The Distribution And Biological Characteristics Of Alian Invasive Plant Cenchrus Pauciflorus

Textual research and investigation on gramineae Cenchrus of Horqin sand determined the annual invasive herb is Cenchrus pauciflorus Benth. As its mature burs can cause mechanical injury, it affects the normal production of husbandary, forestry and agriculture.In Inner Mongolia, Cenchrus pauciflorus Benth mainly occurred in Tongliao, Chifeng, Xing'an meng and Bayannaoer city.The expansion paths were mainly by livestock and vehicles and trains along the roads. In Inner Mongolia, Cenchrus pauciflorus Benth would invade sandy area of Ulanbuhe, Maowusu, Kubuqi, Hunshandak, Hulunbeier and Degraded Sandy Grassland.Cenchrus pauciflorus Benth was in expanding stage in Horqin sand. In fixed and moving sand, the Cenchrus pauciflorus Benth plant population would be steady and dominant.With the importance of Cenchrus pauciflorus Benth increase, the population similarity index increased, while substitution rate decreased, population structure got simple.The investigation of distribution pattern of soil seed bank of Cenchrus pauciflorus Benth showed, seed of Cenchrus pauciflorus Benth distributed in the soil of 0-3 cm depth. Most seed gathered in the soil of 0-1 cm depth in fixed sandy land. Seed of Cenchrus pauciflorus Benth dispersed in 1-15 cm depth in semi-mobile dune. Most seeds existed in 1-3 cm and 7-8 cm depth, especially in 1-3 cm depth sand. With the depth increasement, the germination rate increased in fixed and semi-moble sandy area.The negative binominal formula and the ratio of variance and mean (distribution coefficient) proved the distribution pattern of seed population was cluster distribution. The seed natural disperse distance caused centralizing distribution.Cenchrus Pauciflorus was investigated on flowering behavior and seeding. C. Pauciflorus was andromonoecious and self-pollination plant. Each spikelet had 1-3 florets. The first floret was hermaphrodite and the second is male floret. The pollen viability was 90.86% in average. The floret opening order was usually from terminal down to basal. The seed with bur absorbing water needed 12 hrs to saturation while naked seed needed 2 hrs. The suitable temperature was 25℃for naked seed and bur seed. Removing bur promoted seed germination.The bagging treatment of different part of florets keeping showed different size of seed, weight and geminating rate. The seed of first spikelet got more germinating rate when the second spikelet had been removed in flowering period, while the seed of second spikelet developed well when the first spikelet had been removed in flowering period. The shape of seed got long and narrow.The seed size and germinating capacity were influenced by the difference of the seeding position. The bigger seed on upper spike had germinated early.