甘薯喷施烯效唑的适宜氮水平研究

摘要

【目的】为获得甘薯最佳氮肥和烯效唑配施用量，比较了6个施氮水平下甘薯的干物质积累量(DMA)、蔓薯比(T/R)、各器官氮素含量、甘薯产量、氮素利用率及烯效唑贡献率(UCR)的差异。探讨不同氮肥施用量下，叶面喷施烯效唑与济薯22生长及产量的关系。【方法】在山东平阴安城乡小官村开展甘薯氮肥田间试验，以不施肥为对照(CK)，设6个施氮量处理：0(N0)、45 kg/hm2(N1)、90 kg/hm2(N2)、135 kg/hm2(N3)、180 kg/hm2(N4)、270 kg/hm2(N5)；每个水平设置喷施烯效唑(N-U)和不喷施两个处理，烯效唑喷施浓度为25 mg/L。在移栽后85天、110天和收获期，调查了甘薯的干物质积累量、氮素利用率和产量。【结果】1)增施氮肥可明显增加甘薯地上部干物质积累量(DMA)。喷施烯效唑施氮处理间，除 N1-U外，DMA无明显差异，N3-U、N4-U和 N5-U地上部 DMA相对于氮处理显著降低，说明烯效唑喷施抑制了地上部分徒长；当施氮量大于90 kg/hm2时，氮处理与 N-U处理甘薯地下部 DMA均明显降低，但 N-U处理地下部 DMA均高于氮处理，其中 N1-U和 N2-U与相对应N处理差异显著。2)三个生育期的蔓薯比(T/R)，N-U处理的值均有不同程度地下降，说明烯效唑可起到抑制地上部生长或促进地下部生长的作用。3)喷施烯效唑提高了85天和110天甘薯蔓的氮含量，但对收获期影响不大；同一生育期内，氮处理与 N-U处理块根氮含量曲线在90 kg/hm2附近出现交点，并随着生育期发展慢慢前移，表示可提高块根氮含量的最小施肥量为90 kg/hm2。4)氮处理中产量最高为 N1处理(N 45 kg/hm2)，N-U处理中产量最高为 N2(N 90 kg/hm2)；当施氮量大于90 kg/hm2时，氮处理与 N-U处理产量均显著降低；在同一氮水平下，喷施烯效唑可显著提高 CK-U与 N0-U的产量。5)氮处理中，氮肥贡献率(FCR)和农学效率(AE)随施氮量呈“V”型变化，N1最高；喷施烯效唑使 N2-U处理的 FCR、AE上升，其他处理均下降；偏生产力(PFP)随施氮量增加而降低，喷施烯效唑可使 N-U处理 PFP值上升；烯效唑对产量的贡献顺序为 N2> N0> CK > N4> N3> N5>N1。【结论】氮肥施用量是影响甘薯产量的关键因素，本试验条件下，氮处理甘薯的最佳氮肥用量为45 kg/hm2， N-U处理甘薯的最佳氮肥用量为90 kg/hm2，喷施烯效唑可提高甘薯产量，使地上、地下部协调生长。%Objectives]A field experiment was carried out in order to determine the optimum nitrogen (N) application rate with or without applying uniconazole for dry matter accumulation (DMA), top-root ratio(T/R), N content of above and below-ground biomass, yield, N utilization efficiency and uniconazole contribution rate (UCR) of sweat potato (Jishu22).[Methods]Using sweet potato cultivar of Jishu 22 as material, a field experiment was carried out by setting-up N treatments (N) and N-uniconazole treatments (N-U) with different N application rates in Pingyin, Shandong Province. The N rates in treatments were 0, 45, 90, 135, 180, 270 kg/hm2, recorded as N0, N1, N2, N3, N4, and N5in turn. The uniconazole application rate was 25 mg/L, using no fertilizer as control. Dry matter accumulation (DMA), N utilization efficiency and yield were recorded 85, 110 days after transplanting and during harvesting stage.[Results]1)The DMA of aboveground biomass increased with the increasing of nitrogen application rates, while the DMA in N-U treatments had no differences, except N1-U treatment. Spraying of uniconazole significantly reduced the DMA of aboveground in N3-U, N4-U and N5-U treatments. This suggested that the growth of aboveground biomass was constrained by uniconazole application. The DMA of underground biomass was significantly decreased when N application rate was higher than N2(90 kg/hm2) in both N and N-U treatments with the DMA higher in N-U treatments than that in N treatments. Significant correlation was noted between uniconazole and DMA of underground biomass in N1-U and N2-U treatments. 2) T/R ratio of N-U treatments decreased in all three growing periods, suggesting the retarded aboveground growth and accelerated underground growth by applying uniconazole. 3) Application of uniconazole increased N content of vine of Jishu22 after 85 and 110 days, while after 140 days it didn’t differ. There was a point in N content of storage root of Jishu22 between N and N-U treatments which was near the application rate of N2(90 kg/hm2), this indicated that 90 kg/hm2was the minimum application rate with the aim to increase the N concentration of storage root. 4) The highest yield was found in N1(N 45 kg/hm2) in N treatments and N2-U (N 90 kg/hm2) in N-U treatments, respectively with no further increase in yield with excessive fertilizer application. At the same N application rate, the yield was found to increase in CK-U and N0-U treatments by the application of uniconazole. 5) With increasing N application, fertilizer contribution rate (FCR) and agronomy efficiency (AE) changed following the pattern of “V” in N treatment with the highest value in N1. FCR and AE decreased in all treatments except in N2-U treatment with uniconazole. Partial factor productivity (PFP) decreased with increasing fo N application with greater PFP in N-U treatments than those in N treatments. Uniconazole contribution rate (UCR) to yield followed the order of N2> N0> CK > N4> N3> N5> N1.[Conclusion]Nitrogen application rate is the key factor regulating yield of sweet potato (Jishu22). The study suggested that the optimum N application rate was N145 kg/hm2in N treatment and N290 kg/hm2in N-U treatment. Higher yield and improved growth of aboveground and underground biomass were found after the application of uniconazole.