Effects of different nitrogen forms and their ratios on broccoli yield, quality, and nutrient absorption
A field experiment was conducted to study the effects of different nitrogen forms ((NH2)2CO-N,NO3--N,NH4+-N,and NO3--NH4+) and their ratios on the yield formation,quality,and nutrient (N,P,and K) absorption of broccoli (Brassica oleracea).Fertilization with NO3--N increased the accumulation of nitrate and soluble sugars in ball flower.When the NO3--N:NH4+-N ratio was ranged from 3∶7 to 5:5 and from 5∶5 to 7∶3,respectively,the accumulation of nitrate in the ball flower was reduced,while the soluble sugars content was promoted.Fertilization with (NH2)2CO-N and NH4+-N was conducive to the improvement of Vc content in the ball flower.N fertilization increased the accumulation of N,P,and K in plants,with the highest contents of N,P,and K observed at rosette stage.Throughout the entire growth period,NH4+-N fertilization improved the plant N content,whereas NO3--N fertilization improved the plant K content.At different growth stages,the effects of different N sources on plant P content varied.As compared with applying single N forms,the NO3--N∶NH4+-N ratio ranged from 3∶7 to 5∶5 could improve the yield significantly.It was suggested that a combined application of NO3--N and NH4+-N with an appropriate ratio could improve the productivity,quality,and economic return of broccoli.
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