Abstract:

The effects of different light quality[（white，red，blue，purple and red-blue（3︰1）] on growth and carbon-nitrogen metabolism in tomato seedlings were investigated by using LED lighting in a growth chamber. The results showed that：Compared with white light，purple light inhibited obviously the growth of seedlings，and red light suppressed the growth of roots，while red-blue light led to highest dry matter weight and seedling index；Pn，RuBP carboxylase activities，and contents of sugar and starch in leaves were lowest in purple light，however，highest in red-blue light. The activities of invertases were higher in both red and purple lighting. Red，blue，purple and red-blue light boosted the activities of sucrose synthase，however，red，blue，and purple light reduced the activities of sucrose phosphate synthase（SPS）. The activities of nitrate reductase（NR），glutamine synthetase（GS）and glutamate synthetase（GOGAT）were reduced significantly in red light，but activities of GS and GOGAT，and contents of soluble protein and free amino acid were remarkably improved in purple，blue and red-blue light. In conclusion，red-blue light is more suitable for growth of tomato seedlings，not only promoting carbon assimilation and accumulation of total sugar and starch，but also increasing enzyme activities of nitrogen metabolism and contents of soluble protein and free amino acids.

Key words: tomato, light quality, carbon metabolism, nitrogen metabolism, growth