稗对水稻生长和产量性状的影响及其经济阈值

稗Echinochloa crusgalli Beauv.在稻田的发生危害对水稻生产造成了严重威胁.为明确稗对水稻生长的影响及其经济危害允许水平,采用添加系列试验和模型拟合的方法研究了不同稗草密度下水稻各产量性状的变化规律.研究结果表明,水稻在稗的竞争干扰下,植株的分蘖数、有效穗数、千粒重及产量均随稗草密度的增加而逐渐降低.指数模型y=beax可以较好地拟合稗对水稻分蘖数(y=493.74e-0.0164x,P＜0.0001)、有效穗数(y=437.2e-0.0165x,P＜0.0001)及千粒重(y=21.876e-0.0006x,P＜0.005)的影响,而对数模型y=aLnx b拟合稗与水稻产量(y=-1250.4Lnx 6375.4,P＜0.0001)及产量损失(y=18.844Lnx 3.9182,P＜0.0001)间的关系最佳.稻田使用乙苄、丁草胺、禾大壮、二氯喹啉酸等药剂进行化学除草时,稗的经济危害允许水平在0.71%～1.10%之间,经济阈值在0.85株/m2左右.     

水稻秸秆还田结合炔草酯对禾本科杂草和小麦生长发育的影响

为改进水稻秸秆还田条件下小麦田杂草治理技术,通过田间小区试验研究了不同还田量单独或结合炔草酯施用对后茬小麦田禾本科杂草的控制效果和小麦生长发育及产量的影响。结果表明,随着水稻秸秆单独还田量从1 125 kg/hm2增至4 500 kg/hm2,小麦田杂草发生密度显著下降,4 500 kg/hm2秸秆还田量下小麦分蘖期前杂草发生密度下降60%左右;结合炔草酯施用时,杂草发生密度随秸秆还田量的增加而下降,但不同还田量之间无显著差异,且炔草酯除草活性未受到影响。秸秆还田或炔草酯单独或结合施用均对小麦生长发育无明显的胁迫影响,4500 kg/hm2秸秆单独还田量下,小麦苗期功能叶SPAD值较对照增加7.0%,净光合速率和蒸腾速率分别增加14.9%和12.2%;抽穗期净光合速率、气孔导度、蒸腾速率分别增加28.3%、85.2%和100.0%;千粒重、有效穗数和产量分别增加3.9%、6.7%和16.1%。4 500 kg/hm2秸秆单独还田量对杂草控制效果、小麦生长及产量的影响均与炔草酯推荐剂量单独施用无显著差异,表明该秸秆还田量具有良好的农田生态效应。     

玉米不同密度下间作大豆控草效果及对产量的影响

以贵州主要种植的玉米品种黔单16和大豆品种黔豆2号为材料,开展不同密度下玉米间作大豆控草效果及对产量的影响研究。研究结果表明:玉米种植密度在4.2万~5.55万株/hm~2按1∶1间作大豆对杂草的株抑制率为37.43%~50.30%,鲜质量抑制率47.79%~52.96%,在该密度范围内,抑制效果随着玉米种植密度的增加而增加。玉米单作下田间杂草冠层平均光合有效辐射(PAR)为330.07~698.13μmol/(m~2·s);间作模式田间杂草冠层平均光合有效辐射(PAR)为73.27~108.33μmol/(m~2·s);随着玉米种植密度的增加,各种植模式田间光合有效辐射(PAR)逐渐降低,间作模式光合有效辐射(PAR)普遍高于玉米单作模式,这可能是抑制田间杂草生长的主要原因。在产量上,玉米单作产量随种植密度增加而增加;玉米-大豆间作模式下玉米产量相对稳定,大豆产量随玉米密度增加而增加。在玉米种植高密度下玉米单作产量高于间作模式,但间作模式经济效益高于玉米单作种植模式,以玉米-大豆5.55万株/hm~2密度下田间作物产量经济效益最高。因此,作物合理间作和适当增加种植密度是控制杂草生长,提高作物产量的有效措施。     

水稻对无芒稗的异株克生研究初报

稗草与水稻竞争后降低水稻产量和质量。不同株型水稻与稗草的竞争力存在显著差异 ,高秆大冠层株型水稻可以明显减少产量损失[1,2 ] 。与生态竞争研究相关的水稻异株克生研究近年来日趋活跃 ,埃及科学家Ｈａｓｓａｎ[3,4] 于 1 993～ 1 996年开展了水稻与稗草的异株克生关系的研究 ,发现约有 30份材料可以控制田间稗草 5 0 %～ 90 %的生长。Ｏｌｏｆｓｄｏｔｔｅｒ[5 ] 等在菲律宾国际水稻所进行了水稻异株克生研究 ,发现有 1 1份材料在旱季可以使稗草的干重减少 5 0 %以上 ,2 1份使稗草干重减少 40 %～ 5 0 % ;有 2 1个品种在雨季抑制稗草在…     

宁波沿海地区水稻田稗草发生量及对丙草胺、丁草胺的抗药性检测—以6个样点为例

为研究宁波沿海地区水稻田稗草发生量及对丙草胺和丁草胺的抗药性,本研究以宁波沿海地区土壤盐碱化、碱化和非盐碱化稻田的稗草及土壤中稗草种子库密度为研究对象,通过连续3年的大田试验及室内抗药性分析,研究稗草草相及土壤中稗草种子库密度变化,并对稗草的抗药性进行了分析。结果表明,在调查周期内,宁波沿海的盐碱化稻田稗草发生密度为16.23株/m2,显著高于土壤碱化和非盐碱化稻田中的11.70株/m2和10.10株/m2。盐碱化稻田稗草种子库密度为19 169.17粒/m2,高于土壤碱化稻田的17 224.83粒/m2,并显著高于非盐碱稻田的15 411.33粒/m2。在庵东镇和大徐镇的盐碱稻田中,稗草对丙草胺和丁草胺的相对抗药性指数(RI)分别从调查初始期的4.51和2.88上升至调查末期的5.52和6.14,达到中抗水平;而在土壤碱化稻田和非盐碱稻田中,稗草对丙草胺和丁草胺的RI均维持在相对较低的水平,调查周期内介于1.00~2.33之间,处于低抗水平。因此,在该地区的水稻生产过程中,应尽量改善土质,以控制稗草种群规模、延缓抗药性的产生。     

水稻穗部农艺性状与稻曲病抗性的相关性分析

 人工接种试验和田间多年自然发病调查发现,目前生产上应用的水稻品种均感稻曲病;但在自然条件下,不同水稻品种稻曲病的发生程度存在较大差异,可以人为的分为多病粒高感品种和寡病粒相对抗病的品种。为了探究水稻穗部性状与其病害抗性间的关系,本文对孕穗期不同阶段的不同水稻品种的穗部性状进行了比较分析。结果发现表型为多病粒的高感多病粒品种与表型为寡病粒的相对抗病的品种之间在穗子大小、小花密度、穗鞘闭合程度和密封性、旗叶面积等方面均存在明显差异,寡病粒相对抗病的水稻品种穗鞘闭合程度优于高感多病粒品种。     

转基因抗草铵膦水稻99-1和普通粳稻越富与稗草竞争性的比较

2001～2003年分别按照替换试验设计的模型盆栽抗草铵膦转基因水稻991与稗草、普通粳稻越富与稗草,比较这两个水稻品种与稗草的竞争力。水稻和稗草按照4:0、3:1、2∶2、1∶3和0∶4的比例混种。统计分析结果表明,普通粳稻越富和转基因水稻991对稗草的敏感性存在显著差异。在稗草存在下,转基因抗草铵膦水稻991的干重和根长受稗草抑制程度大于普通粳稻越富;而叶面积指数的趋势相反,991的入侵能力明显低于越富。综合评价为在与稗草的竞争性方面,普通粳稻越富优于转基因抗草铵膦水稻991。     

黑籽雀稗与假臭草的竞争效应研究

替代控制由于对环境友好而日益受到杂草防除专家、学者的青睐。鉴于替代控制所取得的成果,利用牧草黑籽雀稗（Paspalum atuatum）和假臭草（Eupatorium catarium Veldkamp）盆栽混种试验,结果表明：（1）混种时,黑紫雀稗的种间竞争大于种内竞争,而假臭草种间竞争小于种内竞争;（2）黑籽雀稗与假臭草需要相同的资源,在适当的种植比例和适当的种植密度下,两者均有将对手排挤出种群的能力;（3）混种密度、比例、密度×比例对黑籽雀稗与假臭草竞争力均有不同程度的影响;（4）种植密度和比例对假臭草和黑籽雀稗的表型特征存在互作效应。总的来看,黑籽雀稗和假臭草混种时,黑籽雀稗处于劣势,但在适当的混种比例和适当的种植密度下,黑籽雀稗的竞争力完全可以达到与假臭草相当的水平。为了使竞争向着有利的方向进行,可以通过调整种植比例和种植密度来使黑籽雀稗处于竞争优势。     

控制灌溉条件下种植密度对玉米中地77生长和耗水的影响

以玉米中地77为材料,研究了辽西半干旱区控制灌溉条件下种植密度对玉米生长和耗水的影响.结果表明,随着玉米的生长,株高、茎粗、单株叶面积、穗长、轴重、行粒数、穗粒数和穗粒重随种植密度的增加有减小的趋势,穗粗和穗行数受种植密度的影响较小,但叶面积指数、秃尖、日耗水量、阶段耗水量和全生育期耗水量均随着种植密度的增加而增大,全生育期高密度玉米总耗水量高出低密度28.6％;回归分析表明玉米产量和水分利用效率均随种植密度的增加先增大后减小,综合考虑节水和增粮的目的,在辽西半干旱地区控制灌溉条件下,建议玉米中地77种植密度为6 ～ 6.75万株·hm-2.     

水稻田除草剂三唑磺草酮的作用特性

为了明确水稻田除草剂三唑磺草酮(QYR301)的最佳施药条件,以稗草Echinochloa crus-galli和水稻Oryza sativa作为测试靶标,采用温室盆栽法研究了其施药适期、耐雨水冲刷性、温度和光照强度对其除草活性的影响。结果显示:三唑磺草酮对不同叶龄水稻具有较高的安全性,在有效成分360 g/hm^2的剂量下,对2叶期以后的水稻干重抑制率为0%;其除草活性与稗草的叶龄显著相关,其中2~3叶期的稗草最为敏感,有效成分30 g/hm^2的三唑磺草酮对其干重抑制率为95%~98%;三唑磺草酮具有一定的耐雨水冲刷能力,药后降雨间隔达到8 h以上,其除草活性与药后降雨间隔时间无显著相关性,在有效成分30~120 g/hm^2的剂量下,对稗草的干重抑制率为75%~93%;在20~35℃区间,三唑磺草酮药效稳定,对稗草的GR50值在44.6~51.4 g/hm^2之间;相较于中度光照(45%)和低光照(4%),高光照(100%)条件下三唑磺草酮对稗草的干重抑制率显著增加。分析表明杂草叶龄、降雨、温度和光照会显著影响三唑磺草酮除草活性,为使其发挥最大药效,应选择在水稻2叶期以后至稗草2~4叶期,天气晴朗,气温高于20℃的情况下施药;如药后8 h以内遇降雨天气,则需进行补喷。     

Allelopathic potential of K21, selected as a promising allelopathic rice

The agronomic characteristics of a newly bred potent allelopathic rice, K21, including morphological appearance, resembled its female parent, Dongjinbyeo, except for 8 days' earlier heading and 9 cm shorter plant height. The water extract of K21 showed a greater inhibitory effect on the shoot and root growth of barnyardgrass than its female parent, but less than the male parent, Kouketsumochi. At the highest extract concentration of 5.0%, the inhibitory effect of K21 on the shoot growth of barnyardgrass was ≈ 64%, similar to its male parent. The dry weight of the barnyardgrass shoot was reduced by 13.0% when grown with K21 and 30.2% when grown with its male parent. There was no inhibitory effect on the shoot dry weight of barnyardgrass when grown with the female parent. The activity of cinnamic acid 4-hydroxylase in K21 was ≈ 1.8-fold higher than that of the female parent, but significantly lower than that of the male parent. The ρ-coumaric acid content in K21 was ≈ 60% higher than that of the female parent, but it was about half of the male parent. The total amount of phenolic compounds in K21 was ≈ 11.5% higher than in the female parent, but about half of the male parent. The results obtained suggest that the newly bred K21 contains desirable allelopathic traits derived from the male parent, Kouketsumochi, and acceptable agronomic traits from its female parent, Dongjinbyeo.     

双唑草腈的除草活性及对不同水稻品种和后茬作物的安全性

双唑草腈(pyraclonil)为原卟啉原氧化酶(PPO)抑制剂,为明确其在水稻田的应用前景,采用室内生物测定法研究了双唑草腈的除草活性及对不同水稻品种的安全性,通过大田试验作了进一步验证,并评价了双唑草腈对水稻及后茬作物的安全性。结果表明,双唑草腈对水稻田禾本科杂草稗草、阔叶杂草鸭舌草均有很好的除草活性。在室内试验中,该药剂对稻田稗草和鸭舌草的ED50分别为11.50g/hm~2和8.22g/hm~2,均高于对照药剂丙草胺对稗草和鸭舌草的活性;双唑草腈在3种水稻和稗草之间的选择性指数分别为4.15、3.44和3.73,高于对照药剂;田间试验结果显示,1.8%双唑草腈颗粒剂162、216、324g/hm~2处理在药后20、40d对稗草、鸭舌草、节节菜及异型莎草的株防效均在98%以上,显著优于对照药剂80%丙炔噁草酮可湿性粉剂和50%丙草胺乳油;双唑草腈对水稻以及三种主要后茬作物小麦、油菜和小白菜安全。研究表明双唑草腈具有很好的应用前景。     

0.136%赤·吲乙·芸苔可湿性粉剂与五氟磺草胺混用对无芒稗和水稻生长的影响

为探究0.136%赤·吲乙·芸苔可湿性粉剂(WP)与除草剂五氟磺草胺分散油悬浮剂(OD)混用对稗草防除效果及对水稻生长的影响,以无芒稗和水稻为研究对象,设置清水对照、0.136%赤·吲乙·芸苔WP、25 g/L五氟磺草胺OD、0.136%赤·吲乙·芸苔WP+25 g/L五氟磺草胺OD混用4个处理,观察药后无芒稗和水稻的生长情况,测定乙酰乳酸合酶(ALS)活性、叶绿素荧光参数及糖代谢和氮代谢等生理指标。结果表明,与25 g/L五氟磺草胺OD单用相比,0.136%赤·吲乙·芸苔WP+25 g/L五氟磺草胺OD混用处理药后第7天,无芒稗的中毒综合指数显著提高13.2%,ALS活性显著降低27.61%;无芒稗的叶绿素荧光参数(Fv/Fm、ETR、qP)、糖代谢和氮代谢指标均显著下降;水稻的ALS活性、糖、氮代谢水平均显著提高。0.136%赤·吲乙·芸苔WP+25 g/L五氟磺草胺OD混用提高了五氟磺草胺对无芒稗光合作用及糖代谢和氮代谢水平的抑制作用,提高了五氟磺草胺对无芒稗的防除效果;并能缓解五氟磺草胺对水稻的胁迫作用,促进水稻生长。     

三株病原真菌对稗草生防潜力的研究

从稻田中采集自然感病的稗草标样,分离获得10余种病原真菌,经生测,链格孢菌、尖角突脐孢菌和内脐孢菌是3株很有希望的稗草生防潜力菌。对它们的生长及产孢特性、寄主范围及孢子悬浮液喷雾接种对水稻和稗草的致病性等进行了研究。结果表明,3个菌各有优缺点。链格孢菌对稗草致病力稍差,对水稻有轻度感染,但其产孢速度快,产孢量大;尖角突脐孢菌对稗致病力强,对稻无影响,但产生孢子慢,产生菌丝多;内脐孢菌对稗致病力强,对稻安全,菌落生长较慢,但产孢速度快,产孢量多,气生菌丝少。黑暗、空气充足有利于3菌株的生长及产孢。     

Allelochemicals of barnyardgrass‐infested soil and their activities on crops and weeds

Barnyardgrass is one of the most noxious paddy weeds in the world and causes great trouble to many crops. In a bioassay, the aqueous extract of paddy soil infested with barnyardgrass showed phytotoxic action against the growth of the tested crops and paddy weeds, of which rice was the most suppressed among the crops. In contrast, barnyardgrass was the least affected paddy weed. By the use of a separation resin, 18 compounds belonging to terpenes, derivatives of cinnamic acid and ferulic acid, long‐chain fatty acids, and steroids that were potentially involved in the phytotoxic activities in barnyardgrass‐infested soil were isolated and identified by gas chromatography–mass spectrometry analysis. Of these, the quantities of linalool, 4‐terpinenol, coumaran, methyl phenethyl ketone, and methyl ester cinnamic acid were 1.42, 0.37, 0.02, 3.12, and 4.59 μg g^?1 of the wet soil, respectively. The herbicidal activity was varied among these qualified test compounds, in which methyl phenethyl ketone and methyl ester cinnamic acid were more herbicidal than coumaran, linalool, and 4‐terpinenol. A mixture of these compounds was also the least inhibitive against the growth of barnyardgrass, but exerted strong suppression against that of rice and monochoria. The present study demonstrates that barnyardgrass possesses strong phytotoxic properties and releases plant growth inhibitors into the soil to compete with rice and other paddy weeds in its vicinity by a chemical pathway.     

Role of underground parts of barnyardgrass (Echinochloa crus-galli (L.) Beauv. var. formosensis Ohwi) in its sensitivity to thenylchlor in soil

In the present study, the phytotoxic activity of top-soil applied with thenylchlor [2-chloro- N -(3-methoxy-2-thieny)-2',6'-dimethylacetanilide] on the growth of rice ( Oryza sativa L.) was dependent on the emergence depth in soil but its activity on barnyardgrass ( Echinochloa crus-galli (L.) Beauv. var. formosensis Ohwi) was only slightly affected by the emergence depth. However, the phytotoxic activity on barnyardgrass and rice was similar irrespective of the different emergence depths in its treatment to all soil layers. Thenylchlor treatment to the mesocotyl of barnyardgrass induced significant inhibition of shoot elongation, whereas the treatment to the coronal root only inhibited the coronal elongation without inhibiting shoot elongation. Absorption and translocation of ¹⁴C-thenylchlor in barnyardgrass were determined in water culture. The different amounts of radioactivity per plant among the treatments to the underground parts were due to the plant part that came in contact with ¹⁴C-thenylchlor. The radioactivity per dry weight was found to be higher in the basal part of the shoot than in its upper part in all treatments to the underground parts. It was suggested that the phytotoxic activity of thenylchlor on the growth of barnyardgrass in soil is induced by its accumulation in the basal part of the shoot through translocation. This primarily occurs after the absorption substantially by the mesocotyl from the herbicide-treated layer and additionally by other underground parts.     

一种筛选稗草生防潜力菌的简易生测方法

将催芽至露白的稗草和水稻种子直接接种在于PDA培养基上培养形成的 4种稗草病原菌 (交链孢菌、弯孢菌、禾长蠕孢菌稗草专化型、尖角突脐孢菌 )菌落上 ,观察稻、稗苗感病情况 ,调查根、芽生长抑制率。结果表明 ,4种菌对稻、稗的致病性和生长抑制率与常规生测法结果基本吻合。说明在培养基中初步测定、筛选稗草生防潜力菌是可行的。该方法与常规生测法比较 ,可节省一半时间左右 ,同时可减少工作量。     

五氯酚钠防除稻田杂草的试验

在旱秧田、水秧田、旱直播田和水直播田的试验中,播前施用五氯酚钠,每公顷5—20公斤,除草效果不够良好。但在插秧本田的试验中,插前每公顷施用五氯酚钠15—30公厅对防除稗草(Echinochloa crusgalli (L.) Beauv.)和球穗莎草(Cyperus globosus All.)的效果极为良好。以在插秧前一天,每公顷施用30公斤效果最好,对稗草和球穗莎草的防除效果分别达到92.7%和79.6%。插后处理,每公顷施用五氯酚钠15公斤,效果也较好。另外的试验,观察了五氯酚钠不同剂型:颗粒剂、混土、溶液等的防除效果。防除稗草用颗粒剂和混土处理要优于溶液处理;防除球穗莎草则以溶液处理为最好。各处理对水稻均无药害,所有用五氧酚钠处理区的产量均高于不除草区,但较两次人工除草的为低。本文讨论了在秧田和直播田用五氯酚钠防除稗草效果较差的原因。     

Reproduction allocation and potential mechanism of individual allelopathic rice plants in the presence of competing barnyardgrass

BACKGROUND: In spite of increasing knowledge of allelopathic rice as an efficient component involved in paddy weed management, relatively little is known about its reproduction in response to competing weeds. Reproduction allocation of individual allelopathic rice plants in relation to monoculture and mixed culture with competing barnyardgrass in a paddy field was studied, along with analyses of soil nutrients and microbial communities to understand the potential mechanism. RESULTS: At a 1:1 barnyardgrass and rice mixture proportion identified from a replacement series study, biomass, grain yield and major parameters of individual allelopathic rice plants at the mature stage were increased by competing barnyardgrass. There was no difference in allelopathic rice root‐zone soil ammonium N and Olsen P between monoculture and mixed culture. However, mixed culture altered soil microbial biomass C and communities. When mixed with barnyardgrass, allelopathic rice root zone had an 87% increase in soil microbial biomass C. Phospholipid fatty acid (PLFA) profiling indicated that the signature lipid biomarkers of bacteria, actinobacteria and fungi were affected by mixed culture. Principal component analysis clearly identified differences in the composition of PLFA in different soil samples. CONCLUSION: Allelopathic rice specific changes in soil microbial communities may generate a positive feedback on its own growth and reproduction in the presence of competing barnyardgrass in a given paddy system. Copyright © 2012 Society of Chemical Industry