Wang Zhuoqian, Jia Yan, Fu Jinxu, Qu Zhaojun, Wang Xinpeng, Zou Detang, Wang Jingguo, Liu Hualong, Zheng Hongliang, Wang Jin, Yang Liang, Xu Huimin, Zhao Hongwei
Key Laboratory of Germplasm Enhancement, Physiology and Ecology of Food Crops in Cold Region, Ministry of Education, Northeast Agriculture University, Harbin, China.
Bei Da Huang Kenfeng Seed Limited Company, Harbin, China.
Front Plant Sci. 2022 Jun 28;13:890983. doi: 10.3389/fpls.2022.890983. eCollection 2022.
Water shortages and nitrogen (N) fertilizer overuse limit japonica rice production in Northeastern China. The interactions between water-saving irrigation and nitrogen management on rice root and shoot growth is still our research focus. Here, japonica rice (DN425) was subjected to the irrigation methods W1 (flooding irrigation), W2 [mild alternate wetting and drying irrigation (AWD); -10 kPa], W3 (severe AWD; -30 kPa), and different N fertilizer ratios were applied in different growth stages, namely, N1 (6:3:1:0), N2 (5:3:1:1), and N3 (4:3:2:1). From jointing to full heading stages, the highest photosynthate production capacity and root activity were obtained under W1N2. AWD markedly affected the root system and resulted in root senescence at later growth stages. Grain yield and N utilization efficiency were closely and positively correlated with the relative water content, crop growth rate (CGR), leaf area duration (LAD), the increase rate of root length density, root surface area density, and root volume density (RVD) from the jointing to full heading stages. This positive correlation was also observed in the increased rate of root bleeding sap (RBS) under W1N2 and CGR under W2N3. From full heading to maturity stages, N2 could promote root growth, LAD, and CGR under AWD to a greater extent than those under the other treatments. Water use efficiency (WUE) and N uptake efficiency (NUpE) were both negatively associated with the decreased rate of RVD, root dry weight (RDW), and RBS. They were closely and positively correlated with the increased rate of RDW and CGR. Our results suggested that W2N2 treatment delayed root senescence, maintained leaf photosynthesis, optimized the crop growth rate from full heading to maturity stages, and improved grain yield. The optimal grain yield, WUE, and NUpE were achieved at the irrigation water amount and topdressing fertilizer ratio of 41.40-50.34 × 10 and 31.20-34.83 kg ha, respectively.
水资源短缺和氮肥过度使用限制了中国东北地区粳稻的生产。节水灌溉与氮肥管理对水稻根系和地上部生长的相互作用仍是我们的研究重点。在此，粳稻品种（DN425）采用了灌溉方式W1（淹灌）、W2 [轻度干湿交替灌溉（AWD）；-10 kPa]、W3（重度AWD；-30 kPa），并在不同生长阶段施用不同比例的氮肥，即N1（6:3:1:0）、N2（5:3:1:1）和N3（4:3:2:1）。从拔节期到齐穗期，W1N2处理下光合产物生产能力和根系活力最高。AWD显著影响根系系统，导致生育后期根系衰老。籽粒产量和氮素利用效率与拔节期至齐穗期的相对含水量、作物生长速率（CGR）、叶面积持续期（LAD）、根长密度增加率、根表面积密度和根体积密度（RVD）密切正相关。在W1N2处理下的伤流液增加率（RBS）和W2N3处理下的CGR中也观察到这种正相关。从齐穗期到成熟期，N2在AWD条件下比其他处理更能促进根系生长、LAD和CGR。水分利用效率（WUE）和氮素吸收效率（NUpE）均与RVD、根干重（RDW）和RBS的降低速率呈负相关。它们与RDW增加率和CGR密切正相关。我们的结果表明，W2N2处理延缓了根系衰老，维持了叶片光合作用，优化了齐穗期至成熟期的作物生长速率，并提高了籽粒产量。在灌溉水量和追肥比例分别为41.40 - 50.34×10和31.20 - 34.83 kg·ha时，达到了最佳籽粒产量、WUE和NUpE。
