龙爪茅种子休眠解除方法研究

研究了光照(12 h光照/12 h黑暗)和黑暗(24 h黑暗)2种条件下盐酸(HCl)、氢氧化钠(NaOH)、硝酸钾(KNO_3)和赤霉素(GA_3)对摩擦种皮和未摩擦种皮龙爪茅种子萌发的影响。结果表明,龙爪茅种子的休眠主要是其种皮对种胚的束缚引起的机械性休眠,经摩擦种皮处理,空白组的萌发率即可达67%以上。不同浓度的HCl、NaOH、KNO_3及GA_3处理均不能有效解除未经摩擦种皮处理的龙爪茅种子的休眠。摩擦种皮处理的龙爪茅种子经低浓度的KNO_3及GA_3浸泡24 h后萌发率可达80%以上,而经HCl、NaOH以及高浓度KNO_3浸泡相同时间后萌发率急剧下降。光照因素对龙爪茅种子的萌发影响较小,光照条件下的萌发率略高于黑暗条件。     

龙葵果实汁液的除草活性初探

以龙葵(Solanum nigrum L.)、反枝苋(Amaranthus retroflexus L.)为试材,用种子萌发法检测了龙葵果实汁液对其萌发的抑制作用.试验结果证明,龙葵果实汁液中含有除草活性物质,而且活性较高,热稳定性较好,在150 ℃下加热0.5 h依然保持除草活性.龙葵果实汁液对龙葵种子萌发的抑制作用高于对反枝苋的抑制作用.水培14 d,龙葵果实汁液含量为1%时,只能推迟龙葵种子的萌发时间,对最终的发芽率没有影响;含量为5%时,龙葵种子的发芽率仅为的21.5%;含量为10%时能够完全抑制龙葵种子的萌发.含量低于5%时,对反枝苋种子萌没有影响;含量为10%、15%、20%时,反枝苋的发芽率分别为60.00%、43.75%、22.50%.     

高温处理对几种苋属杂草种子萌发的影响

本文选取反枝苋、长芒苋、糙果苋、西部苋、凹头苋、白苋、刺苋和皱果苋8种苋属杂草种子作材料,通过高温处理研究不同苋属种子对高温的耐性,反枝苋的处理温度范围设置为70~130℃,处理时间范围设置为0至8 h;在另一处理中8种苋的处理温度范围设置为110~130℃,处理时间范围设置为0至60 min。结果表明:经过同样条件处理的8种苋属杂草种子在萌发率、胚根长度和胚轴长度3个方面均存在差异;120℃处理1 h或130℃处理30 min,8种苋属杂草的萌发率均为0。     

牛筋草种子休眠解除方法研究

研究了光照(12h光周期)和黑暗两种条件下摩擦脱果皮处理及不同药剂(NaOH、HCl、KNO3及GA3)浸泡处理对脱果皮和未脱果皮牛筋草种子萌发的影响。结果表明,牛筋草种子休眠主要是其果皮对种子的束缚引起的机械休眠,种子一经脱果皮,休眠基本解除,萌发率达61%以上。若用蒸馏水浸泡24 h,萌发率显著升高,达80%。种子的萌发不受光照条件的影响。NaOH、HCl、KNO3及GA3浸泡对未脱果皮的牛筋草种子萌发无任何促进作用。与对照相比,脱果皮的牛筋草种子经NaOH、HCl浸泡后萌发率急剧下降,而经KNO3和GA3浸泡24h后,在一定浓度范围内萌发率均有所提高。     

西农No.24菌株发酵产物对反枝苋的除草活性初步研究

西农No.24菌株是从陕西秦岭山区采集的200份土壤中分离得到的一株放线菌,经初步鉴定为链霉菌属(Streptomyces)。采用微量小杯法,通过发酵、洗脱和高效液相色谱(HPLC)分离,测定西农No.24菌株发酵液对反枝苋Amaranthus retroflexus L.的除草活性。结果表明,该菌株的发酵产物对反枝苋有较强的抑制生长作用。其发酵液对反枝苋种子萌发抑制率为26.7%,主根生长抑制率为80.6%,主茎生长抑制率为66.5%;离子交换液对反枝苋的种子萌发抑制率为42.9%,主根生长抑制率为93.1%,主茎生长抑制率为86.2%。经HPLC分离后得到8个馏份,其中馏份4的除草活性最强,对反枝苋的种子萌发抑制率为86.36%,主根生长抑制率为95.84%,主茎生长抑制率为93.76%。     

青海云杉种子萌发特性

以天祝县青海云杉天然种群种子为研究对象,通过对种子生活力测定,分析种子萌发对温度、光照、水分和盐分胁迫的响应,为引种提供参考数据。结果表明：① 种子的生活力为72%。② 在黑暗条件下,温度小于10 ℃种子不萌发,最适萌发温度25/15 ℃(72%);种子在24 h黑暗和24 h光照条件下的萌发率显著高于14 h光照/10 h黑暗。③ 当NaCl胁迫浓度为50 mmol·L^-1时,可促进种子萌发,当胁迫浓度大于50 mmol·L^-1时,抑制种子萌发;胁迫解除后,随着胁迫浓度的增加,恢复萌发率(RGR)先增加后减小,胁迫浓度为400 mmol·L^-1时,RGR达到最大值13%。④ 随着PEG-6000试剂胁迫渗透势的增加,种子萌发显著减少,在-0.9 MPa时,种子不能萌发;胁迫解除后,RGR先增加后减少,在-0.9 MPa时,达到最大值35%。     

小麦提取物对反枝苋,繁缕生长的化感效应研究

接受抽穗期小麦提取物进行化感效应测定的１０种作物和杂草中，反枝苋和繁缕的生长受到显著影响：提取物浓度５００ｍｇ／ｋｇ时，反枝苋种子发芽率为１４％。用小麦提取物５０ｍｇ／ｍ２进行土壤处理，２个月后反枝苋干重抑制率达８２％，用同样剂量对繁缕进行了茎叶处理，３０天后有７６％～８５％的繁缕死亡     

不同处理对豚草种子休眠与萌发的影响

以进境转基因大豆中截获的豚草种子为材料,通过热水浸泡、浓硫酸处理、双氧水浸泡、高锰酸钾浸泡、赤霉素浸泡、低温处理、去除种皮等方法,研究了不同处理对截获休眠豚草种子萌发的影响。结果表明:300mg/LGA、3.0%H2O2、3～5℃低温沙藏3个月、4个月和去种壳处理对休眠中的豚草种子有一定的刺激作用,但对豚草种子发芽率影响不太明显;3～5℃低温沙藏5个月可使豚草种子发芽率提高至10%。     

化学方法解除野慈姑种子休眠研究

HCl、NaOH、Na2CO3、NaCl、赤霉素（GA3）、芸薹素内酯（BR）浸种处理,探讨溶液浓度、浸种时间对野慈姑（Sagittaria trifolia Linn．）种子萌发的影响。结果表明,NaOH溶液浸种处理可以作为快速解除野慈姑种子休眠、提高发芽率的方法,最佳处理为25％NaOH溶液浸种4h,可使野慈姑种子萌发率达73．00％。HCl溶液浸种处理仅能解除部分野慈姑种子的休眠,20％HCl溶液浸种4h野慈姑种子的发芽率最高;为48．33％。Na2CO3、NaCl、GA3、BR溶液浸种处理,野慈姑种子的最高发芽率分别仅为10．33％、9．33％、11．33％、9．67％,不能用于解除野慈姑种子的休眠。     

113种植物的乙醇提取物对反枝苋和马唐种子萌发及生长的抑制活性

筛选和评价植物资源的除草活性可为新型植物源除草剂的研发提供候选材料和理论依据。本研究用种子萌发法和平皿法，评价了56科113种植物提取物对反枝苋和马唐种子萌发和生长的抑制活性。结果表明，在125 mg DW/mL的供试浓度下，大黄、牡丹皮、大叶三升麻、木香、佩兰、楸树、安息香树、泡桐、短叶罗汉松和杜衡提取物对马唐种子萌发和生长的抑制作用最为明显；牡丹皮、佩兰、木香、鹿藿和短叶罗汉松提取物对反枝苋种子萌发和生长的抑制活性最为明显。毒力测定表明，楸树、木香、杜衡、泡桐、佩兰、安息香树和大叶三升麻提取物对马唐幼根的抑制中浓度（IC₅₀）分别为39.30、5.93、13.93、28.69、8.72、19.19和15.19 mg DW/mL；对马唐幼芽的IC₅₀分别为48.22、8.13、15.28、42.12、22.39、7.78、23.43和12.92 mg DW/mL。木香、牡丹皮、短叶罗汉松、鹿藿、佩兰和紫背浮萍对反枝苋幼根的IC₅₀分别为2.46、2.85、2.59、1.03、2.24和2.79 mg DW/mL；对反枝苋幼芽的IC₅₀分别为7.05、31.21、24.17、4.52和32.72 mg DW/mL。可见，牡丹皮、佩兰、木香、鹿藿和短叶罗汉松5种植物提取物的除草活性较好，具有进一步研究的价值。     

不同化学试剂及人工处理对稗草种子休眠的影响

分别应用不同化学试剂及人工剥去颖壳处理来提高稗草种子的萌发率,不同处理对种子发芽率的影响不同.GA3、浓H2 SO4、KNO3、剥去颖壳处理都有利于稗草种子的萌发,但剥去颖壳破除休眠的效果不理想.通过800～1200 mg/L GA3浸种24 h,浓硫酸浸种10～ 20 min,都能打破稗草种子休眠,使其发芽率超过70％;KNO3溶液可打破部分稗草种子休眠,2％ KNO3浸泡12 h,发芽率为34.67％;NaOH、HC1不宜用于解除稗草种子休眠.     

黄花蒿叶醇提取物除草活性物质的分离及结构鉴定

为明确黄花蒿除草活性及活性物质的成分,本研究采用室内生测法测定了黄花蒿叶醇提物对4种杂草的活性;采用系统溶剂分离、硅胶柱层析分离及气质联用色谱法对提取物进行了分离和结构鉴定。结果表明：5.0 mg/mL的黄花蒿叶醇提物对供试杂草发芽率、发芽势和发芽指数均有一定的抑制作用,抑制作用从大到小的顺序为反枝苋,苘麻,狗尾草,稗,其中对反枝苋、苘麻和狗尾草发芽率的抑制作用较强,均达到85%以上。叶醇提物对杂草发芽势的抑制作用也很强,均达到73%以上。黄花蒿叶醇提物中共鉴定出17种化合物,主要包括青蒿酸、亚油酸和邻苯二甲酸二乙酯等。由此可见,黄花蒿叶醇提物含有大量的除草活性物质,可显著延缓杂草的发芽时间和减少杂草的发芽率。     

Physiological effects of buthidazole on Zea mays L., Amaratithus retroflexus L., Medicago sativa L. and Agropyron repens(L.) Beauv.*

Buthidazole (3-[5-(1,1-dimethylethyl)-1,3.4-thiadiazol-2-yl]-4-hydroxy-l-methyl-2-imidazolidinone) at concentrations of 10^?6-10^?4M did not affect germination of corn (Zea mays L.,‘Pioneer 3780’), redroot pigweed (Amaranlhus retroflexus L.), alfalfa (Medicago saliva L., ‘Vernal’), and quackgrass (Agropyron repens(L.) Beauv.) seeds. Stressing the seeds obtained from mature corn plants treated either pre-emergence or pre- plant incorporated with buthidazole at several rates by accelerated ageing and cold treatments further indicated that this herbicide did not affect germination. Total photosynthesis and dark respiration of corn plants 12 days after pre-emergence application and of redroot pigweed, alfalfa, and quackgrass plants after postemergence application of buthidazole at several rates were measured with an infrared CO₂ analyser. The results suggested that buthidazole was a rapid inhibitor of photosynthesis of the sensitive redroot pigweed and quackgrass plants, with less effect on corn and alfalfa. Buthidazole did not affect respiration of the examined species except for a transitory increase in corn and alfalfa 12 days after pre-emergence or 4 h after postemergence treatment with buthidazole at 0.56 or 1.12 and 2.24 kg/ha, respectively. A long-term inhibition of quackgrass respiration 96 h after treatment with buthidazole at 1.12 and 224 kg/ha was also evident.     

Absorption and translocation of glyphosate with conventional and organosilicone adjuvants

This study was conducted to determine the effects of three organosilicone-based and six conventional organic adjuvants on the absorption and translocation of ¹⁴C-glyphosate in guineagrass and redroot pigweed. The organosilicone adjuvants produced rapid absorption of the ¹⁴C-glyphosate into the redroot pigweed leaves, reaching maximum absorption within 0.5–1.0 h after application. The conventional adjuvants produced slower absorption of the ¹⁴C-glyphosate, as the maximum absorption was not achieved until at least 24 h after application in redroot pigweed, remaining similar until 72 h. In guineagrass, the maximum absorption of the glyphosate was earlier than 24 h with the organosilicone-based adjuvants, compared with longer times for the conventional adjuvants. The organosilicone-based adjuvants also increased the glyphosate translocation in redroot pigweed, but not in guineagrass. Organosilicone adjuvants have the potential to provide greater rainfastness to glyphosate on redroot pigweed and, to a lesser extent, on guineagrass.     

杂草稻落粒粳种子的耐冷性评价

采用低温处理方法评价了杂草稻落粒粳（Orayza sativaL.）种子的耐冷潜力。浸种0~48 h,落粒粳种子平均含水量为17.038%,显著低于栽培稻春江11的20.533%和赣早籼的20.180%,落粒粳颖壳具有比两种栽培稻更强的水分阻隔能力。在相同含水量条件下,经过低温-20℃处理3 h和28℃条件下培养4 d的落粒粳种子发芽率显著高于春江11和赣早籼,落粒粳种子具有更强的耐冷能力。     

生防菌Alternaria amaranthi-3对反枝苋的防治效果

反枝苋Amaranthus retroflexus是一种世界性恶性杂草。为了确定微生物除草剂候选菌Alternaria amaranthi-3防除反枝苋的潜力,通过盆栽试验研究了接种浓度、露期和水乳剂型对A.ama-ranthi-3菌株致病力的影响。结果显示,接种浓度显著影响菌株的致病力,在48h露期条件下,接种孢子浓度为105个/mL时,菌株水剂对反枝苋幼苗生长抑制率为35.55%;浓度为107个/mL时,生长抑制率达到75.25%。露期对该菌株的致病力也有较大影响,在不保湿条件下,菌株水剂对反枝苋的生长抑制率为26.43%,而保湿48h处理的生长抑制率达到77.96%。Span80∶Tween80=1∶3的复配乳化剂和大豆油制备的水乳剂可显著降低露期对菌株防效的影响和提高菌株的致病力,无露期时,菌株水乳剂对反枝苋的生长抑制率达到88.35%,显著高于水剂;48h露期条件下,菌株水乳剂处理的生长抑制率为90.59%,而菌株水剂处理为77.96%。表明通过剂型的改进菌株Alternaria amaranthi-3能有效防除反枝苋。     

天然油菜素内酯对五种牧草种子发芽和胚根下胚轴伸长的影响

用9个不同浓度的天然油菜素内酯溶液浸种处理5种牧草种子,观测其对种子发芽和胚根下胚轴伸长的影响。结果表明,0.01 mg/L浓度处理使苜蓿种子发芽率比对照提高了32.2%,发芽天数缩短了1.4 d;0.01mg/L处理使鲁梅克斯种子发芽率增加了27.8%,0.05 mg/L处理使其发芽天数提前了0.8 d;0.03 mg/L处理使普那菊苣种子发芽率提高了28.9%,发芽天数缩短了0.3 d;0.4 mg/L处理使串叶松香草种子发芽率增加了26.7%,发芽天数提前了1.2 d;0.03 mg/L处理使小冠花种子发芽率提高了23.3%,0.05 mg/L使其发芽天数缩短了0.9 d。0.05、0.07、0.03、0.4和0.03 mg/L处理对苜蓿、鲁梅克斯、普那菊苣、串叶松香草和小冠花胚根下胚轴伸长的促进效应最为明显。     

Competitive effects of redroot pigweed (Amaranthus retroflexus) on the growth indices and yield of corn

The mutual effects of redroot pigweed ( Amaranthus retroflexus ) on corn ( Zea mays ) were evaluated in an experiment conducted in 2005 at the Iranian Plant Protection Research Institute at Qazvin, considering the different densities of redroot pigweed against four different corn densities. Redroot pigweed, at 0, 35, 50, 65, and 80 plants m⁻¹ row⁻¹, was arranged factorially with corn at four, five, six, and seven plants m⁻¹ row⁻¹ in a randomized complete block design. Crop–weed competition resulted in a reduction in the total dry matter, Leaf Area Index, and crop growth rate of corn. Furthermore, an increasing weed density ≤65 plants m⁻¹ row⁻¹ reduced the corn grain yield and biological yield. Overall, six corn plants m⁻¹ row⁻¹ was suggested as the optimum density of this crop in competition with redroot pigweed.     

Interference of redroot pigweed (Amaranthus retroflexus) in green bean (Phaseolus vulgaris)

Weeds that emerge along with or immediately after crop plants usually can reduce the yield of those crops. Two randomized complete block design experiments were conducted during 2006 and 2007 in Tabriz, Iran to determine the critical period of redroot pigweed control in the green bean hybrid “Cantander”. The treatments were weed‐infested and weed‐free plots at 2, 4, 6, 8, 10, and 14 weeks after bean emergence (WABE). The green bean biomass was affected by the early emergence of redroot pigweed, but it was not reduced when redroot pigweed emerged at 10 weeks after crop emergence, along with crop emergence, and grew with green bean until 4 WABE. The redroot pigweed biomass decreased by 2.7 g m^?2 per day when weed emergence was delayed. Each 100 g m^?2 of weed biomass that was produced resulted in a 1.4 kg ha^?1 loss in the green bean yield. When redroot pigweed interference lasted for ≥4 weeks after green bean emergence, the green bean yield was reduced significantly. Weeds, which emerged 2 weeks after green bean and thereafter were controlled, did not decrease crop productivity significantly. The highest crop yield was obtained when the weed emerged at 14 WABE. The critical period of redroot pigweed control, considering a 10% yield loss, was between 19 and 55 days after green bean emergence. Thus, weed control practises should be begun no later than 3 WABE and should continue until at least 8 WABE in order to obtain the maximum green bean yield.