甘蓝型冬油菜及其田间杂草对苗前与苗后共施不同浓度除草剂的响应

Response of Winter Brassica napus L.and Its Field Weeds to Co-Application of Different Concentrations of Herbicides at Pre-and Post-Emergence of Rape Stages

为了探究苗前与苗后除草剂不同浓度单施或共施对冬油菜田间杂草的防效以及对冬油菜生长的影响,以甘蓝型冬油菜(天油2266)为试验材料,选用苗前除草剂(精异丙甲草胺)和苗后除草剂(高效氟吡甲禾灵),于2017—2019年开展大田试验。结果表明,在甘蓝型冬油菜成熟期,共施比单施的总株防效与总鲜重防效平均提升了18.07%和15.07%,株防效和鲜重防效的平均提升幅度达26.78%和40.83%。苗前除草剂施用浓度的增加会减弱其增产效应,增产幅度为20.56%~34.11%,平均增产1801.61kg/hm^(2);苗后除草剂施用浓度的增加有一定减产风险,产量变幅为-2.02%~16.06%;苗前与苗后除草剂共施之下,产量增加784.40~2575.98kg/hm^(2),增产30.17%~99.09%,平均增产1235.00kg/hm^(2),平均增幅47.51%。因此,在冬油菜田应用苗前除草剂能显著抑制杂草暴发。苗前除草剂对越冬前苗期禾本科和阔叶类杂草的防效达9389%和86.98%;成熟期对总杂草的株防效和鲜重防效分别达到76.98%和54.05%。苗后除草剂主要显著地作用于禾本科杂草,对于生育周期较长的北方冬油菜,在禾本科杂草严重发生时可在越冬后再应用苗后除草剂,以防禾本科杂草对冬油菜后期生长产生危害;杂草发生严重,尤其是阔叶类杂草多的田块可适当提高苗前除草剂的施用浓度,以提高冬油菜产出效益,同时,在保障冬油菜籽粒产量的前提下应尽可能低浓度施用苗后除草剂,在禾本科杂草少时可只施苗前除草剂。

This paper aimed to study the effect of single or combined application of different concentrations of herbicides on weeding and growth of winter Brassica napus L.(Tianyou 2266)at pre-and post-emergence of rape stages.A field experiment was conducted from^(2)017 to 2019 with pre-emergence herbicide(S-metolachlor)and post-emergence herbicide(Haloxyfop-r-methyl).Compared with single application,the total control efficiency based on plant and fresh weight of combined application were increased by 18.07%and 15.07%,and the control efficiency based on plant and fresh weight were 26.78%and 40.83%,respectively.The yield increasing effect waked as the concentration of pre-emergence herbicide increasd.And The increased yield of B.napus ranged from^(2)0.56%to 34.11%,with an average of 1801.61 kg/hm^(2).There was a certain risk of yield reduction as the concentration of post- emergence herbicides increased.And its yield variation ranged from-2.02%to 16.06%.Under the co-application,the yield were increased by 784.40~2575.98 kg/hm^(2)with the rates of 30.17%~99.09%,and the average increased by 1235.00 kg/hm^(2)with the rate of 47.51%.Therefore,pre-emergence herbicide could significantly inhibit weed to break out in winter rape fields.The control effects of pre-emergence herbicide on grasses and broadleaved weeds reached 93.89%and 86.98%at seedling stage before overwintering.And the plant and fresh weight control effects on total weeds reached 76.98%and 54.05%at maturity stage,respectively.Post-emergence herbicides mainly act on gramineous weeds.For winter rape with a long growth stage in the northern of China,post-emergence herbicides could be applied after overwintering when gramineous weeds occured seriously,so as to prevent gramineous weeds from causing harm to the later growth of winter rape.In order to improve the yield and benefit of winter rape,the concentration of pre-emergence herbicides should be appropriately increased with the serious occurrence of weeds especially broadleaved weeds in the fields.At the same time,the concentration of post-emergence herbicides should be applied as low as possible under the premise of ensuring the grain yield of winter rape.Only pre-emergence herbicide could be applied when there were few gramineous weeds.