氰氟草酯对泽蛙蝌蚪毒性及风险

研究了氰氟草酯(cyhalofop-butyl)对泽蛙(Rana limnocharis)蝌蚪毒性,室内毒性与田间风险的关系。通过监测氰氟草酯在田间的降解规律,解释其对泽蛙蝌蚪的室内外毒性差异。室内急性毒性试验结果表明,氰氟草酯对泽蛙蝌蚪的24h-LC50和48h-LC50分别为0.718 和0.677 mg·L-1,属于高毒级。田间模拟试验结果表明,100 g·L-1氰氟草酯乳油施药剂量为300 g·hm2以下对泽蛙蝌蚪无影响;100 g·L-1氰氟草酯EC施药剂量在1 500 g·hm-2,蝌蚪死亡率为86.7%。降解动态测定结果表明,氰氟草酯在田间条件下降解极快,1 500 g·hm-2处理,田水中氰氟草酯2 h含量为0.112 mg·L-1,远低于理论初始浓度42.9 mg·L-1。因此,虽然氰氟草酯对泽蛙蝌蚪高毒,但在田间对泽蛙急性毒性风险较低。     

10%氰氟草酯对‘张杂谷10号’叶片生理生化指标的影响

为探究除草剂氰氟草酯对谷子的安全性,以‘张杂谷10号’为材料,分别设置225(1/4×)、450(1/2×)、675(3/4×)、900(1×,推荐剂量)、1 800 mL/hm²(2×)5个10%氰氟草酯水乳剂的处理和对照(CK,0 mL/hm²),测定谷子的农艺性状及生理生化指标。结果表明:随喷药剂量的增加,谷子株高、叶面积、茎粗呈现下降趋势,喷药后45 d,1×、2×的株高、叶面积均显著低于CK。喷药初期,SOD、POD活性呈现先升高后降低的趋势,CAT活性呈现先下降后上升的趋势,MDA含量呈现上升趋势,随喷药时间延长,2×的SOD活性显著低于CK,POD、CAT、MDA均与CK无显著差异。喷药后5 d,1×的叶绿素a(Chla)、叶绿素b(Chlb)、类胡萝卜素(Car)、总叶绿素(Chl_a+b)含量显著高于CK;喷药后45 d,高浓度处理(3/4×、1×、2×)仍显著高于CK,2×的Chla、Chlb、Car、Chl_a+b分别比CK增加29.69%、32.66%和20.17%和30.52%。喷药后5 d,最大光化学效率(F_v/F_m)、PSII表观光合电子传递速率(ETR)、PSII实际光化学效率(Y(II))、光化学淬灭系数(qP)均呈现先升高后下降的趋势,2×的ETR、Y(II)显著低于CK,非光化学淬灭系数(NPQ)与CK无显著差异;喷药后45 d,2×的NPQ比CK增加19.50%。综上,‘张杂谷10号’对氰氟草酯有较强的耐受性,推荐使用900 mL/hm²应用于‘张杂谷10号’谷田生产。     

20% 上格千金对水稻直播田禾本科杂草的防除效果

[目的]明确20％上格千金（氰氟草脂可分散油悬浮剂）防除直播水稻田禾本科杂草的效果和使用剂量,为大面积推广应用提供科学依据。[方法]设6组处理,每组4次重复,采用随机区组设计,进行20％上格千金对水稻直播田稗草、千金子的防效试验。[结果]20％上格千金对稗草和千金子为主的水稻直播田禾本科杂草防除效果良好。当用量为375～525ml／hm^2时,药后25d平均株防效为89．3％～99．0％,45d平均株防效为89．2％-99．0％,平均鲜重防效为89．1％-99．1％,速效性、持效性好。[结论]20％上格千金防除水稻直播田禾本科杂草的经济有效用量为375～525ml／hm^2。     

Physiological basis of differential phytotoxic activity between fenoxaprop-P-ethyl and cyhalofop-butyl-treated barnyardgrass

This study investigated the physiological causes of differences in phytotoxic symptoms shown in barnyardgrass from foliar applications of the herbicides fenoxaprop-P-ethyl and cyhalofop-butyl. When these were applied to the third leaves of the whole plant, the chlorosis and desiccation in the third leaf was greater in fenoxaprop-P-ethyl than cyhalofop-butyl. However, initial growth inhibition of the fourth leaf was greater when using cyhalofop-butyl than when using fenoxaprop-P-ethyl. In the shoot regrowth test, regrowth at five days after treatment (DAT) was smaller in cyhalofop-butyl than in fenoxaprop-P-ethyl; the regrowth at 10 DAT exhibited the reverse trend. The chlorosis (decrease of chlorophylls: carotenoids ratio) in barnyardgrass leaf segments that were floated on herbicide solution was greater in the fenoxaprop-P-ethyl treatment. These results indicate that different herbicidal responses induced by the two herbicides are likely to be related to differential translocation and metabolism. The relatively light chlorosis and desiccation in treated leaves, severe cessation of initial growth (but a lower final herbicidal efficacy in the cyhalofop-butyl treatment) are probably related to its rapid translocation to the meristem region from the treated leaf, followed by faster metabolism. In contrast, the relatively greater chlorosis and desiccation compared to inhibition of initial growth in the fenoxaprop-P-ethyl treatment is likely to be related to its relatively slower translocation and metabolism in the treated leaf.     

氰氟草酯在池塘水中的生物降解

采用室内培养实验方法,研究了氰氟草酯在池塘水中的生物降解。结果表明,水中微生物可有效地促进氰氟草酯的降解,氰氟草酯对池塘水中某些细菌的生长有一定刺激作用,对放线菌和真菌的生长影响不明显。利用选择性培养基,对不同种类细菌进一步培养和鉴定发现,氰氟草酯在池水中的降解微生物主要是假单胞菌和葡萄球菌,代谢机制可能以生长代谢为主。     

氰氟草酯水解动力学研究

研究了氰氟草酯在不同温度、不同pH条件下于水溶液中的降解动态,并通过液相色谱法对水解产物进行了鉴定。结果表明,氰氟草酯在酸性条件下比较稳定,在微酸性及中性条件下水解速度加快,在碱性条件下水解迅速;温度升高水解反应加速,水解反应温度效应系数为2.1~3.0,活化能为74.90 kJ/mol。水解产物主要是(R)-2- -丙酸、(R)-2- -丙酸和(R)-2- -丙酸。     

草甘膦与氰氟草酯对隆线溞的急性毒性研究

在水生食物链中,水溞是连结植物、微生物和动物的关键成员。草甘膦与氰氟草酯被广泛用于防除水生和稻田杂草,研究它们对水溞的毒性,有益于人们关注使用除草剂对水体生态系统的影响。试验以标准水体监测生物——隆线溞(Daphnia carinata)单克隆为材料,研究草甘膦和氰氟草酯对其泳动能力、存活率和趋光性的影响。结果表明,两种除草剂对隆线溞均有明显毒性,草甘膦对隆线溞24, 48和96 h的半致死浓度(LC₅₀)分别为66.58, 29.60和12.33 mg/L,为田间常规用药量的0.15%~0.81%;氰氟草酯对隆线溞24, 48和96 h的LC₅₀依次是63.15, 51.91和34.41 mg/L,为田间常规用药量的17.21%~31.58%。两种除草剂显著影响隆线溞的泳动能力和趋光指数。隆线溞接触草甘膦和氰氟草酯3 h后,导致其趋光指数显著改变的浓度分别是4.59和14.20 mg/L,分别为常规用药量的0.06%和7.10%。因此,草甘膦和氰氟草酯对水溞的毒性大,对水生食物链的影响不可忽视。利用水溞趋光性可快速、灵敏地监测除草剂使用后的水体生物毒性。     

五氟磺草胺和氰氟草酯复配剂对水稻直播田杂草的防除效果及安全性评价

采用田间试验方法研究了五氟磺草胺和氰氟草酯复配剂（五氟磺草胺•氰氟草酯）对水稻直播田杂草的控制效果和应用安全性。结果表明,五氟磺草胺•氰氟草酯对直播稻田的禾本科杂草、阔叶杂草和莎草均具有较好的防除效果,有效成分用量90~180 g/hm2的综合防效可达95%以上,显著优于对照药剂氰氟草酯,与五氟磺草胺、五氟磺草胺+氰氟草酯、丙草胺+苄嘧磺隆的防效相当。五氟磺草胺•氰氟草酯显著降低了稗、鸭舌草种群对田间N、P、K养分的吸收,保持了土壤肥力。五氟磺草胺•氰氟草酯有效成分用量90~120 g/hm2苗后茎叶处理对水稻安全,对后茬小麦、油菜、甘蓝、葱、大蒜等作物无不良影响。     

Reduced rates of tank mixtures for red sprangletop (Leptochloa chinensis [L.] Nees) and greater club-rush (Scirpus grossus [L.] f.) control in rice

A study on the efficacy of tank-mix combinations on the growth of Leptochloa chinensis (L.) Nees and Scirpus grossus (L.) f. at the 3–4-leaf stage was conducted under glasshouse conditions. Sethoxydim plus cyhalofop-butyl at 8 + 25, 16 + 25, 32 + 25, 32 + 12.5, and 32 + 6.25 g ai ha⁻¹ provided good control of L. chinensis , ranging from 89–95%. However, a comparison of the costs of herbicide mixtures revealed that sethoxydim at 32 g ai ha⁻¹ plus cyhalofop-butyl at 6.25 g ai ha⁻¹ were the most cost-effective among the combinations. For Scirpus grossus , bensulfuron plus 2,4-D dimethylamine at 2.5 + 18, 5.0 + 18, 1.25 + 36, 2.5 + 36, and 5.0 + 36 g ai ha⁻¹ gave good control that ranged from 88–93%. Tank-mixing bensulfuron with 2,4-D at 1.25 + 36 g ai ha⁻¹ was, however, the most cost-effective mixture compared to the other mixtures. None of the tank mixtures tested in this study caused injury to the rice seedlings. However, further field studies need to be undertaken to verify these findings.     

稻稗对噁唑酰草胺的非靶标抗药性和对氰氟草酯的交互抗药性

为明确稻稗对噁唑酰草胺的非靶标抗药性和对氰氟草酯的交互抗药性水平,通过剂量反应试验测定辽宁新民(R_1)、黑龙江虎林(R_2)和黑龙江哈尔滨(R_3)3个稻稗种群对噁唑酰草胺的非靶标抗药性和对氰氟草酯的交互抗药性水平。结果显示,R_1、R_2、R_3在喷施细胞色素P450抑制剂杀草强后对噁唑酰草胺的抗性指数比分别为1.14、1.71、2.38,表明R_1对噁唑酰草胺的抗药性与非靶标P450的活性无关,R_2和R_3对噁唑酰草胺的抗药性可能是靶标与非靶标的共同作用。3个稻稗种群对氰氟草酯的抗性指数分别为25.73、12.79、10.29,表明3个稻稗种群都对氰氟草酯产生了交互抗药性。