1Institute of Protected Horticulture，South China Agricultural University，Guangzhou 510642，Guangdong，China|2Institute of Vegetable Production in Huicheng District，Huizhou City，Huizhou 516023，Guangdong，China
Abstract：Effects of phosphorus and potassium on the growth and qualities in bunching onion （Allium fistulosum L.?var.?caespitosum Makino）were studied with hydroponics，in which the solution is 1/2 Hoagland’s，and treatments were P0.125K0.75，P0.125K1.5，P0.125K3，P0.25K0.75，P0.25K1.5（CK），P0.25K3，and the potassium levels were K1 0.75 mmol·L-1，K2 1.5 mmol·L-1，K3 3 mmol·L-1，P1 0.125 mmol·L-1，P2 0.25 mmol·L-1．The results showed that at the same phosphorus level，with the potassium concentration increased，the yield and leaf number of bunching onion gradually increased and the tiller numbers，plant height，length and diameter of cauloid were in increasing trend．The contents of soluble sugar in edible part also gradually increased，while the contents of allicin and pyruvic acid in leaf decreased．At 0.25 mmol·L-1 phosphorus level，with the concentration of potassium increased，the contents of VC in edible part of bunching onion gradually increased，but the contents of nitrate and soluble protein increased first then decreased．The contents of total phenolics and flavone in leaf and stem were the highest when treated with P0.125K1.5.
