12%烯草酮乳油防除油菜田禾本科杂草田间药效试验

田间试验结果表明,12%烯草酮乳油30～40mL/667m2能有效地防除油菜田一年生禾本科杂草。药后60d,对看麦娘、菵草的株防效仍可达91.4%～94.1%,鲜重防效91.8%～95.7%,安全性好,并且增产效果显著。     

40%决灭灵防除春小麦田杂草效果

田间小区试验结果表明，40％快灭灵干燥悬浮剂对春小麦田的藜、木氏蓼、卷茎蓼、香薷、鼬瓣花、苍耳等阔叶杂草有良好的防效效果，在小麦3－4叶期，阔叶杂草株高3－5cm时，用40％快灭灵干燥悬浮剂56．25－75．0g/hm^2进行茎叶喷雾，在此推荐剂量范围内除草效果好，对小麦安全，增产明显。     

潮汐对鸭绿江口湿地入侵种禾叶慈姑分布的影响

河口湿地的特殊环境使其容易成为入侵植物的桥头堡.近年来我们在鸭绿江口湿地发现了一种原产北美,为东亚地区首次记录的慈姑属水生植物Sagittaria graminea,依其种加词的含义,我们将其中文名定为"禾叶慈姑".调查表明,该外来种已有4个主要居群分布在鸭绿江河口湿地近30 Km的江岸边,最大的一个居群其斑块覆盖的总...     

潮汐对鸭绿江口湿地入侵种禾叶慈姑分布的影响

河口湿地的特殊环境使其容易成为入侵植物的桥头堡。近年来我们在鸭绿江口湿地发现了一种原产北美,为东亚地区首次记录的慈姑属水生植物Sagittaria graminea,依其种加词的含义,我们将其中文名定为＂禾叶慈姑＂。调查表明,该外来种已有4个主要居群分布在鸭绿江河口湿地近30 Km的江岸边,最大的一个居群其斑块覆盖的总面积已超过2 000 m2且具有强烈的排它性,显示出典型的入侵种特点。研究表明,对一定水位或潮汐性淹没的要求是该种生长在岸边低位湿地的主要原因,水体的盐度会限制其向近海河口湿地的分布。分析了该种可能的入侵途径及生态风险。     

狼尾草对噁草酮、二甲戊乐灵和异丙甲草胺的抗药性

狼尾草(Pennisetum alopecuroides)是新型的园林观赏植物,在我国具有广阔的发展前景。利用化学除草剂防除狼尾草生产与应用中的杂草问题,对减少生产与管理费用意义很大。采用盆栽方法研究了狼尾草对常用的苗前型除草剂的抗药性,以期找出适宜控制狼尾草杂草的安全除草剂与安全用量。结果表明,狼尾草喷施异丙甲草胺后叶片变为紫红色,产生严重药害,草酮在2700mL/hm2用量下或二甲戊乐灵在3500mL/hm2用量下狼尾草的生长仍安全。     

Quantifying the predatory effect of round goby on Saginaw Bay dreissenids

Invasive dreissenid mussels (D. polymorpha and D. r. bugensis) have fundamentally altered Laurentian Great Lake ecosystems, however in many areas their abundances have declined since the mid-1990s. Another invader, the benthic fish round goby (Neogobius melanostomus), is morphologically adapted to feed on dreissenids and likely affects dreissenid populations; however, the degree of this predatory effect is variable. In 2009 and 2010, we examined round goby abundances, size distributions, diet contents, and diet selectivity in Saginaw Bay, Lake Huron; a shallow bay that has been subjected to numerous anthropogenic stressors. We further used a consumption model to estimate dreissenid consumption by three different size classes of round goby. Round gobies were found throughout the bay and most were smaller than 80 mm total length. Round gobies of all sizes consumed dreissenids (including fish as small as 30 mm total length), though dreissenids were rarely preferred. The relative proportion of dreissenids (by biomass) present in diets of round gobies increased with fish size, but also throughout the year for all size classes. Despite this, overall consumptive effects of round gobies on dreissenids in Saginaw Bay were low. Many dreissenids present in the bay were larger than those consumed by round gobies. Bioenergetics-based model estimates suggest that the smallest round gobies are responsible for the majority of dreissenid consumption. While our findings are limited to soft substrates and influenced by sampling restrictions, our study design allowed us to put bounds on our estimates based upon these multiple sources of uncertainty.     

合蜂群杂草算法及其在灌溉制度优化中的应用

首先针对杂草算法容易早熟收敛的问题,将人工蜂群算法的寻优机制引入其中,提出了一种混合蜂群杂草算法。该算法对杂草种群中的每个个体利用采蜜蜂搜索方式进行变异,对群体最优个体利用跟随蜂搜索方式进行变异,用较优的变异结果替代原有个体,提高了算法的收敛精度。然后,通过对几个标准测试函数进行实验,验证了改进算法的优化性能。最后,将该算法应用到灌溉制度优化问题中,为制定灌溉水量分配方案提供了一种新的工具。     

Effects of fertilizer and weeding in no-tillage and tilled maize

Field trials were carried out on Apomu soil (Psammentic usthorthent) and Egbeda soil (Oxic paleustalf) in southern Nigeria to investigate the effects of fertilizer and weeding on growth and yield of maize (Zea mays L.) under no-tillage and tilled land preparations.On the newly cleared Apomu soil, broadleaved weeds comprised the major portion of the weed flora, with the shrubs being more important under no-tillage. More grasses and sedges were present when the soil was tilled. Regardless of tillage method, there was a 38% yield reduction due to weeds in the unfertilized plots, with yield in tilled plots being almost double that in no-tillage plots. Effect of weed competition in maize can be partially overcome by fertilization as yield reductions due to weeds were 19% in the fertilized plots. Weeding was shown to be necessary even with a first crop following bush clearing especially when the soil fertility was low.On both soil types maize yield responded to fertilizer application. Yield of no-tillage maize was less than that of tilled maize with no or low rates of N application, but with adequate N fertilization yield from no-tillage maize equalled that of tilled maize. Lower yield of no-tillage maize may in part be attributed to severe N stress during early growth. Consequently on low fertility soil, no-tillage maize production is not recommended without adequate N fertilization.     

35％丁苄可湿性粉剂防除水稻秧田和直播田杂草

３５％丁苄可湿性粉剂１９９４～１９９５年防除水稻秧田和直播田杂草的试验。结果表明：秧田在播种后１０天使用丁苄（商品量）１．５、１．８、２．２５千克／公顷，对稗草的防效为８９．７～９３．７％，总杂草防效９６．８～９９．２％。直播稻田在播种后５天使用丁苄１．８、２．２５千克／公颂，对稗草的防效９２．９～９４．１％，总杂草防效９７．８～９９．０％。丁苄对水稻安全。与１０％苄嘧黄隆可湿性粉剂和５０％丁草胺乳油相比，可扩大杀草谱。     

Evaluation of Putative Allelochemicals in Rice Root Exudates for Their Role in the Suppression of Arrowhead Root Growth

In previous studies, 15 putative allelopathic compounds detected in rice root exudates were quantified by GC/MS/MS. In this study, multiple regression analysis on these compounds determined that five selected phenolics, namely caffeic, p-hydroxybenzoic, vanillic, syringic, and p-coumaric acids, from rice exudates were best correlated with the observed allelopathic effect on arrowhead (Sagittaria montevidensis) root growth. Despite this positive association, determination of the phenolic acid dose-response curve established that the amount quantified in the exudates was much lower than the required threshold concentration for arrowhead inhibition. A similar dose-response curve resulted from a combination of all 15 quantified compounds. Significant differences between the amounts of trans-ferulic acid, abietic acid, and an indole also existed between allelopathic and non-allelopathic rice cultivars. The potential roles of these three compounds in rice allelopathy were examined by chemoassay. Overall, neither the addition of trans-ferulic acid nor 5-hydroxyindole-3-acetic acid to the phenolic mix significantly contributed to phytotoxicity, although at higher concentrations, trans-ferulic acid appeared to act antagonistically to the phytotoxic effects of the phenolic mix. The addition of abietic acid also decreased the inhibitory effect of the phenolic mix. These studies indicate that the compounds quantified are not directly responsible for the observed allelopathic response. It is possible that the amount of phenolic acids may be indirectly related to the chemicals finally responsible for the observed allelopathic effect.