Downy brome is one of the most troublesome weeds in no-till wheat production systems of the US Great Plains. Pyroxasulfone is a relatively new, soil-applied residual herbicide (root/shoot growth inhibitor) labeled for...Downy brome is one of the most troublesome weeds in no-till wheat production systems of the US Great Plains. Pyroxasulfone is a relatively new, soil-applied residual herbicide (root/shoot growth inhibitor) labeled for use in wheat. Multiple field experiments were conducted near Huntley, MT from 2012 through 2016 to determine the efficacy of pyroxasulfone to control downy brome in imidazolinone (IMI)-tolerant (Clearfield™) winter wheat. Pyroxasulfone did not cause any injury to wheat in any of the three studies. Downy brome injury with pyroxasulfone preemergence (PRE) only program did not differ between 89 or 178 g·ai (active ingredient)·ha-1 rates, and averaged 82% and 84% in 2 separate studies. In a preplant (PP) burndown program, the addition of pyroxasulfone (178 g·ai·ha-1) to glyphosate improved downy brome end-season injury from 15% to 74%. In a separate study, the end-season injury with pyroxasulfone was greater when applied PRE (84%) compared to the delayed PRE (DPRE) timing (74%). In addition, the water dispersible granule (WDG) formulation of pyroxasulfone performed slightly better than the suspension concentrate (SC) formulation for downy brome injury. Pyroxasulfone applied PRE in the fall at a rate of 89 g·ai·ha-1 followed by (fb) imazamox (44 g·ai·ha-1 rate) applied postemergence (POST) in the spring effectively controlled downy brome (99% end-season injury). Furthermore, the injury was consistent with the standard program comprising of propoxycarbazone (29 g·ai·ha-1) PRE fb imazamox POST in IMI-tolerant winter wheat. In conclusion, pyroxasulfone applied PRE in the fall can be effectively utilized in conjunction with a standard acetolactate synthase (ALS)-inhibitor-based POST herbicide program for a season-long downy brome management in winter wheat.展开更多
【目的】在豆科与禾本科牧草混播草地中不仅存在种内竞争也存在种间竞争,由于不同植物之间竞争力强弱不同,竞争的结果将出现一方逐渐消退,另一方逐渐占据优势的现象,因此研究豆科与禾本科牧草之间竞争与共存机制对于维持混播草地稳定高...【目的】在豆科与禾本科牧草混播草地中不仅存在种内竞争也存在种间竞争,由于不同植物之间竞争力强弱不同,竞争的结果将出现一方逐渐消退,另一方逐渐占据优势的现象,因此研究豆科与禾本科牧草之间竞争与共存机制对于维持混播草地稳定高产具有重要意义。【方法】在温室栽培条件下设置3个氮肥水平(0,75,150kg N·hm-2,记作N0,N75,N150)以及单播和混播两种种植模式(无芒雀麦单播,紫花苜蓿单播,无芒雀麦和紫花苜蓿1﹕1混播),采用相对生物量(RY)、相对密度(RD)、竞争率(CR)和相对产量总值(RYT)以及紫花苜蓿的固氮比例(%Ndfa)和转氮比例(%N Trans)等指标研究无芒雀麦和紫花苜蓿在1﹕1混播中的竞争关系与共存机制。【结果】施氮量从0增加到150 kg N·hm-2,单播中无芒雀麦的地上和地下生物量和分蘖数显著增加(P<0.05),而紫花苜蓿的地上和地下生物量和分枝数无显著变化(P>0.05)。在混播中无芒雀麦的地上和地下生物量和分蘖数也显著增加(P<0.05),在一定程度上抑制了紫花苜蓿的生物量和分枝数。另外,在混播中无芒雀麦以增加分蘖数的方式来扩张地上空间的能力要强于紫花苜蓿。无芒雀麦的单株生物量和分蘖数在混播模式下都极显著高于单播(P<0.01),而紫花苜蓿的单株生物量和分枝数在混播模式下极显著低于单播(P<0.01)。在混播中无芒雀麦的竞争率始终大于1.0,而紫花苜蓿的竞争率始终小于1.0,这说明无芒雀麦的竞争力要大于紫花苜蓿的竞争力,且在整个生育期中,无芒雀麦的竞争力逐渐减弱,而紫花苜蓿的竞争力逐渐增强。在N0处理下,第2次、第3次和第4次取样时,无芒雀麦和紫花苜蓿的相对产量总值(RYT)显著大于1.0(P<0.05),说明无芒雀麦和紫花苜蓿无明显的竞争效应,这主要归功于紫花苜蓿的生物固氮对无芒雀麦的贡献(地上部转移的氮素占无芒雀麦氮素含量的15.26%—29.92%)。在N75和N150处理下,其RYT值与1.0无显著差异(P>0.05)。另外,施入氮肥明显抑制了紫花苜蓿的生物固氮比例和对无芒雀麦的氮素转移的比例,导致混播中无芒雀麦和紫花苜蓿同时竞争土壤氮素和肥料氮。【结论】施入75和150 kg N·hm-2的氮肥增强了无芒雀麦的竞争力,而抑制了紫花苜蓿的生物固氮和对无芒雀麦氮素的转移,二者促进作用减弱,竞争效应增强。展开更多
苜蓿(M ed icag o sa tiva)与无芒雀麦(B rom us innerm is)以0.3:0.7的播种量进行混播试验,测定组分种绝对生长率(AGR)、相对生长率(RGR)、相对产量总和(RYT)以及种间竞争率(CR),探讨不同苜蓿品种+无芒雀麦混播群落种间竞争及稳定性。...苜蓿(M ed icag o sa tiva)与无芒雀麦(B rom us innerm is)以0.3:0.7的播种量进行混播试验,测定组分种绝对生长率(AGR)、相对生长率(RGR)、相对产量总和(RYT)以及种间竞争率(CR),探讨不同苜蓿品种+无芒雀麦混播群落种间竞争及稳定性。结果表明:草地生物量的净积累主要在生育前期,单播和混播草地中杂花苜蓿的AGR和RGR平均值高于敖汉苜蓿(M.sa tiva CV.A ohan);同种苜蓿混播与单播草地生物量快速积累期相同,但不同品种间有所差异,敖汉苜蓿早于杂花苜蓿(M.varia M artin.CV.C aoyuan);苜蓿在孕蕾至初花期、无芒雀麦在拔节至抽穗期AGR和RGR最高,混播降低了苜蓿的AGR和RGR值;在组分频率下,春秋二季种间竞争小于种内竞争(RYT>1),而夏季种间竞争大于种内竞争(RYT<1),苜蓿的竞争力大于无芒雀麦(苜蓿的CR>1);甘农1号杂花苜蓿(M.variaM artin.CV.G annong N o.1)与无芒雀麦混播群落稳定性较好;在苜蓿+无芒雀麦混播群落中,光资源竞争是种间竞争的关键,温度对种间竞争有明显影响,夏季较高的温度减弱了无芒雀麦的竞争力,增强了苜蓿的竞争力;夏季是混播草地中无芒雀麦种群衰退的关键时期。展开更多
文摘Downy brome is one of the most troublesome weeds in no-till wheat production systems of the US Great Plains. Pyroxasulfone is a relatively new, soil-applied residual herbicide (root/shoot growth inhibitor) labeled for use in wheat. Multiple field experiments were conducted near Huntley, MT from 2012 through 2016 to determine the efficacy of pyroxasulfone to control downy brome in imidazolinone (IMI)-tolerant (Clearfield™) winter wheat. Pyroxasulfone did not cause any injury to wheat in any of the three studies. Downy brome injury with pyroxasulfone preemergence (PRE) only program did not differ between 89 or 178 g·ai (active ingredient)·ha-1 rates, and averaged 82% and 84% in 2 separate studies. In a preplant (PP) burndown program, the addition of pyroxasulfone (178 g·ai·ha-1) to glyphosate improved downy brome end-season injury from 15% to 74%. In a separate study, the end-season injury with pyroxasulfone was greater when applied PRE (84%) compared to the delayed PRE (DPRE) timing (74%). In addition, the water dispersible granule (WDG) formulation of pyroxasulfone performed slightly better than the suspension concentrate (SC) formulation for downy brome injury. Pyroxasulfone applied PRE in the fall at a rate of 89 g·ai·ha-1 followed by (fb) imazamox (44 g·ai·ha-1 rate) applied postemergence (POST) in the spring effectively controlled downy brome (99% end-season injury). Furthermore, the injury was consistent with the standard program comprising of propoxycarbazone (29 g·ai·ha-1) PRE fb imazamox POST in IMI-tolerant winter wheat. In conclusion, pyroxasulfone applied PRE in the fall can be effectively utilized in conjunction with a standard acetolactate synthase (ALS)-inhibitor-based POST herbicide program for a season-long downy brome management in winter wheat.
文摘【目的】在豆科与禾本科牧草混播草地中不仅存在种内竞争也存在种间竞争,由于不同植物之间竞争力强弱不同,竞争的结果将出现一方逐渐消退,另一方逐渐占据优势的现象,因此研究豆科与禾本科牧草之间竞争与共存机制对于维持混播草地稳定高产具有重要意义。【方法】在温室栽培条件下设置3个氮肥水平(0,75,150kg N·hm-2,记作N0,N75,N150)以及单播和混播两种种植模式(无芒雀麦单播,紫花苜蓿单播,无芒雀麦和紫花苜蓿1﹕1混播),采用相对生物量(RY)、相对密度(RD)、竞争率(CR)和相对产量总值(RYT)以及紫花苜蓿的固氮比例(%Ndfa)和转氮比例(%N Trans)等指标研究无芒雀麦和紫花苜蓿在1﹕1混播中的竞争关系与共存机制。【结果】施氮量从0增加到150 kg N·hm-2,单播中无芒雀麦的地上和地下生物量和分蘖数显著增加(P<0.05),而紫花苜蓿的地上和地下生物量和分枝数无显著变化(P>0.05)。在混播中无芒雀麦的地上和地下生物量和分蘖数也显著增加(P<0.05),在一定程度上抑制了紫花苜蓿的生物量和分枝数。另外,在混播中无芒雀麦以增加分蘖数的方式来扩张地上空间的能力要强于紫花苜蓿。无芒雀麦的单株生物量和分蘖数在混播模式下都极显著高于单播(P<0.01),而紫花苜蓿的单株生物量和分枝数在混播模式下极显著低于单播(P<0.01)。在混播中无芒雀麦的竞争率始终大于1.0,而紫花苜蓿的竞争率始终小于1.0,这说明无芒雀麦的竞争力要大于紫花苜蓿的竞争力,且在整个生育期中,无芒雀麦的竞争力逐渐减弱,而紫花苜蓿的竞争力逐渐增强。在N0处理下,第2次、第3次和第4次取样时,无芒雀麦和紫花苜蓿的相对产量总值(RYT)显著大于1.0(P<0.05),说明无芒雀麦和紫花苜蓿无明显的竞争效应,这主要归功于紫花苜蓿的生物固氮对无芒雀麦的贡献(地上部转移的氮素占无芒雀麦氮素含量的15.26%—29.92%)。在N75和N150处理下,其RYT值与1.0无显著差异(P>0.05)。另外,施入氮肥明显抑制了紫花苜蓿的生物固氮比例和对无芒雀麦的氮素转移的比例,导致混播中无芒雀麦和紫花苜蓿同时竞争土壤氮素和肥料氮。【结论】施入75和150 kg N·hm-2的氮肥增强了无芒雀麦的竞争力,而抑制了紫花苜蓿的生物固氮和对无芒雀麦氮素的转移,二者促进作用减弱,竞争效应增强。
文摘苜蓿(M ed icag o sa tiva)与无芒雀麦(B rom us innerm is)以0.3:0.7的播种量进行混播试验,测定组分种绝对生长率(AGR)、相对生长率(RGR)、相对产量总和(RYT)以及种间竞争率(CR),探讨不同苜蓿品种+无芒雀麦混播群落种间竞争及稳定性。结果表明:草地生物量的净积累主要在生育前期,单播和混播草地中杂花苜蓿的AGR和RGR平均值高于敖汉苜蓿(M.sa tiva CV.A ohan);同种苜蓿混播与单播草地生物量快速积累期相同,但不同品种间有所差异,敖汉苜蓿早于杂花苜蓿(M.varia M artin.CV.C aoyuan);苜蓿在孕蕾至初花期、无芒雀麦在拔节至抽穗期AGR和RGR最高,混播降低了苜蓿的AGR和RGR值;在组分频率下,春秋二季种间竞争小于种内竞争(RYT>1),而夏季种间竞争大于种内竞争(RYT<1),苜蓿的竞争力大于无芒雀麦(苜蓿的CR>1);甘农1号杂花苜蓿(M.variaM artin.CV.G annong N o.1)与无芒雀麦混播群落稳定性较好;在苜蓿+无芒雀麦混播群落中,光资源竞争是种间竞争的关键,温度对种间竞争有明显影响,夏季较高的温度减弱了无芒雀麦的竞争力,增强了苜蓿的竞争力;夏季是混播草地中无芒雀麦种群衰退的关键时期。
