Studies On Biological Characteristic And Nutritive Value Of Forage Maize Influence By Different Nitrogen Forms

This research was carried out on the farm of Sichuan Agriculture University in 2007.The experiment materials were two types of forage maize,including SAUZ1 and SAUZ2,which was annual and perennial plant separately.It includes two aspects:(1)The influence of low nitrogen condition 150 kg/hm~2 and high nitrogen condition 450 kg/hm~2 to SAUMZ1 and SAUZ2 in growth,yield and feeding value.(2) The influence of four nitrogen forms of ammonium nitrogen and nitrate nitrogen ratio at 1:0,1:0.25,1:0.75 and 1:1 to SAUMZ1 and SAUZ2 in growth,yield and feeding value.The main results are as follows:1.The plant height,leaf length and leaf width of forage maize were significantly increased at low nitrogen condition(150 kg/hm~2) and high nitrogen condition(450 kg/hm~2) respectively. Nitrogen application was beneficial to the growth of forage maize,and the efficiency of forage maize growth by high nitrogen condition was better than low nitrogen condition. Simultaneously,the total fresh yield,fresh matter and dry matter weight per plant of forage maize were significantly increased at low nitrogen condition and high nitrogen condition respectively,also the efficiency of yield by high nitrogen condition was better than low nitrogen condition. Moreover,the Shoot/Leaf ratio had been decreased at the first cutting but increased at the second cutting of SAUZ1,besides the Shoot/Leaf ratio had been increased of SAUZ2.2.It was difference in forage quality of different cutting stages and different parts of plant at low nitrogen condition and high nitrogen condition.Presented as:(1) Though the CP content of SAUZ1 and SAUZ2 had been increased,the EE content had been decreased in different degrees to SAUZ1 in stalks and leaves,the increasing extent of CP content was greater than the decreasing extent of EE content.(2) The NDF content in stalks of SAUZ1 had been decreased significantly at the second cutting stage,and the NDF and ADF content in stalks of SAUZ2 had been decreased significantly too.(3)The IVDMD and RFV content in stalks and leaves of SAUZ1 had been increased significantly at the second cutting stage,but decreased significantly in stalks of SAUZ2.3.As the increasing of nitrate nitrogen proportion at low nitrogen condition and high nitrogen condition,it was suitable for the growth of forage maize,because the plant height,leaf length and leaf width were increased significantly.While the proportion of nitrate nitrogen and ammonium nitrogen was 1:1,the forage maize was growing luxuriantly.Moreover,the total fresh yield,fresh matter and dry matter weight per plant of forage maize were significantly increased respectively,and while the proportion of nitrate nitrogen and ammonium nitrogen was 1:1,the total fresh yield,fresh matter and dry matter weight per plant of forage maize reached to maximum.4.The different proportion of nitrate nitrogen and ammonium nitrogen influenced in the forage quality among nitrogen condition,varieties and cutting stages.Presented as:(1) As the increasing of nitrate nitrogen proportion at low nitrogen condition and high nitrogen condition,the CP content in stalks of SAUZ1 and SAUZ2 had been significantly increased,but EE content in stalks was opposite.While the proportion of nitrate nitrogen and ammonium nitrogen was 1:1,the CP content in stalks of SAUZ1 and SAUZ2 reached to maximum.(2) As the increasing of nitrate nitrogen proportion at low nitrogen condition,the stalks of SAUZ1 were downward trend in NDF and ADF content.While the proportion of nitrate nitrogen and ammonium nitrogen was 1:0.5～1:0.75,the NDF and ADF content in stalks of SAUZ1 were the lowest.But the stalks of SAUZ2 obviously increased in NDF and ADF content,and the NDF and ADF content were the lowest while there's no nitrate nitrogen.As the increasing of nitrate nitrogen proportion at high nitrogen condition,the stalks of SAUZ1 at the first cutting stage and SAUZ2 significantly increased in NDF and ADF content,and the NDF and ADF content were the lowest while there's no nitrate nitrogen.But the stalks of SAUZ1 was significantly increased in NDF and ADF content at the second cutting stage,while the proportion of nitrate nitrogen and ammonium nitrogen was 1:0.75～1:1 that the NDF and ADF content in stalks of SAUZ1 were the lowest.(3) As the increasing of nitrate nitrogen proportion at low nitrogen and high nitrogen condition,the IVDMD and RFV content in stalks of SAUZ1 had been increased significantly at the two cutting stage.It can improve the vitro dry matter digestible and relative feeding value with increasing application of nitrate nitrogen.But the stalks of SAUZ2 obviously decreased in IVDMD and RFV content,it can improve the vitro dry matter digestible and relative feeding value while there's no nitrate nitrogen.