Studies On The Improved Variety Selection, Response To N Fertilizers Of Forages In Grass Family And Their Utilization To Animal Husbandry

The forages in grass family characters of quick grow,are strong in regenerating capacity,high in biomass production,good in palatability.They are the main consumed fodders for grass-eating animals.In this thesis,the improved variety selection,response to N fertilizers of forages in grass family and their utilization to animal husbandry were investigated.The main results are as follows:1.A Study on Selective Breeding of Forage Varieties of Pennisetum and the Relationship between Genotype and Forage QualityThe F1 seeds of hybrid Pennisetum were irradiated with 400Gy(radiative dose was 1.6Gy/min)⁶⁰Coγ-ray and a new variety "Minmu 6" was selected.All results from RAPD, agronomic traits,yield and quality analysis showed that the genotype and traits of"Minmu 6" were significantly different from other sixteen forage varieties."Minmu 6" characters moderate plant morphology,is high in tiller number,plant yield,protein production,low stern/leaf ratio,rather high in crude fiber etc.,i.e.the tiller number/plant was 24.4,which was the second high in all 17 varieties,and was 19.5%lower than that of popularized variety(V1). Its fresh yield was 58.07t/hm² which was 35.1%higher than that of V1,its dry yield was 9.04t/hm² which was 50.7%higher than that of V1.Its protein production was 2.78t/hm² which was 19.8%higher than V1;its stem/leaf ratio was 0.32 which was 15.8%lower than that of V1.Field experiment of 17 varieties(V1～V17)of Pennisetum showed that the tiller number, plant height,stem/leaf ratio,yield and crude protein content had great difference among 17 varieties of Pennisetum.The average tiller number was 17.4/plant,among which the highest was V1(30.3/plant)and the lowest was V2(12.0/plant).The average plant height was 118.2cm, among which the highest was V2(138.7cm),the lowest was V5(69.5cm).The average stem/leaf ratio was 0.49,among which the highest was V8(0.79),the lowest was V12 and V16(0.32).The average dry yield was 5.99t/hm²,among which the highest was V16(9.04t/hm²),the lowest was V5(3.92t/hm²).The average crud protein content was 11.95%, among which the highest was V3(14.40%),the lowest was V16(10.34%).Contrarily,crude fat content,acid detergent fiber(ADF),neutral detergent fiber(NDF)and acid detergent lignin(ADL)had little difference among 17 varieties of Pennisetum.The average crude fat content was 3.06%,among which the highest was V3(3.56%),the lowest was V14(2.55%). The average ADF in field trail was 32.50%among which the highest was V16(34.51%),the lowest was V3(30.52%).The average NDF was 53.20%,among which the highest was V11(56.16%),the lowest was V1(47.46%).The average ADL was 27.85%,among which the highest was V16(29.04%),the lowest was V2(25.78%).The results from RAPD analysis showed the coefficients among 17 varieties of Pennisetum were all over 0.66 which indicated there had near genetic relation among them.However,V2 and V8,V5 and V7,V9 and V10, and V14 and V17 had quite near genetic relation respectively,and their coefficients were all over 0.97 which might be resulted by the same forage variety and named differently.2.Studies on N absorption and transformation efficiency of gramineous forages by ¹⁵N-tracing techniquesBy using ¹⁵N-tracing techniques,the crude protein content,N absorption rate of 10 species of gramineous forages and N transformation efficiency by mice were studied. Experiment showed that,Setaria sphacelata and Pennisetum americanum×P.purpureum got the highest N-utilizing rates which were 31.734%and 30.568%respectively.Panicum maximum Jacq.cv.was 26.144%which has no significant difference with Brachiaria decumbens cv,Paspalum atratum cv..Euchlaena Mexicana Schrad and Lolium perenne L. got lower N-utilizing rates which were 17.744%and 14.816%respectively.Sorghum sudanense(PIPER)Stapf was the lowest which was 5.213%only.The digested rates of 10 ¹⁵N-traced forages in mice were between 27.67%～75.65%,the orders from high to low were Setaria sphacelata(75.65%),Zea Mays L.(74.63%),Lolium perenne L.(68.20%),Sorghum sudanense(65.73%),Euchlaena mexicana Schrad(62.10%),Pennisetum americanum×P. purpureum(58.79%),Brachiaria decumbens cv.(57.65%),Panicum maximum Jacq.cv.(55.68%), Festuca arundinacea Schreb(51.20%)and Paspalum atratum cv.(27.67%),¹⁵N-recovered rates in mice ranged 22.62%～43.90%.The orders from high to low were Sorghum sudanense (PIPER)Stapf(43.90%),Setaria sphacelata(43.10%),Brachiaria decumbens cv.(43.03%), Festuca arundinacea Schreb(42.19%),Lolium perenne L.(31.12%),Euchlaena mexicana Schrad(30.54%),Zea mays L.(30.38%),Pennisetum americanum×P.purpureum(28.14%), Panicum maximum Jacq.cv.(25.48%)and Paspalum atratum cv.(22.62%).The ¹⁵N digested rate of Setaria sphacelata and its ¹⁵N-recovered rate in mice were all at high levels,whereas the ¹⁵N digested rates and its ¹⁵N-recovered rates in mice of Pennisetum americanum×P. purpureum and Euchlaena Mexicana Schrad were at middle levels.Through out the analysis on the efficiency of applying ¹⁵N fertilizer to forages and the transformation to the protein in mice,it revealed that the transforming efficiencies of Setaria sphacelata and Brachiaria decumbens cv.were better and were 59.7%and 22.2%respectively higher than that of Pennisetum americanum×P.purpureum.3.Study on the dynamic regular of biological characteristics in 4 gramineous forages by applying different levels of N fertilizerEffect of 5 N fertilizer-applied levels on the growth,crude protein content and N productive efficiency of 4 species of gramineous forage were investigated.The results showed that,N fertilizer application has the effects to significantly improve the agronomic characters, biomass production and crude protein content of gramineous forages.However,following with the further increase of N applying amount,the effect of N application was weakened. When N applying amount was overused to a certain degree,some of agronomic character appeared a gradually decreasing tendency.The highest crude protein contents of 2 summer grasses(Pennisetum americanum×P.purpureum and Euchlaena Mexicana Schrad)were found at 30^thday after transplanting,which Pennisetum americanum×P.purpureum N4 and Euchlaena Mexicana Schrad N5 reached 23.23%and 25.80%respectively.Following the growth of these forages,the crude protein contents in the plants of 5 N-applying levels were all decreased.The highest average crude protein contents of 2 winter grasses(Lolium perenne L.and Festuca arundinacea Schreb)were found at 40^thday after transplanting, which reached 31.70%and 31.58%respectively.Similarly,following the growth of these winter forages,the crude protein contents in the plants of 5 N-applying levels were all decreased.The determination of amino acid content in the ryegrass at 40^thday after transplanting showed that,its amino acid content increased following with the increase of N fertilizer application.In the treatment N5,the amino acid content in ryegrass reached as high as 33.68%,which occupied 82.21%of the total crude protein content.To compare with N1, the crude protein content increased by 215.6%,the amino acid content increased by 243.3%. This experiment indicated that,the ryegrass growing in pot condition had a high efficiency to transform the applied N fertilizer into amino acid compound.The biomass production and crude protein contents of 4 gramineous forages were gradually increased following with the increase of N-applying amount.However the N productive efficiencies(DMPE,CPPE and NARR)were decreased gradually.When growing in red soil,the average crude protein contents of 5 determinations for 4 gramineous forages ordered from high to low were Festuca Arundinacea > Lolium multiflorum Lam > Euchlaena Mexicana > Pennisetum arnericanum×P.purpureum.But the biomass production of Pennisetum americanum×P.purpureum was much high,its DMPE,CPPE and NARR were greatly higher than those of Euchlaena Mexicana,Lolium multiflorum Lam and Festuca Arundinacea.The SPAD values of 4 gramineous forages were all positively related to their crude protein contents in the stems and leaves.Among which,Pennisetum americanum×P.purpureum showed a very significant relationship.4.Response of nitrate content and the activities of related N metabolic enzymes in gramineous forages to the N fertilizer applicationThe variation regulars of crude protein and nitrate contents,the activities of nitrate reductase and glutamine synthetase of 4 gramineous forages at 4 N-applying levels,as well as the correlativity of crude protein with nitrate contents and N-applying levels with the activities of 2 N metabolic enzymes were investigated.The results showed that,under the same N-applying level,the nitrate contents in winter forages were higher than that in summer forages.Among summer forages,the nitrate content in Euchlaena Mexicana,was higher than that in Pennisetum americanum×P.purpureum;whereas among winter forages,the nitrate content in Festuca Arundinacea was obviously higher than that in Lolium multiflorum Lam. The variation regulars of nitrate contents in 4 gramineous forages were not identical to those of 2 N metabolic enzymes;the variation tendency in the treatments that using same forage species and different N-applying levels was similar.Following with the increase of N application,NO₃^- in leaves,NO₃^- in roots,NR activity in leaves,NR activity in root,GS activity in leaves and GS activity in roots of Pennisetum americanum×P.purpureum showed a gradually increasing tendency.Among the treatments, NO₃^- in leaves of N4 increased by 47.89%to compare with N1;NO₃^- in roots increased by 51.43%;NR activity in leaves increased by 7.79%;NR activity in root increased by 29.90%, GS activity in roots increased by 12.50%,whereas GS activity in leaves showed the tendency of decreasing at first then increasing.NO₃^- in leaves of Euchlaena Mexicana decreased at first,and then increased.The NO₃^- in roots,NR activity in leaves,NR activity in root,GS activity in leaves and GS activity in roots showed the gradually increasing tendency.To compare with N1, NO₃^- in leaves of treatment N4 decreased by 25.20%,NO₃^- in roots increased by 63.94%;NR activity in leaves increased by 25.81%,NR activity in root increased by 11.39%,and GS activity in roots increased by 19.57%,whereas its GS activity in leaves were higher than that in Pennisetum americanum×P.purpureum and showed a declining tendency.NO₃^- in leaves of Lolium multiflorum Lam decreased at first,and then increased.The NO₃^- in roots,NR activity in leaves increased gradually.To compare with N1,NO₃^- in leaves of treatment N4 increased by 8.90%,NO₃^- in roots increased by 77.88%;NR activity in leaves increased by 26.69%. However,the NR activity in root,GS activity in leaves and GS activity in roots showed a declining tendency.Among which,GS activity in roots decreased sharply,reached 23.96%. NO₃^- in leaves and NO₃^- in roots of Festuca Arundinacea increased at first,and then deceased. Its GS activity in leaves increased gradually.To compare with treatment N1,NO₃^- in leaves increased by 68.01%,NO₃^- in roots increased by 53.87%,GS activity in leaves increased by 29.65%.However,NR activity in leaves,the NR activity in root and GS activity in roots showed a declining tendency.Its NR activity in leaves decreased sharply,reached 36.96%.Correlation analysis revealed that,NO₃^- in leaves of Pennisetum americanum×P. purpureum was significantly positive related to the N-applied amount and its NO₃^- in roots. The crude protein content of Euchlaena Mexicana was significantly related to N-applied amount,was very significantly positive related to its NR activity in leaves.The crude protein content of Lolium multiflorum Lam was very significantly related to the N-applied amount, and was significantly positive related to its NO₃^- in roots.5.Study on the dynamic regular in the yield,crude protein and nitrate content of ryegrass under different N applying levels and methodsField experiments were conducted to study the effects of six urea application levels and four application methods on the agronomic traits,the yield,the quality,and the nitrogen producing efficiency of ryegrass,and the correlations among the yield,the content of crude protein,the amino acid content,the amount of N application and many agronomic traits were also investigated.The results showed:N application could significantly increase the tiller number,the plant height,the yield,the content of crude protein and the amino acid content, and there was significant difference to compare with the CK.The increase amplitude of N application on ryegrass became less and the nitrogen production efficiency became low with the increase of the N application amount.When the N application amount was over 100kg/hm² after each cutting,N fertilizer could increase the crude protein content but had little influence on the amino acid content.The increased crude protein was not in form of amino acid,so the amino acid content in ryegrass tended to be stable.When the N application amount was up to 250kg/hm² after each cutting,the plant height and the yield has decreasing trend.In addition,the nitrate N content increased with increasing the N application amount. Especially when the N application amount was over 150kg/hm²,the nitrate N content increased significantly,and even exceeded the 25%poisoning criterion.There were positive correlations among the yield,the plant height,the tiller number,the content of crude protein, and the nitrate N content of ryegrass.The yield was significantly correlated with the N application amount when broadcast application.The content of crude protein and amino acid significantly or extremely significantly correlated with the N application amount.Moreover, there was extremely significant correlation between nitrate and the N application amount. Deep application could influence the tiller number and the plant height,and increase the yield, the crude protein content and the amino acid content.The comprehensive analysis indicated that deep application was beneficial to the growth of ryegrass and 100 kg/hm² N application after each cutting could meet the request for the high yield and good quality production of ryegrass.6.Study on the dynamic regular of the biological characteristics in hybrid pennisetum under different N applying levelsField experiments were conducted to study the effects of four different N application levels on the yield,the crude protein content and the nitrogen production efficiency of hybrid pennisetum,and the correlations among the yield,the crude protein content,the amount of N application and many agronomic traits were also investigated.The results showed:N application could significantly increase the tiller number,the plant height,the yield and the content of crude protein.However,the tiller number was no significantly differences among treatment N2,N3 and N4.Moreover,the plant height,the hay yield and the content of crude protein were also no significantly difference between N3 and N4.There were positive correlations among the fresh yield,the hay yield,the content of crude protein,the tiller number,the plant height and the amount of N application of hybrid pennisetum.The fresh yield was significant correlation with the amount of N application,the tiller number and the content of crude protein,and was extremely significant correlation with the plant height and the hay yield.Moreover,the hay yield was significant correlation with the amount of N application and the tiller number,and was extremely significant correlation with the plant height.The content of crude protein correlated significantly with the amount of N application. Within definite amount range of N application,the amount of dry matter accumulation,the crude protein yield and the amount of nitrogen accumulation increased with the increase of the N application amount.However,N dry matter production efficiency(NDMPE),dry matter production efficiency(DMPE),crude protein production efficiency(CPPE),N agronomy efficiency(NAE)and nitrogen apparent recovery ratio(NARR)decreased gradually with increasing the N application amount.When the N application amount was 100kg/hm²ï½ž300kg/hm²,NARR was 25.73%～45.12%and N recovery efficiency(NRE)was 16.68%～20.35%7.Hybrid pennisetum's response to different fertilizers and its utilization on pollution treatment and animal husbandryUsing "pig-methane-grass" ecological mode,we studied hybrid pennisetum's response to different fertilizers and its effect on pollution treatment and raising fattening pigs.The results showed that,applying 150t/hm² methane liquid to hybrid pennisetum after each harvest could increase the crude protein content,the crude protein content of the hybrid pennisetum reached 13.78%,which was 46.75%higher than that of without fertilization treatment.Furthermore, increasing urea fertilizer after methane liquid application could significantly increase the crude protein content,the crude protein content reached 15.84%and increased by 14.95%to compare with the treatment of only applying methane liquid.After the beating of hybrid pennisetum,there has good effect on raising fattening pigs. Results showed that the daily weightgain at treatmentâ…¡(basic daily diet + straw pulp of applying methane liquid 0.25kg/pig.d),â…¢(basic daily diet + straw pulp of applying methane liquid 0.5kg/pig.d),â…£(basic daily diet + straw pulp of applying methane liquid and urea 0.5kg/pig.d)increased 22.4g,40.4g and 48.4g than treatmentâ… (basic daily diet)respectively. The proportion between diet and carcass at treatmentâ…¡,â…¢andâ…£decreased 4.62%,3.96% and 7.26%than treatmentâ… .The benefit per pig at treatmentâ…¡,â…¢andâ…£increased 26.0, 34.3 and 44.6yuan than treatmentâ… .The amino acid content in pig meat had increased in various degrees.Especially treatmentâ…£had the best effect in the daily weight gain,the proportion between diet and carcass and the benefit per pig.By using "pig-methane-grass" ecological mode,the fertilizer-tolerant hybrid pennisetum was planted in proportion to the area of pig farm.During the growing period,each hm² of forage land is able to consume the methane liquid produced by 1400 fattening pigs. Meanwhile,applying methane liquid would improve the soil fertility.To compare with the tratment without applying fertilizer,the O.M.,total N and total P in the grass land applying methane liquid for continuosly 3 years were increased by 182.0%,58.7%and 166.3% respectively,but total K was decreased by 36.7%.For this reason,after long-term planting hybrid pennisetum and only applying methane liquid,the soil became lack of K elements,so we need applying K fertilizer to suppliment to K loss in the grass land.