Zhang Xiangqian, Xu Yunji, Du Shizhou, Qiao Yuqiang, Cao Chengfu, Chen Huan
Crops Research Institute, Anhui Academy of Agricultural Sciences, Hefei, Anhui, China.
Joint International Research Laboratory of Agriculture and Agri-product Safety, The Ministry of Education of China, Yangzhou University, Yangzhou, Jiangsu, China.
Front Plant Sci. 2023 Aug 29;14:1199168. doi: 10.3389/fpls.2023.1199168. eCollection 2023.
Optimizing the N application amount and topdressing ratio can increase crop yield and decrease N loss, but its internal mechanisms have not been well studied, especially from the aspects of population dynamics and structure, ear fruiting traits. Here, field experiments, with three N rates 120 (N1), 180 (N2), and 240 (N3) kg N ha and three N topdressing ratios T1 (7:3), T2 (6:4), and T3 (5:5) were conducted. At the same N level, results showed that the N accumulation amounts in the leaf, grain, and plant in T2 were higher than in T3 and T1, and increasing 60 kg N ha (N3 compared to N2, N2 compared to N1) significantly enhanced N accumulation amounts. The effect of the N topdressing ratio on partial factor productivity of applied N was consistently T2 > T3 > T1, but T1 was more conducive to improving N utilization efficiency for grain and biomass production. After the jointing stage, compared to T1 and T3, T2 was more conducive to increasing the population growth rate of plant height, leaf area index, leaf area growth rate, dry matter weight, dry matter accumulation rate, light interception rate, and spikelets of population, and the above-mentioned indexes of population could be significantly enhanced by increasing 120 kg N ha. T2 increased the fruiting spikelets per ear, grains per ear, grain weight per ear, fruiting rate per ear, grain filling rate per ear, and yield but decreased the sterile spikelets at the top and bottom and imperfect grains per ear. Increasing N from 120 kg ha to 180 kg ha or from 180 kg ha to 240 kg ha significantly enhanced yield. The N accumulation amount in the grain, leaf, plant, leaf area growth rate, dry matter accumulation rate, light interception rate, population spikelets, fruiting spikelets per ear, grain filling rate, and yield were significantly positively correlated with each other. This study demonstrates a suitable N application rate with a N topdressing ratio 6:4 would more effectively improve N efficiency, population dynamics, structure, ear fruiting traits, and yield, but the effect of the N topdressing ratio is not as significant as that of increasing 60 kg N ha.
优化施氮量和追肥比例可提高作物产量并减少氮素损失，但其内在机制尚未得到充分研究，尤其是在群体动态与结构、穗部结实性状方面。在此，进行了田间试验，设置了三个施氮量水平，分别为120（N1）、180（N2）和240（N3）千克氮/公顷，以及三个追肥比例T1（7:3）、T2（6:4）和T3（5:5）。在相同施氮水平下，结果表明，T2处理下叶片、籽粒和植株中的氮素积累量高于T3和T1处理，每公顷增加60千克氮（N3相较于N2，N2相较于N1）显著提高了氮素积累量。追肥比例对氮肥偏生产力的影响始终为T2>T3>T1，但T1更有利于提高籽粒和生物量生产的氮素利用效率。拔节期后，与T1和T3相比，T2更有利于提高株高、叶面积指数、叶面积生长速率、干物质重量、干物质积累速率、群体透光率和群体小穗数的群体生长速率，每公顷增加120千克氮可显著提高上述群体指标。T2增加了每穗结实小穗数、每穗粒数、每穗粒重、每穗结实率、每穗籽粒灌浆速率和产量，但减少了顶部和底部的不育小穗数以及每穗不完善粒数。每公顷施氮量从120千克增加到180千克或从180千克增加到240千克显著提高了产量。籽粒、叶片、植株中的氮素积累量、叶面积生长速率、干物质积累速率、群体透光率、群体小穗数、每穗结实小穗数、籽粒灌浆速率和产量之间显著正相关。本研究表明，追肥比例为6:4的适宜施氮量能更有效地提高氮效率、群体动态、结构、穗部结实性状和产量，但追肥比例的效果不如每公顷增加60千克氮显著。
