Molecular Soil Biology 2025, Vol.16, No.4, 214-229 http://bioscipublisher.com/index.php/msb 215 The purpose of this study is to systematically organize these current soil improvement methods and see their application and actual effects in off-season planting of Leonurus japonicus. We will also analyze the effects of these methods on soil properties, microorganisms, yield and medicinal material quality. At the same time, we will point out which problems are still unresolved and which areas are controversial. Finally, we also want to provide some scientific suggestions and references for future actual planting and research directions. 2 Biological Characteristics of Leonurus japonicus 2.1 Growth requirements: climate, soil type, nutrient needs Leonurus japonicus, also known as motherwort, is an annual or biennial herbaceous plant of the Lamiaceae family. In China, it is often used as a traditional Chinese medicine, especially suitable for regulating menstruation, promoting blood circulation, and relieving pain. ‘Tongzi’ is an excellent variety selected and bred in recent years. This variety has strong adaptability and many medicinal ingredients. The most suitable growth temperature for L. japonicus is between 18 ℃~28 ℃. It is relatively heat-resistant, but not cold-resistant, and is particularly afraid of frost. During the emergence and seedling stage, if the temperature is too low, it will not grow well. Therefore, it should be planted when there is no frost, or some insulation measures should be used. It likes light and humid environment, needs sunlight, and the air should have appropriate humidity. It is more suitable to grow in soft, breathable, well-drained loam or sandy loam, and the soil pH is preferably between pH 6.0-7.5. If it is heavy clay or saline-alkali land, its roots will not grow well and the medicinal ingredients will be less. L. japonicus has a relatively high demand for nitrogen, phosphorus and potassium, especially when it grows branches and blooms, it is particularly sensitive to nitrogen. Trace elements such as calcium, magnesium and boron will also affect the formation of its efficacy. Therefore, soil nutrients must be balanced, which is critical to increasing yield and efficacy (Zhang et al., 2018; Li et al., 2019). 2.2 Off-season cultivation feasibility and sensitivity L. japonicus has a short growth period, generally taking 90 to 110 days from planting to harvest. This gives it a certain ability to be planted off-season. However, it is very sensitive to temperature. If the temperature is too low, the seeds will not germinate easily and the seedlings will grow slowly. In this way, the germination rate will be low and the root system will not develop well. Therefore, when planting in winter and spring or late summer and early autumn, it is necessary to use facility agriculture, such as plastic greenhouses, small arch greenhouses, and ground film insulation and moisture retention methods to adjust the environment. When planting off-season, it is also prone to problems such as pests and diseases, insufficient sunlight or soil compaction. If the soil itself has poor drainage and air permeability, the problem will be more serious, and the plant may also be infected with root rot or chlorosis (Li et al., 2023). To successfully plant off-season, you must first have good soil and necessary auxiliary facilities. 2.3 Relationship between soil conditions and crop performance L. japonicus is very sensitive to the structure and physical and chemical properties of the soil. If the soil is loose, well-ventilated, and has a lot of organic matter, its germination rate, number of branches, yield of the aboveground part, and medicinal ingredients (such as leonurine, protocatechuic acid, etc.) will be higher. Conversely, if the soil is high in salt, too acidic, unevenly nutritious, or severely compacted, its roots will be short, the leaves will turn yellow, the flowers will become fewer, and the yield and quality will decrease. Through some soil improvement methods, such as adding humic acid, microbial agents, biochar, etc., the soil can be made looser, more breathable, and easier to retain water and fertilizer, which can greatly improve the performance of L. japonicus during off-season planting (Shang et al., 2014; Wu et al., 2024). In addition, the types of microorganisms in the improved soil are also more stable, which is conducive to the healthy development of the root environment and enhances the resistance of the plant. Therefore, when planting L. japonicus, especially when it is to be planted off-season, improving the soil is a very important step. 3 Soil Constraints in Off-Season Cultivation 3.1 Soil compaction and waterlogging in off-season When planting L. japonicus in winter, spring or late summer, greenhouses are often used. This closed environment, coupled with frequent watering and rain, can easily make the soil surface hard and airtight. As a result, the roots
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