Introduction

Systems of agricultural production are directly threatened by global warming, which has major ramifications for the security of the world’s food supply1. Using field experiments and global climate simulations, researchers have carried out systematic investigations to evaluate the possible effects of global warming on agricultural output2. Maize is a primary food crop that is extensively grown and produced in China3. It is used in feed, manufacturing, and bioenergy production, as well as providing a large number of raw materials to the food industry. For the population’s living and dietary composition, maize is vital as one of the main food sources, especially in developing countries4. Compared to rice and wheat, maize’s reproductive processes are more vulnerable to high temperatures since it is a heat-sensitive crop5. According to studies, high temperatures impair grain by weakening pollen activity and interfering with fertilization and pollen tube formation6. Furthermore, the crop’s above ground section may sustain direct physical damage as a result of severe meteorological conditions such as intense rain and wind7.

Lodging is a phenomenon in which a plant is permanently displaced from upright growth8. One significant component affecting grain output is lodging9. The main categories of lodging are stem lodging and root lodging10. Research suggests that lodging of the roots and stems reduces maize output by 14% and 28%, as well11,12. Plant stem lodging is usually characterized by the breaking of the spike or lower internode, which is caused by the interaction between the plant’s own mechanical properties and meteorological disturbances such as wind, rain, and hail13. A variety of effective methods have been developed to deal with this problem, including traditional breeding and biotechnology, optimization of fertilization strategies (e.g., reduced and delayed nitrogen fertilizer application, supplementation with potassium and phosphorus), utilizing plant growth regulators, and controlling weeds in order to produce shorter, stronger stalks8. Several studies have suggested that roots are essential in identifying root lodging14. However, because of their greater tensile strength, which combines with the soil to form a root-soil relationship akin to a “reinforced concrete structure,” Thereby, the development of the roots as a key link between the soil and the above-ground part of the plant is a necessary factor for evaluating the anchoring capacity of the plant15,16,17. The role of soil properties in plant anchoring is at two levels. Firstly, the compactness of the soil affects its effectiveness in holding plants; secondly, soil conditions also regulate the development of the root system, which indirectly affects the root system’s role in supporting plants. In addition, it also reduces the quality of corn kernels and limits the use of agricultural machinery, thereby complicating the harvesting process. Therefore, it is important to solve the problem of the lodging of maize production.

Preceding experiments have found that wind speed and lodging rate are positively proportional and the combined influence of wind and rain tends to cause lodging18. It has been shown that high wind is an external factor that affects lodging, and strong winds before and after the tasseling stage can lead to lodging rates of 86.0-98.5%19. Furthermore, there was a very strong association between planting density and lodging rates20. Planting technique is another important element that influences lodging, in addition to planting density and factors related to root. Warming raised the danger of lodging by promoting the growth and advancement of maize stalks, changing their internal structure, and decreasing their resistance to wind thrust, as demonstrated by Liu Dongyao et al.21. Furthermore, it has been demonstrated that ridge and furrow rainfed planting greatly raises the center of gravity height and coefficient of ear position of corn in comparison to without mulch planting, increasing the risk of lodging22. Traditional mulch film planting has poor grip and shallow root dispersion, which makes them prone to lodging. There is a shortage studies on planting technology that efficiently manage plant lodging issues.

Dry land areas have promoted a variety of mulching cultivation methods to suit local conditions, each with unique yield-enhancing effects and mechanisms. Research reports on the applicability of maize mulching measures in dry-crop areas have shown that UPM and FSS are suitable for areas with annual rainfall of 313–545 mm and average annual temperatures between 5.4 and 10.4 °C23. In the initial phases of maize’s spring growth, UPM with FSS can increase soil moisture content for crop growth. And FSS can reduce the cost of manual seedling release and achieve yield and income stability for sustainable corn production in semi-arid areas24. However, its effect on the resistance to lodging is not clear. Hence, the major targets of this work were to (i) clarify the impacts of each treatment on mechanical characteristics and root morphology in spring corn plants, (ii) identify the influence of each treatment on yield, and (iii) evaluate lodging risk and economic benefits.

Materials and methods

Site

The trial location was located in Xiaotan Village, Xinfu District, Xinzhou City, Shanxi Province, China (112.43°E, 38.24°N). The temperate continental monsoon climate zone includes the research region. The temperature was 20 °C on average. In 2022 and 2023, the total amount of precipitation that fell on maize throughout its growing season was 376.1 and 294.1 mm, respectively. The months of July through September saw the most rainfall. (Fig. 1) The test field’s soil texture is sandy loam. The fertility status of the 0–60 cm soil layer of the test field is shown in Table S1.

Fig. 1
figure 1

Temperature and precipitation during the growing season of maize, 2022–2023.

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Experimental design

The experiment was arranged as a randomized block design with three replicates, and three treatments. The trial design utilized 29 cm interplant spacing within rectangular plots of 7 m × 5 m (35 m² per experimental unit). The trial configuration achieved a plant population density of 67.6 × 10³ ha− 1. The commonly used corn hybrid XianYu 335, characterized by taller stems and less developed root systems, was used in the experiment. The fertilizer used in the experiment was urea-formaldehyde slow-release compound fertilizer (245 kg N ha− 1, 136 kg P2O5 ha− 1, 91 kg K2O ha− 1), a one-time basal application. The planting methods were (1) FSS, sowing on the side of the plastic film (60 cm width) micro ridge (5 cm), (2) UPM, sowing on the plastic film (flat planting), and (3) CK, sowing without mulch (flat planting), as illustrated in Fig. 2. Polyethylene films of 0.01 mm thickness with dual width specifications (60/80 cm) were procured from Shanxi Ming Sheng Plastic Factory for the trial. During the 2022 and 2023 growing seasons, corn was sown on May 20 and May 21, respectively. Harvest dates are September 30, and October 5, respectively.

Fig. 2
figure 2

Schematic representation of the experimental treatments and corresponding photographs of maize seedlings under each treatment condition.”

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Sampling and measurements

Plant traits

At the physiological maturity period (R6), three plants were selected from each plot and their plant height, cob height were measured and cob coefficient (ratio of cob height to plant height) was calculated25. The thickness, rind penetration strength, and breaking strength of the third stem node the plant (the third internode at the base of plant) were measured at the tasseling stage (VT). The above indicators are randomly selected from each field, not the same sample. The data on plant traits for each treatment are shown in Supplementary Table S2.

Root pulling force

In the VT phase, the stalks were removed from the plants at 30 cm over the ground, and the bottom of the plant was fixed with a string and a root pulling force tester (Beijing Jinyang Wanda Technology Co., Ltd., Beijing, China). The force used to uproot the root system vertically was measured.

Lodging rate

Heavy winds and rains were encountered on August 22, 2022 (94 days after sowing) and September 2, 2023 (107 days after sowing), which resulted in the lodging of maize. On August 22, 2022, the temperature was 21.7 °C and rainfall was 23.3 mm. on September 2, 2023, the temperature was 22.5 °C and 18.4 mm of rainfall was recorded. The following day, a field survey was carried out to determine the fall rate per plot8. The growth stages at 96 and 107 days after sowing were the R3 period and R2 period, respectively.

Root morphology

Root samples were collected at the VT and R6 stages. The volume of soil used in the experiment was 12,500 cm3. Three collections were made in each experimental field, each at a depth of 60 cm in 20 cm layers. Filtering the soil using a 0.5 mm sieve, the samples were cleaned and stored26. The recording metrics involved the root length and diameter of the samples. Root length were measured using an HP Scanjet 8200 (Hewlett-Packard, Palo Alto, CA, USA) and an image analyzer (Delta-T Area Meter Type AMB2; Delta-T Devices, Cambridge, UK).

Root length density (RLD), Root surface area density (RSAD), and Root dry weight density (RDWD) were calculated using the following equations.

$${\text{RLD}}\,\left( {{\text{mm}}^{{\text{2}}} {\text{cm}}^{{{\text{ - 3}}}} } \right){\text{ = }}\frac{{{\text{Root}}\,{\text{length}}\left( {{\text{mm}}} \right)}}{{{\text{soil}}\,{\text{volume}}\left( {{\text{cm}}^{{\text{3}}} } \right)}}$$
$${\text{RSAD}}\,\left( {{\text{mm}}^{{\text{2}}} {\text{cm}}^{{{\text{ - 3}}}} } \right){\text{ = }}\frac{{{\text{Root}}\,{\text{surface}}\,{\text{area}}\left( {{\text{mm}}^{2} } \right)}}{{{\text{soil}}\,{\text{volume}}\left( {{\text{cm}}^{{\text{3}}} } \right)}}$$
$${\text{RDWD}}\,\left( {{\text{g}}\,{\text{dm}}^{{{\text{ - 3}}}} } \right){\text{ = }}\frac{{{\text{Root}}\,{\text{dry}}\,{\text{weight}}\left( {\text{g}} \right)}}{{{\text{soil}}\,{\text{volume}}\left( {{\text{cm}}^{{\text{3}}} } \right)}}$$

Yield

Yield determination was accomplished by collecting three rows of samples from the center area of each experimental field. The yield components and seed yield of each plot were then examined, and the yield of maize was computed at 14% moisture27.

Economic benefit

In this research, the difference in economic benefits between different mulching treatments was mainly determined by the amount or selling price of plastic-film mulching and the labor costs consumed. Thus, net income is equal to yield gains minus costs. Costs include the costs of materials (including corn seed, fertilizer, and mulch), labor (including land preparation, plastic-film mulching, fertilizer application, seeding, harvesting, and seedling release), and machinery application (including tillage and harvesting).

Statistical analysis

The data was assessed using software called SPSS. Excel was used to determine the standard deviations for each treatment. The significance of intergroup disparities(P < 0.05)was assessed using ANOVA coupled with LSD post hoc testing protocols. Graphs were created using SigmaPlot software. In this study, structural equation models (SEMs) were built based on an R language platform for investigating the mechanisms linking mechanical properties, root morphology, root nutrient uptake capacity, root lodging rate, and crop yield. Significant paths were integrated through a best-fit SEM framework, and the path coefficients quantitatively characterized the direction and strength of the linear relationships between variables.

Results

Mechanical traits

Different mulching methods had significant effects on plant mechanical characteristics. The rind penetration strength in FSS was 12.3% and 17% larger than in UPM and CK, respectively. Relative to the CK, the breaking strength under FSS and UPM showed respective increments of 46% and 37.2%. Similarly, the up rooting strength indication of FSS and UPM elevated by 53.1% and 47.2% over the CK (Table 1).

Table 1 Effect of mulching treatments on the mechanical characteristics at corn growth stages (VT) in 2022 and 2023.
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Root characteristics

Root diameter and root length

At the VT stages, the FSS and UPM significantly increased the root diameter by 26.2% and 20% in the surface 0–20 cm of soil and by 74.8% and 55.7% in the root length in contrast with CK, respectively. At the R6 stages, the FSS and UPM enhanced root diameter by 47.7% and 37.2% in this soil layer, respectively, as well as root length by 51.7% and 25.9% as compared to CK. Moreover, these indicators were greater in FSS than in CK in the soil layer between 20 and 40 centimeters in depth, while within the deeper pedogenic horizon (40–60 cm), the differences were not significant in the other treatments (Table 2).

Table 2 Effect of mulching methods on the root diameter and root length at soil layer 0–60 cm for 2022 and 2023 corn growth stages (VT and R6).
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Root length density, root surface area density, and root dry weight density

As shown in Table 3, film mulch considerably raised RLD, RSAD, and RDWD in spring corn. Within the top 0 to 20 centimeters of soil, the RLD, RSAD, and RDWD were 52.9%, 44.2%, and 79.2% greater at the VT stages of the FSS treatment than in the CK. These indicator were 40.7%, 24.3%, and 26.8% more for UPM than in CK. FSS had indicators that were 76.5%, 66%, and 65% higher than CK at the R6 stages.The individual indicators of UPM were higher by 35.5%, 33.6%, and 39.6%, respectively, compared to the CK.

Table 3 Effect of mulching treatments on root length density, root surface area density, and root dryweight density at soil layer 0–60 cm for 2022 and 2023 corn growth stages (VT and R6).
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In the middle soil horizon (20–40 cm), the RLD, RSAD, and RDWD of FSS at the VT periods increased by 62.3%, 92.4%, and 68.6%, compared with that of CK. Similarly, these values of UPM were 24.2%, 15.5%, and 59.3% larger than the CK. During the R6 periods, the FSS values in this layer were 50.9%, 92.4%, and 68.5% greater than those in CK. The indicators of UPM were 15.5%, 30.8%, and 37.5% greater than those of CK (Table 3).

Root absorption area, active absorption area, and root volume

Film mulch significantly increased root volume, root absorption area, active absorption area of spring maize. In the VT phase, in the first 0–20 cm of soil, FSS and UPM treatments boosted root volume by 71.9% and 30.1%, respectively, in contrast to CK. Both FSS and UPM treatments drastically improved the capacity of roots to take in, with the root absorption area and active root absorption area of the FSS enhanced by 26.1% and 32.9%, respectively, and that of the UPM treatment by 27.1% and 24.7%, respectively, in contrast to that of CK. At the R6, the FSS treatment’s root volume, root absorption area, and active absorption area were 34.9%, 55%, and 86.8% more than those of the CK, respectively. In comparison to the CK, the UPM treatment exhibited notable advances in these indices, with enhancements of 48.8%, 37.8%, and 17.9%, respectively. Besides, in the 20–60 cm soil depth range, the FSS treatment presented considerably greater root volume, root absorption area, and active absorption area than the CK treatment (Table 4).

Table 4 Effect of mulching methods on root absorption area, active absorption area, and root volume at soil layer 0–60 cm for 2022 and 2023 maize growth stages (VT and R6).
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Lodging rate

The rate of lodging showed a significant variation between the treatments. The total lodging rate, stem lodging rate, and root lodging rate of FSS were 82.9%, 77.4%, and 85.6% lower than that of UPM, respectively. These indicators of FSS were 92.5%, 81.2%, and 91.5% lower, respectively, than in CK (Fig. 3).

Fig. 3
figure 3

Effect of mulching methods on lodging rate in 2022 and 2023.

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Yield

Different mulching treatments were significantly different on yield. Data in Table 5 showed that FSS treatment increased spring maize yield, number of ears harvested, and thousand kernel weight by 14.2%, 14.7%, and 14%, respectively, while UPM treatment increased them by 5%, 7.2%, and 5%, respectively, compared to CK.

Table 5 Effect of mulching treatments on maize yield and its components.
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Correlation among yield, plant characteristics, root morphological, root lodging rate, and mechanical traits

The root lodging rate was markedly inversely connected with mechanical traits (Rind Penetration Strength, Breaking Strength, Up Rooting Strength) and root length, root volume, RLD, and RSAD. In addition, the root lodging rate was weakly inversely associated with root diameter, root absorption area, active absorption area, and RDWD. We also found that rind penetration strength, up rooting strength were weakly a positive association with ear height coefficient. Furthermore, a significant inverse relationship was observed between yield and lodging rate, while yield demonstrated a positive association with root morphological traits.These relationships suggest that the rate of lodging is severely affected by root morphology, which in turn affects yield (Table 6).

Table 6 Correlation among yield, plant characteristics, root morphological, lodging rate, and mechanical traits of spring maize.
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Net income

Although both FSS and UPM have the potential to enhance yield efficiency, there are notable differences in their respective cost structures, particularly in terms of expenditures on labor and the utilization of plastic film. The amount used of UPM plastic film increased by 33.6% and the overall cost input increased by 13.6% when compared to FSS. Furthermore, UPM’s manual “seedling release” resulted in higher labor costs and dropped production efficiency. According to the findings, the FSS treatment’s net profits were superior to those of the CK and UPM treatments by 16% and 15.8%, respectively (Tables 7 and 8).

Table 7 Effects of different treatments on economic benefits of maize production during 2022–2023.
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Table 8 Effect of different treatments on labor cost inputs in maize production during 2022–2023.
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Discussion

Strong root systems enhance yield and resilience to root lodging by improving root anchoring and enhancing nutrient and water uptake28. FSS exhibited favorable root characteristics with UPM in this study, suggesting that film mulching encourages root development. This is in keeping with the results obtained by Wang et al., which discovered that film mulching improved soil nitrogen utilization, encouraged root growth, and raised soil moisture, all of which inspired a boost in maize yield29. Roots are crucial for controlling crop growth and development aside from their function in absorbing water and nutrients30. One of the root system’s key structural characteristics is root diameter, which can vary to offer various physiological functions. To put it another way, plants can control the root diameter to adjust to their surroundings31. Thus, the morphological characteristics of the roots—such as their length, diameter, volume, etc.—have a significant impact on how well nutrients and water are absorbed. Combined with the results of this study, the root morphology indicators of FSS treatments at the VT and R6 phases were far bigger than those of UPM and CK. This denoted that FSS had a significantly larger root diameter, root length, and root volume, which led to deeper rooting and a stronger root fixation capacity (Tables 1 and 2 ). Moreover, the yield, breaking strength, and uprooting strength of FSS were also significantly increased, while the ear position coefficient of the corn and lodging rate were greatly reduced (Table S2, Fig. 3 ), This may be due to the significantly improved soil physical conditions for plastic film mulch-side seeding than flat mulched planting32. There are two primary areas where improvement is evident. First, the optimized soil environment promotes root development and expands the contact area between the root system and the soil, thus enhancing the anchoring ability of the plant. Second, Increased soil firmness appears to result in tighter inter-root soils, which may, to some extent, enhance the plant’s resistance to lodging33,34. The decline in yield and mechanical characteristics of UPM treatment may be due to limitations in root penetration capacity of conventional planting practices. Low root anchorage capacity is insufficient to withstand heavy rain or windy conditions. Higher lodging rate was a factor in lower yields.

The RLD, RSAD, and RDWD all play key roles in determining a crop’s ability to absorb water and nutrients. They are also key indicators of root growth dynamics and the root system’s expected response to environmental conditions35,36. The spatial distribution pattern and development and expansion of the crop root system directly affect its capacity to obtain water and nutrients, which ultimately determines the level of crop development and production. Our analysis indicated that RLD, RSAD, and RDWD were extremely weaker in UPM treatment than in FSS treatment (Table 3). This indicates that poor root development in UPM is an important cause of the high root lodging rate. The absorbing area of the root can be used as an evaluation index of water and nutrient uptake capacity, while its active absorbing area reflects the metabolic vigor of the roots37. The results demonstrate that the yield, the root absorption area, and the active absorption area of the UPM were much weaker than those of the FSS at the R6 period (Tables 4 and 5). This indicated that UPM treatment maize root nutrient uptake was weaker, and there was a risk of root senescence. This may be related to the increase in soil temperature. It has been suggested that early senescence occurs in flat mulching cultivation due to the increase in soil temperature during the late reproductive stage, which blocks gas exchange in the tilled soil, leading to accelerated maturation of plant root tissues, which in turn triggers root senescence38. Previous studies have shown that the FSS treatment lowered soil temperature, soil accumulation temperature at the late reproductive stage than the UPM treatment39. This may be the reason for the root defects affecting the UPM treatment. In addition, higher soil temperatures change the partitioning of photoassimilates to roots, inhibiting root growth or altering root architecture, which in turn reduces root anchorage strength. Also, hyperthermic environments stimulate cellular hyperplasia, leading to biomechanical deficiencies characterized by attenuated cell wall deposition and vascular bundle degradation, which collectively heighten lodging vulnerability40,41. In the latest research, Sun39 found that film-side sowing has lower soil temperature and soil accumulation temperature in the last stages of reproduction than flat mulching planting, which helps to maintain leaf photosynthesis, maintain normal grain filling, delay leaf senescence, and achieve the effect of stabilizing and increasing yields. This aligns with the results of the current investigation.

The ear height coefficient, root characteristics, and culm anchorage capacity demonstrate synergistic relationships as evidenced by agronomic research22. It was discovered that uprooting strength is closely connected with yield and adversely related with root lodging8. In this study, we discovered that root lodging rate was strongly negatively linked with mechanical traits throughout cultivation approaches and crop development stages. The rate of lodging was inversely associated with root characteristics indicators (Table 6; Fig. 4).

Fig. 4
figure 4

Structural equations for the correlation of mechanical properties, root morphology, root nutrient uptake capacity, root lodging rate, and yield under different treatments were obtained by modeling. Significance levels are indicated by *P < 0.05, **P < 0.01, and ***P < 0.001.

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In addition, we constructed a model to explore the association between mechanical properties, root morphology, nutrient uptake capacity, root lodging rate and crop yield (Fig. 4). Among the latent variables, mechanical properties had the most significant effect on root lodging rate. After analysis, root morphology and root nutrient uptake capacity directly affect crop yield. Hence, these characteristics are critical for rational cultivation, as they improve maize root resilience to lodging. This implies that maize’s poor root system under flat mulching cultivation conditions is the primary cause of yield decrease and low root system resistance to lodging. Thus, boosting root development could be an essential strategy to improve maize root system resilience to downing and grain yields. Furthermore, additional physical characteristics may need to be examined in future trials to better understand root system sensitivity to lodging. The results of the work provide feasible technical guidelines for agricultural producers to improve the resistance of maize to lodging.

Farmers generally aim for high yields and returns. Based on this, this study evaluated the cost inputs and economic benefits of the treatments (Tables 7 and 8). The results showed that the cost of UPM increased by about $150 ha-1 compared to CK, mainly from the increase in mulch procurement and labor cost. The finding that FSS significantly reduces the cost expenditure on plastic films by reducing the amount of mulch used compared to UPM is in line with the findings of established studies24. In addition, the FSS technique sows the seeds on the side of the mulch without the need to manually release the seedlings, thus saving $85.72 ha-1 in labor cost. It has been shown that mulching methods that do not require additional labor investment can achieve better profitability, and this conclusion is also suitable for the FSS technique employed in this study42,43. In this research, one of the main factors influencing earnings is whether or not to invest more labor. If the artificial seedling link is not considered, the additional labor input is practically non-existent. However, in terms of yield performance, FSS > UPM > CK. Furthermore, UPM had an average annual lodging rate of 40%, which was considerably larger than that of FSS (5.5%), implying that it would make harvesting at the maturity stage more difficult, requiring labor intervention and increasing costs. If the additional labor costs in farmers’ field management are taken into account, the yield gains cannot fully compensate for this expenditure. Therefore, the net benefit of FSS is superior to UPM regardless of whether the additional labor cost is included or not. In summary, FSS shows an enormous chance to enhance the economic efficiency of the indigenous non-irrigated agroecosystems and resistance to lodging.

Conclusion

FSS significantly promoted root development and increased aboveground breaking strength and rooting strength. It enhanced the resistance of spring corn to lodging with the highest yield and economic benefits. UPM was at risk of root senescence in the late reproductive stage, with reduced mechanical properties and reduced resistance to lodging, resulting in lower yields. Corn root lodging rate was substantially inversely correlated with mechanical properties, root length, RLD, RSAD, and weakly negatively correlated with plant cob coefficient, root diameter, and RDWD. It indicates that the poorer root system of corn cultivated in flat mulch is the critical cause for the poorer root lodging resistance. Therefore, these findings are of great practical importance for enhancing the yield and resistance of lodging within the water-limited agroecological zones of northwestern China.