Improving yield and nitrogen use efficiency of hybrid indica rice through optimizing nitrogen application strategies in the rice season under different rotation patterns

Improving the yield and nitrogen use efficiency of hybrid rice through rational use of controlled-release nitrogen fertilizer and urea topdressing

“…The N treatments ( Table 1 ) were as follows: (1) no N application (N 0 ); (2) local conventional urea-N (180 kg ha -1 ) practice (N 1 , 120 kg N ha -1 as a base + 60 kg N·ha -1 as a tiller fertilizer) ( Sun et al., 2012 ); and (3) application of polymer-coated controlled-release N fertilizer (150 kg ha -1 ) under total N reduction (N 2 , 100% as a base). Previous studies by our group and others have shown that most hybrid indica rice belongs to heavy-panicle type varieties (single panicle weight > 5.0 g) and revealed that topdressing conventional urea-N (panicle N application accounts for 20% of the total N amount) at the panicle initiation stage ( Yang et al., 2014 ; Sun et al., 2023a ) was beneficial for improving grain-filling and grain yield. Based on these, in the present study, we used 150 kg N ha -1 as a base level and conventional urea-N (30 kg ha -1 ) at 20% of the total N amount as a top dressing; four treatments with different controlled-release N and conventional urea-N ratios were established: (4) 80%:0% (N 3 ); (5) 60%:20% (N 4 ); (6) 40%:40% (N 5 ); and (7) 20%:60% (N 6 ).…”

“…Improving NUE not only improves the economic benefits but, more importantly, the N fertilizers are absorbed by the plants and remain in the soil-plant system, which reduces the pollution of the ecological environment and the harm to human health ( Peng et al., 2006 ; Sun et al., 2023a ). Wu et al.…”

“…Rice ( Oryza sativa L.) is one of the major food crops worldwide ( Mohanty, 2013 ; Sun et al., 2023a ). With population growth and economic development, it is estimated that by 2030, the world’s total rice production will have to increase by 60% and 20% in China to meet demand ( Peng et al., 2009 ; Guo et al., 2023 ).…”

“…To obtain high rice yields, the application rate of fertilizer has been greatly increased; however, the nitrogen use efficiency (NUE) has decreased ( Peng et al., 2009 ). The average NUE worldwide is approximately 46%, whereas that in China is only 30-35% ( Peng et al., 2006 ; Sun et al., 2023a ). For this reason, many scholars have explored methods for improving the NUE through variety selection ( Ma and Yuan, 2015 ; Li et al., 2023 ), straw return ( Yu et al., 2022 ), N fertilizer application ( Zhu et al., 2021 ), soil testing formula fertilization ( Chen et al., 2021 ), and leaf color diagnosis ( Peng et al., 1996 ; Pampolino et al., 2007 ).…”

Effects of postponing nitrogen topdressing on starch structural properties of superior and inferior grains in hybrid indica rice cultivars with different taste values

“…The experiment employed a two-factor, completely randomized design, incorporating diverse strategies for managing N fertilizer and different varieties. Based on a stable and efficient reduction of nitrogen application rate of 150 kg N hm -2 ( Sun et al., 2023 ), three N management practices were established: zero N (denoted as N 0 ), local farmer practice (basal N fertilizer: tillering N fertilizer: panicle N fertilizer=7:3:0, denoted as N 1 ) ( Shu et al., 2021 ; Shu et al., 2022 ), postponing N topdressing (basal N fertilizer: tillering N fertilizer: panicle N fertilizer=3:1:6, denoted as N 2 ). The N fertilizer (urea) was managed as follows: The base fertilizer was applied 1 d before transplanting, the tillering fertilizer was applied 7 d after transplanting, and the panicle fertilizer was applied at a 1:1 ratio during the inverse fourth-leaf and second-leaf stages.…”