Ecological Adaptability Of Tausch's Goatgrass (Aegilops Tauschii Coss.)

Tausch's goatgrass (Aegilops tauschii Coss.), an annual or perennial grass weed, is classified asAegilops. Tausch's goatgrass is an invasive alien species and is a close relative to the wheat (Triticumaestivum). The morphology and growth cycle is very similar to wheat, Tausch's goatgrass competes withwheat for water, light, nutrients and space, is a serious issue on wheat yield and quality. In recent years,an estimated330,000ha are infested in winter wheat fields in Hebei, Shanxi, Shandong, Henan, andShaanxi provinces. Increasing damage and rapid spreading made it a serious weed species in winterwheat fields.Weed biology and ecology are the basis of the weed management systems, Studies were conductedto determine the adaptability of Tausch's goatgrass in winter wheat fields, competitive relationship withwheat, impacts on the yield of wheat, and the potential distribution in China and the world from2009to2012. The main conclusions are as follows:1. The effects of environmental factors affecting seed germination and seedling emergence wereevaluated in laboratory and greenhouse experiments. The germination of Tausch's goatgrass seedsoccurred at temperatures ranging from5to35℃, with optimum germination attained between15and25℃. Tausch's goatgrass seed is rather tolerant to low water potential and high salinity stress.Medium pH and light have no significant effect on seed germination. Highest emergence (>80%)occurred from depths of1to3cm, but no seedlings emerged when burial depth reached9cm.2. Tausch's goatgrass emergence, tillering dynamics, height and fresh weight changes were closelyrelated to temperature. Tausch's goatgrass has two main seedling emergence peaks, one in earlywinter from late October to early November (the weekly average temperature of16.2~11.6℃),about75~87%emerged, and the other in later spring from late March to early April (the weeklyaverage temperature rose to about10℃), about13~25%emerged. Tausch's goatgrass tilleringability is stronger than wheat.30~35d (about mid-November) after the sowing of the wheat,Tausch's goatgrass and wheat tillered at the same time, and formed the tiller peak.3. Based on the economic infestation level of A. tauschii and the obtained logarithmic model, theeconomic threshold of A. tauschii was5.71plants·m-2for manual control and was2.35plants·m-2for chemical control by3%Mesosulfuron OF.4. The study indicate that the placement of fertilizer had a significant effect on the growth anddevelopment of both Tausch's goatgrass and winter wheat. Tausch's goatgrass competition withwinter wheat was reduced when fertilizer was placed deep in the soil closer to the wheat seeds,however, when fertilizer was broadcast, Tausch's goatgrass competition with winter wheat waseither enhanced or stayed the same compared to the nonfertilized infested check. It appears thatwith broadcast application, Tausch's goatgrass seedlings had easy access to fertilizer, compared towheat seedlings. Placing fertilizer deep in the soil and closer to the wheat seedlings reduced the access of Tausch's goatgrass to nutrients and favored wheat seedlings. In the absence of Tausch'sgoatgrass, broadcast, deep band, and deep spot fertilizer applications increased wheat yield18.0,25.5, and24.7%, respectively, when compared to the weed-free, nonfertilized check. In thepresence of Tausch's goatgrass, wheat yields were increased8.1,22.0, and25.3%with broadcast,deep band, and deep spot placement, respectively.5. The genetic similarity coefficient (GS) in the six provinces of Shaanxi, Shanxi, Shandong, Hebei,Henan, and Jiangsu is most greater than0.9. Their relationship is close, little genetic differences.The genetic clustering and the geographical origin of the materials have some correlation.6. The global potential distribution area of Tausch's goatgrass is mainly between30and45°degreesnorth latitude. West Asia, Mid-east, the Mediterranean coast of south-eastern Europe and northernAfrica are the main suitable areas for Tausch's goatgrass. In China the suitable areas for Tausch'sgoatgrass are mainly distributed in Henan, Hebei, Shandong, southwest of Shanxi, Guanzhong Plainof Shaanxi, the central and south of Ningxia, southeast of Gansu, north of Hubei, Jiangsu and Anhuiprovinces. As the global climate change, the potential distribution range of Tausch's goatgrass willvary according to different emissions scenarios. With greenhouse gases under the A1b emissionsscenario, by2050, the potential distribution of Tausch's goatgrass will have a tendency to expand.While under A2a and B2a emissions scenarios, the low-and medium-risk areas will tend todecrease, but the high-risk areas will not change significantly.