1College of Horticulture，Nanjing Agricultural University，Nanjing 210095，Jiangsu，China|2Vegetable Research Center，Beijing Academy of Agriculture and Forestry Sciences，Beijing 100097，China
Abstract：By seedling culture without substrate nutrient solution，this experiment studies the effects of different nutrition solution concentrations on the growth of cucumber（Cucumis sativus L.）seedlings. The results showed that the seedling had lower plant height，thinner stem diameter，lower biomass，weaker resistance to stress，smaller root volume and lower seedling index under lower concentration treatments（0.5 and 1.0 times nutrition solution），which were related to deficient nutrition supply under low concentrations，thus the growth and development of seedlings were slowed down．Under higher concentration（2.0 times nutrition solution）treatment，the seedling growth was inhibited during the earlier stage．While in the late stage，although the seedling growth speed was accelerated，its robust degree was still low，due to the un-eliminated stress．The treatment of 1.5 times nutrition solution had significantly promoted the seedling growth，effectively improved the seedling biomass，increased robust seedling index and root activity，and had better coordination between seedling growth rate and resistance．Its promotion role was much bigger than stress effect．Therefore，1.5 fold of nutrition solution is the optimal concentration for nutrient solution seedling culture without substrate．
