Effects of different nitrogen forms on nutrient uptake,yield formation and quality of cabbage

This study determined the effects of different nitrogen forms[(NH2) 2 CO-N,NO3--N,NH4 +-N, NO3--N∶NH4 +-N]on nutrient uptake,yield formation,and quality of spring cabbage(Brassica oleracea var. capitata).A field experiment was conducted at Yuzhong(104°12′E,35°85′N),China in 2012,where eight different N forms and various ratios of different N forms were applied to the crop in a completely randomized block design with three replicates.The results showed that the application of NO3--N∶NH4 +-N in 3∶7was conducive to the improvement of the stem diameter of cabbage.The fertilization with single NH4 +-N could increase the numbers of leaves.The use of NH4 +-N improved the content of N and use of NO3--N improved the content of K,but the P content varied with N sources in different organs of cabbage.Cabbage supplied with the ratios of NO3--N∶NH4 +-N ranging from 3∶7to 7∶3was conducive to improve the contents of nitrogen, phosphorus and potassium in leaves,head and roots of cabbage,and could improve photosynthesis of leaves. Compared with single nitrogen fertilizer forms,the combined application of NH4 +-N and NO3--N could obviously improve the yield of cabbage.The application of NO3--N:NH4 +-N ranging from 3∶7to 5∶5had the better effect on increasing yield,and the ratio of NO3--N∶NH4 +-N 5∶5was the best.The fertilization with single NO3--N increased the accumulation of nitrate,and reduced Vc content in cabbage.Cabbage supplied with the ratios of NO3--N∶NH4 +-N ranging from 3∶7to 7∶3reduced the accumulation of nitrate and increased the content of soluble sugars,and the application of NO3--N∶NH4 +-N in 5∶5had the best results. The application of(NH2) 2 CO-N or NH4 +-N was conducive to the improvement of Vc content in the leaves of cabbage.We concluded that the ratios of NO3--N∶NH4 +-N ranging from 3∶7to 7∶3significantly improved the yield and quality of cabbage,and the application of NO3--N∶NH4 +-N in 5∶5had best effect.