 1 (QZ1), Qingzhenxi rootstock No. 2 (QZ2), Qingzhenxi rootstock No. 8 (QZ8), Qingzhenxi rootstock No. 16 (QZ16), Qingzhenxi rootstock No. 20 (QZ20), Qingzhenxi rootstock No. 39 (QZ39), Qingzhenxi rootstock Laoshan No. 3 (LS3), Qingzhenxi rootstock Laoshan No. 4 (LS4), and apple rootstocks B68, G935, T337 and T18 preserved by the College of Horticulture of Hebei Agricultural University.

[0025] This invention comprehensively evaluates the salt and alkali tolerance of 17 apple rootstocks, with the salt and alkali tolerance ranked from strongest to weakest as follows:

[0026] QZ2>XJ2>QZ1>QZ8>XJ1>XJ4>T18>XJ3>QZ16>QZ39>B68>QZ20>PYTC>LS4>T337>G935>LS3.

[0027] This invention describes a method for planting apples in saline-alkali land. NaCl is used as the neutral salt, and NaHCO3 as the alkaline salt to simulate a combined saline-alkali stress environment on apple rootstocks. The salt and alkali tolerance of 17 apple rootstock species was comprehensively evaluated. The study found that salt and alkali stress significantly affected the physiological characteristics of apple rootstocks, manifested as a decrease in chlorophyll content, an increase in malondialdehyde (MDA) content, and changes in the activity of antioxidant enzymes (SOD, POD). The salt and alkali tolerance of each rootstock was comprehensively evaluated using the membership function method. The results showed that the salt and alkali tolerance of the 17 apple varieties, from strongest to weakest, was as follows: QZ2>XJ2>QZ1>QZ8>XJ1>XJ4>T18>XJ3>QZ16>QZ39>B68>QZ20>PYTC>LS4>T337>G935>LS3. By screening apple rootstock varieties with strong salt and alkali tolerance, this invention provides important varietal resources for apple cultivation in saline-alkali land and offers a theoretical basis for a deeper understanding of the salt and alkali tolerance mechanisms of apple rootstocks, which is of great significance to the sustainable development of the apple industry. The beneficial effects of this invention are:

[0028] 1. Compared with existing technologies, this invention uses NaCl as a neutral salt and NaHCO3 as an alkaline salt to simulate a salt-alkali combined stress environment on apple rootstocks under salt-alkali cross-stress, and comprehensively evaluates the salt-alkali tolerance of 17 apple rootstocks. The results show that the salt-alkali tolerance of the 17 apple varieties, from strongest to weakest, is as follows: QZ2>XJ2>QZ1>QZ8>XJ1>XJ4>T18>XJ3>QZ16>QZ39>B68>QZ20>PYTC>LS4>T337>G935>LS3.

[0029] 2. Compared to existing technologies, this invention further incorporates a soil matrix, vermiculite or modified vermiculite, and native potting soil from saline-alkali land for composite improvement. The soil matrix is ​​one or more of perlite, coconut coir, and peat moss. By improving soil aeration and water retention, it enhances root respiration and nutrient absorption, helps improve salt retention and permeability in the matrix, and makes it easier for roots to absorb and accumulate sodium. + Cl - This exacerbates the severity of ion stress and saline-alkali stress. Attached Figure Description

[0030] Figure 1 Fresh and dry weights of leaves, stems, and roots of 17 types of apple rootstocks were measured after treatment according to the methods of Comparative Example 1 and Example 3.

[0031] Figure 2 The changes in MDA content of 17 types of apple rootstocks after treatment according to the methods of Comparative Example 1 and Example 3 were investigated.

[0032] Figure 3 The changes in SOD activity of 17 types of apple rootstocks after treatment according to the methods of Comparative Example 1 and Example 3 were investigated.

[0033] Figure 4 The changes in POD activity of 17 types of apple rootstocks after treatment according to the methods of Comparative Example 1 and Example 3.

[0034] Figure 5 The changes in H2O2 content were observed in 17 types of apple rootstocks after treatment according to the methods of Comparative Example 1 and Example 3.

[0035] Figure 6 The changes in chlorophyll content of 17 types of apple rootstocks after treatment according to the methods of Comparative Example 1 and Example 3 were studied.

[0036] Figure 7 The changes in root vitality of 17 types of apple rootstocks after treatment according to the methods of Comparative Example 1 and Example 3.

[0037] Figure 8 The changes in soil salinity and soil pH after treating 17 types of apple rootstocks according to the methods of Comparative Example 1 and Example 3.

[0038] Figure 1-8 The “Control” corresponds to Example 1, and “NaCl+NaHCO3” corresponds to Example 3. Detailed Implementation

[0039] The parameters of the specific chemical substances used in the examples are from the following sources:

[0040] In Examples 1-11 and Comparative Examples 1-2, the experiments were conducted in the greenhouse of the Third Branch of Hebei Agricultural University. The potted plants were 250 mm high, 190 mm in diameter at the top, and 170 mm in diameter at the bottom.

[0041] The original soil of saline-alkali land described in Examples 1-11 and Comparative Examples 1-2 was taken from the top 0-20cm layer of saline-alkali land in the coastal plain area of ​​Cangzhou City. After removing stones and plant residues, it was naturally air-dried, mixed, and passed through a 15-mesh sieve.

[0042] In Test Examples 1-4, the experimental materials were apomixis apple rootstocks provided by the Qingdao Academy of Agricultural Sciences. The varieties were Pingyi Sweet Tea (PYTC), Xiaojin Begonia No. 1 (XJ1), Xiaojin Begonia No. 2 (XJ2), Xiaojin Begonia No. 3 (XJ3), Xiaojin Begonia No. 4 (XJ4), Qingzhenxi rootstock No. 1 (QZ1), Qingzhenxi rootstock No. 2 (QZ2), Qingzhenxi rootstock No. 8 (QZ8), Qingzhenxi rootstock No. 16 (QZ16), Qingzhenxi rootstock No. 20 (QZ20), Qingzhenxi rootstock No. 39 (QZ39), Qingzhenxi rootstock Laoshan No. 3 (LS3), and Qingzhenxi rootstock Laoshan No. 4 (LS4). Apple rootstocks B68, G935, T337, and T18 were preserved by the College of Horticulture of Hebei Agricultural University.

[0043] Tea polyphenol extract: extracted with 70wt% ethanol aqueous solution, with a material-to-liquid ratio of 1:25 g / mL, an extraction temperature of 90℃, an extraction time of 1 hour, and an extraction frequency of 1 time.

[0044] Sophora flavescens extract: extracted with 80wt% ethanol aqueous solution, with a material-to-liquid ratio of 1:40 g / mL, an extraction temperature of 95℃, an extraction time of 6 hours, and an extraction frequency of 1.

[0045] Sophora japonica flower extract: extracted with 60wt% ethanol aqueous solution, with a material-to-liquid ratio of 1:25 g / mL, an extraction temperature of 30℃, an extraction time of 1 hour, and an extraction frequency of 1 time.

[0046] Example 1

[0047] The following is a method for growing apples in saline-alkali land:

[0048] An apple rootstock was subjected to NaCl salt-alkali stress treatment at a concentration of 85 mmol·L⁻¹. -1 The treated pH was 8.6. The grafted seedlings were placed in 4 kg of potting soil and managed for 15 days. The potting soil was the original soil of the saline-alkali land. When the rootstock seedlings grew to 25 leaves, the apple rootstock seedlings were transplanted into the saline-alkali land along with the potting soil, with the pot opening 1 cm above the ground.

[0049] Example 2

[0050] The following is a method for growing apples in saline-alkali land:

[0051] An apple rootstock was subjected to NaHCO3 salt-alkali stress treatment at a concentration of 85 mmol·L⁻¹. -1 The treated pH was 8.6. The grafted seedlings were placed in 4 kg of potting soil and managed for 15 days. The potting soil was the original soil of the saline-alkali land. When the rootstock seedlings grew to 25 leaves, the apple rootstock seedlings were transplanted into the saline-alkali land along with the potting soil, with the pot opening 1 cm above the ground.

[0052] Example 3

[0053] The following is a method for growing apples in saline-alkali land:

[0054] An apple rootstock was subjected to salt-alkali stress treatment with NaCl and NaHCO3 at a weight ratio of 1:1. The concentration of the salt-alkali stress treatment was 85 mmol·L⁻¹. -1 The treated pH was 8.6. The grafted seedlings were placed in 4 kg of potting soil and managed for 15 days. The potting soil was the original soil of the saline-alkali land. When the rootstock seedlings grew to 25 leaves, the apple rootstock seedlings were transplanted into the saline-alkali land along with the potting soil, with the pot opening 1 cm above the ground.

[0055] Comparative Example 1

[0056] The following is a method for growing apples in saline-alkali land:

[0057] An apple rootstock was grafted into a 4kg pot of soil and managed for 15 days. The pot soil was the original soil of the saline-alkali land. When the rootstock seedling had 25 leaves, the apple rootstock seedling and the pot soil were transplanted into the saline-alkali land, with the pot opening 1cm above the ground.

[0058] Test Example 1

[0059] Thirty seedlings of the same growth were selected from each variety of apple rootstock. Each variety was divided into two groups of 15 seedlings each. The apple rootstocks were treated according to the method of planting apples in saline-alkali land in Comparative Example 1 and Example 3, and growth-related indicators were measured, including plant height and biomass.

[0060] The method for measuring plant height is as follows: Use a measuring tape to measure the plant height, and select 5 plants of the same growth for each apple rootstock variety.

[0061] The biomass was determined as follows: Each apple rootstock variety was divided into three parts: root, stem, and leaf. All parts were measured using tap water and 0.1 mol / L... -1 Rinse three times with HCl and deionized water, wipe dry, and then determine the fresh weight of each part using a 0.01% balance. Next, blanch at 105℃ for 30 minutes, and then dry at 65℃ for 72 hours until constant weight. Finally, determine the dry weight of each part after drying. The total fresh weight and total dry weight are the sum of the fresh and dry weights of each part, summarized as follows: Figure 1 As shown.

[0062] Figure 1The results showed that salt-alkali stress significantly inhibited the growth of apple rootstock seedlings. The treated seedlings exhibited leaf chlorosis and wilting, and their growth was significantly worse than the control group. Furthermore, salt-alkali stress significantly affected the dry and fresh weight of the plants. Fifteen days after stress treatment, except for XJ2, the leaf dry weight and fresh weight of other varieties were significantly lower than the control group; except for LS3, the stem dry weight of other varieties was also significantly lower than the control group; except for XJ2, LS3, QZ1, QZ20, and B68, the stem fresh weight of other varieties was significantly lower than the control group; and the root dry weight and fresh weight of all varieties were significantly lower than the control group. These results indicate that salt-alkali stress severely inhibits the growth and development of apple rootstock seedlings.

[0063] Test Example 2

[0064] Thirty seedlings of uniform growth were selected from each apple rootstock variety. Each variety was divided into two groups of 15 seedlings each. Following the methods used in Comparative Example 1 and Example 3 for planting apples in saline-alkali soil, physiological indicators of the rootstocks were measured, including malondialdehyde (MDA), hydrogen peroxide (H2O2) content, antioxidant enzyme activity, chlorophyll content, root activity, soil pH, and soil salinity. Figure 2-5 As shown.

[0065] The methods for determining malondialdehyde (MDA), hydrogen peroxide (H2O2) content, and antioxidant enzyme activity are as follows: 0.1 g of fresh leaves from each apple rootstock variety were placed in 1 mL of PBS solution (pH 7.8) for extraction and homogenized in an ice bath at 4°C and 12000 r·min. -1 After centrifugation for 10 minutes, the supernatant was collected and the contents of MDA and H2O2, and the activities of superoxide dismutase (SOD) and peroxidase (POD) were detected using kits produced by Suzhou Grease Biotechnology Co., Ltd. Data were processed and plotted using Excel 2016 software. Figure 2-5 As shown.

[0066] Figure 2 The results showed that under combined salt-alkali stress, the malondialdehyde (MDA) content in the leaves of all 17 apple rootstock species increased, with the increase varying among varieties. Specifically, under combined salt-alkali stress, the MDA content in the leaves of 14 apple rootstock species increased significantly. Compared with the control group, QZ1 and QZ2 showed a higher MDA content at 85 mmol·L⁻¹. -1 The increase in MDA content was smallest in the treated groups, at 26.8% and 26.4%, respectively; while the increase was largest in G935. Specifically, at 85 mmol·L⁻¹ -1 The increases in MDA content in the leaves of each rootstock under the treatments were as follows: XJ1 11.06 nmol·g -1 XJ2 9.71 nmol·g-1 XJ3 12.77 nmol·g -1 XJ412.72 nmol·g -1 LS3 12.15 nmol·g -1 LS4 10.63 nmol·g -1 QZ1 28.87 nmol·g -1 QZ1612.83 nmol·g -1 QZ20 13.52 nmol·g -1 QZ39 11.16 nmol·g -1 PYTC 7.62 nmol·g -1 B68 8.53 nmol·g -1 G935 59.73 nmol·g -1 T337 43.20 nmol·g -1 .

[0067] Figure 3 The results showed that under combined salt and alkali stress, the activity of superoxide dismutase (SOD) in the leaves of 17 apple rootstocks increased significantly. Among them, the SOD activity of QZ8 showed the largest increase during the stress process, reaching 85 mmol·L⁻¹. -1 Under stress, the SOD activity of XJ1 increased by 97.3% compared to the control group; while the increase in SOD activity of XJ2 was the smallest, only 46.9%. This indicates that XJ1 has the strongest ability to utilize SOD enzymes to scavenge reactive oxygen species, while QZ1's ability is relatively weak.

[0068] Figure 4 The results showed that with increasing stress concentration, the peroxidase (POD) activity in the leaves of 17 apple rootstocks generally decreased, and the degree of decrease varied among varieties. Compared with the control group (0 mmol·L⁻¹), the POD activity decreased by 0.5%. -1 Compared to B68 and XJ4, at 85 mmol·L⁻¹ -1 The decrease in POD activity under stress was relatively small, with QZ2 showing the smallest decrease and G935 showing the largest decrease. Specifically, the changes in POD activity in the leaves of each rootstock were as follows: XJ1 decreased by 41.5%, XJ2 by ​​44.1%, XJ3 by 50.1%, LS3 by 45.7%, LS4 by 64.1%, QZ1 by 45.1%, QZ16 by 40.4%, QZ20 by 50.3%, PYTC by 51.4%, and T337 by 33.4%.

[0069] Figure 5The results showed that salt-alkali stress leads to the accumulation of reactive oxygen species (ROS) in plants, with hydrogen peroxide (H2O2) being an important form of ROS. Changes in H2O2 content can reflect the degree of oxidative stress in plants under salt-alkali stress. With increasing stress concentration, the H2O2 content in the leaves of 17 apple rootstocks generally showed an increasing trend, and the rate of increase varied among varieties. At 85 mmol•L... -1 Under the treatment, the H2O2 content in the leaves of all rootstocks increased significantly compared with the control group (P<0.001). Among them, T337, QZ1 and G935 showed the smallest increase in H2O2 content, at 51.4%, 44.3% and 36.9% respectively; while XJ2 showed the largest increase, reaching 179.7%.

[0070] The method for determining chlorophyll content is as follows: Leaves from each variety of apple rootstock were removed, cleaned, and dried. They were then cut into thin strips approximately 0.1 cm long and mixed thoroughly, avoiding the midrib. 0.1 g of each strip was weighed and placed in a 10 mL centrifuge tube. 8 mL of 80% acetone was added, and the mixture was shaken well and allowed to stand at room temperature in the dark. The mixture was shaken 3-4 times during this period. The extraction was carried out for 24 hours until the leaf tissue turned completely white. The chlorophyll content was measured using a UV-2250 spectrophotometer (Shimadzu, Kyoto, Japan) at wavelengths of 663 nm, 645 nm, and 470 nm, with 80% acetone used as a control for zeroing. The contents of chlorophyll a, chlorophyll b, carotenoids, and total chlorophyll were calculated separately. Data were then processed and plotted using Excel 2016 software. Figure 6 As shown.

[0071] Figure 6 The results showed that changes in chlorophyll content could reflect the degree of damage caused by salt-alkali stress to plants. The changes in chlorophyll content varied significantly among apple rootstocks with different tolerances to salt-alkali combined stress. With increasing stress concentration, the chlorophyll content of leaves from all 17 apple rootstocks generally showed a decreasing trend, but the magnitude of the decrease varied. At the 85 mmol / L treatment, the chlorophyll content of leaves from all rootstocks was significantly lower than that from the control (P<0.001). Compared with the control group, G935, QZ1, and XJ2 showed the smallest decrease in chlorophyll content at 85 mmol / L, decreasing by 54.4%, 53.6%, and 51.3%, respectively; B68 showed the largest decrease, reaching 84.1%.

[0072] The method for determining root vigor is as follows: Take 0.5g of root tip sample from each apple rootstock variety and place it in a 15mL centrifuge tube. Add an equal volume mixture of 10mL 0.4% TTC solution and phosphate buffer to fully immerse the roots. Incubate at 37℃ in the dark for 1.5h, then add 2mL of 1mol·L⁻¹ solution. -1Sulfuric acid was used to terminate the reaction, and a blank control experiment was performed simultaneously, with sulfuric acid added first in the blank control group. Root samples were removed, dried, and extracted with ethyl acetate. After adjusting the volume, the absorbance was measured at 485 nm using a UV-2250 spectrophotometer (Shimadzu, Kyoto, Japan). Root activity was calculated using a standard curve, with units of mg·g. -1 ·FW -1 Data organization and charting using Excel 2016 software, such as... Figure 7 As shown.

[0073] Figure 7 The results showed that different apple rootstocks exhibited varying tolerance to salt-alkali stress, and changes in root activity served as an important indicator of salt-alkali tolerance. Rootstock varieties with strong salt-alkali tolerance showed a smaller decrease in root activity under salt-alkali stress, while those with weak tolerance showed a larger decrease. With increasing stress concentration, the root activity of the 17 apple rootstocks generally showed a decreasing trend, and the degree of decrease varied among varieties. At 100 mmol·L⁻¹... -1 Under these treatments, the root vigor of all rootstocks decreased significantly compared to the control group. Specifically, PYTC showed the largest decrease, at 67.0%, while XJ3 showed the smallest decrease, at only 23.4%. The decreases for other varieties were as follows: XJ1 (58.1%), XJ2 (42.7%), XJ4 (44.3%), LS3 (54.9%), LS4 (47.5%), QZ1 (50.4%), QZ16 (53.6%), QZ20 (59.9%), QZ39 (49.0%), B68 (41.8%), G935 (37.3%), and T337 (41.6%). Data was processed and plotted using Excel 2016 software. Figure 7 As shown.

[0074] The methods for determining soil pH and soil salinity are as follows: Take 0.8g of air-dried soil sample from each variety of apple rootstock, add distilled water, and prepare a soil suspension. The water-to-soil ratio is typically 2.5:1 to 5:1. Stir the soil suspension to fully disperse the soil particles. After stirring, let it stand for 30 minutes to allow the soil particles to settle. Insert the pH electrode into the soil suspension and record the pH value after the reading stabilizes. Insert the salinity meter electrode into the soil suspension and read and record the soil salinity. During the measurement process, the sample temperature should be controlled at 25±1℃. Data processing and plotting are performed using Excel 2016 software. Figure 8 As shown.

[0075] Figure 8The results showed that soil salinity and pH are important indicators for measuring the degree of salt-alkali stress, reflecting its comprehensive impact on plant growth and soil ecosystems. Increased soil salinity and pH work together to significantly inhibit plant growth and development. For example, alkaline salt stress generally has a more severe inhibitory effect on plant growth than neutral salt stress. Salt-alkali stress directly affects root growth and vigor, leading to shorter, thinner roots and a decrease in root surface area and absorption capacity. The results indicated that at 100 mmol·L⁻¹, soil salinity and pH are significantly affected. -1 Under the treatment, the soil salinity of each rootstock was significantly increased compared with the control group (P<0.001), and the soil pH value also increased significantly, with the increase in soil pH value being relatively consistent across varieties.

[0076] Excel 2016 was used for data processing and plotting. GraphPad Prism 10 was used for one-way ANOVA and correlation analysis. Duncan's method was used for multiple ratio analysis (P=0.05). The salt and alkali tolerance of 17 rootstocks was comprehensively evaluated by combining the membership function method.

[0077] The salt and alkali tolerance coefficient for a single indicator is obtained using formula (2-12):

[0078] Salt and alkali tolerance coefficient = (treated test value / control test value) × 100% (2-12)

[0079] If the index is positively correlated with salt and alkali tolerance, the membership function can be used to calculate it using formula (2-13):

[0080] U(Xij)=(Xij-Xjmin) / (Xjmax-Xjmin) (2-13)

[0081] If the index is negatively correlated with salt and alkali tolerance, it can be calculated using the inverse membership function of formula (2-14):

[0082] U(X)=1-(Xij-Xjmin) / (Xjmax-Xjmin) (2-14)

[0083] In the formula:

[0084] Xij—Measured value of index j for variety i;

[0085] Xjmax — The maximum value of the j index in the variety;

[0086] Xjmin — The minimum value of index j in the variety.

[0087] The salt and alkali tolerance coefficients of each evaluation index for each experimental material were calculated using formulas. If the measured index showed a negative correlation with the stress concentration, a larger value indicated a weaker salt and alkali tolerance of the rootstock; conversely, if the index showed a positive correlation with the stress concentration, a larger value indicated a stronger salt and alkali tolerance of the rootstock. Correlation analysis was performed on the salt and alkali tolerance coefficients of the six physiological indicators of salt and alkali tolerance for each rootstock. The results showed that the chlorophyll content and MDA content of the rootstock leaves were significantly positively correlated (P<0.05), as shown in Table 1.

[0088] This study systematically evaluated the salt and alkali tolerance of 17 apple rootstocks under simulated saline-alkali combined stress. The results showed significant differences in the physiological responses and tolerance of different apple rootstocks under salt and alkali stress. Specifically, changes in physiological indicators such as chlorophyll content, malondialdehyde (MDA) content, antioxidant enzyme activities (SOD, POD), and hydrogen peroxide (H2O2) content reflected the adaptability of each rootstock under salt and alkali stress.

[0089] Under salt-alkali stress, the decrease in chlorophyll content and the increase in MDA content are important indicators for assessing the salt-alkali tolerance of rootstocks. The results showed that rootstocks such as QZ1 and XJ2 exhibited strong salt-alkali tolerance, with smaller decreases in chlorophyll content and lower increases in MDA content. Conversely, rootstocks such as QZ20 showed weaker salt-alkali tolerance, with a significant decrease in chlorophyll content and a significant increase in MDA content. Furthermore, changes in antioxidant enzyme activity also reflected the antioxidant capacity of the rootstocks.

[0090] Finally, the membership function values ​​of each index were calculated using the membership function formula, and the average value of the membership function values ​​was taken as the salt and alkali tolerance evaluation index. Comparisons were made between different rootstocks, and the results are summarized in Table 2. The larger the average membership function value, the stronger the salt and alkali tolerance of the rootstock. The order of salt and alkali tolerance of the 17 apple rootstocks from strongest to weakest is: QZ2>XJ2>QZ1>QZ8>XJ1>XJ4>T18>XJ3>QZ16>QZ39>B68>QZ20>PYTC>LS4>T337>G935>LS3.

[0091] Table 1

[0092]

[0093] Table 2

[0094]

[0095] Example 4

[0096] The following is a method for growing apples in saline-alkali land:

[0097] An apple rootstock was subjected to salt-alkali stress treatment with NaCl and NaHCO3 at a weight ratio of 1:1. The concentration of the salt-alkali stress treatment was 85 mmol·L⁻¹. -1 The treated pH was 8.6. The seedlings were grafted into 4 kg of potting soil and managed for 15 days. When the rootstock seedlings had 25 leaves, the apple rootstock seedlings and potting soil were transplanted into saline-alkali land, with the pot opening 1 cm above the ground.

[0098] The potting soil is a mixture of 2 kg of native saline-alkali soil, 0.2 kg of perlite, 0.5 kg of coconut coir, 0.3 kg of peat moss, and 1 kg of vermiculite.

[0099] Comparative Example 2

[0100] The following is a method for growing apples in saline-alkali land:

[0101] Apple rootstocks were subjected to salt-alkali stress treatment with NaCl and NaHCO3 at a weight ratio of 1:1. The concentration of the salt-alkali stress treatment was 85 mmol·L⁻¹. -1 The treated pH was 8.6. The seedlings were grafted into 4 kg of potting soil and managed for 15 days. When the rootstock seedlings had 25 leaves, the apple rootstock seedlings and potting soil were transplanted into saline-alkali land, with the pot opening 1 cm above the ground.

[0102] The potting soil is a mixture of 2 kg of saline-alkali soil, 0.2 kg of perlite, 0.5 kg of coconut coir, 0.3 kg of peat moss, 0.5 kg of biochar, and 0.5 kg of vermiculite.

[0103] The method for preparing the biochar is as follows:

[0104] 3 kg of cotton stalks were mixed and calcined at 450℃ for 1.5 hours, and then passed through a 50-mesh sieve to obtain biochar.

[0105] Example 5

[0106] The following is a method for growing apples in saline-alkali land:

[0107] Apple rootstocks were subjected to salt-alkali stress treatment with NaCl and NaHCO3 at a weight ratio of 1:1. The concentration of the salt-alkali stress treatment was 85 mmol·L⁻¹. -1 The treated pH was 8.6. The seedlings were grafted into 4 kg of potting soil and managed for 15 days. When the rootstock seedlings had 25 leaves, the apple rootstock seedlings and potting soil were transplanted into saline-alkali land, with the pot opening 1 cm above the ground.

[0108] The potting soil is a mixture of 2 kg of saline-alkali soil, 0.2 kg of perlite, 0.5 kg of coconut coir, 0.3 kg of peat moss, and 1 kg of biochar and vermiculite.

[0109] The preparation method of the biochar composite vermiculite is as follows:

[0110] 1 kg of vermiculite and 3 kg of cotton stalks were mixed and calcined at 450℃ for 1.5 hours, and then passed through a 50-mesh sieve to obtain biochar composite vermiculite.

[0111] Example 6

[0112] The following is a method for growing apples in saline-alkali land:

[0113] Apple rootstocks were subjected to salt-alkali stress treatment with NaCl and NaHCO3 at a weight ratio of 1:1. The concentration of the salt-alkali stress treatment was 85 mmol·L⁻¹. -1 The treated pH was 8.6. The seedlings were grafted into 4 kg of potting soil and managed for 15 days. When the rootstock seedlings had 25 leaves, the apple rootstock seedlings and potting soil were transplanted into saline-alkali land, with the pot opening 1 cm above the ground.

[0114] The potting soil is a mixture of 2 kg of native saline-alkali soil, 0.2 kg of perlite, 0.5 kg of coconut coir, 0.3 kg of peat moss, and 1 kg of modified vermiculite.

[0115] The modified vermiculite is prepared as follows:

[0116] S1. Mix 1 kg of vermiculite and 3 kg of cotton stalks and calcine at 450℃ for 1.5 hours, then pass through a 50-mesh sieve to obtain biochar composite vermiculite;

[0117] S2. Add 1 kg of biochar composite vermiculite to 10 kg of 1 wt% citric acid aqueous solution and soak for 3 hours. Remove and dry at 70°C to obtain the modified vermiculite.

[0118] Example 7

[0119] The following is a method for growing apples in saline-alkali land:

[0120] Apple rootstocks were subjected to salt-alkali stress treatment with NaCl and NaHCO3 at a weight ratio of 1:1. The concentration of the salt-alkali stress treatment was 85 mmol·L⁻¹. -1 The treated pH was 8.6. The seedlings were grafted into 4 kg of potting soil and managed for 15 days. When the rootstock seedlings had 25 leaves, the apple rootstock seedlings and potting soil were transplanted into saline-alkali land, with the pot opening 1 cm above the ground.

[0121] The potting soil is a mixture of 2 kg of native saline-alkali soil, 0.2 kg of perlite, 0.5 kg of coconut coir, 0.3 kg of peat moss, and 1 kg of modified vermiculite.

[0122] The modified vermiculite is prepared as follows:

[0123] S1. Mix 1 kg of vermiculite and 3 kg of cotton stalks and calcine at 450℃ for 1.5 hours, then pass through a 50-mesh sieve to obtain biochar composite vermiculite;

[0124] S2. Add 1 kg of biochar composite vermiculite to 5 kg of 0.01 wt% sodium phosphate aqueous solution, stir at room temperature for 12 hours, and then dry at 70°C to obtain phosphorus-loaded biochar composite vermiculite.

[0125] S3. Add 1 kg of phosphorus-loaded biochar composite vermiculite to 10 kg of 1 wt% citric acid aqueous solution and soak for 3 hours. Remove and dry at 70°C to obtain the modified vermiculite.

[0126] Example 8

[0127] The following is a method for growing apples in saline-alkali land:

[0128] Apple rootstocks were subjected to salt-alkali stress treatment with NaCl and NaHCO3 at a weight ratio of 1:1. The concentration of the salt-alkali stress treatment was 85 mmol·L⁻¹. -1 The treated pH was 8.6. The seedlings were grafted into 4 kg of potting soil and managed for 15 days. When the rootstock seedlings had 25 leaves, the apple rootstock seedlings and potting soil were transplanted into saline-alkali land, with the pot opening 1 cm above the ground.

[0129] The potting soil is a mixture of 2 kg of native saline-alkali soil, 0.2 kg of perlite, 0.5 kg of coconut coir, 0.3 kg of peat moss, and 1 kg of modified vermiculite.

[0130] The modified vermiculite is prepared as follows:

[0131] S1. Mix 1 kg of vermiculite and 3 kg of cotton stalks and calcine at 450℃ for 1.5 hours, then pass through a 50-mesh sieve to obtain biochar composite vermiculite;

[0132] S2. Add 1 kg of biochar composite vermiculite and 1 g of tea polyphenol extract to 5 kg of 0.01 wt% sodium phosphate aqueous solution, stir at room temperature for 12 hours, and then dry at 70 °C to obtain phosphorus-loaded biochar composite vermiculite.

[0133] S3. Add 1 kg of phosphorus-loaded biochar composite vermiculite to 10 kg of 1 wt% citric acid aqueous solution and soak for 3 hours. Remove and dry at 70°C to obtain the modified vermiculite.

[0134] Example 9

[0135] The following is a method for growing apples in saline-alkali land:

[0136] Apple rootstocks were subjected to salt-alkali stress treatment with NaCl and NaHCO3 at a weight ratio of 1:1. The concentration of the salt-alkali stress treatment was 85 mmol·L⁻¹. -1 The treated pH was 8.6. The seedlings were grafted into 4 kg of potting soil and managed for 15 days. When the rootstock seedlings had 25 leaves, the apple rootstock seedlings and potting soil were transplanted into saline-alkali land, with the pot opening 1 cm above the ground.

[0137] The potting soil is a mixture of 2 kg of native saline-alkali soil, 0.2 kg of perlite, 0.5 kg of coconut coir, 0.3 kg of peat moss, and 1 kg of modified vermiculite.

[0138] The modified vermiculite is prepared as follows:

[0139] S1. Mix 1 kg of vermiculite and 3 kg of cotton stalks and calcine at 450℃ for 1.5 hours, then pass through a 50-mesh sieve to obtain biochar composite vermiculite;

[0140] S2. Add 1 kg of biochar composite vermiculite and 1 g of Sophora flavescens extract to 5 kg of 0.01 wt% sodium phosphate aqueous solution, stir at room temperature for 12 hours, and then dry at 70 °C to obtain phosphorus-loaded biochar composite vermiculite.

[0141] S3. Add 1 kg of phosphorus-loaded biochar composite vermiculite to 10 kg of 1 wt% citric acid aqueous solution and soak for 3 hours. Remove and dry at 70°C to obtain the modified vermiculite.

[0142] Example 10

[0143] The following is a method for growing apples in saline-alkali land:

[0144] Apple rootstocks were subjected to salt-alkali stress treatment with NaCl and NaHCO3 at a weight ratio of 1:1. The concentration of the salt-alkali stress treatment was 85 mmol·L⁻¹. -1 The treated pH was 8.6. The seedlings were grafted into 4 kg of potting soil and managed for 15 days. When the rootstock seedlings had 25 leaves, the apple rootstock seedlings and potting soil were transplanted into saline-alkali land, with the pot opening 1 cm above the ground.

[0145] The potting soil is a mixture of 2 kg of native saline-alkali soil, 0.2 kg of perlite, 0.5 kg of coconut coir, 0.3 kg of peat moss, and 1 kg of modified vermiculite.

[0146] The modified vermiculite is prepared as follows:

[0147] S1. Mix 1 kg of vermiculite and 3 kg of cotton stalks and calcine at 450℃ for 1.5 hours, then pass through a 50-mesh sieve to obtain biochar composite vermiculite;

[0148] S2. Add 1 kg of biochar composite vermiculite and 1 g of Sophora japonica extract to 5 kg of 0.01 wt% sodium phosphate aqueous solution, stir at room temperature for 12 hours, and then dry at 70 °C to obtain phosphorus-loaded biochar composite vermiculite.

[0149] S3. Add 1 kg of phosphorus-loaded biochar composite vermiculite to 10 kg of 1 wt% citric acid aqueous solution and soak for 3 hours. Remove and dry at 70°C to obtain the modified vermiculite.

[0150] Example 11

[0151] The following is a method for growing apples in saline-alkali land:

[0152] Apple rootstocks were subjected to salt-alkali stress treatment with NaCl and NaHCO3 at a weight ratio of 1:1. The concentration of the salt-alkali stress treatment was 85 mmol·L⁻¹. -1 The treated pH was 8.6. The seedlings were grafted into 4 kg of potting soil and managed for 15 days. When the rootstock seedlings had 25 leaves, the apple rootstock seedlings and potting soil were transplanted into saline-alkali land, with the pot opening 1 cm above the ground.

[0153] The potting soil is a mixture of 2 kg of native saline-alkali soil, 0.2 kg of perlite, 0.5 kg of coconut coir, 0.3 kg of peat moss, and 1 kg of modified vermiculite.

[0154] The modified vermiculite is prepared as follows:

[0155] S1. Mix 1 kg of vermiculite and 3 kg of cotton stalks and calcine at 450℃ for 1.5 hours, then pass through a 50-mesh sieve to obtain biochar composite vermiculite;

[0156] S2. Add 1 kg of biochar composite vermiculite, 0.5 g of Sophora flavescens extract, and 0.5 g of Sophora japonica extract to 5 kg of 0.01 wt% sodium phosphate aqueous solution, stir at room temperature for 12 hours, and then dry at 70 °C to obtain phosphorus-loaded biochar composite vermiculite.

[0157] S3. Add 1 kg of phosphorus-loaded biochar composite vermiculite to 10 kg of 1 wt% citric acid aqueous solution and soak for 3 hours. Remove and dry at 70°C to obtain the modified vermiculite.

[0158] Test Example 3

[0159] Using QZ2 apple rootstock as the test object, 130 seedlings with uniform growth were selected and divided into 13 groups of 10 seedlings each. The seedlings were treated according to the methods for planting apples in saline-alkali land in Comparative Examples 1-2 and Examples 1-11, and their relative electrical conductivity was measured.

[0160] Take a fresh leaf from the QZ2 apple rootstock treated with the methods for planting apples in saline-alkali soil in Comparative Examples 1-2 and Examples 1-11. Wash the surface of the leaf with tap water to remove any surface dust, then rinse twice with distilled water. Afterward, use absorbent paper to dry the surface of the leaf. Use a punch to collect a leaf sample, avoiding the midrib. Weigh 0.1g of the leaf sample and soak it in 10mL of distilled water. After standing for 1 hour, measure the initial conductivity of the solution using a conductivity meter. After the measurement, place the centrifuge tube in a water bath at 100℃ and stir for 20 minutes. After cooling to room temperature, shake well and measure the actual conductivity. Prepare 3 sets of samples for each comparative example and example, calculate the relative conductivity, and summarize the results as shown in Table 3. The calculation formula is as follows:

[0161] Relative conductivity (%) = (S1-S0) / (S2-S0) × 100%;

[0162] In the formula:

[0163] S0—the electrical conductivity of distilled water;

[0164] S1—Initial conductivity;

[0165] S2 — Actual conductivity value.

[0166] Table 3

[0167]

[0168] The relative electrical conductivity of leaves is used to measure cell membrane integrity and salt-alkali stress adaptability. The higher the relative electrical conductivity of leaves, the greater the degree of salt-alkali stress treatment on the apple rootstock of the comparative example or embodiment.

[0169] In Comparative Example 1, no salt-alkali stress treatment was performed, and the cell membrane integrity was largely maintained without salt-alkali stress. Examples 1-2 involved either NaCl or NaHCO3 as single salt-alkali stress treatments. Compared to Comparative Example 1, both NaCl-induced salt stress and NaHCO3-induced alkaline stress disrupted the selective permeability of the membrane. In Example 3, a mixture of both was used for salt-alkali stress treatment, resulting in a further increase in conductivity, indicating that the synergistic effect of NaCl and NaHCO3 exacerbated intracellular Na+ oxidative stress. + Cl - and HCO3 - The accumulation of sodium in the soil increases the degree of membrane damage and salt stress. Example 4, based on Example 3, added perlite, coconut coir, peat moss, and vermiculite to the original potted soil in saline-alkali land for improvement. This improved soil aeration and water retention, enhanced root respiration and nutrient absorption, and helped increase salt retention and permeability in the substrate, making it easier for roots to absorb and accumulate sodium. + Cl -This further increases the relative conductivity value. Example 5, based on Example 4, incorporates a biochar composite vermiculite obtained through the co-calcination and carbonization of cotton stalks and vermiculite. This retains the porous adsorption characteristics and oxygen-containing functional groups on the surface of cotton stalk biochar, while utilizing the layered structure and cation exchange capacity of vermiculite to significantly enhance the adsorption of Na+ from the soil by apple rootstock. + Cl - Adsorption and fixation of salt ions. Comparative Example 2 added biochar and vermiculite, but only physically mixed them without composite calcination modification, thus failing to form a stable synergistic adsorption structure. The adsorption and accumulation effect on salt was limited, and the conductivity was lower than that of the composite Example 5. Example 6, based on Example 5, underwent citric acid acidification modification. The citric acid further increased the number of carboxyl and hydroxyl groups and other oxygen-containing functional groups on the surface of the biochar-vermiculite composite after impregnation, enhancing the neutralization capacity of alkaline ions in saline-alkali soils and simultaneously improving the adsorption of Na+. + Cl - The adsorption and exchange efficiency is reduced, exacerbating ion stress and increasing the relative conductivity of leaves and the degree of salt and alkali stress.

[0170] Example 7, based on Example 6, incorporates phosphorus loading. Phosphorus can coordinate with oxygen-containing functional groups on the surface of the biochar-vermiculite composite, further optimizing the surface charge distribution and enhancing its resistance to Na+. + Cl - The specific adsorption and ion exchange capacity of the plant promotes the transport and accumulation of salt ions to the roots, exacerbating cell membrane damage. Examples 8-10, based on Example 7, added tea polyphenol extract, sophora flavescens extract, and sophora japonica extract, respectively. The active ingredients in these natural extracts can regulate the permeability of root cell membranes, promote the active absorption and transport of salt ions by the roots, and further enhance the degree of ion stress. Example 11 uses a combination of sophora flavescens extract and sophora japonica extract. By utilizing the synergistic effect of the active ingredients of the two extracts, the absorption and accumulation efficiency of salt ions by the roots is enhanced, maximizing the aggravation of salt-alkali stress effects, promoting the absorption and accumulation of salt ions by the roots, exacerbating ion stress, and ultimately increasing the relative conductivity of leaves and the degree of salt-alkali stress.

[0171] Test Example 4

[0172] Using QZ2 apple rootstock as the test object, 80 seedlings with uniform growth were selected and divided into 8 groups of 10 seedlings each. The seedlings were treated according to the method of planting apples in saline-alkali land in Examples 4-11. The apple rootstock seedlings were transplanted into saline-alkali land along with the potting soil and then managed normally. The cuttings were taken out every 7 days to observe rooting. On the 45th day, the total number of roots and the number of roots of the cuttings were counted. The average number of roots = total number of roots of cuttings / number of roots. The average number of roots is summarized in Table 4.

[0173] Table 4

[0174]

[0175] In Example 4, vermiculite, perlite, and coconut coir were used as basic substrates to improve the original saline-alkali soil, initially improving soil aeration and water retention, providing sufficient oxygen for root respiration, and reducing the risk of root hypoxia and rot. Example 5 used biochar composite vermiculite made from co-calcined cotton stalks and vermiculite. Its porous structure provides physical support for root growth, promotes the differentiation of root epidermal cells into adventitious roots, and promotes root development. Example 6 further increased the number of oxygen-containing functional groups on the surface of the biochar composite vermiculite through citric acid modification, enhancing its neutralization capacity for alkaline ions and salt ion adsorption efficiency, optimizing the acid-base environment around the roots, avoiding the inhibition of root growth by alkaline stress, promoting root cell metabolism, and increasing the average number of roots. Example 7's phosphorus loading modification improved ion exchange specificity, further reducing the inhibition of roots by soil salinity stress. Phosphorus, as an essential nutrient for root growth, can promote the activity of root meristems, accelerate root cell division and elongation, and improve rooting efficiency. Examples 8-10, based on Example 7, added natural extracts such as tea polyphenols, sophora flavescens, and flavonoids. Tea polyphenols can scavenge free radicals generated during root growth, reduce oxidative damage under saline-alkali stress, and protect root cell integrity, but their direct promoting effect on root growth is relatively weak. Sophora flavescens extract has antibacterial activity, inhibiting the growth of harmful microorganisms in the roots, reducing root diseases, and promoting the differentiation of adventitious buds, thus increasing the average number of roots. Sophora japonica extract can regulate the content of endogenous auxin in plants, regulate root physiological activity, and promote root cell division and growth. Example 11 used a combination of sophora flavescens extract and Sophora japonica extract, utilizing the synergistic effect of their active ingredients. Sophora flavescens extract inhibits harmful bacteria in the roots and ensures a healthy root growth environment, while Sophora japonica extract regulates the activity of growth-related enzymes and increases the level of endogenous auxin. The synergistic effect of the two promotes root growth and maximizes the average number of roots.

[0176] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A method for planting apples in saline-alkali land, characterized in that, The method is as follows: Treat apple rootstocks with salt and alkali stress, graft them into potted soil and manage them for 14-16 days. When the rootstock seedlings have grown to 24-26 leaves, transplant the apple rootstock seedlings along with the potted soil into the saline-alkali land, with the pot opening 0.8-1.2cm above the ground. The potting soil is a mixture of saline-alkali soil, soil matrix, and vermiculite in a weight ratio of 1.5-2.5:0.5-1.5:0.5-1.

5. The potting soil is a mixture of saline-alkali soil, soil matrix, and modified vermiculite in a weight ratio of 1.5-2.5:0.5-1.5:0.5-1.

5. The modified vermiculite is prepared as follows, in parts by weight: S1. Mix 0.5-1.5 parts vermiculite and 2-4 parts cotton stalks and calcine at 400-500℃ for 1-2 hours, then pass through a 40-60 mesh sieve to obtain biochar composite vermiculite; S2. Add 0.5-1.5 parts of biochar composite vermiculite to 8-12 parts of 0.5-1.5wt% citric acid aqueous solution and soak for 2-4 hours. Remove and dry at 60-80℃ to obtain the modified vermiculite.

2. The method for planting apples in saline-alkali land as described in claim 1, characterized in that, The modified vermiculite is prepared as follows, in parts by weight: S1. Mix 0.5-1.5 parts vermiculite and 2-4 parts cotton stalks and calcine at 400-500℃ for 1-2 hours, then pass through a 40-60 mesh sieve to obtain biochar composite vermiculite; S2. Add 0.5-1.5 parts of biochar composite vermiculite and 0.0005-0.0015 parts of extract to 8-12 parts of 0.005-0.015wt% sodium phosphate aqueous solution, stir at room temperature for 10-15 hours, take out and dry at 65-75℃ to obtain phosphorus-loaded biochar composite vermiculite; S3. Add 0.5-1.5 parts of phosphorus-loaded biochar composite vermiculite to 8-12 parts of 0.5-1.5wt% citric acid aqueous solution and soak for 2-4 hours. Remove and dry at 60-80℃ to obtain the modified vermiculite.

3. The method for planting apples in saline-alkali land as described in claim 1, characterized in that, The salt and alkali used in the salt and alkali stress treatment is a mixture of NaCl and NaHCO3 in a weight ratio of 0.5-1.5:0.5-1.

5.

4. The method for planting apples in saline-alkali land as described in claim 1, characterized in that, The concentration of the salt-alkali stress treatment was 80-90 mmol·L⁻¹. -1 .

5. The method for planting apples in saline-alkali land as described in claim 1, characterized in that, The pH after the salt and alkali stress treatment was 8.5-8.

8.

6. The method for planting apples in saline-alkali land as described in claim 1 or 2, characterized in that, The soil matrix is ​​one or more of perlite, coconut coir, and peat moss.

7. The method for planting apples in saline-alkali land as described in claim 1, characterized in that, The apple rootstock varieties mentioned are as follows: Pingyi Sweet Tea, Xiaojin Begonia No. 1, Xiaojin Begonia No. 2, Xiaojin Begonia No. 3, Xiaojin Begonia No. 4, Qingzhen series rootstock No. 1, Qingzhen series rootstock No. 2, Qingzhen series rootstock No. 8, Qingzhen series rootstock No. 16, Qingzhen series rootstock No. 20, Qingzhen series rootstock No. 39, Qingzhen series rootstock Laoshan No. 3, Qingzhen series rootstock Laoshan No. 4, and apple rootstocks B68, G935, T337 and T18 preserved by the College of Horticulture of Hebei Agricultural University.

8. The method for planting apples in saline-alkali land as described in claim 1, characterized in that, The apple rootstock variety is Qingzhen No. 2.

Images