| In this research, the field experiment was conducted in2011-2013in order to compare the difference in forage yield, quality and stress resistance of BMR forage sorghum varieties under different utilization pattern, analyze the change regulation of nutritive values, build the model equation of BMR-6and BMR-12forage sorghum types, and study on the relationship between acid detergent lignin and lodging resistance index. The results showed as following:(1) The study on the utilization pattern showed that fresh and dry yield of different types of BMR sorghum had a decreased trend in the same treatments, and the type of BMR-6presented a higher decreased range; the yield performance of BMR-6sudangrass had a increased trend while there was a declined trend in type of BMR-6sorghum x sudangrass hybrid. However, the characteristics of yield, quality and stress resistance of different BMR forage sorghum varieties in the same types shown the certain differences (P<0.05).(2) The research of nutritive values showed that there were significant (p＜0.05) differences in nutritive values and anatomy parameters between BMR and other FS types whereas no differences (P>0.05) were observed in photosynthetic indexes. When compared with non-BMR types (WMR and GMR), the mean ADL, NDF and ADF content of BMR types (BMR-6and BMR-12) were decreased respectively by28.0%,4.1%and5.8%while the mean CP content was increased by8.0%during the two years. Especially, BMR-12types had significantly (P<0.05) lower ADL content and higher CP content than that of BMR-6based on their dynamic curve regression model. The nutritive values of forage sorghum types were ranked as following:BMR-12>BMR-6>GMR>WMR. This BMR traits of forage sorghum was begin to express from jointing stage (plant height130cm).(3) Regression model of the nutritive values from BMR-6and BMR-12forage sorghum responsed to growing days (53～93days after sowing) in2012and2013were builted. We can draw a conclusion from above model that the growing regulation of NDF, ADF and ADL value fit in cubic curve regression model with increasing growth days (53～93days after sowing), and the CP content had the liner exponential decay response to the growing days in BMR-6and-12populations.(4) Result showed the mean ADL content of20.94g kg-1in BMR-12lines was significant (P＜0.05) less than that of43.45g-kg-1in N-12lines, however, the lodging resistance index (LRI) of BMR-12plants was significantly (P<0.05) higher than that of N-12lines. The spearman’s correlation analysis demonstrated that there was no significantly correlation (P>0.05) between the ADL content and lodging resistance index (LRI) in BMR-12and N-12materials (R=-0.44, R=-0.21, respectively).(5) Using RACE and RT-PCR technology, a1424bp full-length cDNA, containing a open reading frame (ORF) of1089bp encoding a protein of362amino acids, was obtained. The molecular mass of the putative protein was about39.6kDa, and the pi was about5.6. It was named SsCOMT and deposited in GenBank (accession No. KJ101565). Sequence comparison showed that two point mutations were present in the BMR-12but not in wild-types, the second mutation changed amino acid129of the protein from Gln (CAG) to a stop codon (UAG). The relative expression level of COMT gene reduced significantly, which probably lead to ADL content decrease in BMR-12mutant. |
