Analysis On The Important Agronomic Evaluation And Quality Traits Of Two Perennial Forage Maize Populations

MTP-1(2n=74,MMTTPP)and MTPP-1(2n=MMTTPPPP)were allopolyploids derived from maize(2n=2x=20,MM),T.Dactyloides(2n=4x=72,TTTT)and Z.Perennis(2n=4x=40,PPPP).Two backcross populations were successfully constructed from the backcross between two allopolyploids and Z.Perennis.The experiment was conducted at the Wenjiang experimental base and Chongzhou modern experimental base of Sichuan Agricultural University from 2015 to 2016 in order to determine the potential yield and best harvest period of the backcross progenies in the southwest region,China,and to determine which allopolyploid is better for breeding perennial forage maize.Specially,biological characters,forage yield,nutritional quality,relative feed value and cutting time of backcross progenies were studied.The test results include the following four aspects:1.The fresh yield of MTP-1 population in the first and second year was 39.63～74.57t/hm2 and 17.78～58.3 1t/hm2,respectively.There was a significant difference between lines.The first and second year average yields were 56.30 t/hm2 and 39.99 t/hm2,respectively.In the second year,the fresh yield was seriously reduced.The two-year average yield of the MTP-1 population was 96.29 t/hm2.The fresh yield of MTPP-1 population in the first and second year was 23.63～88.85t/hm2 and 24.21～89.21 t/hm2,respectively.Such as MTP-1 population,a significant difference between lines was found.The first and second year average yields were 52.18t/hm2 and 52.09t/hm2,respectively.The fresh yield between two years is stable.The two-year average yield of the MTPP-1 population was 104.27t/hm2.The total yield of MTPP-1 backcross population was higher and more stable,indicating that it was more suitable as an important core germplasm resource for forage breeding.2.Yucao No.5,a new forage variety that have been identified,that was similar to origin of backcrossing groups was selected as a control.In the MTP-1 population,the total yield of P6,P9 and P30 had no significant difference with Yucao No.5,accounting for 21.05%of the total population.There were not significant differences between all lines and Yucao No.5.However,the total yield of PP10,PP11,PP19,PP5,PP3,PP16 and PP17 in MTPP-1 population was significantly higher than that of Yucao No.5,accounting for 30.43%of the total population.PP7 and PP21 were no significant difference than Yucao No.5,accounting for 8.7%of the total population.It is further explained that the MTPP-l is more suitable as a breeding parent,and the success rate of new forage maize from MTPP-1 progenies is higher.However,it is undeniable that the fresh yield of individual strains were comparable to that of Yucao No.5 in the MTP-1 population.3.In order to more accurately predict the nutrient composition(CP,ADF,NDF and CA)of perennial forage maizes,it is necessary to establish the NIRS models of the main nutrient of perennial forage maizes.The NIRS prediction models of CP,ADF,NDF and CA were established in this experiment.Rcal 2 and Rval 2 were all higher than 0.81 and RPD were all greater than 2.4.The results showed that the established NIRS models could be suitable for predicting the main nutritional value of perennial feeding maizes.4.In the same growth period,there were significant differences in the quality and yield of varieties.Before the tasseling period,the fresh weight and dry matter yield of all lines increased significantly.After the tasseling period,the fresh and hay yield of all strains tends to be stable.The nutritional concentration of crude protein(CP),crude fat(EE)and crude ash(CA)were gradually decreased with the delay of growth period.Neutral detergent fiber(NDF)and acid detergent fiber(ADF)showed a gradual accumulation.Considering yield and nutrient quality,the new forages should be harvested in tasseling stage in order to produce better biomass and nutritive value.