Characteristics On Growth And Reproduction Of Digitaria Ciliaris Sowing Different Times On Songnen Plain

Crabgrass(Digitaria ciliaris) is an annial tuft plant of grass family, which mainly lives on roadside, wilderness, wastelandand widely distribute in subtropical and temperate regions of the world. It's also a major malignant weed in orchard and dry land. There are several mainly methods to Prevention and control weed, such as Chemical, mechanical, manual, alternative control ecological manage and so on.Reproduction of plant is affected by photoperiod, with the relative concentration time of the flowering and fruiting. So there is prolonged reproductive growth / reduces the reproductive growth, but also the phenomenon of crabgrass. Studying on the response of crabgrass to different sowing time and investigating the change of their quantitative traits under different sowing times on Songnen Plain can provide scientific basis for understanding and controlling weed populationsExperiments were carried out in 2006 and 2007. A random experimental design was used, with eight sowing dates and three replications. By big sample, statistic and analyze growth and reproduction characteristics of this weed on the Songnen planted in different times. The results showed that all quantitative traits of crabgrass have greater phenotypic plasticity and the longer time interval to be sown, the greater the difference. At the same time,this plasticity is with some regularity. Tiller height, tiller biomass, spike biomass of the tufts increased with the shortening of extending the shorten growth time. Reverse, 1000-seed weight, heading rate and reproductive allocation (RA) decreased with the extension of the shorten growth time. There is some similarity about phenotypic plasticity and its variation, but also some differences between two years. This is related to climatic differences between years.In the area of Songnen Plain, it is about three months from the early days of May to August that Crabgrass could germinate. So this Crabgrass is managed very difficult as one kind of serious weeds. Integrated our experiment data, weeding young seedlings emerging before July can be the most effective weed-control strategy in Songnen Plain. It was proposed that the crabgrass germinated before July should be controlled timely in the seedling stage.