9Blom-Zandstra M. Nitrate concentration and reduction in dif- ferent genotypes of lettuce [J]. J Ame Soc Hort Sci, 1986, 11 (6) : 908 -911.
10Kotsirasa A, Olympiosa C M, Drosopoulosb J, Passam H C. Effects of nitrogen form and concentration on the distribu- tion of ions within cucumber fruits [ J ]. Horticuhurace, 2002, 95 : 175 - 183.
