Study On The Nutrient Ingredient Of High Yield And Quality Pakchoi

China is a large country on vegetable production, whose total yield is on the top of the world. Pakchoi ( Brassica chinensis ) has the broadest distribution, largest cultural area and most popularities among vegetable production. The soilless culturing pakchoi plays a great role in anniversary proportional supply of vegetables.In this study, pakchoi was used as an experimental material to study the effect of nitrate nitrogen (NO3- -N), phosphorous (P), potassium (K) and ammonium nitrogen (NH4+-N) on yield, main qualities (nitrate and Vc content) of pakchoi and select the optimal ingredient of the four factors. Adopting the 416-B optimum compound design, a four variances quadratic equation of pakchoi yield and the content of nitrate and Vc was obtained by calculating with SAS, among which the nitrate, Vc content and the yield of pakchoi were applied as aim factors; NO3- -N, P, K and NH4+-N were applied as controlled variances. Finally, an optimal ingredient of nitrate nitrogen, phosphorous, potassium and ammonium nitrogen was found with optimum finding program and mathematical methods. The experimental results were showed as follows:1. Nitrate nitrogen was the main factor in increasing the yield and affecting the main qualities of pakchoi and could improve the yield, the content of Vc and nitrate accumulation of pakchoi in an appropriate certain concentration range.2. Ammonium nitrogen was one of the major factors in increasing Pakchoi yield and Vc content and decreasing the amount of nitrate, too. While it might cause ammonia poisoning when used high concentration.3. The single effect of phosphorous on nitrate, Vc content and yield of pakchoi was smaller than that of nitrogen, but it also could play an important role when interacted with nitrogen (nitrate nitrogen and ammonium nitrogen) and potassium.4. Potassium was also a main factor in affecting pakchoi yield and main qualities. In an appropriate concentration range (below "1" level), the content of Vc and the yield of Pakchoi would increase after the potassium concentration had been improved, meanwhile the nitrate content of pakchoi would decrease when increasing potassium concentration. The best effect would be obtained at "1" concentration level.5. Optimal Pakchoi ingredient would be: NO3- -N 0.482 (7.46 mmol/1) , P 0.741 (1.24 mmol/1) , K 0.491(6.65 mmol/1) and NlV-N 0.877 (2.27 mmol/1).6. In the conditions of theoretical model of optimal ingredient, thecomprehensive evaluation of Pakchoi yield and main qualities was better than that of the control, which was showed the theoretical model of optimal ingredient was truthful and feasible.