The aim of this study was to provide the theoretical and technical support for the innovation of green, high-yield, high-quality and high-efficient unmanned cultivation technology system of wheat.

According to the situation of accelerating land transfer and large-scale operation, decreasing labor force engaged in agricultural production, and more efficient and comfortable farming methods, the integrated unmanned cultivation technology of wheat was put forward through the integration study of “agronomy-machinery-intelligence”, that is, using new technology, new product and new equipment to simplify and integrate the whole process of wheat production, and complete wheat production with the least number of operations, the least number of machines and unmanned operations. On the basis of exploratory experimental research, the integrated unmanned cultivation technology of wheat (IU) and conventional mechanized high-yield cultivation techniques of wheat in experimental area (CK) were set up as treatments in Dazhong Farm of Yancheng, Jiangsu Province in 2019-2020, 2020-2021 and 2021-2022, to study the traits and differences of wheat yield formation among different technology treatments, analyze the high-yield traits of IU, and put forward the technical approaches of IU.

The IU increased wheat yield by 3.0%-5.9% compared with CK, and significant differences were observed between treatments of some varieties or some growing seasons. In terms of yield components, the spike number was IU>CK (significant differences were observed between treatments of some varieties or some growing seasons), the grains per spike were IU>CK (P>0.05), the total grains were IU>CK (P<0.05), and the 1000-kernels weight was IU<CK (P>0.05), indicating that the IU increased wheat yield by stabilizing the grains per spike and 1000-kernels weight, and increasing the spike number. In the production of photosynthetic matter, the culm number, leaf area index, dry matter accumulation at the main growth stages, the leaf area duration and crop growth rate in the main growth periods, and the culm fertility and grain leaf ratio were all expressed as IU>CK (significant differences were observed between treatments of some varieties or some growing seasons), which laid a material foundation for the yield increase of the IU. This paper not only summarized the technical approaches and basic technologies of IU but also discussed the development of IU from the aspects of integrated cultivation, unmanned cultivation, “agronomy-machinery-intelligence” fusion degree, key agronomy technology and comprehensive evaluation.

The yield under IU was equivalent or significantly increased to that under CK. And the high-yield cultivation of wheat was realized with less agricultural machinery and labor and unmanned operation, which was an effective way for the development of agricultural modernization production. In the future, multi-faceted collaborative innovation and investment should be strengthened to accelerate the application and large-scale promotion of this technology.

Compared with continuous flooding, the water-saving irrigation can increase water use efficiency. However, the effects of water-saving irrigation on yield and quality in rice paddies have not been clearly defined. The objective of this study was to identify the systematic effects of water-saving irrigation on rice yield and quality through Meta-analysis techniques.

In the present study, a total of 34 studies that adapted a water-saving treatment and continuous flooding as the control involving 263 paired observations were included across this dataset. The meta-analysis was conducted to identify the responses of yield and quality to water-saving irrigation as affected by experimental type, water-saving irrigation type, cropping system, rice type, the period of water-saving irrigation, soil total nitrogen (N), soil texture, N rate, and the number of N application.

Overall, the water-saving irrigation did not significantly affect grain yield and quality relative to continuous flooding. In terms of water-saving irrigation type, the moderate water-saving irrigation increased brown rice rate (+0.9%), milled rice rate (+1.5%), and head milled rice rate (+2.3%), but did not affect grain yield, chalkiness percentage, chalkiness degree, length/width ratio, amylose content, gel consistency, and protein content relative to continuous flooding. However, the severe water-saving irrigation significantly decreased grain yield (-22.1%), brown rice rate (-2.7%), milled rice rate (-2.7%), and head milled rice rate (-3.6%), and increased chalkiness percentage (+28.0%) and chalkiness degree (+46.7%), while no marked differences were observed on length/width ratio, amylose content, gel consistency, and protein content. Furthermore, compared with continuous flooding, the water-saving irrigation reduced protein content (-9.8%) of late rice, but did not affect that of early rice, middle rice, and single rice.

Compared with continuous flooding, the moderate water-saving irrigation could improve rice milling quality, and did not affect grain yield, appearance quality, cooking and eating quality, and nutrition quality. The severe water-saving irrigation significantly reduced rice yield, milling quality, and appearance quality, while no significant effects were found on cooking and eating quality and nutrition quality. The results provided an insight to evaluate the responses of grain yield and quality to water-saving irrigation.

The experiment was conducted to clarify the differences in the yield and quality of double cropping high-quality late indica rice and the selection criteria for variety tapes under mechanical transplanting (MT) and mechanical direct seeding (MS).

Early-maturing late indica rice, medium-maturing late indica rice, moderately late-maturing late indica rice, late-maturing late indica rice and extremely late-maturing late indica rice were used as materials, and two planting methods including MT and MS were set to study the yield and quality characteristics of high-quality late indica rice.

(1) The seed setting rate and the number of spikelets in the population of the high-quality late indica rice under MT were significantly higher than that under MS, and the 1000-grain weight under MT also increased, finally the actual yield was significantly increased. For MT, the medium-maturing late indica rice had the highest yield, followed by moderately late-maturing late indica rice; while for MS, the early-maturing late indica rice had the highest yield, followed by medium-maturing late indica rice. (2) Compared with MS, the processing quality of high-quality late indica rice varieties under MT was better for the significantly higher brown rice rate, milled rice rate and head rice rate, but the appearance quality deteriorated because of the increased chalky rice rate and chalkiness degree. The cooking quality improved for higher gel consistency, breakdown, taste value and lower amylose content. The highest brown rice rate, milled rice rate, and head rice rate were all found in medium-maturing late indica rice under two planting methods, chalky rice rate and chalkiness degree among different varieties showed the trend of extremely late-maturing late indica rice<late-maturing late indica rice<moderately late-maturing late indica rice<medium-maturing late indica rice<early-maturing late indica rice. For mechanical transplanting high-quality late indica rice, the best cooking and taste and nutritional quality appeared in moderately late-maturing late indica rice, followed by medium-maturing late indica rice. For mechanical direct seeding high-quality late indica rice, medium-maturing late indica rice had the best cooking and taste and nutritional quality, early-maturing late indica rice also had high taste. (3) The milled rice rate and head rice rate were significantly positively correlated with daily mean temperature in 20 days after full heading, and the chalkiness rate and chalkiness degree were significantly positively correlated with daily mean temperature and daily mean maximum temperature. Taste value was observed to be significantly positively correlated with daily mean temperature and daily mean maximum temperature in 20 days after full heading.

Therefore, based on the comprehensive consideration of high yield and good quality, medium-maturing late indica rice and moderately late-maturing late indica rice were the most suitable for the mechanical planting method, while the moderately late-maturing late indica rice could also be considered for more attention to good tasting. The early-maturing late indica rice were the most suitable for mechanical direct seeding method, and medium-maturing late indica rice could be considered to use for obtaining high quality.

This study aimed to provide the theoretical and technical support for the innovation of green, high-yield, high-quality and high-efficiency unmanned dry direct-seeded (UDDS) cultivation technology of rice.

Medium-maturing medium japonica rice (Nanjing 5718) was selected as the experimental material, with unmanned carpet seedling mechanical transplantated (UCSMT), and conventional carpet seedling mechanical transplantated (CSMT) serving as control methods. A three-year field experiment was conducted to assess the impact of UDDS on growth, yield formation, quality characteristics of rice, and its economic benefits.

(1) Although UDDS was carried out with 2-3 days earlier than the control, it exhibited a full growth cycle that was 12-13 days shorter than those of UCSMT and CSMT, primarily due to the shortened period from sowing to jointing stage. (2) The average yield under UDDS from 2020 to 2022 was 10.5 t·hm^-2, representing a 3.0% increase than that of CSMT, although this difference was not statistically significant. In comparison with UCSMT, UDDS exhibited a significant yield reduction of 5.4%, and this decrease could be attributed to a reduction in the spikelet number per panicle, resulting in fewer total spikelet numbers and a decrease in dry matter accumulation and transport capacity from heading to maturity. (3) Compared with CSMT, UDDS exhibited slightly reduced processing quality, amylose, and protein contents, with no significant differences were observed. However, the significant reductions in chalkiness percentage and degree were noted, while the taste value increased, though not significantly. Compared with UCSMT, UDDS demonstrated a significant decrease in head milled rice rate, chalkiness percentage, degree, and amylose content, and protein content also decreased, though not significantly. Additionally, UDDS exhibited higher RVA peak viscosity and a significant improvement in taste value. (4) Under the UDDS mode, the cost of rice planting decreased, and the net income increased by 1.15 × 10³ yuan·hm^-2 and 0.93 × 10³ yuan·hm^-2, than that under UCSMT and CSMT, respectively.

In the rice-wheat rotation system, UDDS realized the synergy of high yield and income increase, and improved the appearance quality and cooking and eating quality of rice, the UDDS cultivation technology should be optimized in terms of improving the total spikelet number, accumulation and translocation of dry matter during filling stage, thereby getting the goals of high rice yield, great quality, and efficient synergy, simultaneously.