杂草稻与栽培稻苗期根系形态和生理特性比较

杂草稻较强的抗逆性以及对栽培稻的竞争优势与杂草稻的较快生长速率、较强光能利用率等地上部分生物学特性密切相关,但其根系形态及生理特性对其竞争力和抗逆性的影响鲜有报道。本试验以5个不同地区杂草稻种群为材料,以栽培稻(日本晴)为对照,测定播种后10、20、30 d杂草稻和栽培稻根系形态(总根长、根表面积和根体积等)和根系生理(根系总吸收表面积、活跃吸收表面积和根系氧化力)指标。结果表明,播种后30 d,江苏省5个不同杂草稻种群根系形态生理均高于日本晴,杂草稻各种群的根系总根长、根系总表面积、总体积分别显著高于栽培稻36. 02%～91. 45%、63. 21%～90. 02%、61. 97%～149. 30%;杂草稻各种群的根系总吸收表面积、活跃吸收表面积、根系氧化力分别显著高于栽培稻24. 98%～124. 43%、42. 60%～163. 30%、31. 95%～67. 37%。研究结果揭示了杂草稻在苗期具有较强的根系活性,从根系发育及代谢能力角度进一步阐述了杂草稻的竞争优势和抗逆性机制。     

不同环境因子对江苏省杂草稻与常规栽培稻发芽势影响的比较

为了搞清楚杂草稻与常规栽培稻萌发特性的差异,采用培养皿水培法,进行了温度、pH值、水势及NaCl胁迫对杂草稻与常规栽培稻发芽势影响的比较研究。结果为：15℃和20℃条件下,杂草稻均具有强于常规栽培稻的发芽势。在pH值为6和8条件下,杂草稻的发芽势也强于常规栽培稻。同样在水势为-0．3MPa和180mmol／LNaCl浓度条件下,杂草稻的发芽势也强于常规栽培稻。说明杂草稻萌发过程的抗逆性强于常规栽培稻,具有较强的环境适应能力,能更有效地竞争环境资源。     

抛秧田杂草的发生与除草剂防效

水稻抛秧栽培是近几年新发展的水稻栽培新技术,它便于机械化操作,降低了劳动强度,提高了劳动生产率。由于水稻抛秧田在立苗阶段田间不建水层,极有利于杂草的发生,并对化除效果有一定影响。而且抛秧田的稻根开始是裸露在地面,稻苗对除草剂的反应也有异于常规栽插稻田。为此,1995年作者对抛秧稻田的杂草消长、化除效果及除草剂     

玉米不同种植密度、耕作模式和水分管理对杂草的影响

使用农艺措施调控农田杂草的发生和生长是生态控草的重要研究内容,为明确玉米种植密度、耕作模式和水分管理对田间杂草的影响,将玉米种植密度分别设置为6.0万、7.5万株/hm~2,耕作模式分别设置为翻耕、免耕,水分管理分别设置为玉米播种前浇水、玉米播种后浇水,在玉米大喇叭口期调查杂草的数量和鲜质量。结果表明,与种植密度为6.0万株/hm~2时相比,玉米在7.5万株/hm~2的种植密度下杂草的密度和杂草地上部鲜质量均有下降的趋势。翻耕模式下,水分管理对杂草密度的影响不显著,玉米播种后浇水处理比播种前浇水处理的杂草鲜质量减少26.4%;免耕模式下,玉米播种后浇水处理的杂草密度和鲜质量均显著低于玉米播种前浇水处理(P0.05),前者杂草密度、地上部鲜质量分别比后者减少36.7%、30.9%。研究表明,玉米播种密度增加,田间杂草密度和鲜质量均有减少的趋势,但不显著;无论是翻耕还是免耕,玉米播种前浇水均有利于杂草获得竞争优势,杂草鲜质量显著高于玉米播种后浇水。     

稻田草害防除实践和研究的进展(译摘)

在古代,人们都公认在淹水下生长的水稻对杂草的竞争比旱稻要强,旱稻的草害问题更严重。选用淹水栽培可说是传统除草的第一步。第二步大概是稻苗的移植。在直播稻栽培中,水稻从出苗起就与杂草竞争,如稻田整地粗放,杂草将与新出现的水稻幼苗作激烈竞争,而栽插的秧苗则以极大的竞争优势超过移植后出现的杂     

6种除草剂对豫南稻区直播再生稻头季稻田中杂草的防效及安全性评价

通过田间试验,验证了6种除草剂对豫南稻区直播再生稻田的除草效果及水稻安全性。结果表明：药后14 d, 40%■草·丁草胺EC 1 875 mL/hm²、39%甲戊·■草酮SC 1 800 mL/hm²、12%二甲戊灵EC+48%丁草胺EC 1 500 mL/hm²对田中多数杂草均有较好的株防效。药后21 d, 40%■草·丁草胺EC 1 875 mL/hm²对稗、莎草科杂草以及部分阔叶杂草的株防效均达91.75%～100.00%;39%甲戊·■草酮SC1 800 mL/hm²对莎草科杂草的株防效为75.00%,对其他杂草的株防效均在80.24%～100.00%;12%二甲戊灵EC+48%丁草胺EC 1 500 mL/hm²对稗、阔叶杂草的株防效均达100.00%,对莎草科杂草的株防效在67.00%～83.25%之间。以上3个处理鲜重防效均高于其他处理,且三者间差异不显著;实际产量分别比对照提高13.21%、10.12%、14.52%;以上3个处理分别比对照...     

小春免耕除草剂的选择及应用技术

稻茬田不经翻耕 ,直接撬窝移栽油菜和播种小麦的免耕栽培方法以其省工省时、节本增效而被广大农户采用。在四川 ,免耕栽培面积不断扩大 ,免耕配套技术也更加科学、规范。怎样正确选择免耕除草剂和掌握好免耕除草剂的应用技术 ,是确保免耕化除效果的关键。现将免耕除草剂的选择原则和应用技术介绍如下 :1　正确选择免耕除草剂的原则1.1　必须是灭生性广谱除草剂　因为免耕田杂草发生早 ,生长快 ,如川西水稻收割约 10d后开始萌发 ,13～ 2 0d为萌发高峰期。到作物播栽前 ,草籽萌发出土达 81%～ 85 % ;密度大 ;种类多 ,常见种类 2 5种以上 ,如果…     

西瓜感染黄瓜绿斑驳花叶病毒后糖分代谢与倒瓤的关系

为揭示人工接种黄瓜绿斑驳花叶病毒(Cucumber green mottle mosaic virus,CGMMV)后西瓜糖分代谢与倒瓤的关系,采用高效液相色谱法测定了接种CGMMV后西瓜的葡萄糖、果糖、蔗糖含量变化,采用比色法测定了糖酵解途径关键酶及蔗糖代谢相关酶活性的变化。结果显示,西瓜苗感染CGMMV后,果实中葡萄糖、果糖、蔗糖含量均较对照发生明显变化,接种处理后葡萄糖含量在授粉7~28 d显著高于对照,之后迅速下降,35 d时显著低于对照,仅为对照的24.87%;果糖含量仅在授粉后7~14 d高于对照,21~35 d显著低于对照;接种处理和对照的蔗糖含量在授粉后14~35 d均逐渐上升,但14~35 d接种处理显著低于对照。接种处理后己糖激酶、磷酸果糖激酶和果糖激酶活性均在授粉后7~14 d显著低于对照,21~28 d显著高于对照,35 d时显著低于对照;丙酮酸激酶活性授粉后7~21 d显著低于对照,35 d时显著高于对照;酸性转化酶和中性转化酶活性在授粉后7~21 d显著低于对照,35 d时高于对照;蔗糖磷酸合成酶和蔗糖合成酶活性均显著低于对照,其中蔗糖合成酶活性在授粉后28 d时仅为对照的21.32%。推断西瓜苗接种CGMMV后糖酵解的4个关键酶协同作用,调控糖酵解,进而调控葡萄糖和果糖的积累与代谢,同时蔗糖代谢相关酶活性降低,阻碍蔗糖合成,即西瓜苗感染CGMMV导致倒瓤与其糖分的合成与代谢密切相关。     

直播稻田水浆管理对杂草发生与控制作用研究

不同的水浆管理杂草发生有较大的差异,干湿相间和湿润无水管理,杂草发生量最大,出草较早,杂草发生的种类也略多。播种后一直灌浅水,杂草发生量最小,出草也最晚,但对水稻出苗和长势影响较大。播种后7 d湿润无水,再灌浅水对杂草有较好的控制作用,对稻苗生长影响较小。     

拜田净防除水直播稻田杂草试验

供试直播稻田以稗草为优势种，伴生水苋菜、异型莎草、陌上菜等。拜田净 50％可湿性粉剂用量为 250～ 300 g/hm2，使用适期为水直播稻播后 6～ 8 d(稗草 1.5叶期 )，以喷雾为主，如稻田有薄水层也可加细土或化肥拌种撒施。防除稗草药后 15 d，校正防效为 90.4％；药后 28 d，校正防效为 92.2％，鲜重防效 91.5％。对异型莎草、水苋菜、陌上菜等一年生莎草科杂草和阔叶杂草有兼除效果，如加入苄嘧磺隆混用防效更加理想。拜田净对稻苗安全，保产效果显著。拜田净防除水直播稻田杂草试验@管丽琴$上海市嘉定区农业技术推广服务中心! 201800 …     

苏南苏中苏北地区3个杂草稻生物型萌发特性比较研究

为了搞清楚江苏地区杂草稻不同生物型在萌发特性上的差异,选择了苏南、苏中和苏北地区3个杂草稻生物型及2个常规栽培稻品种,采用种子生测法,进行了温度、水势、盐分、pH值和埋土深度对杂草稻与常规栽培稻种子萌发影响的研究。结果表明,在萌发适宜温度范围方面,JT-3、JD-4〉SY63〉GY-LZC〉WYJ7;不同水势条件下,JT-3、JD-4的萌发率〉GY-LZC的萌发率〉常规栽培稻的萌发率。JT-3、JD-4在每个盐浓度处理下的萌发率〉GY-LZC的萌发率;在pH值7~8范围之外,JT-3、JD-4的萌发率〉GY-LZC的萌发率〉常规栽培稻萌发率;当埋土深度在4~7 cm范围内,常规栽培稻的出苗率〉杂草稻。     

Susceptibility to imazamox in Italian weedy rice populations and Clearfield® rice varieties

The introduction of imidazolinone‐tolerant rice varieties has made selective Oryza sativa (weedy rice) control possible. We hypothesised that Italian weedy rice populations have variable degrees of susceptibility to imazamox prior to imidazolinone‐tolerant variety introduction. To this end, 149 Italian weedy rice populations collected from fields never before cultivated with imidazolinone‐tolerant varieties were tested in a glasshouse‐based, whole‐plant response screening study. Imazamox was applied to all populations post‐emergence at a rate of 70 g a.i. ha^?1, resulting in 70–90% shoot biomass reduction in the majority of cases. The results prompted a second study of the seedling dose response of four weedy rice populations from the initial study group. Three imidazolinone‐tolerant and one conventional rice variety were also included. The seedling roots were cut six days after germination and exposed to different concentrations of imazamox. The root regrowth associated with each concentration‐exposure was then measured. Imazamox concentrations to inhibit weedy rice root growth by 50% varied by about two orders of magnitude, or between 0.0018 and 0.12 mm . Even with this result, imidazolinone‐tolerant varieties were at least 31.8 times less susceptible than weedy rice populations, suggesting that Italian weedy rice populations were not tolerant to imazamox before introduction of these varieties.     

Inter‐ and intrapopulation variation in dormancy of Oryza sativa (weedy red rice) and allelic variation in dormancy‐linked loci

Oryza sativa (weedy red rice), the same species as cultivated rice, is a serious problem in rice production worldwide. Seed dormancy contributes to its persistence. We determined the effect of germination temperature and after‐ripening period on germination capacity (GC) of red rice seeds from Arkansas rice fields in three production zones. We also determined the gene diversity (GD) of dormancy‐linked loci among selected populations. The germination behaviour was evaluated at three temperatures (1°C, 15°C and 35°C) and four after‐ripening periods (0, 30, 60 and 90 days) in two independent experiments. Germination response to temperature and after‐ripening time differed among and within populations in each production zone. Overall, populations from the Delta and Grand Prairie were more dormant than those from White River. Regardless of ecotype or production zone, incubation at 35°C (mean GC = 84–100%) favoured the germination of seeds after‐ripened for 60 days. Germination of these seeds was most variable at suboptimal temperature (15°C), with mean GC ranging from 44 to 97%; at 1°C, none of the seeds germinated. Primary dormancy was released in the majority of populations after 90 days of after‐ripening. Blackhull populations generally had lower mean GC than strawhull populations, regardless of temperature, and required longer after‐ripening time to release dormancy. They also showed a higher inter‐ and intrapopulation variation in germination and after‐ripening than strawhulls and had the highest gene diversity (GD = 0.55–0.58) among test populations. Non‐dormant strawhulls were most distant (D = 0.63) from dormant blackhulls. Ecotype influenced genotypic clustering more than the dormancy trait.     

Chemical control of weedy rice in precise hill‐direct‐seeded rice in South China

Precise hill‐direct‐seeded rice, which is both cost‐ and labor‐saving, is based on the direct seeding of rice by using a precision rice hill‐drop drilling machine. Weedy rice (Oryza sativa f. spontanea), also known as “red rice”, is a major weed in precise hill‐direct‐seeded rice, causing an ≤80% yield loss and a reduction in grain quality. The aim of this study was to evaluate the control efficiency of weedy rice by pretilachlor (a pre‐emergence herbicide) and fenclorim (a safener) and their safety for precise hill‐direct‐seeded rice in two consecutive years. The amount of rice seed germination was accelerated by soaking the seeds in the safener at 0.67 g ai L^?1 for 1 h before sowing. The pre‐emergence pretilachlor treatments were applied 2 days after sowing cultured rice. The inhibition of the shoot fresh weight of the cultured rice was reduced by 3.3, 6.4 and 7.4% with 450, 900 and 1350 g ai ha^?1 of pretilachlor at 32 days after sowing (DAS) and that of the root fresh weight was reduced by 2.6, 4.9 and 8.1%, respectively. With fenclorim and pretilachlor in a precise hill‐direct‐seeded rice field in 2010 and 2011, the weedy rice control efficiency at 32 DAS was reduced by 100 and 98.0%, respectively. The pre‐emergence pretilachlor treatments that were applied at 2 DAS were much more efficient in the weedy rice control and less inhibitory to the cultured rice growth. The rice yield was increased by 26.1–26.7% in the mechanical precise hill‐direct‐seeded rice, relative to the manual‐seeding rice, with the application of fenclorim and pretilachlor.     

Gene flow from weedy red rice (Oryza sativa L.) to cultivated rice and fitness of hybrids

BACKGROUND: Gene transfer from weeds to crops could produce weedy individuals that might impact upon the evolutionary dynamics of weedy populations, the persistence of escaped genes in agroecosystems and approaches to weed management and containment of transgenic crops. The present aim was to quantify the gene flowrate from weedy red rice to cultivated rice, and evaluate the morphology, phenology and fecundity of resulting hybrids. Field experiments were conducted at Stuttgart and Rohwer, Arkansas, USA. Twelve red rice accessions and an imazethapyr‐resistant rice (Imi‐R; Clearfield^?) were used. RESULTS: Hybrids between Imi‐R rice × red rice were 138–150 cm tall and flowered 1–5 days later than the rice parent, regardless of the red rice parent. Hybrids produced 20–50% more seed than the rice parent, but had equivalent seed production to the majority of red rice parents. Seeds of all hybrids were red, pubescent and dehisced at maturity. For the majority of hybrids, seed germination was higher than that of the red rice parent. The gene flowrate from red rice to rice was 0.01–0.2% and differed by red rice biotype. The hybrids had higher fecundity and potential competitive ability than the rice parent, and in some cases also the red rice parent. CONCLUSIONS: Red rice plants are vectors of gene flow back to cultivated rice and other weedy populations. The progeny of red rice hybrids from cultivated rice mother plants have higher chances of persistence than those from red rice mother plants. Gene flow mitigation strategies should consider this scenario. Copyright © 2009 Society of Chemical Industry     

Weed suppression ability of upland rice under low-input conditions in West Africa

Weeds are a major constraint to upland rice production in west Africa. The objectives of this investigation were to study differences in weed suppression ability among upland rice cultivars and to determine the morphological traits involved. Twelve contrasting cultivars, including West African indigenous Oryza glaberrima (Steudel) lines and traditional and improved O. sativa L., were cultivated under natural weed competition and low-input conditions in Côte d'Ivoire in two seasons. Significant differences between cultivars were observed in weed biomass at 100 days after seeding (DAS) in 1994 and 1995, indicating differences in their competitive ability. Weed biomass was negatively correlated with rice root growth at early growth stages and with rice shoot and root growth at later growth stages. Across cultivars, grain yields with a single hand-weeding were 60% in 1994 and 49% in 1995 of those in plots that were weeded regularly. High grain yields in weedy plots were associated with low weed biomass. IG 10, an O. glaberrima cultivar, was the most competitive against weeds.     

杂草稻对粳稻生长及产量的影响

在同期播种情况下,和粳稻相比,杂草稻出苗时的叶片更肥长、营养生长期的植株更高、分蘖数多达4倍以上。不同生物型杂草稻的落粒性差异较大。杂草稻密度愈高对栽培粳稻的产量影响愈大。     

双环磺草酮·双唑草腈对杂草稻的生物活性及对水稻的安全性

为了明确10%双环磺草酮·双唑草腈GG对杂草稻的生物活性及对水稻的安全性,采用盆栽法测定了10%双环磺草酮·双唑草腈GG不同剂量对不同叶龄杂草稻的生物活性和对不同秧龄移栽水稻的安全性。结果表明,10%双环磺草酮·双唑草腈GG 1 500～4 500 g/hm~2对萌芽期至3叶期的杂草稻有很高的活性,且在4 500 g/hm~2剂量下对15～25 d秧龄的移栽水稻生长无不良影响。但该药药效显现速度较慢,一般在施药后3～4周达到最佳防效。杂草稻萌芽期对该药剂最敏感,随着杂草稻叶龄的增加使用剂量需相应提高。本着高效、经济、安全的原则,防除杂草稻的最佳时期应在其萌芽期至2叶期,推荐使用剂量杂草稻萌芽期为1 500～2 250 g/hm~2、杂草稻立针期至2叶期为2 250～3 000 g/hm~2。     

Aerial seed germination and morphological characteristics of juvenile seedlings in Commelina benghalensis L.

Seed germination, seedling emergence, and the morphological characteristics of juvenile seedlings of Commelina benghalensis L. were observed. For aerial seeds collected in September and October, seedling emergence peaked in April and June for large seeds and from June to August for small seeds, whereas seedling emergence for large seeds collected in November showed peaks in March and April under natural rainfall conditions, and in April and June under irrigation conditions. Seedlings from small seeds emerged intermittently over a longer period from April to August under both conditions. Aerial seeds of C. benghalensis germinated on wet filter paper on the second day after seeding (DAS) for large seeds and the fourth DAS for small seeds. The germination percentage for large seeds was higher than that for small seeds by the 14th DAS. The germination percentage for large aerial seeds showed no significant difference between light and dark conditions. However, the percentage for small aerial seeds was higher under light than under dark conditions. Seedlings from large aerial seeds emerged on the third DAS at 0–50 mm soil depths. The percentage of emergence at 0 and 1 mm soil depths increased until the 30th DAS, whereas those at soil depths of 5–50 mm showed no change after the 9th DAS. There was no emergence at a soil depth of 100 mm. Seedlings from small aerial seeds emerged on the 6th DAS at 0–1 mm soil depths, with the percentage increasing until the 30th DAS. Although seedlings at 5 and 10 mm soil depths also emerged on the 6th DAS, there was no change in the percentage after the 12th DAS. There was no emergence at soil depths of 20–100 mm. The hypocotyl and taenia (part of the cotyledon connected to the seed) in juvenile seedlings that emerged from soil depths of 50 mm were longer than those in seedlings emerging from a soil depth of 1 mm.     

中国北方杂草稻幼苗对干旱胁迫的生理响应

以杂草稻heb07-2、wr04-6及巴西陆稻IAPAR9为研究材料,采用人工气候箱培养幼苗,利用20%聚乙二醇6000（PEG-6000）模拟干旱条件,研究了杂草稻及巴西陆稻幼苗叶片和根系生理特性标的变化。结果表明：干旱胁迫下,杂草稻heb07-2幼苗的叶片与根系具有较高的超氧化物歧化酶（SOD）、过氧化氢酶（CAT）、抗坏血酸过氧化物酶（APX）活力;杂草稻heb07-2的可溶性糖含量、可溶性蛋白含量高于其它材料。杂草稻heb07-2细胞膜系统保持完整,膜质过氧化程度小于其它材料,表明干旱胁迫对杂草稻heb07-2伤害较小,具有较强苗期抗旱性。