Do reduced water and nitrogen input in rice production necessarily reduce yield?

Abstract

This study explored the effects of water and nitrogen management on yields, as well as water and nitrogen use efficiency, in the production of rice (Oryza sativa L.). The study aimed to provide theoretical and technical support for high yield practices and efficient resource utilization. Three replicate splitplot experiments were conducted in the field using flooding irrigation and controlled irrigation as the primary treatments. The secondary treatments included no nitrogen application, the farmers' usual nitrogen management, optimized nitrogen treatment, and uniform nitrogen application. Uniform nitrogen achieved the highest yield (11.91-14.12 10 3 kg ha -1 ) with controlled irrigation, in which case 20% less nitrogen is applied than in the case of optimized nitrogen treatment and farmers' usual nitrogen management. Controlled irrigation + uniform nitrogen required 24.18-35.82% less irrigation than flooding irrigation. Controlled irrigation + uniform nitrogen yielded the lowest reduction (18.52-20.00%) in the dry weight of deep roots (20-30 cm) within 30 days after heading. Comparatively, this reduction was 27.54-30.26 and 38.71-42.11% under controlled irrigation + optimized nitrogen treatment and controlled irrigation + farmers' usual nitrogen management, respectively. At the heading stage, light interception was highest under uniform nitrogen. Nitrogen recovery efficiency under uniform nitrogen was 8.53-17.88 and 46.77-60.79% higher than that under optimized nitrogen treatment and farmers' usual nitrogen management, respectively. Furthermore, nitrogen use efficiency under uniform nitrogen was 19. 84-29.70 and 76.16-94.44% higher than that under optimized nitrogen treatment and farmers' usual nitrogen management, respectively, low-intensity/ high-frequency nitrogen application combined with water-saving irrigation can greatly reduce water and nitrogen input while maintaining a stable yield to achieve food security and efficient resource utilization in rice production.K e y w o r d s: rice (Oryza sativa L.), water management, nitrogen fertilizer management, water and nitrogen use efficiency, yield

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.…”