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.

Biaxial rotary tillage in dryland (DBRT) can complete biaxial rotary tillage with straw incorporation, secondary suppression, and ditching, and it has been previously studied in direct-seeded rice and wheat.  However, the effects of DBRT on the mechanically transplanted rice yield and greenhouse gas emissions remain unclear.  To evaluate the effects of DBRT on improving the food security of mechanically transplanted rice and reducing the greenhouse gas emissions, we conducted an experiment for two years with wheat straw incorporation.  Three tillage methods were set up: DBRT, uniaxial rotary tillage in dryland and paddy (DPURT), and uniaxial rotary tillage in paddy (PURT).  The results showed that compared with DPURT and PURT, DBRT increased the yield of machine-transplanted rice by 7.5–11.0% and 13.3–26.7%, respectively, while the seasonal cumulative CH₄ emissions were reduced by 13.9–21.2% and 30.2–37.0%, respectively, and the seasonal cumulative N₂O emissions were increased by 13.5–28.6% and 50.0–73.1%, respectively.  Consequently, DBRT reduced the global

Blast resistance and grain quality are major problems in hybrid rice production in China.  In this study, two resistance (R) genes, Pi46 and Pita, along with the gene Wx^b, which mainly affects rice endosperm amylose content (AC), were introgressed into an elite indica restoring line, R8166, which has little blast resistance and poor grain quality through marker-assisted selection (MAS).  Eight improved lines were found to have recurrent genome recovery ratios ranging from 88.68 to 96.23%.  Two improved lines, R163 and R167, were selected for subsequent studies.  R167, which has the highest recovery ratio (96.23%), showed no significant differences in multiple agronomic traits.  In contrast, R163 with the lowest recovery ratio (88.68%) exhibited significant differences in heading date and yield per plant compared with the recurrent parent.  At two developmental stages, R163 and R167 had greatly enhanced resistance to blast over the recurrent parent.  Similar trends were also observed for agronomic traits and blast resistance in R163- and R167-derived hybrids when compared with the counterparts from R8166.  In addition, R163, R167, and their derived hybrids significantly improved the grain quality traits, including amylose content (AC), gel consistency (GC), chalky grain rate (CGR), and degree of endosperm chalkiness (DEC).  It confirmed the success of efficiently developing elite restoring lines using MAS in this study.

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.  Utilizing crop straw boards and high-density seedling raising can reduce labor demand and enhance rice yield.  This study aimed to investigate the effects of seeding density and transplanting age on tillering patterns, panicle formation rates, and yield to determine optimal cultivation practices for maximizing rice yield.  Two-year field experiments were conducted in Sihong County, 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 impact on tillering patterns, panicle formation rates, and yield.  Innovative crop straw boards were employed to enhance planting efficiency and reduce dependence on seedling-raising soil.  This approach also lessened tillage layer destruction, promoting sustainable practices.  The results indicated that increasing seeding density significantly altered tillering and panicle formation patterns, 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 transplanting age promoted the emergence and panicle formation of lower-position tillers, mitigating these negative effects.  Specifically, compared to traditional methods (150 g/tray, 20-day seedlings), the higher seeding density (300 g/tray) and shorter 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, improving tillering efficiency.  These findings provide actionable recommendations for optimizing rice cultivation practices and contribute to sustainable agricultural development.