| The experiment was conducted at the maize Sci-tech zone of Shandong Agricultural University in 2003 and 2004. The new-type forage grass-annual Sorghum-sudangrass hybrid and ite parents-Sorghum and sudangrass were regarded as the researching object. Two objectives were to determine in the experiment:(1)Comparison of yield,forage nutritive value and mineral concentrations in Sorghum-sudangrass hybrid,Sorghum and sudangrass.(2)Effects of different nitrogen application on yield,forage nutritive value and the physiological characteristic in Sorghum-sudangrass hybrid,Sorghum and sudangrass. All the varieties were cultured in field and pools,and the analysis of physiology and biochemisitry was applied in the Key laboratory of Crop biology Science,due to determine the regulation and control measures of high yield and high quality in Sorghum-sudangrass hybrid. The results showed that: 1. Yield of Sorghum-sudangrass hybrid There were significantly difference in yield of Sorghum-sudangrass hybrid and Sorghum,Sudangrass. Compared with sorghum and sudangrass,Sorghum-sudangrass hybrid(Wancao2 and Jingkecao1)were the highest in fresh matter yield(FM)and dry matter yield(DM). The FM and DM of Wancao2 increased respectively 83.8% and 121.9% than sudangrass while Jingkecao1 increased 98.6% and 139.9% respectively than sudangrass. Analysis by component and distribution of matter yield,stalks were the main component of FM,but stalks and leaves play an equally important role in DM and GE component. 2. Forage nutritive value of Sorghum-sudangrass hybrid Compared with Sorghum and Sudangrass,Sorghum-sudangrass hybrid were the highest in crude protein(CP),ether extract(EE) and the lowest in nitrogen-free extract(NFC). Sorghum-sudangrass hybrid were the highest in yield of CP, EE, NFC and gross energy(GE) while sorghum were secondary and sudangrass were the lowest. The yield of CP,EE,CF increased were effected by the increase of both dry matter yield and forage nutritive components content. The yield of NFE increased as the result of the harvest biomass increased highly,which was over the degree of NFE content decreased. The improvement of forage nutritive value in Sorghum-sudangrass hybrid was mainly caused by significant increase of CP and EE. 3. Mineral concentrations and distributions of Sorghum-sudangrass hybrid Compared with Sorghum and Sudangrass,Sorghum-sudangrass hybrid had numerically higher concentrations of N,P,K,S,Cu and Zn while the reverse was true for Ca,Mg and Mn. The organs of all the varieties were divided into leaves,stalks,stubbles and roots. The accumulated capabilities of each organ were different in mineral concentrations. The results showed that the accumulated capabilities both to N and P were leaves>stalks>stubbles> roots,to Kwas stalks>leaves>stubbles>roots,to S was leaves>stalks>roots >stubbles,both Ca and Mg were stubbles>stalks>leaves> roots,to Cu was roots>leaves>stubbles>stalks,Mn and Zn concentrations were not consistent in different organs. The accumulated order of N,P,K,S,Ca,Mg in Sorghum-sudangrass hybrid,Sorghum and Sudangrass were not consistent,the general accumulated order was N>K>Ca>Mg>P>S. The levels of N,P,K,S,Ca,Mg,Mn in leaves and stalks of Sorghum-sudangrass hybrid tend to higher while S,Cu and Zn were lower than the minimum requirements for dairy cattle. 4. Effects of nitrogen application on yield of Sorghum-sudan grass hybrid Under three nitrogen treatments(N0,0kg/hm2;N1,300kg/hm2;N2,600kg/hm2),the effects on yield of Sorghum-sudangrass hybrid,Sorghum and Sudangrass were not consistent. The yield of Sorghum-sudangrass hybrid and Sudangrass were the highest at N1 level while the yield of Sorghum were thehighest at N2 level. The amplitude of yield in Sorghum-sudangrass hybrid was the highest by the nitrogen application. Compared with N2 application(600kg/hm2),the heterosis in high yield and forage quality of Sorghum-sudangrass hybrid was more marked in N1 application(300kg/hm2). 5. Effects of nitrogen application on forage nutritive value of Sorghum-sudangrass hybrid The content of CP and EE in leaves were higher than in stalks,while the reverse was true for CF and CA in different nitrogen application strategies. The content of CP was increased but CA was decreased by the application of nitrogen,consequently the forage nutritive value and edibility of Sorghum, Sudangrass and Sorghum-sudangrass hybrid were improved. Under different nitrogen application stategies,the yield of CP,EE,CF,CA,NFE and GE in Sorghum were the highest at N2 level,while Sorghum-sudangrass hybrid and Sudangrass had the highest yield of CP,EE,CF,CA,NFE and GE at N1 level. The effects of nitrogen application stategies on forage nutritive value were the same as the harvest biomass. Compared with Sorghum and Sudangrass,Sorghum-sudangrass hybrid had the highest yield of CP,EE,CF,CA,NFE and GE. 6. Effects of nitrogen application on physiological characteristic of Sorghum-sudangrass hybrid The content of soluble sugar in Sorghum-sudangrass hybrid,Sorghum and Sudangrass was increased by the application of nitrogen,and the content of soluble sugar in leaves and stalks increased when it was higher in stubbles. The content of free amino was effected highly by the the application of nitrogen,which was increased simultaneously following the increased quantity of nitrogen. Compared with Sorghum and Sudangrass,the content of soluble sugar and free amino in Sorghum-sudangrass hybrid were the lowest. The activity of SOD was the highest at N2 level,and the activity of CAT,POD,APX in Sorghum-sudangrass hybrid were increased simultaneously... |
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