甘薯喷施烯效唑的适宜氮水平研究

Suitable nitrogen fertilizer rate for foliar spray of uniconazole in sweet potato

【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/hm^2(N_1)、90 kg/hm^2(N_2)、135 kg/hm^2(N_3)、180 kg/hm^2(N_4)、270 kg/hm^2(N_5);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/hm^2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/hm^2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/hm^2。4)氮处理中产量最高为N1处理(N 45 kg/hm^2),N-U处理中产量最高为N2(N 90 kg/hm^2);当施氮量大于90 kg/hm^2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,N_1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N_2>N_0>CK>N_4>N_3>N_5>N_1。【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/hm^2,N-U处理甘薯的最佳氮肥用量为90 kg/hm^2,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 fieldexperiment 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/hm^2,recorded as N_0, N_1, N_2, N_3, N_4, and N_5 in 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 N_1-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（90kg/hm^2） 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 N_1-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 N_2（90 kg/hm^2）, this indicated that 90 kg/hm^2 was 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/hm^2） in N treatments and N_2-U（N 90 kg/hm^2） 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 N_1. FCR and AE decreased in all treatments except in N_2-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 N_2 N_0 CK N_4 N_3 N_5 N_1. 【Conclusion】Nitrogen application rate is the key factor regulating yield of sweet potato（Jishu22）. The study suggested that the optimum N application rate was N1 45 kg/hm^2 in N treatment and N_2 90 kg/hm^2 in N-U treatment. Higher yield and improved growth of aboveground and underground biomass were found after the application of uniconazole.