氮肥用量对设施滴灌栽培番茄产量品质及土壤硝态氮累积的影响

为了明确滴灌条件下设施番茄适宜的氮肥施用量，选择北京市顺义区代表性日光温室进行田间试验，设置0、90、180、270、360、450kg·hm^-2 6个氮肥水平，研究不同氮肥用量对设施滴灌栽培番茄产量、品质及土壤硝态氮累积分布的影响。结果表明：氮肥施用量为0～360kg·hm^-2时，随氮肥施用量的增加番茄产量增高；当施氮量超过360kg·hm^-2时，番茄产量随施氮量增加却呈下降趋势。番茄品质随施氮量的增加而提高，当施氮量为450kg·hm^-2时，番茄果实的糖酸比最高，风味较佳。随着施N量的增加，各层土壤硝态氮含量明显增加，尤其当施氮量大于270kg·hm^-2时，土壤硝态氮含量显著增加。施氮量360kg·hm^-2为0—100cm土壤硝态氮累积量增加的拐点，土壤硝态氮累积量与0-360kg·hm^-2施氮量呈线性相关。结合北京郊区土壤肥力状况，番茄氮肥推荐施用量为270-360kg·hm^-2,在当前农民习惯施氮量450kg·hm^-2条件下，减少氮肥用量20％～40％，可以达到设施番茄高产、优质，且环境风险较小的目的。

Effects of Nitrogen Rates on Tomato Yield and Quality and Soil Nitrate Accumulation Under Drip Irrigation in Solar. Greenhouse

Soil excessive nitrogen（N ） causes nitrate pollution in water, Optimal N fertilizer would maintain plant yield and improve water quality. A field trial was carried out to examine the effects of six N application rates（ 0,90,180,270,360,450 kg N· hm^-2） on yield and quality of tomatoes and soil nitrate accumulation in solar greenhouses with drip irrigation in Shunyi District, Beijing. Tomato yield was high- est at 360 kg N· hm^-2. The highest ratio of soluble sugar to titratable acid contents in tomato fruit was observed at 450 kg N· hm^-2. Soil nitrate concentration increased significantly with increasing N application rates, particularly when the rates exceeded 270 kg N· hm^-2. These results suggest that the N application rates of 270-360 kg·hm^-2, 60%-80% of the typical N application rate, would be optimal for tomato growth and soil nitrate control under drip irrigation in greenhouses. This represents a 20%-40% reduction of the typical N application rate of 450 kg·hm^-2, and a significant improvement in tomato yield and quality and a reduction in the risk of nitrate release into environment.