不同施氮量对大棚莴苣根系形态及产量和品质的影响

Effects of Different N Rates on Root Morphology,Yield and Fruit Quality of Lettuce Cultivated in Plastic Greenhouse

采用大棚栽培田间小区试验,研究了不同施氮量下莴苣根系形态特征的动态变化,以及不同施氮水平对莴苣产量和品质的影响。结果表明:与农民习惯施氮相比,减氮40%处理对莴苣根系生长有显著促进作用,主要表现为根表面积和体积以及总根长显著增加;但氮肥对莴苣根增粗生长的促进作用主要表现在生长后期。减氮40%处理下的莴苣产量和Vc含量最高。莴苣茎硝酸盐含量随施氮量的增加呈线性增加,农民习惯施氮处理下,莴苣茎硝酸盐含量最高,达到1 291.9 mg/kg,已超过农产品安全质量无公害根茎类蔬菜的安全标准。

Field experiments were carried out to study the effects of different N rates on dynamic changes of root morphological characteristics and the yield and quality of lettuce cultivated in plastic greenhouse. The results showed that as compared with farmer habitual N usage, 40% reduction of N fertilizer input enhanced significantly lettuce root growth, mainly in increasing the root surface area, volume and total root length greatly; but the promotion of nitrogen fertilizer on root diameter was only observed in the late stages of growth. The highest yield and vitamin C contents were obtained in the treatment of 40% reduction of N fertilizer input. Furthermore, nitrate contents of lettuce increased with increase of N fertilizer input. With farmer habitual N usage, nitrate content of lettuce reached as high as to 1 291.9 mg/kg and exceeded the safety standard of safety and quality of agricultural products for root vegetables.