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Using chemical seed dormancy breakers with herbicides for weed management in soyabean and wheat
- Das, T K, Das, D K
- Weed research 2018 v.58 no.3 pp. 188-199
- Cyperus rotundus, annual weeds, cost effectiveness, costs and returns, germination, gibberellic acid, herbicide mixtures, imazethapyr, isoproturon, metsulfuron, pendimethalin, perennial weeds, periodicity, potassium nitrate, seed dormancy, soybeans, tubers, weed control, wheat
- Variable dormancies result in periodicity in the germination of weeds and make weed control a repetitive practice. Under some conditions, repeated applications of selective herbicides can lead to the dominance of perennial weeds like Cyperus rotundus. Our hypothesis was that applying a chemical dormancy breaker (DB) plus herbicide mixture would better control a mixture of weed species. Three experiments were designed to develop a cost‐effective DB treatment and to evaluate its dose with herbicides tank‐mixtures for effective weed management. KNO₃ and gibberellic acid GA₃ as dormancy breakers offered comparable effects, but KNO₃ was more economical than GA₃. KNO₃ at a 6% concentration was more effective in promoting weed germination than a 3% concentration in soyabean. A combination of KNO₃ (6%) and pre‐emergence pendimethalin 0.75 kg a.i. ha⁻¹ + imazethapyr 0.10 kg a.i. ha⁻¹ controlled annual weeds by 99% and reduced C. rotundus growth by 83%. This treatment gave significantly higher soyabean yield and net returns. Similarly, a tank‐mixture comprising of clodinafop 0.06 kg a.i. ha⁻¹ + metsulfuron 0.006 kga.i. ha⁻¹ was more effective against weeds than pre‐emergence tank‐mix application of pendimethalin 0.75 kg a.i. ha⁻¹ + carfentrazone‐ethyl 0.02 kg a.i. ha⁻¹ and isoproturon 0.75 kg a.i. ha⁻¹. The use of pre‐emergence tank‐mixture of pendimethalin 0.75 kg a.i. ha⁻¹ + imazethapyr 0.10 kg a.i. ha⁻¹ should exhaust seed/tuber bank if repeated and reduce the application cost of herbicides by 50% and the dose, residue and cost of pendimethalin by 25%.