Conventional transplanted rice (TPR) has been increasingly replaced by direct-seeded rice (DSR) because of its low water and labour requirements. Whether and how DSR can be as productive as TPR has received widespread attention. Here, a comprehensive meta-analysis was performed to quantify the effects of direct seeding on rice yield and identify the management and environmental factors that contribute to the yield gap between DSR and TPR. The results showed that, overall, the yield of DSR was 12% lower than that of TPR. However, the yield loss of DSR relative to TPR was highly variable depending on management practices, soil type, and climate conditions, ranging from −2% to −42%. Weed and water management and climatic stress had the largest impact on yield performance, resulting in over 15% yield variation. With respect to soil properties, the yield gap can be significantly reduced by planting in areas with high organic carbon content, such as clayed and acidic soils. Furthermore, the DSR yield penalty was only 4% in a high-yielding condition compared to 14% in a low-yielding condition. All these factors indicate that optimizing management practices is necessary to improve DSR yield performance and narrow the yield gap between DSR and TPR. In conclusion, DSR could produce comparable yields to TPR but is more prone to yield losses due to inappropriate management practices, unsuitable soil properties, and climatic stresses.

Genetic improvement has been devoted to increasing rice yield by increasing the spikelet number per panicle and the spikelet/leaf ratio. As a result, indica-japonica hybrid rice “Yongyou” varieties with large panicles and superhigh yield potential have been developed. These varieties exhibit significantly higher grain yield and nitrogen use efficiency for grain (NUEg) under moderate and high N supply conditions due to their large sink size, but their yield performance remains obscure under low N input and low soil fertility conditions. In the present study, we investigated four varieties including Yongyou2640 (YY2640, large-panicle india-japonica hybrid variety), Yangliangyou6 (YLY6, two-line indica hybrid variety), Quanyou6 (QY6, three-line indica hybrid variety), and Huanghuazhan (HHZ, indica inbred variety) under two low soil fertility treatments [LF (removing half of soil depth) and CK] and two N fertilizer rates (0 and 100 kg N ha⁻¹) in Central China. The results showed that the grain yield of YY2640 was more responsive to fertility than that of other varieties, which was 19.4–42.3% higher than that of the other three varieties under CK N100 treatment, but it was 14.5–19.4% lower than that of YLY6 and QY6 under LF N0 and LF N100. A higher spikelet/leaf ratio resulted in more biomass and N partition to panicles rather than to leaves under LF N0 and N100. Slightly more post-flowering dry matter obtained from higher leaf N content and crop growth rate failed to compensate for the adverse effects of reduced pre-flowering dry matter accumulation and stem-to-grain translocation during grain filling. This led to the lower NUEg of YY2640 than YLY6 and QY6 under low soil fertility conditions. Based on these findings, the present study suggested that the source–sink relationship of the super hybrid varieties should be optimized according to the soil N supply condition.

Yield potential has been significantly increased through hybrid rice breeding in the past, however, the genetic gain in grain yield is becoming marginal in recent years, especially in farmers’ field. The increase in climate variability is one potential reason for the stagnant rice grain yield. Moreover, overuse of nitrogen fertilizer and poor grain quality of hybrid rice reduce its advantage over inbred rice. The present study evaluated seventy‐eight elite hybrid varieties in 2014–2018 aiming to determine the climate variability and its influences on grain yield, nitrogen use efficiency (NUE), and grain protein content of the newly bred rice hybrid varieties simultaneously. It was found that daily maximum and minimum temperature, daily radiation varied significantly across planting years. The extreme differences for T_max, T_min, and radiation were 2.0°C, 1.5°C, and 3.6 MJ m⁻² d⁻¹, respectively. Overall, grain yield of 22 varieties was significantly increased in comparison to that of the control cultivar Yangliangyou6 (YLY6), which was closely dependent on the planting year. Grain yield of these elite varieties ranged from 9.69 to 11.97 t ha⁻¹, and NUE for grain production (NUEg) from 47.3 to 60.9 kg kg⁻¹. The inter‐annual variation in grain yield, NUEg, and grain protein content was significantly related to the average daily minimum temperature (T_min), due to its effects on grain filling percentage and harvest index. Moreover, these three properties are mutually correlated for all varieties across five years: grain yield positively correlated with NUEg (R² = 0.46) and negatively correlated with protein content (R² = 0.32), whereas NUEg negatively related to protein content (R² = 0.49). These results suggest that enhancing the adaptation to climate variability in hybrid rice breeding is essential and urgent for sustainable rice production in China.

Methane (CH₄) is a potent greenhouse gas, and rice paddies are a major source of agricultural CH₄ emissions. Water management and nitrification inhibitors can significantly affect CH ₄ emissions, but their coupled effects on rhizospheric CH₄ emissions remain unclear. This study employed a rhizobox experiment to investigate the effects of three water management practices—continuous flooding irrigation (C), wetting irrigation (W), and alternate wetting and drying irrigation (A)—and the nitrification inhibitor DMPP (3,4-dimethylpyrazole phosphate) on CH₄ emissions from rice paddies. The results revealed that the rhizosphere was the primary zone for CH₄ emissions, with fluxes up to eight times greater than those from the bulk soil. In all the treatments, peak CH₄ emissions consistently occurred during the rice maturity stage. This peak is attributed to increased carbon availability from root senescence, coupled with soil redox conditions primarily dictated by the respective water management regime. Water management emerged as the primary driver of emission reduction. Compared with C, A significantly reduced cumulative CH₄ emissions by approximately 83.0% in the bulk soil and by 96.9% in the rhizosphere. The application of DMPP further enhanced this mitigation effect, particularly under W and C conditions, leading to an additional 23.06% to 35.94% reduction in bulk soil CH₄ emissions. The observed mechanisms of DMPP addition likely extend beyond its traditional role as a nitrification inhibitor. In conclusion, alternating wetting and drying irrigation with DMPP addition most effectively suppressed CH₄ emissions by synergistically regulating water–carbon–nitrogen coupling processes. This study highlights the central role of rhizospheric processes in reducing emissions, providing a deeper theoretical foundation for developing targeted low-carbon management strategies for rice paddy cultivation.