摘要：Field studies were conducted in 2017 at Concord in northeast Nebraska to evaluate how timing of weed removal and application of pre-emergence (PRE) herbicides influences the growth of soybean.The studies were laid out in a split-plot arrangement of 14 treatments (2 herbicide regimes and 7 weed removal timings) with four replicates.The 2 herbicide regimes were: No PRE and PRE application of a premix of sulfentrazone plus imazethapyr (140 plus 28 g ai ha-1).The 7 weed removal timings were: V1,V3,V6,R2 and R5 soybean growth stages,as well as weed free and weedy season long.Soybean growth parameters (leaf area and dry matter) were collected at R6 growth stage.Delayed timing of weed removal significantly influenced the soybean growth by reducing leaf area and dry matter.Without the application of PRE herbicides,a 5% reduction in soybean leaf area and dry matter occurred when weed removal was delayed until 100 growing degree days after emergence (GDD;equivalent to V1 soybean stage or 10 days after emergence [DAE]).Meanwhile,the use of PRE herbicide prevented the same level of reduction until 382 GDD (V5 soybean stage;34 DAE).The practical implication is that the use of PRE herbicides protected soybean growth and delayed the need for post-emergence application of herbicides by three weeks after soybean emergence.
其他摘要：Poljski ogledi su izvedeni tokom 2017.godine na lokalitetu Concord na severoistoku savezne države Nebraska,SAD.Cilj ogleda je bio da se oceni kako različita vremena uklanjanja korova i primena PRE-EM herbicida utiču na rast i razvoj useva soje.Ogled je rađen po principu splitplot rasporeda sa 14 tretmana (2 različita režima primene PRE-EM herbicida i 7 različitih vremena uklanjanja korova) u četiri ponavljanja.Dva režima primene PRE-EM herbicida: režim bez primene PRE-EM herbicida i režim sa primenom PRE-EM herbicida na bazi mešavine sulfentrazona i imazetapira (140 i 28 g a.s.ha-1).Sedam vremena uklanjanja korova je bilo: V1,V3,V6,R2 i R5 faza razvoja soje,kao i nezakorovljena i zakorovljena kontrola.Vegetativni parametri soje (lisna površina i suva masa) su ocenjivani tokom R6 faze razvoja useva.Odloženo vreme uklanjanja korova je imalo značajnog uticaja na rast soje,time što su lisna površina i suva masa bili značajno redukovani.Bez primene PRE-EM herbicida redukcija lisne površine i suve mase soje za 5% se poklopilo sa odlaganjem uklanjanja korova od 100 GDD nakon nicanja soje (što korespondira sa V1 fazom razvoja soje,odnosno 10 dana nakon nicanja [DNN] useva).Međutim,primena PRE-EM herbicida je dodatno odložila ovo smanjenje,što korespondira sa 382 GDD nakon nicanja soje (što se poklapa sa V5 fazom razvoja soje,odnosno sa 34 DNN-a soje).Na osnovu dobijenih rezultata može se konstatovati da primena PRE-EM herbicida može da zaštiti soju od smanjenja rasta i odloži POST-EM primenu herbicida i do tri nedelje nakon nicanja useva.
关键词：weed interference;soybean;pre-emergence herbicides;crop growth and development.
其他关键词：kompeticija korova i useva;soja;PRE-EM herbicidi;rast i razvoj useva.
