旱直播稻抑草潜力的评价

利用旱直播稻自身的竞争及化感作用,评价旱直播稻品种（品系）对杂草的抑制作用。采用田间小区试验方法,评价旱直播稻对杂草的竞争能力和耐受能力。通过测定旱直播稻特征化感次生物质含量计算出的化感指数来评价其化感潜力;在旱直播稻播种后45 d,杂草生物量与旱直播稻的生物量成显著负相关、与相对竞争强度成显著的正相关。旱稻品系‘HF04’和‘HF011’对杂草的抑制作用最强,前者抑草能力强表现在竞争力,后者抑草能力强表现在耐受杂草竞争力和化感作用。     

Joint effects of biotic and abiotic stressors on winter wheat suppression of Bromus tectorum

In winter wheat systems in the Northern Great Plains of the United States, Bromus tectorum and wheat streak mosaic virus (WSMV) commonly co‐occur. While independent effects of these pests on wheat yields have been well documented, to our knowledge, no study has investigated whether WSMV modifies interactions between wheat and B. tectorum. Furthermore, the impact that environmental stressors such as nutrient availability have on these interactions has not been addressed. We conducted a randomised split‐plot field study over 2 years to investigate the effects of WSMV and nitrate (N) availability on winter wheat suppression of Bromus tectorum. The study included four N treatments (10–19, 20–31, 31–84, and 85–207 kg ha^?1) and two WSMV treatments (mechanically inoculated or control). Increasing soil N increased the susceptibility of wheat to WSMV infection. In 2009, wheat in the lowest and highest N levels had 24% and 65% of plants infected respectively. However, regression analysis indicated that interactive effects of wheat competition, N and WSMV did not play a consistent role in B. tectorum growth. Specifically, the effect of both wheat density and distance from row on B. tectorum biomass remained constant across inoculation treatments, suggesting that wheat inoculated with WSMV suppressed B. tectorum as effectively as healthy wheat. Furthermore, wheat had a greater impact on B. tectorum growth in higher N environments, even though incidence of WSMV infection in wheat was highest. Overall, our results suggest that WSMV infection may not change the ability of wheat to suppress B. tectorum.     

3种除草剂对水稻旱直播阔叶杂草防效及安全性研究

为明确不同除草剂茎叶处理对旱直播水稻田旱生阔叶杂草防除及安全性的影响,采用随机区组试验设计,选用30% 2,4-滴丁酸钠盐AS、84%氯酯磺草胺WG、480 g/L灭草松AS 3种除草剂在水稻4叶期、5叶期施用,施药后每间隔7 d测定杂草株防效、鲜重防效和水稻目测药害,同步测定水稻生长指标和抗逆酶活性。结果表明:30% 2,4-滴丁酸钠盐AS 900.0 g/hm2在水稻4叶期的杂草防效最佳,第28天杂草株防效及鲜重防效仍可达93.55%和96.42%,且对大龄鸭跖草防效显著,施药后水稻生长与人工除草相比无显著差异。叶片SOD、POD活性和MDA含量均先升后降,至施药后28 d恢复正常。30% 2,4-滴丁酸钠盐AS 900.0 g/hm2可高效防除阔叶杂草,该药剂在水稻4叶期和5叶期施用对旱直播水稻安全。     

The influence of nitrogen supply on the ability of wheat and potato to suppress Stellaria media growth and reproduction

Summary This paper tests the hypothesis that increased soil nitrogen supply reduces the growth of late-emerging weeds in wheat and potato by enhancing canopy leaf area development and thereby reducing the availability of light for weed growth. Two series of experiments were conducted: one in spring wheat (1997, 1999) with sown Stellaria media and one in potato (1998, 1999) with naturally emerged weeds, including S. media . For each crop, two cultivars were grown at three levels of nitrogen supply. In wheat, as in a monoculture of S. media , total dry weight and seed number of the weed increased with soil nitrogen supply, whereas in potato the opposite was found. Increased soil nitrogen supply increased the nitrogen uptake of S. media in wheat, despite the reduced light availability, indicating that S. media in wheat was limited by nitrogen. In potato, on the other hand, growth of S. media was limited by light availability, which decreased with increased soil nitrogen supply . We conclude that the differences in response of S. media in wheat and potato to additional nitrogen supply are attributable to the dual influence of soil nitrogen supply on light and nitrogen availability, which are mediated by the crops.     

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。     

Modelling the effect of crop and weed on herbicide efficacy in wheat

Recommended field application rates of herbicides have to give effective weed control in every situation and are, thus, often higher than that required for specific fields. An understanding of the interaction between crop:weed competition and herbicide dose may, in many cases, allow herbicide application rates to be reduced, important both environmentally and economically. We have developed a model of the interaction between crop:weed competition and herbicide dose, using an empirical model of the relationship between crop yield and weed biomass (related to weed density), and an empirical model of the relationship between weed biomass and herbicide dose. The combined model predicts crop yield, given herbicide dose and weed biomass at an interim assessment date. These crop yield loss predictions may be used to quantify the herbicide dose required to restrict yield loss to a given percentage. Parameters of the model were estimated and the model tested, using results from experiments, which used cultivated oats ( Avena sativa ) or oilseed rape ( Brassica napus ) as model weeds in a crop of winter wheat ( Triticum aestivum ).For the crop:weed:herbicide combinations investigated there was little increase in crop yield for herbicide dose rates above 20% of recommended field rates, in broad agreement with the model predictions. There may still be potential for further reduction below this level on economic grounds; the model could be used to estimate the `break-even' herbicide dose.     

Competition between weeds and wet season transplanted paddy rice for nitrogen use, growth and yield in the central and northern regions of Laos

To quantify the effect of weeds on the nitrogen (N) use, growth and yield of wet season paddy rice in the central and northern regions of Laos, we surveyed the paddy fields in these regions in October 1999 and November 2000. We found 13 weed species in total, but there were few major weeds abundant at the survey sites. In the infertile soils under rainfed conditions, weed growth was poor. Rough rice yield, the number of panicles, the number of seeds per square meter, the above-ground biomass of paddy rice and the amount of N accumulated in the above-ground biomass of paddy rice (amount of N in rice) were suppressed by competition with weeds. However, harvest index (HI) and nitrogen use efficiency (NUE) of paddy rice were not suppressed by competition with weeds. The amount of N in rice was suppressed by competition with weeds, the number of panicles decreased as the amount of N in rice decreased, and the number of seeds per square meter decreased as the number of panicles decreased. As a result, rough rice yield was suppressed by competition with weeds. The weeds competed with paddy rice for N uptake during the productive tillering stage. However, the ability of paddy rice to compete for N uptake with weeds was not reduced under rainfed lowland conditions. When the weeds were completely removed, the amount of N in rice increased. Rough rice yield may be increased by 10% under rainfed lowland conditions and by 17–19% under irrigated conditions.     

沟灌渗透对直播水稻干物质积累和产量的影响

采用田间对比试验、植株分析方法,研究了相同畦宽(200cm)、不同灌水量的沟灌渗透栽培和常规淹水栽培对直播水稻茎蘖生长及干物质积累的影响。结果表明:不同时期直播水稻茎蘖生长、干物质积累、冠层叶性状和产量在不同处理之间均存在一定的差异;其中,以处理1(节水38.6%的沟灌渗透)的茎蘖生长适宜,分蘖质量高,干物质积累量大,冠层叶叶绿素含量高,有效穗数、穗长、穗粒数、实粒数和千粒重显著高于常规淹水处理,增产达8.74%。     

Influence of soil moisture on the competitive ability and seed dormancy of Sinapis arvensis in spring wheat

Two experiments were carried out, one in 1995 and one in 1997, to investigate the competitive abilities of two spring wheat cultivars with Sinapis arvensis L. The spring wheat cultivars (Baldus and Canon) of contrasting growth habit were grown with and without S. arvensis under two different moisture regimes (10% and 70% of field capacity). In 1995, S. arvensis was found to be less competitive when subjected to moisture stress, resulting in smaller wheat yield losses in dry soil than in moist soil. In both years, seed production of S. arvensis was reduced by competition and moisture stress, and the seeds produced by plants that had been grown in drier soil were small and had negligible dormancy. Hence, in dry conditions, the competitiveness of S. arvensis and its potential to produce persistent seed may be reduced. Some differences between the two wheat cultivars were evident: cv. Baldus was more competitive against S. arvensis than cv. Canon. This could be attributed to differences in canopy structure.     

Effects of density and sowing pattern on weed suppression and grain yield in three varieties of maize under high weed pressure

We tested the hypothesis that improved weed suppression by maize can be achieved through increased crop density and spatial uniformity. Field experiments on three varieties of maize sown at three densities (5, 7 and 10.5 seeds m^?2) and in two spatial patterns (grid pattern and rows) under very high weed pressure from Brachiaria brizantha were performed in 2012 and 2013. We measured weed biomass 1 month after sowing and at harvest, and grain yield at harvest. Density, variety and sowing pattern all had strong and significant effects on both weed biomass and yield. On average, weed biomass was reduced (by 72% in the first year and 58% in the second year), and grain yield was increased (by 48% and 44%) at the highest density in the grid pattern compared with standard sowing practices (medium density, row pattern). There was a significant density × variety interaction, which is evidence for genetic differences in the response of the varieties to density in characteristics that influence weed suppression. The variety that suppressed weeds best at high density had the lowest variation in the angle of insertion of the oldest living leaf at harvest (leaf 6), supporting the hypothesis that reduced phenotypic plasticity may be advantageous for weed suppression under high density and spatial uniformity. Increased density and uniformity can contribute to weed management in maize in many cases, potentially reducing the need for herbicides or mechanical weed control.     

水分对旱稻土壤及植株中主要营养元素含量的影响

在防雨棚池栽条件下研究了不同水分处理下土壤矿质元素的释放及旱稻植株对矿质元素的吸收利用特点。结果表明：土壤水分对土壤N、P、K含量及植株养分吸收存在明显影响。随着土壤水分含量的提高,土壤硝态氪含量显著下降,氨态氪含量显著上升;磷素在低水分处理下先升高后基本保持较高水平,而在高水分处理下有一个升降升的变化过程;钾素在65％、100％水分处理下在分蘖中后期显著大于其它水分处理,而在分蘖前期各水分处理都有一个先降后升的变化趋势。在植株对矿质元素的吸收上,100％水分处理下植株体内的全氮含量一直呈下降趋势,65％、75％处理下磷素变化呈“U”型,其余各处理下植株体内的N、P、K含量都呈W型变化。随土壤含水量的增加,旱稻植株对N、P、K的吸收总量均增加。     

Changes in functional diversity and intraspecific trait variability of weeds in response to crop sequences and climate

How weed communities assemble represents one the key issues of weed science. For a decade, functional approaches have been applied to investigate the processes that govern weed community assembly. In most previous studies, trait values have been generally averaged over multiple populations and habitats. Consequently, conspecifics display similar trait values while neglecting the considerable influence of intraspecific variability to detect changes in functional diversity in response to environmental drivers. However, this influence has been shown to be critical, especially, at local scales. Here, we studied changes in weed functional diversity at the field scale in four crop sequences. We focused on intra‐ and interspecific variability of four key functional traits involved in response to resource acquisition processes, the latter being modified by climate, management and competition. The relative influence of intra‐ and interspecific variability among the crop sequence types was highlighted using a diversity partitioning approach. It provides evidence for substantial amount of intraspecific variability in the weed community and underlines its essential role in response to fine‐scale environmental drivers. In addition, we investigated the response of the three most abundant species to competition with the crop, the growing season and the crop sequence type. We highlighted that these species showed a wide range of combinations of trait values, suggesting the co‐existence of several successful strategies. Based on these results, we emphasise that neglecting intraspecific variability can lead to substantial underestimations of the functional weed response to management and crop‐weed competition at the field scale.     

控水灌溉对寒地水稻物质生产及灌浆动态和产量的影响

以垦鉴稻5号为材料,采用负压式土壤湿度计监测土壤水势,通过防雨棚内的盆栽控水试验,较系统地研究了水稻返青至成熟期-8～ -10 kPa的间歇控水灌溉对寒地水稻物质生产、灌浆动态和产量影响.主要结果如下:控水处理使供试品种的穴穗数减少1.54％;穗粒数增加了3.93％;优、中、劣势粒的结实率分别增加了3.53％、12.7...     

360g／L吡氟·氟噻·呋草酮悬浮剂对冬小麦田杂草的防除效果及对后茬作物的安全性

为明确360g／L吡氟·氟噻·呋草酮悬浮剂在小麦田的应用前景,采用田间小区试验方法,观察其对小麦田主要杂草的控制作用和对小麦及后茬作物玉米、大豆、花生的安全性。结果表明：360g／L吡氟·氟噻·呋草酮悬浮剂对小麦田主要杂草猪殃殃、蔺草、硬草、播娘蒿等一年生杂草均有好的防除效果,随用药量的增加防效逐渐提高;药后180d株防效和鲜重防效均在90％以上,优于异丙隆常规剂量处理,显著提高了小麦的产量;药后226d的土壤残留对后茬作物玉米、大豆、花生安全,对其苗期生长及产量无不良影响。     

嘧草醚对双季稻田杂草的防效及后茬作物的安全性影响

为明确嘧草醚及其相关除草剂混用对移栽田杂草的防效及其对水稻和后茬作物的安全性,于2018年在江西双季稻田进行了田间试验。结果表明:10%嘧草醚WP对稗Echinochloa crus-galli有优异的防除效果,有效剂量45～120 g/hm~2处理药后45 d对早稻和晚稻田稗草的防效均在90%以上,且对水稻和后茬作物油菜、白菜、紫云英、小麦和马铃薯生长安全,但对阔叶类鸭舌草和莎草类异型莎草的防效较差;10%嘧草醚WP分别与10%苄嘧磺隆WP和25 g/L五氟磺草胺OD混用,对早稻和晚稻田稗草、鸭舌草和异型莎草的防效均达91%以上,且对水稻生长安全;而与扑草净混用对杂草的防效略低,且对水稻会产生药害,严重影响产量。因此,对于以稗草为优势种群的水稻田,可选用10%嘧草醚WP 45～60 g/hm~2进行防治;对于禾本科杂草、阔叶杂草和莎草科杂草发生并重的水稻田,可选择10%嘧草醚WP 30～45 g/hm~2与10%苄嘧磺隆WP或25 g/L五氟磺草胺OD 20～30 g/hm~2混用进行治理。     

Cross-resistance pattern and alternative herbicides for Cyperus difformis resistant to sulfonylurea herbicides in Korea

A Cyperus difformis L accession from Chonnam province, Korea was tested for resistance to the sulfonylurea herbicide, imazosulfuron. The accession was confirmed to be resistant (R) and was cross-resistant to other sulfonylurea herbicides, bensulfuron-methyl, cyclosulfamuron and pyrazosulfuron-ethyl, the pyrimidinyl thiobenzoate herbicide, bispyribac-sodium, and the imidazolinone herbicide imazapyr, but not to imazaquin. Multiple resistance was tested using twelve herbicides with target sites other than acetolactate synthase (ALS). The R biotype could be controlled by other herbicides with different modes of action such as butachlor, carfentrazone-ethyl, clomeprop, dithiopyr, esprocarb, mefenacet, oxadiazon, pretilachlor, pyrazolate and thiobencarb, applied to soil at recommended rates. Several sulfonylurea herbicide-based mixtures can control both the R and S biotypes of C difformis, except sulfonylurea plus dimepiperate, molinate or pyriftalid, and pyrazolate plus butachlor. Although mixtures of sulfonylurea herbicides might be more effective, they should be avoided and used only in special cases. In terms of in vitro ALS activity, the R biotype was 1139-, 3583-, 1482-, 416-, 5- and 9-fold more resistant to bensulfuron-methyl, cyclosulfamuron, imazosulfuron, pyrazosulfuron-ethyl, bispyribac-sodium and imazapyr, respectively, than the S biotype. The in vivo ALS activity of the R biotype was also less affected by the sulfonylurea herbicides, imazosulfuron and pyrazosulfuron-ethyl, than the S biotype. Results of in vitro and in vivo ALS assays indicated that the resistance mechanism of C difformis to ALS inhibitor herbicides was primarily due to an alteration in the target enzyme, ALS. Greenhouse experiments showed delayed flowering and reduced seed production of the R biotype, which could possibly result in reduced fitness. This unusual observation needs to be confirmed in field situations.     

华北平原冬小麦麦田覆盖对土壤温度和生育进程的影响

通过秸秆和薄膜覆盖田间试验,研究了不同覆盖材料对冬小麦田土壤温度(5 cm)以及冬小麦生长发育、穗分化、干物质积累和分配、营养生长期间的N转移、产量和水分利用效率的影响.结果表明,秸秆覆盖平缓了冬小麦整个生育期土壤温度的变化,使冬季土壤温度提高0.63℃,越冬后降低0.35℃;春季降温效应延长了冬小麦穗分化的时间,平均缩短了灌浆持续时间2 d;低温增加了冬小麦穗期干物质和N含量向收获期非籽粒转移的效率,最终造成产量和水分利用效率降低了1.98%和0.14 kg/m3.薄膜覆盖提高了冬小麦灌浆前土壤温度0.44℃,增温效应促进了作物生长,整个生育期的生物量提高116.0 kg/m2;穗分化时期的增温效应使得该处理冬小麦不易形成大穗,同时灌浆期的低温效应影响了籽粒的饱满度,最终产量和水分利用效率分别降低了3.24%和0.17 kg/m3.研究认为,秸秆覆盖和薄膜覆盖具有保墒效应,但其产生的温度效应对冬季作物生长发育造成不利影响,使得最终产量和水分利用效率并没有提高.     

Weed species composition of maize fields in Germany is influenced by site and crop sequence

During the last decade, maize has become the crop with the second largest acreage in Germany. Therefore, agricultural advisors and the plant protection sector are interested in an overview of the weed species composition in maize fields, their determining factors and trends. From 2001 to 2009, a weed survey was conducted in 1460 maize fields throughout Germany. Data on crop management and soil characteristics were collected via farmer questionnaires. Principal component analysis and redundancy analysis were used to analyse patterns in weed species composition. The late spring and summer germinating species Chenopodium spp., Echinochloa crus‐galli and Solanum nigrum occurred with high densities and frequencies, but their occurrence was determined by different factors. Other frequent weed species were those that typically accompany autumn‐sown crops. The variation in species composition was significantly related to environmental factors (9.1% explained variance), particularly geographical latitude and precipitation, and management factors (4.7% explained variance), particularly crop sequence. The relative importance of these factors seems universal, when compared with surveys in other crops and regions. The factor ‘year’ was of minor importance (0.9% explained variance). Over the 9‐year period, no changes in weed species composition could be determined. The results suggest that despite the limited impact of crop management on weed species composition, farmers can use crop sequence to suppress individual species. The survey furthermore sets a baseline against which future changes can be measured in a landscape of rapidly changing agricultural land use.     

8%精噁唑甘草胺可分散油悬浮剂对直播水稻田禾本科杂草的防效及后茬作物的影响

为明确新型水直播稻田除草剂精噁唑甘草胺以及对照药剂对于直播稻田禾本科杂草的防除效果以及对于水稻及后茬作物的安全性, 于2019年在江西宜春市上高县水稻田进行了大田杂草防效试验以及后茬作物安全性研究。结果表明:8%精噁唑甘草胺OD对于直播水稻田的禾本科杂草具有良好的防除效果, 120 g/hm2 以及200 g/hm2 剂量处理对于禾本科杂草的防效均在88%以上。而且所有处理对于水稻均无药害产生, 实现增产, 并对后茬作物生长安全。综上所述, 新型直播稻田除草剂精噁唑甘草胺对直播水稻田禾本科杂草有良好防除效果, 可以在市场上推广应用。