Abstract: Tomato potting seedlings were treated under different floor level of water supply in media
(RWC was 90％ ，75％ ，60％ ，45％ ，30％ respectively)，and discussed the relationship between tt1e
changes of C，N metabolic products and development． The main results were as below：soluble sugar and
reduetive sugar usually as carbon metabolic materials and osmotic solutes． increased in lear with water supply
decreasing，whieh enhanced adaptive ability in adversity to keep normal metabolism． Starch content in tomato
leaf increased with less water supply．similar to total carbohydrate change． Relationship of“sink—source’’was
altered under different water supply status．Less water supply made NRA (Nitrate activity)increase signifi—
cantly，yet which could not retrieve N loss due to water deficit．C
， N metabolism was Begative eorrelati0n．
and C／N ratio increased with water supply decreased，while development degree showed delayed trend
． The
first anthesis， sum of earlier three anthotaxy flowers
． and earlier stage yield of the treatment 0f 75％ RWC
floor level seedlings were better than which of the treatment of 90％ RWC floor leve1． n0 significallt difference
between the above two treatments，SO 75％ floor level of wate r·supply could be as referenee for potting seed．
1ings irrigation．

Key words: Tomato, Potting seedlings, Substratum, Water content, C, N metabolism, Growth anddevelopment