| Sudangrass(Sorghum sudanense(Piper)Stapf.) is the main warm-season graminaceous forage grass in the south of China, which has all kinds of exellent resistance to leanness and other tough conditions. Sudangrass grown on every unit area land can yield more methane than maize can, but it is very suspecitible to leaf spot disease. In order to solve this problem, Sorghum propinquum and sudangrass had been crossed and generated a long-distant hybrid F1 whose resistance is strong and presented good agronomic traits, but the disease resistance, color of seed, thousand kernel weight, mature period and plant height of F2 generation is separated terribly. Embryonic callus treated by colchicine which was induced by young panicle of F1 hybrid of sudangrass and Sorghum propinquum as explant during tissue culture could generate tetraploid which supplied renovation materials for energy forage dual-purpose untilization sudangrass breeding.In this experiment, somatic mutant SS2010-2 and SS2010-3 which was induced by colchicine treating F1 (HS) hybrid of sudangrass and Sorghum propinquum was compared with sudangrass 2098 and HS which were control. Root tips chromosome counting and flow cytometry analysis were performed to indentify ploidy of SS2010-2 and SS2010-3, leaf epidermis stomatal apparatus and mesophyll cell chloroplasts ultrastructure were observed, stem and leaf anatomical structure of control and new materials were compared; and by analysing comprehensive agronomic traits, dry matter yield and chemical composition of the cell wall of energy use index, energy use value of new materials was also evaluated synthetically. The main results are as follows:(1) Cytological characteristic SS2010 and SS2010-3 were different from control significantly. By means of root tips chromosome counting and flow cytometry analyzing, SS2010-2 and SS2010-3 were identified as allotetraploid. Compared to sudangrass 2098, stomatal apparatus length and width of upper and lower leaf epidermis of SS2010 and SS2010-3 were increased significantly, stomatal apparatus density of SS2010-2 upper and lower leaf epidermis were decreased significantly. Compared to HS, stomatal apparatus length and width of upper and lower leaf epidermis of SS2010-2 were increased significantly, stomatal apparatus length of lower leaf epidermis and width of upper and lower leaf epidermis of SS2010-3 were increased significantly, stomatal apparatus density of SS2010-2 and SS2010-3 were decreased significantly. Compared to sudangrass 2098 and HS, chloroplasts number of SS2010-2 were increased significantly.(2) Significant difference presented in leaf and stem anatomical structure of SS2010-2 and SS2010-3 compared to control. Compared to sudangrass 2098 and HS, leaf thickness, lower epidermis thickness, bulliform cell length, bigger vascular bundle area and bigger vascular area of SS2010-2 were increased significantly, leaf blade smaller vascular bundle density were decreased significantly; Compared to sudangrass 2098, leaf thickness and leaf blade smaller vascular bundle density were increased significantly. Compared to HS, lower epidermis thickness and bulliform cell length were decreased significantly, leaf blade smaller vascular bundle density were increased significantly.Compared to Sudangrass 2098 and HS, the outer sclerenchyma tissue thickness, central vascular area and the ratio of central bigger vascular area between central vascular bundle area of SS2010-2 were increased significantly, the outer sclerenchyma tissue thickness, vascular bundle density, central bigger vascular area and the ratio of central bigger vascular area between central vascular bundle area of SS2010-3 were increased significantly; central vascular bundle area of SS2010-3 were less than HS significantly.(3) Comprehensive agronomic traits of SS2010-2 and SS2010-3 generated significant variation compared with that of control. Compared to sudangrass 2098, plant height, the number of tillers and leaf length of SS2010-2 were decreased and increased significantly separately. Compared to HS, plant height and leaf length of SS2010-2 were decreased significantly, plant height, leaf length, leaf width and stem diameter were decreased significantly. Days from transplanting to heading of SS2010-2 and SS2010-3 were 29 and 35 days more than sudangrass 2098 respectively, Days from transplanting to wilting of SS2010-2 and SS2010-3 were 15 and 20 days more than sudangrass 2098 respectively, Mean leaf spot disease grade of SS2010-2 and SS2010-3 were 3.7 and 3.8 less than sudangrass 2098 respectively. Compared to HS, days from transplanting to heading of SS2010-2 and SS2010-3 were 18 and 24 days more than that of Sudangrass 2098, days from transplanting to wilting of SS2010-2 and SS2010-3 were 1 day less and 4 days more, mean leaf spot disease grade of SS2010-2 and SS2010-3 were invariant and 0.1 less. SS2010-3 was self-fruitful while SS2010-2 whose anthers abortive but stigma can be fertilized was not, both of them are perennial.(4) Plant dry matter yield of SS2010-2 and SS2010-3 were varied significantly with control. Compared to sudangrass 2098, individual plant dry matter yield of SS2010-2 was increased significantly while that of SS2010-3 was decreased significantly. Compared to HS, individual plant dry matter yield of SS2010-2 and SS2010-3 was decreased significantly. Compared to sudangrass 2098, lignin content of SS2010-2 and SS2010-3 were decreased significantly. Compared to HS, cellulose+hemicellulose and lignin content of SS2010-3 were decreased significantly.(5) Compared to control, energy utilization index of cell wall chemical composition of SS2010-2 and SS2010-3 were presented some difference. The score of energy utilization index of cell wall chemical composition of SS2010-2, SS2010-3, HS, sudangrass 2098 were 74.06,71.64,75.84,72.96 and 75.62 separately, the score of SS2010-2 was higher than Sudangrass 2098. |
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