| Aegilops tauschii is an invasive weed and widely distributed in winter wheat field in China,and causes significant economic losses to China’s wheat production.In order to determine the germination biological characters of different populations of Ae.tauschii and the allelopathic effects of different crop straws on Ae.tauschii,and select pre-emergence herbicides to control effectively Ae.tauschii,this study was conducted to determine the effects of various environmental factors on the germination and emergence of Ae.tauschii,the allelopathic effects of decomposed liquids of different crop straws on the seeds germination and seedling growth of Ae.tauschii,and the viability of pre-emergence herbicides to control Ae.tauschii by the pot method in greenhouse and field experiments.The main results are as follows:1.Aegilops tauschii was able to germinate across a wide range of constant temperatures(5～35℃),and the optimum temperature for its germination was range of 15～20℃.Compared with constant temperature,variable temperature had no significant effect on the germination of Ae.tauschii.Germination was completely inhibited when dry seeds were exposed to a temperature of 160℃ for 5 min,and a similar response was observed for pre-soaked seeds at100℃.Germination was not affected by light or pH,and could do well in the pH range of3～10.Aegilops tauschii germination was relatively tolerant to low osmotic potential and high salt stress,and salt tolerance varied among different populations,especially the‘HN’population which had higher tolerance to salt stress than other populations.The optimum buried depth for emergence was range of 1～3 cm,but emergence of Ae.tauschii was completely inhibited at depths greater than 8 cm.2.When the concentration was set at 6.25 mg/mL,in addition to significantly increasing seedling dry weight of Ae.tauschii,the decomposed liquids of maize straw significantly inhibited its seed germination rate,seed germination index,seedling root length and seedling height;the decomposed liquids of oilseed rape straw significantly inhibited its seedling root length,but could not significantly affect on its seed germination rate,seed germination index and seedling height;the decomposed liquid of rice straw significantly promoted its seed germination index,seedling root length and seedling height,but had no significant effect on its seed germination rate;the decomposed liquid of rice hull significantly inhibited its seedling root length and promoted its seed germination index and seedling height,but could not significantly affect on its seed germination rate.However,when the concentration was above 25 mg/mL,allelopathic effects of the decomposed liquids of four crop straws on Ae.tauschii were all inhibition,and the inhibiting effects were enhanced along with the increase of the concentration of decomposed liquid.In addition,the decomposed liquid of maize straw showed the highest inhibiting effect on Ae.tauschii,followed by oilseed rape straw,rice hull,and rice straw.Moreover,it was found that seedling root length of Ae.tauschii was more sensitive to allelopathic effects of decomposed liquids of crop straws than the other biomarkers,and allelopathic effects of decomposed liquids was greater on the germination index than the germination rate during the seed germination.3.The laboratory experiment results indicated that the bioactivity of these nine herbicides on Ae.tauschii was acetochlor,oxadiazon,flucarbazone-Na,flufenacet,diflufenican,isoproturon,butachlor,pendimethalin and butralin in order.The selectivity indexes of acetochlor,flufenacet,oxadiazon and isoproturon against between wheat hongdi 95and Ae.tauschii were 0.3,0.3,0.3 and 0.7,respectively,and between wheat shannong 22 and Ae.tauschii were 1.0,0.6,1.0 and 1.1,respectively.So these four herbicides had a low selectivity index for wheat hongdi 95 and wheat shannong 22 when used to control Ae.tauschii.4.The mixed results indicated that the joint effect type was all additive when isoproturon was mixed with flufenacet or oxadiazon on B.japonicus,Ae.tauschii,G.aparine and M.aquaticum.Moreover,the mixture of isoproturon and flufenacet(2:1)had a high selectivity index for the trial wheat when used to control weeds dominated by B.japonicus and M.aquaticum,while the selectivity index was low when this mixture was used to control weeds dominated by Ae.tauschii and G.aparine.And the mixture of isoproturon and oxadiazon(4:1)had a high selectivity index for wheat shannong 22 and low for wheat hongdi 95 when used to control B.japonicus,Ae.tauschii,G.aparine and M.aquaticum.5.The field experiment results showed that the control efficiency of the mixture of isoproturon and flufenacet(2:1)at 600,750 and 900 g a.i./hm~2 was better on B.japonicus,G.aparine,D.sophia than Ae.tauschii.And the control efficiency of the mixture of isoproturon and oxadiazon(4:1)at 600,750,900 g a.i./hm~2 was balanced and high on B.japonicus,Ae.tauschii,G.aparine and D.Sophia at 30 d after treatment.With the increase of the quantity of weeds emergence,the two mixtures still had a better control efficacy on the total plant control effect and the total fresh weight effect of weeds at 60 d after treatment.Compared with the control herbicides,the control efficiency of the two mixtures was significantly enhanced,and it was also safe for the emergence and seedlings growth of wheat.In conclusion,Aegilops tauschii had a wide adaptability to various environmental factors,among which temperature and buried depth were major factors affecting its germination and emergence;the decomposed liquids of different crop straws had concentration effect on the germination and seedling growth of Ae.tauschii,and the decomposed liquid of maize straw showed the highest inhibiting effect on Ae.tauschii among these four crop straws,and seedling root length of Ae.tauschii was more sensitive to allelopathic effects of decomposed liquids of crop straws than the other biomarkers;oxadiazon,acetochlor and flufenacet had the higher bioactivity to Ae.tauschii among the 9 kinds of pre-emergence herbicides,but the selectivity index was low for the trial wheats;the mixtures of isoproturon mixed with flufenacet or oxadiazon had certain control effect on Ae.tauschii and the selectivity index was low for the trial wheats in greenhouse,while there were no significant phytotoxicity symptoms to wheat in field experiment.The results would provide theoretical basis for integrated control of Ae.tauschii and enrich the system of herbicide in wheat fields. |
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