减量施氮对大棚黄瓜产量和品质的影响

Examining the effects of reduced nitrogen fertilization on the yield and fruit quality of greenhouse cultivated cucumber

利用在东部沿海丘陵区玻璃大棚中的长期定位试验,设置农民习惯施氮(N1,800kg·hm^(-2))、氮减量25%(N2,600 kg·hm^(-2))、氮减量50%(N_3,400 kg·hm^(-2))、不施肥(CK)4种不同化肥施氮水平和施有机肥(ON,400 kg N·hm^(-2))处理,研究了不同施氮量对黄瓜产量及品质的影响.结果表明:与农民习惯施氮相比,施氮量减少50%能保证黄瓜的果实产量,并大幅提高经济效益.不同处理黄瓜果实硝酸盐含量范围在94.2~136.1 mg·kg^(-1),均未超过我国蔬菜卫生安全标准,不同施肥处理比CK增加了18.1%~44.5%,其中N_3处理下增加幅度最小.施用化肥降低了黄瓜果实中Vc、可溶性糖和可溶性蛋白含量,在施氮量600 kg·hm^(-2)处理中最低.不同施氮处理在短期内改变土壤pH等理化性质,然而在过量施肥条件下黄瓜产量、经济效益与土壤性质无显著相关性.因此,在东部沿海丘陵区的大棚生产条件下,氮肥施用量减少50%可以保证黄瓜产量和果实品质.

A long-term fertilizer experiment was conducted to determine the precise effects of nitrogen（ N） fertilization on the yield and quality of cucumber,which were grown in greenhouse located in the coastal hilly region of East China. This work included four treatments with varying levels of chemical N application（ N1,800 kg·hm^-2,N2,600 kg·hm^-2 and N3,400 kg·hm^-2,CK,no fertilization） plus ON（ organic N 400 kg·hm^-2）. Results showed that a 50% reduction of N fertilization（ N3） produced no significant effects on yield,when compared with the local conventional practice（ N1）. Importantly,fruit nitrate content for cucumbers with N fertilization ranged from 94.2 to 136.1 mg·kg^-1,which was acceptable according to the National Food Safety Standard of China.However,when compared with no fertilization control,N fertilization increased nitrate content by18.1%-44.5%. Chemical N fertilization resulted in a decrease of vitamin C,soluble sugar and soluble protein contents in cucumber,and caused significant temporary changes of soil p H and other chemical and physical properties of the soil. No significant correlations were found between cucumber yields,economic benefit and soil property variables under the excessive use of N fertilizer. It was concluded that N fertilization could be reduced by half with no significant reduction of fruit yield and quality for cucumbers cultivated in greenhouse located in the coastal hilly region of East China.