The experiment was conducted in Shangxiao Town, Zhenyuan County, Qingyang City (107.2′ E, 35°68′N, 1295m above sea level) situated in Gansu Province, China, during the period of 2018 to 2020. The soil types observed were dark loessial soil. The average annual precipitation recorded was 510mm during the year 2018. Based on the data depicted in Figure 1 , the annual precipitation was documented as 646.0mm. Throughout the growth phase, Zhenyuan experienced a rainfall of 575.8mm in 2019. Zhenyuan encountered rainfall quantities of 587.5mm in 2020. It is noteworthy that the precipitation in 2018 exceeded that of both 2019 and 2020. Additionally, the average temperature during the growth period for corn cultivation, which spans from April to September, exhibited a gradual decline from 2018 to 2020. Specifically, the average temperatures were recorded as 20.17 °C, 19.45 °C, and 19.43°C for the respective years. The chemical properties of the test site soil are presented in Table 1 (Zhang et al., 2023).

These treatments, namely SH, HH, FP and CK differed in terms of cover methods, planting densities, and fertilizer management. With the exception of the CK treatment, all other treatments received uniform application of N, P, K, and organic fertilizer prior to land preparation and film covering. No additional fertilizer was introduced throughout the entire growth period. Field management adhered to practices employed in high-yield fields. Sowing was conducted using the full film double ridge furrow method, employing a polyethylene membrane with a width of 0.7mm and thickness of 0.01mm. The experimental plot consisted of a row measuring 5m in length, with line spacing of 0.75m and plant spacing of 0.30m. The planting density was 75000 plants per hectare. All seedlings were managed under the general field management methods. Four treatments were applied, and each was repeated 3 times. Effective accumulated temperature, growth length and photosynthetically active radiation can be found in Table 2 . Detailed information regarding each treatment can be found in Table 3 . Each year, all treatments received a basal application in the form of triple superphosphate (16% P₂O₅), N(100% N) and M (100% M). N and P were obtained STANLEY. M of (N + P2O5 + K2O ≥ 5%; organic content ≥ 45%)) was obtained HONGYUAN.

No potassium fertilizer(K) was added. The experiment involved testing four treatments within the same plot, all of which had uniform fertility. The experiment had four treatments each consisted three replications. The experiment encompassed a substantial area of 225m². The experiment utilized the spring maize variety of Xianyu 335, which exhibited robust stress resistance and consistent yield stability. Maize was planted in late April and harvested in late September. No irrigation throughout the entire growth period of maize.

The data were analyzed using SPSS software (version 21.0: IBM Corp., Armonk, NY, USA). The data was analyzed using a two-way analysis of variance with Duncan’s multiple-range test. A value of p< 0.05 was considered statistically significant, and a value of p < 0.01 was considered very significant. Origin 2021 (Origin Lab, Massachusetts) software was used to draw graphs. The tables and graphics were created using Excel 2019.

The yield was significantly different from different cultivation modes (P < 0.05). The yield order of the different cultivation modes was SH>HH>FP>CK, and the data of the 3-year field trial showed the same trends ( Table 4 ). Maize yield was significantly higher under SH, HH and FP cultivation modes as compared to the CK in 3-year(P<0.05). In the 3-year trial, the average yield of SH, HH and FP cultivation modes increased by 34.01%, 48.68% and 56.39% compared with CK cultivation mode. SH and HH cultivation modes increased by 22.24% and 33.92% compared with FP cultivation mode. SH cultivation mode increased by 15.01% compared with HH cultivation mode. The average yield of 2018 increased by 11.05% and 24.94%, compared with 2019 and 2020, respectively. The CK cultivation mode had the largest increase in yield in 2020 compared with 2019 and 2020 yields, increasing by 38.37% and 25.90%. The yield in 2018 of the SH, HH, FP, CK cultivation modes 38.41%, 8.56%, 4.29%, 4.88% and 25.91%, 20.78%, 20.42%, 30.85% was increase as in 2019 and 2020.

The WUE order of different cultivation modes was SH>HH>FP>CK, the data of the 3-year field trial showed the same trends. WUE was significantly higher under SH, HH and FP cultivation modes as compared to the CK in 3-year(P<0.05). In the 3-year trial, SH, HH, and FP cultivation modes of average WUE were 34.34%, 47.19% and 57.99% increase as CK cultivation mode. SH and HH cultivation modes were 19.57% and 36.02% lager than the FP cultivation mode. The average WUE in 2018 20.53% and 16.19% was increase as in 2019 and 2020 ( Table 5 ).

As shown in Figure 2 , the SPAD values of maize in seedling stage, jointing stage, silking stage, and filling stage of different cultivation modes during the experimental period showed that SH>HH>FP>CK. During the three-year period, the SPAD values of SH, HH and FP cultivation modes was on an average 27.71%, 54.21% and 59.81% in seedling stage ( Figure 2A ), 28.07%, 40.01% and 55.80% in jointing stage ( Figure 2B ), 33.21%, 41.05% and 58.16% in silking stage ( Figure 2C ) and 33.19%, 47.80% and 49.25% in filling stage ( Figure 2D ) greater than CK cultivation mode. The SPAD values in 2019 and 2020 were lower by 4.53% and 7.23% than in 2018.

The P_n of maize in seedling stage, jointing stage, silking stage, and filling stage different significantly among different cultivation modes. The P_n order of the different cultivation modes was SH > HH > FP > CK, and the data of the 3-year field trial showed the same trends in different stage. During the three years, the P_n of SH, HH and FP cultivation modes was on an average 15.26%, 18.71% and 29.86% in seedling stage ( Figure 3A ), 7.54%, 18.46% and 22.89% in jointing stage ( Figure 3B ), 15.47%, 22.48% and 22.89% in silking stage ( Figure 3C ) and 25.31%, 29.79% and 35.27% in filling stage ( Figure 3D ) greater than CK cultivation mode. The average P_n in 2019 were higher by 14.33% and 21.07% than in 2018 and 2020.

The LAI of maize in seedling stage, jointing stage, silking stage different significantly among different cultivation modes. The LAI order of the different cultivation modes was SH > HH > FP > CK, and the data of the 3-year field trial showed the same trends in different stage. During the three years, the average LAI of SH, HH and FP cultivation modes increased by 59.77%, 77.01% and 82.83% in seedling stage ( Figure 4A ), 21.91%, 48.44% and 61.37% in jointing stage ( Figure 4B ), 18.16%, 47.47% and 61.33% in silking stage ( Figure 4C ) compared with CK cultivation mode. The average LAI in 2020 were higher by14.33% and 21.07% than in 2019 and 2020.

The root index of different cultivation modes were different ( Figure 5 ). SH cultivation mode significantly enhances maize root length ( Figure 5A ), root diameter ( Figure 5B ), number of root tips( Figure 5C ) and root surface ( Figure 5D ) area with a 71.10%, 10.75%, 61.79% and 51.70% higher root length than that of CK cultivation mode. Root length was higher 0.44% and 8.34% in 2020 than that of 2018 and 2019, root diameter, number of root tips, root surface area were significantly higher 14.69%, 25.87%, 46.06% and 8.92%, 10.45%, 22.18% in 2018 than that of 2019 and 2020.

There was a highly significantly positive correlation between yield and WUE, P_n in silking and filling stage, LAI, SPAD value and root index, but was not correlated with P_n in seedling and jointing stage ( Table 3 ). The highly significantly positive correlation was detected between WUE and Pn in silking and filling stage, LAI, SPAD value and root index. Significantly positive relationship between WUE and P_n in seedling and jointing stage.

In Li Shangzhong’s study, an analysis was conducted on the maize yield and WUE of various film cover cultivation modes. The findings revealed that the full-film double-row furrow cultivation mode exhibited a significant increase of 21.9% and 31.3% in yield and WUE, when compared with the open field cultivation mode (Li et al., 2020). The cultivation mode had a significant impact on the yield and nutrient use efficiency of dryland spring maize (Zhu, 2009). This trend was similar with the results of Lal and Stewart and Zhong et al. for the same region. However, the WUE-yield relationship was quadratic when the full range of yield was considered (Zhong and Shangguan, 2014). The optimization of cultivation modes or the implementation of integrated agronomic measures has been found to have a significant impact on crop yield improvement (Jin, 2013). Our results demonstrates that the SH, HH modes exhibited superior yields, as evidenced by significantly higher of yield and WUE compared to the FP and CK cultivation modes.

The main place of plant photosynthesis is the leaf, which directly affects plant absorption and light energy utilization. LAI is an important indicator reflecting plant growth, development and light energy utilization, and maize should maintain a high LAI to achieve high yields (Zhang et al., 2011). Liu et al. found that LAI with the A3 treatment increased at the early growth stage (tillering) compared with A0 but decreased in subsequent growth stages and became lower than A0 at maturity. This may be due to the fast consumption of soil N by straw decomposition mediated by microbes and crop growth at early growth stages, resulting in insufficient nutrient supplies for subsequent growth (Liu et al., 2023. Cai et al., 1986). The application of CRF treatment resulted in a significant improvement in leaf chlorophyll content, delayed the reduction in chlorophyll levels in the leaf, enhanced the Leaf Area Index (LAI), and increased the maximum P_n during the pod-filling and mature stages of peanut growth (Liu et al., 2019). Nitrogen fertilizer transport can effectively regulate root growth, SPAD value is the result of the integrated effect of multiple factors (Zhuang et al., 2013). The previous study showed that rational fertilization is conducive to increase the maize LAI, improve the leaf SPAD value, and enhance the Pn of maize after spatulation (Bian et al., 2008). Previous studies on maize yield, LAI and SPAD value under different cultivation modes found that the LAI and SPAD of the super-high yielding cultivation mode increased by 80.03% and 13.73%, compared with than that of the farmer mode in Tibetan areas of the Western Sichuan Plateau. Our results demonstrates that the super-high yield mode and high yield and efficient cultivation mode exhibited superior yields, as evidenced by significantly higher values of LAI, P_n and SPAD values compared to the FP and CK cultivation modes. LAI, P_n and SPAD values of increase is due to the increase in rain, and the need for later compound synthesis. Furthermore, the SH and HH cultivation modes demonstrated a longer duration period of LAI, P_n and SPAD values.

The relationship between the size of the crop root system and crop yield is significant. A robust root system plays a crucial role in providing adequate nutrients and water for the growth and development of corn, thereby facilitating the realization of its high yield potential. Researchers have observed a noteworthy positive correlation between indicators such as root dry weight, root length, root surface area, and crop yield ( Table 6 ). The root development of summer maize is subject to alterations in response to variations in soil conditions and cultivation practices, whereby tillage technique, sowing depth, planting density, and fertilizer conveyance all exert notable impacts on root growth (Guan et al., 2014; Wang et al., 2014; Cao et al., 2015). The growth and development of the root system were significantly influenced by planting density. As density increased, the growth space for the maize root system decreased (Chen et al., 2017). The findings of this study demonstrate that the cultivation modes of SH and HH cultivation modes resulted in significantly higher root length, root surface area, root tip number, and root diameter compared to FP and CK cultivation modes. These results indicate that SH and HH cultivation modes effectively enhance the growth and development of maize root systems, leading to improved root system absorption performance. Therefore, given the prevailing circumstance of diminishing agricultural land, altering the cultivation mode emerges as the primary determinant for augmenting maize yield. Specifically, enhancing fertility, strategically planning planting density, and implementing mulching techniques are crucial in elevating maize yield in the northern region.