1 Introduction

Drought is a major problem affecting wheat production. As climate change becomes more and more evident, water shortages are becoming more common and more severe in major wheat-producing areas, such as the Mediterranean region, the North China Plain, and some semi-arid regions (Guan et al., 2015; Peng et al., 2019; Madejón et al., 2024). This water shortage may get worse in the future and may affect food security. To ensure stable wheat production, we have to find ways to make it more drought-resistant.

The root system of wheat is the key to absorbing water and nutrients. Especially in drought, root length, root density, and root vitality directly affect whether wheat can absorb water from deep in the soil (Muñoz-Romero et al., 2010; Huang et al., 2012). Different tillage methods have different effects on the root system. Conservation tillage and no-tillage can make roots grow deeper and more active, and the soil has better water retention capacity, while traditional tillage does not have these advantages (Hobson et al., 2022; Du et al., 2023).

This study investigated the effects of different tillage practices on wheat root development and drought resistance, compared root growth parameters and water use efficiency under different tillage systems, evaluated the effects of tillage-induced root optimization on wheat yield and drought resistance, and provided tillage management recommendations to improve wheat productivity under climate-induced water stress and develop sustainable wheat production strategies in response to climate change.

2. Root Development Characteristics in Wheat

2.1 Morphological construction and growth stage characteristics of roots

Wheat roots are mainly composed of seminal roots and lateral roots. The length, number, angle and surface area of roots vary greatly depending on the variety and growth time. Some varieties grow roots very fast in the early growth stage, with many and long seminal roots, which is usually associated with high yield and late maturity (Xie et al., 2017; Adeleke et al., 2020). The angle and distribution of seminal roots are also critical because it determines how much soil the plant can explore, which is particularly important for adapting to drought (Manschadi et al., 2008; Richard et al., 2015). During drought, the ratio of wheat roots to leaves will increase, and the internal structure of the roots will also change, which means that the roots will change their morphology according to the environment (Figure 1) (Chen et al., 2021).

Figure 1 Morphology and structure of wheat roots under drought stress (Adopted from Chen et al., 2021) Image caption: (A) Morphology of wheat roots. (B-C) Microstructure of YM13 root cross section under control condition and drought stress. (D-E) Microstructure of YN19 root cross section under control condition and drought stress. CC, control condition; Co, cortex; DS, drought stress; Ph, phloem; VC, vascular cylinder; XV, xylem vessel. Scale bars: (A) 8 cm, (B-E) 50 µm (Adopted from Chen et al., 2021)

2.2 Role of roots in water and nutrient uptake

Roots are the main tool for plants to absorb water and nutrients, especially when there is a lack of water. If the roots grow deep and are densely distributed, the plant can absorb water from deeper soil, which will make it more drought-resistant (Khodaee et al., 2021). Root length density, wood thickness and total root surface area directly affect the efficiency of water and fertilizer absorption. The better these characteristics are, the better the crop can ensure yield and quality under difficult conditions (Li et al., 2021; Cheng et al., 2024). Now many gene loci (QTLs) related to these traits have been found, which are very useful for breeding and can help us select more drought-resistant wheat.

2.3 Interactions between roots and soil microorganisms

Wheat roots and soil microorganisms will affect each other. The roots secrete some substances that attract beneficial microorganisms to gather together to form a good rhizosphere environment. This microbial community helps to improve the efficiency of nutrient absorption and enhance wheat resistance (Alrajhi et al., 2024). Now, with the advancement of root phenotyping technology and molecular technology, we know more about this interaction. It can be said that roots are not only tools for absorbing water and fertilizer, but also help establish a microbial circle that is important for crop health, which is increasingly valued in adapting to harsh environments.

3 Classification and Features of Tillage Practices

3.1 Comparison of conventional tillage and no-tillage

Traditional tillage (CT) generally involves deep tillage, using plows and harrows to turn the soil, and also turning the straw in the ground into the soil. Although this method is common, it will destroy the soil structure. No-tillage (NT) is different. It tries not to move the soil, leaving the straw from the previous season on the surface to maintain the original soil state. This method helps to maintain soil structure, increase organic matter, and make the microorganisms in the soil more active. However, no-tillage also has problems, such as easy soil compaction and more difficult weed control (Peixoto et al., 2020; Bezboruah et al., 2024). Traditional tillage is prone to causing more greenhouse gas emissions and nutrient loss. Although no-tillage reduces these problems, it may also take away more nitrates due to stronger water infiltration (Kraut-Cohen et al., 2019; Bhattacharyya et al., 2022).

3.2 Definition and application of reduced/conservation tillage

Reduced tillage, also known as conservation tillage, is a practice that reduces soil disturbance. It does not turn the land as frequently as traditional tillage. Common methods include strip tillage, mulching tillage and ridge cultivation. The purpose of doing this is to retain as much straw as possible on the surface, reduce soil erosion by rain, make the soil healthier, retain moisture, and store more carbon (Porwollik et al., 2019). More and more people in the world are using conservation tillage, but the methods used in each place are different. Because it can help conserve water and soil and improve biodiversity, it is important in promoting sustainable agriculture (Bezboruah et al., 2024; Wang et al., 2024). This method can also help cope with climate change and is suitable for reference when making agricultural plans in different regions.

3.3 Straw mulching and its water-retaining mechanism

Straw mulching is part of conservation tillage, which is to spread the harvested straw on the ground. This method can block the sun and wind, reduce water evaporation, and make the soil temperature more stable (Bezboruah et al., 2024). The covered straw can also improve the soil structure, increase the organic matter in the soil, help soil and water conservation, and prevent the soil from being washed away by rain. Combining straw mulch with reduced tillage is very helpful in retaining moisture and improving crop drought resistance.

4 Tillage-Induced Modulation of Root Development

4.1 Effects on root structure and morphology

Different tillage methods affect the morphology and structure of wheat roots. Compared with conventional tillage (CT), no-tillage (NT) is more conducive to root growth. For example, when the soil is not compacted, no-tillage can make the roots grow deeper and denser, and can also increase the total amount of roots (Hobson et al., 2022). Most of the time and in different soil layers, wheat roots are generally longer under no-tillage, which is very helpful for increasing yields when water is scarce (Muñoz-Romero et al., 2010). However, conventional tillage can sometimes make more roots in the upper soil, probably because tillage makes the soil looser and the roots can get in more easily. Overall, no-tillage and reduced mechanical compaction methods can help wheat roots grow better downward and make the soil structure healthier.

4.2 Root vitality and water uptake efficiency

Roots usually grow more vigorously when no-tillage or deep tillage is used, which can also improve water absorption capacity. More roots, especially deep roots, can help wheat absorb water from deeper soil, which is critical in drought weather (Muñoz-Romero et al., 2010). In no-till fields, the soil structure is better, with vertical cracks or biopores, which makes it easier for water to reach the roots and allows roots to absorb water more smoothly (Hobson et al., 2022). Because the roots grow well and absorb more water, wheat in no-till fields can maintain good yields when there is little rain and is more drought-resistant.

4.3 Temporal and spatial root growth dynamics

Tillage methods also affect the growth of roots at different times and in different soil layers. No-till allows roots to maintain a high growth level throughout the growth period, and the roots can be distributed more evenly in all soil layers (Muñoz-Romero et al., 2010). In contrast, traditional tillage allows roots to be mainly concentrated in the upper layer, with fewer roots in the lower layer (Muñoz-Romero et al., 2009). But no matter which method is used, the timing of rainfall is also important, especially during the tillering period. If there is rain at this time, the roots will grow better. Over time, the difference in root distribution between no-till and traditional tillage will become more and more obvious. No-till is more conducive to root growth that is deeper and wider, and has greater drought resistance.

5 Effects of Tillage on Drought Resistance

5.1 Physiological indicators: leaf water potential, stomatal conductance

Different tillage methods will affect some key physiological indicators of wheat drought resistance. Compared with traditional tillage, such as no-till or conservation tillage, wheat leaves can retain better water during drought, and photosynthesis will not drop too much at once (Madejón et al., 2023; 2024). Under traditional tillage, drought often causes wheat leaves to lose water content, stomata to close, and photosynthesis rate to deteriorate. Under no-till conditions, if phosphorus and potassium fertilizers are added, water evaporation can be reduced and crop drought resistance can be improved (Galstyan et al., 2022).

5.2 Soil moisture retention and water use efficiency

No-till or less tillage can keep water in the ground longer. Studies have found that compared with traditional tillage, no-till can allow the soil to store 16% to 20% more water (Madejón et al., 2024). These tillage methods can also make rainwater more effectively used, helping crops maintain yields during droughts (Sun et al., 2024). Practices such as cross-slope ridge cultivation and strip tillage can also allow water to penetrate deeper, reduce soil compaction, and better control water (Li et al., 2024; Sojnóczki et al., 2024). Traditional tillage often causes the soil to dry out and even forms a hard layer, which makes it difficult for roots to grow downward and affects water absorption (YB et al., 2017).

5.3 Root-shoot coordination and yield stability under stress

Tillage methods affect the growth of wheat roots and its performance under drought conditions. No-till and conservation tillage can make wheat roots grow more, the ratio of roots to aboveground parts is more reasonable, and mycorrhizae are easier to form, all of which help wheat better utilize resources and stabilize yields when water is scarce (Madejón et al., 2023). On the other hand, under traditional tillage, drought can easily cause yield reductions, and the root-crown ratio decreases, indicating that wheat is more difficult to adapt to stress. If crop rotation or joint tillage is adopted, the yield can be more stable and wheat can better cope with weather changes, which is particularly useful in drought-prone areas (Sojnóczki et al., 2024; Sun et al., 2024).

6 Case Studies: Drought Adaptation under Tillage Regimes

6.1 No-till vs. conventional tillage in North China

In North China, experiments were conducted in many fields and found that compared with conventional tillage (CT), no-tillage (NT) and a crop rotation method called NC (normal tillage for winter wheat and no-tillage for summer corn) can allow the soil to store more water during droughts. After using the NC method, the available water in the field increased by about 19.7%, the yield was more stable during droughts, and the water use efficiency was higher than other methods. This shows that in semi-arid areas, the combination of no-tillage and crop rotation is a good choice, which can make crops more drought-resistant and the yield is not easy to drop (Sun et al., 2024).

6.2 Root development under conservation tillage in the Huang-Huai region

In the Huanghuai region, conservation tillage (such as reduced tillage and returning straw to the field) has been proven to be very helpful for good root growth. This farming method can increase the number and variety of microorganisms in the soil and enrich the soil nutrients. Compared with traditional tillage, conservation tillage can make the soil "ecosystem" healthier, and when drought comes, it has less impact on the food web in the soil. This better soil environment is conducive to the growth of stronger roots for wheat, allowing it to survive when there is less water (Figure 2) (He et al., 2019; Ling et al., 2025).

Figure 2 Root weight density of winter wheat within the 0-45 cm soil depth under various tillage practices at jointing, anthesis and 20 DAA in the 2014-2016 growing seasons. Results presented as the mean of 2 years. P, plowing tillage; R, rotary tillage; SR, strip rotary tillage; SRS, strip rotary tillage after subsoiling. Error bars represent SEM; n=3. Different letters indicate significant differences between treatments. FT, FS and FT × FS represent F-values of tillage, soil layers and their interaction in variance analysis respectively. *P < 0.05; **P < 0.01 (Adopted from He et al., 2019)

6.3 Straw-return tillage and water use improvement in arid northwest areas

In the arid areas of Northwest China, leaving straw directly in the field is a simple and effective way. It allows the soil to retain more water and use water more efficiently. Conservation tillage methods such as straw mulching can help the land store more water, so that wheat and other crops can survive longer when encountering drought weather and are not prone to yield reduction. This is particularly important in places where extreme droughts often occur (Sun et al., 2024; Ling et al., 2025).

7 Concluding Remarks

Tillage methods affect the development of wheat roots and their drought resistance. Compared with conventional tillage (CT), conservation tillage methods such as no-tillage (NT) and reduced tillage (RT) generally make it easier for the soil to retain water, and also allow the roots to grow denser and have more mycorrhizae, so that water can be better utilized during droughts and yields are more stable. However, there is a problem with no-tillage, which is that it is easy to harden the soil, especially in deep areas, which will prevent deep roots from growing and absorbing deep water. Reduced tillage can find a better balance between root preservation and yield preservation. In droughts, the amount of wheat roots will decrease and their shape will change. However, if conservation tillage is used, this effect can be mitigated. This is because this method allows roots, soil and microorganisms to cooperate better, which is very helpful to crops.

Which tillage method is best depends on the local soil, climate and planting conditions. In areas prone to drought, using no-tillage or back-tillage can allow the soil to retain more water and help the roots and microorganisms cooperate better. However, sometimes you still have to turn the land regularly, such as using rotary tillage, to prevent the soil from hardening and allow the roots to grow deeper. Weeds must also be controlled, especially when re-tilling, otherwise weeds will grab water during droughts, which will reduce production. If conservation tillage can be combined with other methods, such as retaining straw and crop rotation, it can also make drought resistance stronger.

Future research can consider more comprehensive tillage methods. For example, combining the benefits of conservation tillage with some special measures to control soil hardening while helping roots grow better and adapt to drought weather. Now, the analysis of root traits, soil biology and precision agriculture are becoming more and more advanced, and they can also help us develop more reasonable management methods based on the conditions of each plot of land. As the climate becomes more and more unstable, selecting wheat varieties with strong roots and drought resistance, and combining them with appropriate tillage methods, has become the key to stable production and income.

Acknowledgments

I appreciate Dr Xu from the Hainan Institution of Biotechnology for her assistance in references collection and discussion for this work completion.

Conflict of Interest Disclosure

The author affirms that this research was conducted without any commercial or financial relationships that could be construed as a potential conflict of interest.

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