中文摘要：

氮肥的施用量和形态对植物的影响很大。实验借助于一种新型光谱仪SPAD-502叶绿素仪,研究了不同氮肥水平和氮肥形态对苗期玉米叶片叶绿素含量的影响。结果表明,每公顷施用0,100和200 kgN时,SPAD值在43.3-43.7之间,差异不显著;每公顷施用400 kgN时最后一片展开叶的叶绿素含量显著高于对照和每公顷施用100和200 kgN的处理,估计可能与肥料中其他成分有关,但原因尚需进一步研究。通过不同形态氮肥试验,表明氨态氮处理的叶片叶绿素含量显著高于硝态氮处理,可能的原因是：（1）氨态氮易于吸收,施用初期效果快;（2）氨态氮中微量元素比较高。

英文摘要：

The level and form of nitrogen fertilizer could significantly influence the growth and development of plant. The present paper studied the content of chlorophyll by the instrument SPAD-502 after treated with different nitrogen fertilizer level and different nitrogen fertilizer form. The results showed that the contents of chlorophyll in the last expanding leaf of maize seedling treated by levels of 0, 100 and 200 kgN · hm^-2 respectively had no significant difference, with the value of SPAD ranging from 43. 3 to 43. 7, but when the nitrogen fertilizer level got to 400 kgN· hm^-2, the content of chlorophyll in the last expanding leaf of maize seedling increased significantly, which can be caused by other components in the nitrogen fertilizer, which needs to be further studied. The experiments of nitrogen form showed that maize seedling treated by ammonia nitrogen （（NH4）2 SO4 ） contained more chlorophyll than that treated by saltpeter nitrogen （Ca（NO3）2）, and the statistical analysis was significant. The reason for the effect of nitrogen form on the content of chlorophyll of maize seedling leaf could be： （1） it is easier for plants to absorb ammonia nitrogen （（NH4）2SO4 ） than saltpeter nitrogen （Ca（NO3）2 ）; （2） ammonia nitrogen （（NH4）2 SO4 ） contains more trace elements which can promote the growth and development of plants.