水肥一体化条件下密植高产玉米适宜追氮次数研究

毛圆圆; 薛军; 翟娟; 张园梦; 张国强; 明博; 谢瑞芝; 王克如; 侯鹏; 李召锋; 李少昆

doi:10.11674/zwyf.2022194

摘要:

目的研究水肥一体化条件下密植高产玉米适宜的追氮次数，为密植高产玉米氮肥运筹模式提供理论支撑和实践依据。

方法以玉米品种‘登海618’为试材，种植密度为12万株/hm²。基施氮肥为36 kg/hm²，追施氮肥为324 kg/hm²，并设置5个氮肥追施次数，分别为追施2次(NT2)、追施4次(NT4)、追施6次(NT6)、追施8次(NT8)和追施10次(NT10)，通过调查产量、干物质积累量、植株形态、茎秆机械强度、经济效益等，揭示追氮次数对玉米产量形成和抗倒伏能力的调控机制。

结果与NT2相比，NT4、NT6、NT8、NT10处理在2个生长季成熟期的平均叶面积指数分别提高5.5%、11.3%、15.2%、15.1%，吐丝至成熟期的光合势分别提高3.1%、8.6%、10.0%和5.7%，干物质快速积累的持续时间分别延长2、6、8、5天，最大积累速率分别提高4.4%、9.2%、14.8%和7.2%，地上部总干物质积累量分别增加7.5%、18.9%、23.9%、10.8%，产量分别提高6.2%、8.7%、12.3%和7.1%，氮肥偏生产力分别提高5.5%、7.5%、11.8%和7.1%，氮肥农学利用效率分别提高了40.8%、51.5%、82.5%和48.1%，经济效益分别提高10.3%、14.0%、20.1%、10.6%。随氮肥追施次数增加，玉米吐丝前营养器官干物质转运量对籽粒的贡献率呈先降低后升高的趋势，吐丝后干物质积累量对籽粒的贡献率呈先升高后降低的趋势，NT8处理的吐丝前营养器官干物质转运量最低，吐丝后干物质积累量最高。NT6和NT8处理的株高、穗位、茎秆抗折断力、基部节间穿刺强度、压碎强度、弯曲强度较高，NT2和NT10处理较低。

结论合理的氮肥追施次数可以延缓玉米叶片衰老进程，维持吐丝后较高的光合势，延长干物质快速积累的持续期并提高积累速率，增加吐丝后干物质量，同时，提高了茎秆基部节间的机械强度，增强了茎秆抗倒伏能力。氮肥分8次追施处理玉米的产量最高，达到22442 kg/hm²，氮肥农学利用效率和氮肥偏生产力分别为15.18和62.09 kg/kg，经济效益为2.94万元/hm²。在本研究密植和肥水灌溉条件下，氮肥分8次追施的效果最佳。

Abstract:

Objectives This study investigates the suitable nitrogen topdressing times in maize under high plant density and drip irrigation to achieve the highest yield and nitrogen efficiency.

Methods A field experiment was carried out in Shihezi City, Xinjiang. The maize variety Denghai 618 was planted in a high density of 12×10⁴ plants/hm². The rate of nitrogen fertilizer applied as base fertilizer was 36 kg/hm². The N rate of 324 kg/hm² was topdressed twice (NT2), 4 times (NT4), 6 times (NT6), 8 times (NT8) and 10 times (NT10), respectively. We studied the leaf area index (LAI), dry matter accumulation (DMA), yield, plant morphology, stem mechanical strength, and economic benefits.

Results Compared with the NT2, NT4, NT6, NT8, and NT10 increased the average LAI by 5.5%, 11.3%, 15.2%, and 15.1%, photosynthetic potential by 3.1%, 8.6%, 10.0%, and 5.7% from silking to maturity stage, and prolonged the duration of dry matter rapid accumulation by 2 days, 6 days, 8 days, and 5 days. Similarly, the maximum dry matter accumulation rates increased by 4.4%, 9.2%, 14.8%, and 7.2%, and the total shoot dry matter accumulation increased by 7.5%, 18.9%, 23.9%, and 10.8%, respectively. NT4, NT6, NT8 and NT10 increased yield by 6.2%, 8.7%, 12.3% and 7.1%, nitrogen partial productivity by 5.5%, 7.5%, 11.8% and 7.1%, and nitrogen agronomic efficiency by 40.8%, 51.5%, 82.5% and 48.1%, respectively. As a result, the economic benefits increased by 10.3%, 14.0%, 20.1% and 10.6%, respectively. An increase in the frequency of N fertilizer topdressing decreased maize dry matter transfer from the vegetative organs to dry grain weight before silking and subsequently increased. In contrast, the proportion of maize dry matter accumulation to dry grain weight after silking increased and subsequently decreased. The volume of dry matter translocation and dry matter accumulation after silking were higher in NT8 than in other treatments. The plant height, spike position, stem breaking strength, basal internode puncture strength, crushing strength and bending strength were higher in NT6 and NT8, and lower in NT2 and NT10.

Conclusion The appropriate N topdressing times delayed leaf senility at the later stage of spinning and maintained high photosynthetic potential, promoting the accumulation and translocation of dry matter after the silking stage. Thus, a high yield, N utilization efficiency, and economic benefit were achieved. Simultaneously, the appropriate N topdressing frequency also benefited the formation of stem mechanical strength and improved stem lodging resistance. Therefore, topdressing N 324 kg/hm² in 8 times showed the best result for yield, N utilization efficiency, and economic benefit under the high plant density and drip irrigation conditions.

水肥一体化条件下密植高产玉米适宜追氮次数研究

Optimum times of nitrogen topdressing in high-yield maize under high plant density and fertigation