Combined fertilization method for improving baby cabbage quality and yield under drip irrigation condition

Abstract

The invention discloses a combined fertilization method for improving baby cabbage quality and yield under a drip irrigation condition, and belongs to the technical field of baby cabbage cultivation. When the base fertilizer is applied, the amount of the compound fertilizer is reduced by 30%, the organic fertilizer and the complex microbial inoculant are applied in a combined mode, the calcium magnesium nitrate fertilizer is applied in the rosette stage, and potassium sulfate is applied in the heading stage, so that the growth index, biomass accumulation, yield and quality of baby cabbage are remarkably and synergistically improved, and mineral absorption is promoted; it is proved that the yield and quality of baby cabbage can be remarkably improved by applying the organic fertilizer and applying the microbial fertilizer, the organic fertilizer mineralization can be improved by applying the microbial fertilizer, the soil fertility can be improved, the content of soil organic matter, alkali-hydrolyzable nitrogen, available phosphorus and quick-acting potassium can be increased, meanwhile, the soil enzyme activity constant is increased, the soil fertility is improved, and therefore the yield and quality of baby cabbage are improved.

Description

Technical Field

[0001] This invention belongs to the field of baby bok choy cultivation technology, and in particular relates to a combined fertilization method for improving the quality and yield of baby bok choy under drip irrigation conditions. Background Technology

[0002] Baby bok choy (Brassica rapa subsp. pekinensis), an annual vegetable of the Brassica genus, has become a core category supporting the supply of vegetables in northern greenhouses and southern open fields during the winter and spring seasons, thanks to its excellent commercial and nutritional properties (such as crisp and tender texture, rich in vitamin C, dietary fiber, and minerals) and wide ecological adaptability. It is of great significance for ensuring market stability, improving agricultural efficiency, and increasing farmers' income. With the continuous improvement of consumption upgrades and the increasing demands for agricultural product quality, the cultivation goals of baby bok choy have shifted from simply pursuing high yields to a comprehensive improvement that considers commercial appearance (uniformity of head shape, net yield), internal nutritional quality (vitamin and soluble sugar content), and safety indicators (nitrate accumulation).

[0003] Fertilizer, as a core element in regulating the soil-crop system, profoundly influences soil physicochemical and biological properties through its application patterns, thereby determining vegetable yield and quality. However, the long-term excessive reliance on chemical fertilizers under the pursuit of high yields, while achieving short-term increases, has led to severe ecological risks such as soil compaction, secondary salinization, rhizosphere microecological imbalance, and environmental pollution. These risks not only threaten product quality and agricultural sustainability but also pose potential health concerns. Therefore, exploring optimized fertilization patterns that can effectively reduce chemical fertilizer application while maintaining or improving the overall production performance of vegetables has become a research hotspot.

[0004] Existing research has confirmed the feasibility of optimizing fertilization patterns to improve the yield and quality of baby bok choy. For example, multiple field trials have shown that reducing the amount of fertilizer (e.g., by 30%-50%) and applying an appropriate amount (e.g., 400-600 kg / 667 m²) are effective. 2 The combined application of organic fertilizer can synergistically promote the growth of baby bok choy, increase yield per unit area, and significantly improve core quality indicators such as soluble sugars and vitamin C. Furthermore, the application of microbial agents combined with organic fertilizer can achieve a win-win situation of increased yield and improved soil quality under the background of reduced chemical fertilizer application. In addition, water and nutrient supply, as two key environmental factors regulating the physiological and ecological processes of vegetables, can be managed synergistically (i.e., fertigation) to significantly improve water and fertilizer use efficiency, reduce resource loss, and improve soil properties by optimizing the root zone microenvironment. Guyuan City, located in the Ningnan mountainous area, has a high altitude, abundant sunshine, and a cool climate, making it an important production base for cool-climate vegetables. Although drip irrigation has been promoted in this region as an important technology to improve water resource utilization efficiency, systematic research on the effects of different fertilization patterns under drip irrigation on the growth, yield, and quality of baby bok choy remains lacking. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a combined fertilization method for improving the quality and yield of baby bok choy under drip irrigation conditions. Based on the ecological characteristics of the Guyuan cold-climate vegetable production area, this invention systematically evaluates the effects of various fertilization modes under drip irrigation on the growth (plant height, canopy width, yield), quality (vitamin C, soluble protein, soluble solids, total soluble sugar, and crude fiber content), and mineral content (Fe, Zn, and Ca content) of baby bok choy. The optimal mode that maximizes the comprehensive benefits of yield and quality is obtained, providing technological support for a green and efficient cultivation system in the region.

[0006] This invention provides a combined fertilization method for improving the quality and yield of baby bok choy under drip irrigation conditions, comprising the following steps: spreading compound fertilizer, organic fertilizer and compound microbial agent on the ground surface, laying drip irrigation pipes after rotary tillage, and then transplanting baby bok choy seedlings; drip irrigating calcium magnesium nitrate fertilizer and urea during the rosette stage, and drip irrigating potassium sulfate during the heading stage.

[0007] Furthermore, the application rate of the compound fertilizer is 25 kg / 667 m³. 2 The application rate of the organic fertilizer is 400 kg / 667 m³. 2 The application rate of the compound microbial agent is 0.5 kg / 667 m³. 2 .

[0008] Furthermore, the compound fertilizer contains 28.0% N, 5% P2O5, and 7% K2O; the compound microbial agent contains ≥1 billion live bacteria / g; and the organic fertilizer contains more than 5% N, P2O5, and K2O, and more than 45% organic matter.

[0009] Furthermore, the application rate of the calcium magnesium nitrate fertilizer, calculated as CaO, is 5.0 kg / 667 m³. 2 The calcium magnesium nitrate fertilizer contains more than 52% CaO.

[0010] Furthermore, based on nitrogen element, the amount of urea applied is 2.3 kg / 667 m³. 2 The total nitrogen content in the urea is above 46.0%.

[0011] Furthermore, the amount of potassium sulfate applied, calculated as K2O, is 13.0 kg / 667 m³. 2 The potassium sulfate contains more than 52% K2O.

[0012] Furthermore, the spacing between the transplanted baby bok choy seedlings is 20cm and the row spacing is 30cm.

[0013] Furthermore, the baby bok choy seedlings are 25-30 days old and have 4-6 true leaves.

[0014] Compared with the prior art, the present invention has the following advantages and technical effects:

[0015] This invention reduces the amount of compound fertilizer by 30% when applying basal fertilizer, and combines it with organic fertilizer and compound microbial agents. Calcium magnesium nitrate fertilizer is applied as a top dressing during the rosette stage, and potassium sulfate is applied as a top dressing during the heading stage. This significantly and synergistically improves the growth indicators of baby bok choy (plant height increased by 12.61%, crown width increased by 18.32%), biomass accumulation (total dry weight increased by 46.64%), and yield (11030 kg / 667 m²). 2 Compared to the control (48.05% increase), the quality of baby bok choy improved (key indicators such as vitamin C increased by 47.92%-87.5%, and nitrate content decreased significantly). It also promoted mineral absorption (Fe, Zn, and Ca content increased by up to 83.33%), confirming that applying organic fertilizer in combination with microbial fertilizer can significantly improve the yield and quality of baby bok choy. Applying microbial fertilizer can increase the mineralization of organic fertilizer, improve soil fertility, increase the content of soil organic matter, alkaline nitrogen, available phosphorus, and available potassium, and at the same time increase the soil enzyme activity constant, thereby improving soil fertility and thus improving the yield and quality of baby bok choy. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 In Figure a, the effect of different fertilization treatments on the height of baby bok choy plants is shown, and in Figure b, the effect of different fertilization treatments on the crown width of baby bok choy plants is shown.

[0018] Figure 2 The effects of different fertilization treatments on the yield of baby bok choy;

[0019] Figure 3 The effects of different fertilization treatments on the quality of baby bok choy were investigated, where a represents nitrate content, b represents vitamin C content, c represents crude fiber content, d represents soluble protein content, e represents soluble total sugar content, and f represents soluble solids content.

[0020] Figure 4 The effect of different fertilization treatments on the iron content of baby bok choy;

[0021] Figure 5 The effect of different fertilization treatments on the Zn content of baby bok choy;

[0022] Figure 6 The effects of different fertilization treatments on the calcium content of baby bok choy. Detailed Implementation

[0023] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0024] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0025] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0026] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The description and examples are intended to be exemplary only.

[0027] The terms “include,” “including,” “have,” and “contain” used in this article are all open-ended terms, meaning that they include but are not limited to.

[0028] With the improvement of living standards, consumers' demand for vegetables has shifted from simply focusing on appearance to considering both nutrition and appearance. How to simultaneously improve the quality and yield of vegetables is a pressing problem that needs to be solved for the healthy development of agriculture. For a long time, chemical fertilizers have played a significant role in ensuring rapid crop yield growth, but the current overuse of chemical fertilizers has hindered the advancement of high-quality agriculture. Therefore, research on the application of chemical fertilizers in agricultural production is increasing. Replacing some chemical fertilizers with organic fertilizers is a major way to achieve reduced fertilizer use and increased efficiency. Replacing some chemical fertilizers with organic fertilizers has significant effects on improving soil fertility and increasing vegetable yield and quality. Studies by Ma Gui et al. have shown that under the combined application of 30% organic nitrogen and 70% chemical nitrogen, the activities of soil sucrase, alkaline phosphatase, urease, and catalase are enhanced, and the nitrogen, phosphorus, and potassium contents of cabbage heads are increased by 36.53%, 25.59%, and 22.38%, respectively, compared to the application of chemical fertilizers alone.

[0029] Water and fertilizer are crucial factors influencing the growth, development, yield, and quality of vegetable crops. A significant coupling effect exists between water and nutrients, and appropriate water-fertilizer combinations can effectively improve vegetable quality. Compared to surface irrigation, subsurface drip irrigation effectively increases the yield and water efficiency of field crops, vegetables, and fruits. Therefore, optimizing fertilization under drip irrigation conditions can significantly reduce water and fertilizer input and leaching losses, substantially improve water and fertilizer utilization, and reduce the accumulation of soil mineral nitrogen and water-soluble salts, which is of great significance for the green and sustainable production of greenhouse vegetables.

[0030] This invention addresses the problem of low water and fertilizer utilization efficiency caused by excessive irrigation and fertilization in vegetable production in cool regions. It explores the effects of different fertilization treatments under irrigation conditions on the growth and yield of baby bok choy, and proposes the optimal fertilization model under drip irrigation conditions, providing a reference for baby bok choy production in cool areas. Vegetables have different water and fertilizer requirements at different growth stages; therefore, this invention explores the optimal fertilization model based on the fertilizer requirements of baby bok choy at different growth stages (roselet stage and heading stage), providing practical guidance for precise fertilization in baby bok choy production.

[0031] To clarify the synergistic effects of staged regulation of drip irrigation topdressing and reduced basal application on the production of baby bok choy in the cold region of Guyuan, this invention established nine treatments (including conventional fertilization CK, and combinations of staged regulation of drip irrigation topdressing and reduced basal application T1-T8) using Jinhai baby bok choy as the test material. The results showed that treatment T3 (basal fertilizer: 30% reduction in compound fertilizer + 400 kg / 667 m² of organic fertilizer) was the most effective. 2 +0.5kg / 667m² of bacterial agent 2 Apply 5 kg of calcium magnesium nitrate fertilizer per 667 m² during the rosette stage. 2 Top-dress with potassium sulfate at 13 kg / 667 m² during the heading stage. 2 The overall performance was the best, with a significant increase in plant height (12.61%), crown width (18.32%), and root-to-crown ratio (42.86%) compared to the control (CK), and a yield of 11,030 kg / 667 m². 2 (Increased by 48.05%), and simultaneously improved quality (soluble protein increased by 87.5%, solids increased by 57.69%); principal component analysis confirmed that the T3 treatment had the highest comprehensive score (2.41 points). This indicates that the "30% reduction in compound fertilizer as basal application + synergistic application of organic fertilizer / microbial agent + staged calcium-magnesium / potassium drip irrigation topdressing" model can achieve high yield and high quality synergy, providing a reference for improving the high-yield and high-quality cultivation of baby bok choy under drip irrigation conditions.

[0032] This invention was conducted from April to July 2025 in the Experimental Demonstration Zone of the National Agricultural Science and Technology Park in Guyuan City, Ningxia Hui Autonomous Region (Yaomo Village, Pengbao Town, Yuanzhou District, Guyuan City). The area is located in the hinterland of the eastern foothills of the Liupan Mountains, at an altitude of 1740m. It has the climatic characteristics of "cold spring, cool summer, short autumn, and long winter" and belongs to the cold climate zone of the southern Ningxia mountainous area. Table 1 shows the basic physicochemical properties of the 0-20cm layer of the tested soil.

[0033] Table 1

[0034]

[0035] The fertilizer sources in this embodiment of the invention are shown in Table 2.

[0036] Table 2

[0037]

[0038] In this embodiment of the invention, transplanting refers to the process of transplanting seedlings cultivated in a seedbed to the field for planting. The seedlings are 25-30 days old and have 4-6 true leaves.

[0039] Comparative Example 1

[0040] This comparative study was conducted in a vegetable greenhouse, using ridge planting. The specific planting and fertilization methods are as follows:

[0041] S1. Base fertilizer application (April 16, 2025):

[0042] After measuring the compound fertilizer, it was spread on the surface of the experimental plot. Rotary tillage was used to thoroughly mix the fertilizer with the soil. Drip irrigation pipes were then laid after tillage. The compound fertilizer was applied at the conventional rate of 35 kg / 667 m². 2 The specific dosage is as follows: Nitrogen (as N): 10 kg / 667 m³ 2 Phosphorus (as P2O5): 1.8 kg / 667 m³ 2 Potassium (as K2O): 2.5 kg / 667 m³ 2 ;

[0043] S2. Planted on May 2, 2025:

[0044] The plant spacing was set at 20cm, the row spacing at 30cm, and the planting area was 68.25m². 2 (6.5m wide, 10.5m long), with 3 repeatings set in parallel;

[0045] S3. Topdressing (applied via drip irrigation):

[0046] S3-1. Drip irrigation topdressing during the rosette stage (20 days after transplanting):

[0047] Application method: Apply urea through drip irrigation pipes. Specific dosage: Urea (as nitrogen): 2.3 kg / 667 m² 2 ;

[0048] S3-2. Topdressing with drip irrigation during the heading stage (10 days after the rosette stage):

[0049] Application method: Apply potassium sulfate through drip irrigation pipes. Specific dosage: Potassium sulfate (as K2O): 13.0 kg / 667 m² 2 ;

[0050] S4. Harvesting begins on June 15, 2025.

[0051] Example 1

[0052] This example was conducted in a vegetable greenhouse, using ridge planting. The specific planting and fertilization methods are as follows:

[0053] S1. Base fertilizer application (April 16, 2025):

[0054] Compound fertilizer, organic fertilizer, and compound microbial agent were mixed after being measured and spread on the surface of the test plot. Then, rotary tillage was used to thoroughly mix the fertilizer with the soil. After tillage, drip irrigation pipes were laid. The compound fertilizer was applied at a rate of 28.6% less than the conventional amount, at 25 kg / 667 m². 2 The specific dosage is as follows: Nitrogen (as N): 7.0 kg / 667 m³ 2 Phosphorus (as P2O5): 1.25 kg / 667 m³ 2 Potassium (as K2O): 1.75 kg / 667 m³ 2 Organic fertilizer: 400 kg / 667 m² 2 Compound microbial agent: 0.5 kg / 667 m³ 2 ;

[0055] S2. Planted on May 2, 2025:

[0056] The plant spacing was set at 20cm, the row spacing at 30cm, and the planting area was 68.25m². 2 (6.5m wide, 10.5m long), with 3 repeatings set in parallel;

[0057] S3. Topdressing (applied via drip irrigation)

[0058] S3-1. Drip irrigation topdressing during the rosette stage (20 days after transplanting):

[0059] Application method: Apply calcium magnesium nitrate fertilizer and urea through drip irrigation pipes. The specific dosage is: urea (calculated as nitrogen): 2.3 kg / 667 m² 2 Calcium magnesium nitrate fertilizer (calculated as CaO): 5.0 kg / 667 m²2 ;

[0060] S3-2. Topdressing with drip irrigation during the heading stage (10 days after the rosette stage):

[0061] Application method: Apply potassium sulfate through drip irrigation pipes. Specific dosage: Potassium sulfate (as K2O): 13.0 kg / 667 m² 2 ;

[0062] S4. Harvesting begins on June 15, 2025.

[0063] Comparative Example 2

[0064] Same as Example 1, except that: S1. no compound microbial agent was applied in the basal fertilizer; S3-1. no calcium magnesium nitrate fertilizer was applied in the drip irrigation topdressing during the rosette stage.

[0065] Comparative Example 3

[0066] Same as Example 1, except that calcium magnesium nitrate fertilizer was not applied during drip irrigation topdressing in S3-1.

[0067] Comparative Example 4

[0068] Same as Example 1, except that no compound fertilizer was applied in S1. Base fertilizer and no calcium magnesium nitrate fertilizer was applied in S3-1. Drip irrigation topdressing during the rosette stage.

[0069] Comparative Example 5

[0070] Same as Example 1, except that no compound fertilizer was applied in S1.

[0071] Comparative Example 6

[0072] Same as Example 1, except that in S1, no compound fertilizer and compound microbial agent were applied in the base fertilizer.

[0073] Comparative Example 7

[0074] Same as Example 1, except that in S1, no compound fertilizer and compound microbial agent were applied in the basal fertilizer, and in S3-1, no calcium magnesium nitrate fertilizer was applied in the drip irrigation topdressing during the rosette stage.

[0075] Comparative Example 8

[0076] This comparative study was conducted in a vegetable greenhouse using ridge planting. The base fertilizer in this study consisted of compound fertilizer and organic fertilizer; no subsequent topdressing was applied. Specific planting and fertilization methods are as follows:

[0077] S1. Base fertilizer application (April 16, 2025):

[0078] After measuring and mixing the compound fertilizer and organic fertilizer, the mixture was spread on the surface of the test plot. Then, rotary tillage was used to thoroughly mix the fertilizer with the soil. The specific dosage was as follows: Compound fertilizer was applied at the conventional rate; Nitrogen (as N): 10 kg / 667 m² 2 Phosphorus (as P2O5): 1.8 kg / 667 m³ 2 Potassium (as K2O): 2.5 kg / 667 m³ 2 Organic fertilizer: 400 kg / 667 m² 2 ;

[0079] S2. Planted on May 2, 2025:

[0080] The plant spacing was set at 20cm, the row spacing at 30cm, and the planting area was 68.25m². 2 (6.5m wide, 10.5m long), with 3 repeatings set in parallel;

[0081] S3. Harvesting begins on June 15, 2025.

[0082] Table 3 shows the fertilizer application rates for each treatment in Example 1 and Comparative Examples 1-8.

[0083] Table 3 Fertilizer application rate for each treatment (kg·667m³) -2 )

[0084]

[0085] An examination of the quality and yield of baby bok choy

[0086] 1. Effects of different fertilization treatments on plant height and canopy width of baby bok choy

[0087] The plant height and crown width of the baby bok choy harvested in Example 1 and Comparative Examples 1-8 were measured with a steel tape measure. Ten plants were randomly selected from each example or comparative example for measurement. Three replicates were performed for each example and comparative example. Preliminary statistical analysis of the data was conducted using Excel 2010. Analysis of variance and principal component analysis were performed using SPSS 23.0. Graphs were generated using Origin 22.0 software. The same applies below.

[0088] Figure 1 In figure a, the effect of different fertilization treatments on the plant height of baby bok choy is shown; in figure b, the effect of different fertilization treatments on the crown width of baby bok choy is shown. Figure 1It can be seen that different fertilization treatments have a significant impact on the plant height and crown width of baby bok choy. The trends in plant height and crown width are basically consistent, proving that the effects of different treatments on the overall growth of the aboveground parts of the plant are synergistic. Compared with the control (CK), treatments T1, T2, T3, and T5 all significantly promoted plant height and crown width growth, with T3 showing the most significant promoting effect, increasing plant height by 12.61% and crown width by 18.32% compared with CK. Among the other treatments, the plant height and crown width of baby bok choy were significantly reduced compared with CK, with the T8 treatment showing the smallest reductions in plant height and crown width, decreasing by 5.87% and 9.49% respectively compared with CK.

[0089] 2. Effects of different fertilization treatments on the fresh and dried quality and root-to-shoot ratio of baby bok choy

[0090] The dry and fresh weight of plants, to a certain extent, indicates the degree of biomass accumulation in plants. The root-to-shoot ratio reflects the distribution of substances within the plant and is an important indicator of the coordinated growth of the plant's root system and above-ground parts. The fresh weight of the baby bok choy harvested in Example 1 and Comparative Examples 1-8 was determined by direct weighing. After weighing the fresh weight, the baby bok choy was blanched at 105℃ for 30 minutes and then dried at 80℃ until constant weight was obtained. Three replicates were performed for each example and comparative example. Table 4 shows the effects of different fertilization treatments on the dry and fresh weight and root-to-shoot ratio of baby bok choy.

[0091] Table 4

[0092]

[0093] Note: Different lowercase letters in the same column indicate that the differences between different treatments are significant at the 0.05 level, and the same applies below.

[0094] As shown in Table 4, the fresh and dry weight and root-to-crown ratio of baby bok choy increased under treatments T1, T2, T3, T4, and T5 compared to the control (CK), while treatments T6, T7, and T8 significantly decreased these. Among these, treatment T3 showed the best promoting effect on baby bok choy growth, increasing the aboveground fresh weight by 44.50%, aboveground dry weight by 46.15%, underground fresh weight by 40.63%, underground dry weight by 50%, whole plant dry weight by 46.64%, and root-to-crown ratio by 42.86% compared to the control (CK).

[0095] 3. Effects of different fertilization treatments on the yield of baby bok choy

[0096] After the baby bok choy matured, the yield was harvested and examined in Examples 1 and 1-8. The yield was then converted to per 667m³. 2 The yield is the total yield. The effects of different fertilization treatments on the yield of baby bok choy are as follows: Figure 2 As shown. Figure 2 It can be seen that different fertilization treatments have a significant impact on the yield of baby bok choy. Among them, the T3 treatment yielded the highest yield, which was 11030 kg / 667 m².2 The yield of the first treatment was 48.05% higher than that of the control (CK), followed by treatments T2, T1, and T5, which increased by 37.32%, 20.13%, and 8.99% respectively compared to the control. The lowest yield was observed after treatment T8, at 6020 kg / 667 m³. 2 It was 19.19% lower than the control (CK).

[0097] 4. Effects of different fertilization treatments on the quality of baby bok choy

[0098] The nitrate, vitamin C, crude fiber, soluble protein, soluble solids, and total soluble sugar contents of baby bok choy harvested from Examples 1 and Comparative Examples 1-8 were determined. Vitamin C content was determined using the xylene extraction colorimetric method; soluble protein content using the Coomassie brilliant blue staining method; total soluble sugar content using the anthrone colorimetric method; nitrate content using the salicylic acid colorimetric method; nitrate content using ultraviolet spectrophotometry; and soluble solids content using a refractometer method. Crude fiber content was determined using a non-enzymatic gravimetric method. Each treatment was measured in triplicate. The effects of different fertilization treatments on the quality of baby bok choy were investigated as follows. Figure 3 As shown.

[0099] Depend on Figure 3 It was found that, compared with the control (CK), the contents of vitamin C, soluble protein, soluble solids, soluble total sugar, and crude fiber were significantly increased under treatments T1, T2, T3, T4, and T5, and significantly decreased under treatments T6, T7, and T8. The highest values ​​were observed under treatment T3, with increases of 47.92%, 87.5%, 57.69%, 52.63%, and 75% respectively compared to the CK, while the lowest values ​​were observed under treatment T8, with decreases of 21.51%, 28.13%, 25%, 23.68%, and 25% respectively. Notably, compared with the CK, treatments T1, T2, T3, T4, and T5 significantly reduced the nitrate content of the baby bok choy, while treatments T6, T7, and T8 showed an increasing trend in nitrate content, significantly increasing by 7.69%, 13.57%, and 21.72% respectively.

[0100] 5. Effects of different fertilization treatments on the mineral content of baby bok choy

[0101] The mineral elements of baby bok choy harvested in Example 1 and Comparative Examples 1-8 were determined by inductively coupled plasma optical emission spectrometry (ICP-OES). The mineral elements (Fe, Zn, Ca) content of baby bok choy were determined by inductively coupled plasma optical emission spectrometry (ICP-OES). Each treatment was measured in triplicate. Figure 4 To investigate the effects of different fertilization treatments on the iron content of baby bok choy. Figure 5 To investigate the effects of different fertilization treatments on the Zn content of baby bok choy. Figure 6The effects of different fertilization treatments on the calcium content of baby bok choy.

[0102] Depend on Figure 4 , Figure 5 and Figure 6 It was found that different fertilization treatments significantly affected the Fe, Zn, and Ca content of baby bok choy. Treatment T3 showed the best effect in increasing the Fe, Zn, and Ca content, significantly higher than the control (CK) by 71.43%, 83.33%, and 65.93%, respectively. Under treatments T2, T1, and T5, the Fe content increased by 46.43%, 25%, and 17.86% compared to the CK; the Zn content increased by 50%, 25%, and 16.67%, respectively; and the Ca content increased by 47.25%, 29.12%, and 19.23%, respectively. Treatment T8 showed the lowest mineral element content, decreasing by 28.57% (Fe), 25% (Zn), and 18.68% (Ca) compared to the CK, respectively.

[0103] Baby bok choy has a high calcium requirement; calcium deficiency can lead to heart rot and failure to form heads. Baby bok choy is rich in calcium and potassium, approximately 2-3 times higher than Chinese cabbage, making it an ideal vegetable for maintaining neuromuscular excitability and normal function, as well as preventing rickets. Therefore, calcium content is a crucial indicator for monitoring the safety and quality of baby bok choy. In this invention, under the same drip irrigation conditions, the T3 treatment showed the highest calcium content in baby bok choy. This is because calcium magnesium phosphate fertilizer was added to the T3 treatment. As a fast-acting fertilizer, its application significantly promoted root growth in baby bok choy. This indicates that calcium magnesium nitrate fertilizer replaced traditional nitrogen fertilizer, simultaneously supplementing nitrogen (N) and trace elements (CaO / MgO). It demonstrates that low calcium levels limit root growth in baby bok choy, while increased calcium levels significantly improve root growth.

[0104] 6. Principal component analysis of various indicators of baby bok choy

[0105] Principal Component Analysis (PCA) is widely recognized in agricultural research for the comprehensive evaluation of crop traits. It is a common multi-index evaluation method that can transform multiple correlated observation indicators into a few new indicators that can reflect the main information of multiple variables through dimensionality reduction. Then, a comprehensive evaluation is carried out based on the factor scores of each sample, reducing the amount of computation and making the evaluation results more objective and reasonable.

[0106] Table 5 shows the eigenvalues ​​and variance contribution rates of the principal component analysis. As can be seen from Table 5, Principal Component 1 (growth and yield drivers (related to plant height, crown width, aboveground fresh weight, and yield)) has an eigenvalue of 8.92 and a variance contribution rate of 49.56%, making it a key component explaining data variation and representing the most significant summary of the overall differences in the original indicators. Principal Component 2 (quality and nutrition factors (related to soluble protein, soluble solids, vitamin C, and Ca and Fe element content)) has an eigenvalue of 4.37 and a variance contribution rate of 24.28%, supplementing the explanation of the remaining significant variation. Principal Component 3 (root system and stress resistance factors (related to root-to-shoot ratio, underground dry weight, and nitrate content)) has an eigenvalue of 2.15 and a variance contribution rate of 11.94%. The cumulative variance contribution rate of the first three principal components reaches 85.78%, indicating that these three principal components can effectively represent the main information of the original data, achieving data dimensionality reduction. Subsequent analysis will focus on these three principal components.

[0107] Table 5

[0108] principal component Eigenvalues Variance contribution rate / % Cumulative variance contribution rate / % Principal component 1 8.92 49.56 49.56 Principal component 2 4.37 24.28 73.84 Principal component 3 2.15 11.94 85.78

[0109] Table 6 shows the comprehensive scores for different fertilization treatments.

[0110] Table 6

[0111]

[0112]

[0113] Table 6 presents the performance of each fertilization treatment in the three principal components and the overall score. Treatment T3 achieved high scores in principal component 1 (2.87 points), principal component 2 (1.15 points), and principal component 3 (0.98 points), with an overall score of 2.41 points, ranking first. This indicates that this fertilization treatment has a significant effect on improving the indicators in multiple dimensions and is a superior fertilization mode. Treatments T2 and T1 had overall scores of 1.72 points and 1.24 points, respectively, ranking second and third, indicating that their fertilization effects were good, but weaker than T3. The overall scores of CK and T4, T6, T7, and T8 were negative, indicating that these fertilization treatments did not effectively promote the improvement of the indicators and may even have a negative impact. Among them, T8 had the worst overall score of -2.24 points.

[0114] This invention conducted principal component analysis on 13 indicators across three aspects—growth, yield, and quality traits—of baby bok choy, reducing the 13 indicators to 3 principal components. The cumulative variance contribution rate reached 85.79%, and the comprehensive score determined that the T3 fertilization treatment was suitable for baby bok choy. This indicates that the T3 fertilization mode should be prioritized under drip irrigation conditions, while avoiding ineffective fertilization treatments (such as T8). The four-element synergistic drip irrigation fertilization mode provided by this invention offers a reference for the efficient cultivation of baby bok choy in cool regions.

[0115] This invention systematically evaluates the comprehensive effects of various fertilization strategies under drip irrigation on the yield formation (plant height, canopy width, and yield per unit area), core quality (soluble sugars, vitamin C, nitrates), and element content such as calcium in baby bok choy. Principal component analysis was used to rank the nine fertilization treatments (including the control) from highest to lowest as follows: T3 > T2 > T1 > T5 > T4 > CK > T6 > T7 > T8. This indicates that the four-element synergistic drip irrigation fertilization model (30% reduction in compound fertilizer as basal application + 400 kg of organic fertilizer / 6 kg of microbial agent as synergistic application + staged drip irrigation topdressing of calcium, magnesium, and potassium fertilizers) can effectively promote the growth of baby bok choy, increase yield, and effectively improve its quality. The research results provide a reference technical paradigm for the green production of vegetables in cool regions.

[0116] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A combined fertilization method for improving the quality and yield of baby bok choy under drip irrigation conditions, characterized in that, Includes the following steps: Compound fertilizer, organic fertilizer, and compound microbial agent are spread on the ground. After rotary tillage, drip irrigation pipes are laid, and then baby bok choy seedlings are transplanted. During the rosette stage, calcium magnesium nitrate fertilizer and urea are drip-irrigated as top dressing, and during the heading stage, potassium sulfate is drip-irrigated as top dressing.

2. The combined fertilization method according to claim 1, characterized in that, The application rate of the compound fertilizer is 25 kg / 667 m³. 2 The application rate of the organic fertilizer is 400 kg / 667 m³. 2 The application rate of the compound microbial agent is 0.5 kg / 667 m³. 2 .

3. The combined fertilization method according to claim 2, characterized in that, The compound fertilizer contains 28.0% N, 5% P2O5, and 7% K2O; the compound microbial agent contains ≥1 billion live bacteria / g; and the organic fertilizer contains more than 5% N, P2O5, and K2O, and more than 45% organic matter.

4. The combined fertilization method according to claim 1, characterized in that, The application rate of the calcium magnesium nitrate fertilizer, calculated as CaO, is 5.0 kg / 667 m³. 2 The calcium magnesium nitrate fertilizer contains more than 52% CaO.

5. The combined fertilization method according to claim 1, characterized in that, The amount of urea applied, calculated based on nitrogen, is 2.3 kg / 667 m³. 2 The total nitrogen content in the urea is above 46.0%.

6. The combined fertilization method according to claim 1, characterized in that, The amount of potassium sulfate applied, calculated as K2O, is 13.0 kg / 667 m³. 2 The potassium sulfate contains more than 52% K2O.

7. The combined fertilization method according to claim 1, characterized in that, The spacing between transplanted baby bok choy seedlings was 20cm and the row spacing was 30cm.

8. The combined fertilization method according to claim 1, characterized in that, The baby bok choy seedlings are 25-30 days old and have 4-6 true leaves.

Images