Mechanical transplanting has been the largest planting mode of rice production, particularly in the rice-wheat double cropping area. But the soil preparation of rotary tillage (ploughing) cannot fully meet the requirements of machine planting in recent years, due to the single function, high failure rate, and low tillage quality. Flat, clean and solid can be expected for the high quality of rice planting and yield. The main purpose of this study is to explore the tillage and soil preparation for the high yield and quality of machine-transplanted rice under the total wheat straw returning. The experiment was carried out in the rice growing season of 2021 and 2022. The rice variety was taken as Nanjing 5718. The straw treatment was selected as the main area, whereas, the tillage was as the sub-area. Among them, the yield of previous wheat was about 7.2 and 8.3 t/hm² in the experimental field in 2021 and 2022, respectively, where the amount values of straw were 12.9 and 15.4 t/hm², respectively. Two straw treatments were set: straw without returning to the field (S1) and straw full returning to the field (S2). The straw was removed from the field in the S1 treatment using manual harrowing. The straw was returned to the field in the S2 treatment using rotary tillage. Three tillage modes and land preparation were: integrated dryland biaxial rotary tillage (T1), dryland uniaxial rotary tillage + paddy field uniaxial rotary tillage (T2), and paddy field uniaxial rotary tillage (T3). Some parameters were then determined, including the tiller number, leaf area index, dry matter, grain yield, as well as the processing, appearance and eating quality of rice. The results showed that the rice yield increased by 4.54% to 5.45% (P<0.05) under S2+T1 treatment, compared with the S1, whereas, the rice yield decreased by 1.77% to 2.41% and 4.11% to 6.48% (P<0.05) under T2 and T3, respectively. The rice yield was ranked in the descending order of T2>T1>T3 under the S1 treatment, whereas, the order of T1>T2>T3 was found under the S2 treatment. The rice yield in T1 treatment was depended mainly on the panicles, dry matter accumulation, and harvest index. The total returning of wheat straw was reduced the amylose content, the area and degree of chalkiness for the better appearance quality, protein content, and taste value, compared with the S1. In addition, there was the increase in the peak viscosity and breakdown value of starch, as well as the gelatinization and palatability of rice under the S2. The chalkiness and the taste value were ranked in the descending order of T2>T3>T1, and T1>T2>T3, respectively. The taste value under the T1 increased by 3.36%-5.90%, 7.44%-11.30%, and 1.38%-4.65%, 6.28%-11.23%, respectively, compared with the T2 and T3. In summary, the T1 treatment was greatly contributed to synergistically improve the rice yield, appearance quality, nutritional quality, and taste value of machine-transplanted rice under the total wheat straw return. The finding can provide the data and theoretical support for the integrated single tillage under the full return of wheat straw to the field in the rice wheat double cropping area during mechanical transplanting.

Film-covered rice cultivation has been significantly enhanced by the biodegradable films, film-covered mechanical transplanting, and controlled-release fertilizers. Mechanical and simple rice farming can be expected for environmentally friendly and sustainable agriculture. Film-covered mechanical transplanting is increasing in large-scale rice production. The promising approach can also offer to streamline the field operations with low labor inputs for high production efficiency. However, it is still lacking in the impacts of the film-covered cultivation on the rice yield, quality, and economic benefit. In this study, a systematic evaluation was implemented on the yield, quality, and economic benefit of the film-covered mechanically transplanted rice. The experimental materials were taken as the conventional japonica rice, indica-japonica hybrid rice, and hybrid indica rice varieties. Four treatments were also set as the film-covered cultivation with one-time application of controlled-release nitrogen fertilizer (FMCS), film-covered cultivation with multiple applications of conventional nitrogen fertilizer (FMCF), non-film-covered cultivation with one-time application of controlled-release nitrogen fertilizer (NFCS), and non-film-covered cultivation with multiple applications of conventional nitrogen fertilizer (NFCF). Mechanical transplanting was then simulated under farming scenarios. The results indicated that the fertilization methods obviously significantly impacted the yield performance trend of the film-covered cultivation. Specifically, the rice yield was ranked as the FMCS, NFCS, NFCF, FMCF, with significant differences observed between some treatments(P＜0.05). Among them, the FMCS was achieved in the high yield by optimizing the effective panicle numbers and grains per panicle, increasing total spikelet numbers, and maintaining seed-setting rates and thousand-grain weights. In terms of the rice quality, the FMCS increased the head rice rate by 0.8% and 1.5%, respectively, compared with NFCS and NFCF, whereas the chalkiness degree was reduced by 13.6% and 18.7%, respectively. Some significant differences were also observed to improve the processing and appearance qualities. Additionally, the FMCS shared a 0.9% reduction in the protein content, compared with the NFCF. Its taste value score was 2.2% and 1.0% lower than that of FMCF and NFCS, respectively, although there were no statistically significant differences. As such, the taste value of the FMCS remained, compared with the NFCS treatment. The increasing protein and amylose contents were attributed to the better cooking and eating quality of the rice. The economic benefit of FMCS was 525 Yuan/hm² lower than that of NFCS. Its ratio of output to input was also lower than those of both NFCS and NFCF. The reason was the obvious significant increase in the film and planting costs. Its profitability outstandingly exceeded that of NFCF, due to the suitable variety selection. Furthermore, the evaluation model was integrated with the analytic hierarchy process, the membership function of the optimal indices, and the fuzzy evaluation index. The overall value of FMCS was found to be lower than that of NFCS, but higher than that of NFCF. The significance of differences among these three treatments varied across years and rice varieties. Its relatively high benefits were then achieved in FMCS over the conventional cultivation. Therefore, the FMCS mode exhibited considerable potential for application among treatments in this experiment. Further optimization was also required for cost reduction and efficiency enhancement. Some recommendations were given on the membrane materials to reduce the costs, fertilizer application strategies to optimize the yield and rice quality, and mechanical operations for high efficiency. Additionally, it is critical to the physiological and ecological mechanisms underlying the growth and development of rice under film-covered cultivation. Integrated technologies can also be expected to promote the high-yield, quality, and efficiency film-covered rice cultivation in sustainable agriculture.

Planting density and grain filling are important cultivation practices and physiological processes that affect the yield and quality of indica-japonica hybrid rice. Elucidating how planting density influences the yield and quality of indica-japonica hybrid rice by regulating physiological processes such as grain filling, and revealing the relationships between grain filling characteristics and yield as well as quality, is of great significance. This study selected two indica-japonica hybrid rice varieties with different yield levels as experimental materials and conducted a two-year field experiment under four planting densities. The results showed that increasing the planting density of two indica-japonica hybrids affected photosynthesis, enzyme activities, and grain filling rate, reducing the brown rice rate, milled rice rate, head rice rate, protein content, and amylose content, while increasing chalkiness. However, the increase in tiller number enlarged the population and extended the grain filling duration. Consequently, the yield of the two hybrids increased significantly by 5.47%–11.38% and 4.76%–10.93%, respectively, and the taste values of superior grains (SG) and inferior grains (IG) increased by 0.83%–5.35%, 0.54%–2.45% and 0.96%–2.24%, 0.73%–2.65%, respectively. Analysis of the relationships between grain filling characteristics and yield as well as quality in indica-japonica hybrid rice revealed that a higher grain filling rate contributed to increases in brown rice rate, milled rice rate, head rice rate, protein content, and amylose content, while reducing chalkiness degree and chalky grain percentage. In contrast, a longer grain filling duration not only helped improve rice taste value but was also one of the main reasons for high yield.

To increase the yield of indica-japonica hybrid rice, it is crucial to explore their photosynthetic and population characteristics at different yield levels and quantify their response to varying planting densities. In this study, a two-year field experiment was conducted to test two indica-japonica hybrid rice varieties with different yield potentials (12 t ha⁻¹ and 15 t ha⁻¹, respectively) at four planting densities (D1: 21 cm × 30 cm; D2: 18 cm × 30 cm; D3: 16 cm × 30 cm; D4: 14 cm × 30 cm). High yield indica-japonica hybrid rice was primarily charcterized by a high number of spikelets per panicle and a greater spikelet weight, which increased the single panicle’s weight. In addition, rational material translocation and a coordinated source-sink relationship contributed to dry matter accumulation. Open plant morphology optimized leaf enzyme activity at all stages, improved photosynthesis, and increased yield by 20.54%–21.60%. Increasing the planting density of indica-japonica hybrid rice somewhat restricted the growth of the rice population, leading to decreases in spikelets per panicle, 1000-grain weight, seed-setting rate, plant height, length of the top three leaves, leaf width, leaf angle, and the number of primary and secondary branches. However, the higher number of basic seedling resulted in more effective panicles and an increase in total spikelets, increasing the yield of each variety by 4.17%–8.48% and 2.39%–12.71%, respectively. Optimum dense planting of indica-japonica hybrid rice will benefit the sink capacity and a synergistic increase in both yield and economic benefit. This study offers crucial theoretical insights and practical significance for increasing indica-japonica hybrid rice yield and ensuring food security.

The high labor demand during rice seedling cultivation and transplantation poses a significant challenge in advancing machine-transplanted rice cultivation. This problem may be solved by increasing the seeding rate during seedling production while reducing the number of seedling trays. This study conducted field experiments from 2021 to 2022, using transplanting seedling ages of 10 and 15 days to explore the effects of 250,300, and 350 g/tray on the seedling quality, mechanical transplantation quality, yields, and economic benefits of rice. The commonly used combination of 150 g/tray with a 20-day seedling age in rice production was used as CK. The cultivation of seedlings under a high seeding rate and short seedling age significantly affected seedling characteristics, but there was no significant difference in seedling vitality compared to CK. The minimum number of rice trays used in the experiment was observed in the treatment of 350–10 (300 g/tray and 10-day seedling age), only 152–155 trays ha^–1, resulting in a 62% reduction in the number of trays needed. By increasing the seeding rate of rice, missed holes during mechanical transplantation decreased by 2.8 to 4%. The treatment of 300–15 (300 g/tray and 15-day seedling age) achieved the highest yields and economic gains. These results indicated that using crop straw boards can reduce the application of seedling trays. On that basis, rice yields can be increased by raising the seeding rate and shortening the seedling age of rice without compromising seedling quality.

In the face of agricultural labor shortages, reducing labor and costs in rice production while meeting demand or increasing yield is crucial for sustainable agricultural development. Using crop straw boards and raising seedlings at a high-density can reduce labor demand and enhance rice yield. This study investigated the effects of seeding density and transplanting age on tillering patterns, panicle formation rates, and yield to determine the optimal cultivation practices for maximizing rice yield. Two-year field experiments were conducted in Sihong County, Jiangsu Province, China, using the japonica rice variety Nanjing 5718. Five seeding densities (150–350 g/tray) and four transplanting ages (10–25 days) were evaluated to assess their impacts on tillering patterns, panicle formation rates, and yield. Innovative crop straw boards were employed to enhance planting efficiency and reduce dependence on soil for raising seedlings. This approach also lessened tillage layer destruction, promoting sustainable practices. The results indicated that increasing seeding density significantly altered tillering and panicle formation patterns by reducing the occurrence and panicle formation rates of lower-position tillers. Although the occurrence of middle- and high-position tillers increased, the overall number of panicles per hill decreased, especially at higher densities, negatively affecting yield. Reducing the transplanting age promoted the emergence and panicle formation of lower-position tillers, thus mitigating these negative effects. Specifically, compared to traditional methods (150 g/tray, 20-day seedlings), the higher seeding density (300 g/tray) and reduced transplanting age (15-day seedlings) increased total panicle number by 3.79–4.73% and yield by 3.38–5.05%. Combining higher seeding densities with reduced transplanting ages offers significant advantages over conventional practices by enhancing resource utilization and improving tillering efficiency. These findings provide actionable recommendations for optimizing rice cultivation practices and contribute to sustainable agricultural development.

China’s total grain output has exceeded 650 million tons since seven years ago, with the great achievement of ever-increased grain output for 18 consecutive years. However, China’s cereal production is facing many severe challenges, such as the shortage of agricultural resources per capita, higher cost for crop production per hectare, sharp decrease of labor population and progressively increase of grain import. Therefore, it is necessary to discuss the frontiers and the directions of scientific and technological innovation in China’s field crop cultivation. According to the existing problems in field crop production, the major scientific and technological requirements of China’s field crop were elaborated, such as the cooperative cultivation of high-quality and high-yield and high-efficient, the green cultivation of carbon fixation and energy conservation and emission reduction, and the “unmanned” intelligent cultivation. The scientific and technological frontiers and development status and trends of field crop cultivation at home and abroad were analyzed emphatically. The key scientific and technological breakthrough directions and paths were pointed out in three aspects: The coordination cultivation of high-quality and high-yield and high-efficient, the green cultivation of carbon fixation and energy saving and emission reduction, and the “unmanned” intelligent cultivation. Finally, the measures and suggestions for scientific and technological innovation of China’s field crop cultivation were put forward from the aspects of policy top-level design and effective investment, increasing the research and development of basic theories, the key technologies and practical products, and increasing the cultivation of compound talents. In the future, it is necessary to significantly improve grain quality and planting efficiency under the premise of continuously increasing grain yield through the collaborative cultivation of high-quality, high-yield and high efficiency in field crop cultivation. Through the green cultivation of carbon fixation and energy conservation and emission reduction, less material input and high efficient utilization of resources can be achieved. Through integration and innovation of various aspects of agronomy and agricultural machinery intelligence, the “unmanned” intelligent cultivation can be constructed for greatly less labor input and higher efficiency of large-scale production. Finally, it is to realize Chinese style modernization of field crop production, to ensure grain security and effective supply of agricultural products.