Abstract: There are two kinds of hydrological analysis,i.e.,structural imitation model which cares forinner laws of hydrological process and black box medel which discusses the relationship betweeninput and output no matter how water moves in the system. Based on the gray system theory,this paper attempted to establish black box medels of rainfaoo-surface flow relationship in threedifferent types of catchments on coastal highland of Xiaoliang Experimental Station.Thesemodels were: GM(2.1)models of one-time rainfall(mm)to surface flow(mm)and GM(2.1)models of monthly rainfall(mm)to surface flow coefficient in three catchments. Based on thetests over a long time peried, it has demonstrated high accurancy for prediction of surface flowthrough rainfall by these medels.

Key words: tomato seedling, NO, copper stress, subcellular distribution, chemical form.