Search

In order to optimize N application and understand how the different combinations of water and N management affect grain filling characteristics and yield, we designed three irrigation regimes (W1 submerged irrigation, W2 alternate irrigation, W3 dry cultivation), and different N application strategies at 180 kg ha−1 in 2010 and 2011. The relationship between grain filling characteristics and grain yield formation were respectively investigated. The results revealed that there were obvious interacting effects of irrigation regime and N application strategies on grain yield and grain-filling characteristics as well. Compared with W1 and W3 treatments, under W2, the N-fertilizer should account for 30% base, 30% tillering, and 40% panicle fertilizer with the last being applied equally at 4th and 2nd leaves emerged from the top. Correlation analysis revealed that grain filling rate during middle grain-filling stage was the largest and contribute more than 50% to grain-filling. Grain yield was significantly related to grain filling rate (Gmax or Gmean), final weight of a kernel (A), and mean grain filling rate (MGR) of the early, mid and late stages during grain filling in inferior spikelets, which is the important reason for water and N coupling effect further to increase yield and fertilizer use efficiency. [ABSTRACT FROM AUTHOR]

Rice yields have stabilized in the Chengdu Plain, and the implementation of integrated paddy field farming has shown potential for enhancing resource utilization. However, further investigation is required to clarify its impact on production sustainability. Accordingly, this study compared grain yields, energy use, greenhouse gas emissions, and economic benefits of single cropping rice (SCR), rice-duck symbiosis (RDS), and rice-fish symbiosis (RFS) over a three-year period (2018–2020). The grain yields were 16.24%–23.96 % higher in SCR than in RDS and RFS, but nitrogen fertilizer use was reduced by 31.93%–32.15 % in RDS and RFS, and the partial factor productivity of nitrogen was increased by 21.96–23.82 %. RDS and RFS required 1.87–2.00 times more energy than SCR and were only 55.36%–57.80 % as efficient as SCR. They also had higher CO 2 (36.10%–42.20 %) and CH 4 (8.01%–28.88 %) emissions but lower N 2 O (0.02%–21.18 %) emissions than SCR. Economically, RDS and RFS produced 1.30–1.48 times higher net benefits with 1.44–1.47 times higher costs than SCR. The benefit-cost ratio of RFS was comparable to SCR and 11.38%–11.87 % higher than RDS. In summary, RDS and RFS consume more energy (feed accounts for more than half) but provide higher yields and better-quality proteins, which are crucial to improving farmer motivation and ensuring protein availability. [Display omitted] • A 3-year field experiment was conducted to assess integrated paddy field farming. • Yields, energy use, greenhouse gas emissions, and economic benefits are assessed. • Rice-fish symbiosis is a low-pollution, high-yield farming mode. [ABSTRACT FROM AUTHOR]