| Tall fescue(Festuca arundinacea Schreb.)and kentucky bluegrass(Poa pretensis L.)are commonly used perennial pasture and turfgrass and their reproductions are mainly based on seeds.During the process of seed production,weeds infestation is an important factor restricting seed yield.Identifying and formulating safe and efficient herbicides suitable for grass seed production is a problem that urgently needs to be solved.This study was conducted in"Zhigeng Garden"of School of Agriculture and Biology,Shanghai Jiao Tong University from March 2015 to September 2016.Using tall fescue and kentucky bluegrss as experiment materials,effects of 5preemergence herbicides,19 postemergence herbicides and 6 self-formulated herbicides on weeds control and seed production was investigated and evaluated which provided the theoretical basis and technical support for further establishment of high and stable yield system of the two grass lines.1.The result of identifying preemergence herbicides shows:Premetryn and pendimethalin are suitable preemergence herbicides for seed production of tall fescue,under which the seed yields of tall fescue are higher than control,793.3 kg/hm~2 and 768.2 kg/hm~2,respectively.And there is no significant difference in seed yield between weeds control by hand and applying prometryn or pendimethalin.The weeds control of applying prometryn or pendimethalin is 69%and 44%,respectively,which have no significant difference compared with trifluralin(59%).Premetryn and Trifluralin are suitable preemergence herbicides for seed production of kentucky bluegrass,under which the seed yields of kentucky bluegrass are higher than control,248.3 kg/hm~2 and 200.9 kg/hm~2,respectively.And there is no significant difference in seed yield between weeds control by hand and applying premetryn or trifluralin.The weeds control of applying premetryn or trifluralin is 30%and 59%,respectively,which have no significant difference compared with acetochlor(58%).Jinduer significantly inhibited the growth and yield of tall fescue and kentucky bluegrass,which is unsuitable for seed production of the two grass lines.2.The result of identifying postemergence herbicides shows:Tribenuron-methyl,MCPA-Bentazone and Florasulam·Fluroxypyr 1-methylheptyl ester are suitable postemergence herbicides for seed production of tall fescue,under which the seed yields of tall fescue have no significant difference compared with weeds control by hand.The reductions of seed yield are less than 10%and the amount of reductions are smaller than other herbicides.The weeds control of applying these three herbicides are good(weeds injury rates are 63%,87%and 95%,respectively,7-days post-application).Sigraa broad,pyroxsulam and traxos are unsuitable for seed production of tall fescue,which obviously inhibited the growth and yield of tall fescue.Bentazone,tribenuron-methyl and MCPA are suitable postemergence herbicides for seed production of kentucky bluegrass,which have little influences on seed yields and smaller amount of reductions in seed yields compared with weeds control by hand,and seed yield is 33%higher than control.Weeds injury rates are 68.4%,55.8%and 73%,respectively.Fenoxaprop-p-ethyl,traxos and fusillade significantly inhibited the growth and yield of kentucky bluegrass.3.The result of identifying self-formulated herbicides shows:Group 4and group 5 performed well in seed yields of tall fescue and weeds control and are herbicides suitable for seed production of tall fescue.The seed yields are 604 kg/hm~2 and 541 kg/hm~2,respectively.And weeds injury rates are93.3%and 96.2%two weeks post-application,respectively.Group 4 and MCPA+Fluroxypyr are suitable for seed production of kentucky bluegrass,under which the seed yields are higer than control(437 kg/hm~2 and 420kg/hm~2,respectively).There is no significant difference in seed yields among the two self-formulated herbicides and tribenuron-methyl.Weeds injury rates are 93.72%and 85.36%two weeks post-application,respectively. |
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