氮肥用量对滨海滩涂区甘薯干物质积累、氮素效率和钾钠吸收的影响

我国沿海滩涂种植能源作物甘薯有广阔的前景。为确定苏北滩涂区甘薯适宜施氮量,比较了6个施氮水平下甘薯的成活率(SR)、商品率(CR)、蔓薯比(V/T)、干物质积累(DMA)、氮素累积值(NAV)、氮利用效率(NUE)、氮收获指数(NHI)及钾钠吸收的差异。结果表明:(1)施氮量与甘薯地上部分DMA和NAV均呈极显著正相关(P<0.01,余同),对地下部分NAV影响较小(P>0.05)。(2)与不施氮比较,施氮60 kg(N)·hm-2对甘薯的V/T、SR、NUE和NHI均无显著影响。(3)甘薯的CR、地下部分和块根DMA以及理论产量(NAV×NUE×NHI)均以施氮60 kg(N)·hm-2显著高于其他处理。施氮量超过60 kg(N)·hm-2,施氮量与甘薯的V/T值呈极显著正相关,与SR、CR、NUE、NHI、地下部分和块根DMA均呈极显著负相关。(4)甘薯对钾钠的吸收量均随施氮量的增加而增加,二者呈极显著正相关。甘薯地上部分钾钠含量均在施氮量为60 kg(N)·hm-2时达到最高值。施氮量对钾钠含量比没有影响。因此,苏北滩涂区甘薯适宜施氮量为60 kg(N)·hm-2。

Effects of nitrogen application rate on dry matter accumulation, nitrogenefficiency, and potassium and sodium uptake of sweet potato (Ipomoea batatas) in coastal North Jiangsu Province

Sweet potato (Ipomoea batatas) is a high energy crop with great potentials in the coastal areas in China. In order to determine optimum nitrogen (N) application rate (NAR) in sweet potato production, a field experiment was conducted in coastal North Jiangsu Province. Survival rate (SR), commodity rate (CR), dry weight vine-tuber ratio (V/T), dry matter accumulation (DMA), N accumulation (NAV), N use efficiency (NUE), N harvest index (NHI), and potassium (K) and sodium (Na) uptakes of sweet potato were investigated under six N levels (N0~N5). The N levels were 0 kg(N)·hm^-2(N0), 60 kg(N)·hm^-2 (N1), 120 kg(N)·hm^-2 (N2), 180 kg(N)·hm^-2 (N3), 240 kg(N)·hm^-2 (N4), and 300 kg(N)·hm^-2 (N5), respectively. The results were summarized as follows: (1) A sig-nificant positive correlation was noted between NAR and aboveground DMA or NAV at P < 0.01, but no significant correlation ex-isted between NAR and root NAV at P > 0.05. (2). Compared with N0, N1 treatment had no significant effects on sweet potato V/T, SR, NUE and NHI. (3) Sweet potato CR, root and tuber DMA as well as theoretical yield (TY=NAV×NUE×NHI) were highest under N1 treatment. When sweet potato NARs were 60~300 kg(N)·hm^-2 , significant positive correlation existed between NAR and V/T at P < 0.01. However, significant negative correlation was noted among SR, CR, NUE, NHI, root and tuber DMA of sweet potato at P < 0.01. (4) There was significant positive correlation between K and Na uptake at P < 0.01; both of which increased with increasing NARs. K and Na contents of aboveground tissues of sweet potato under N1 treatment were significantly higher than those under other treatments. However, K/Na ratio for the whole plant was not different among treatments. The study suggested that the optimum NAR in sweet potato fields in coastal North Jiangsu Province was 60 kg(N)·hm^-2.